GG

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Managing water use in specialitychemicals’ manufacture: a signposting guide

This Good Practice Guide was produced by

Envirowise

Prepared with assistance from:

Enviros

Managing water use in specialitychemicals’ manufacture: a signposting guide

Foreword

It goes without saying that all speciality chemical companies should value watermanagement very highly for both environmental as well as cost saving reasons. Did you know that the combined water and effluent costs for speciality chemicalcompanies are between 1.5% - 4% of production costs? Did you know that manycompanies have already reduced their water consumption by between 5% and 50% byadopting the practices set out in this Guide? Perhaps your company has the potentialfor this kind of saving.

This excellent new Guide from Envirowise is designed for companies like yours to improve theirwater management performance by adopting a systematic approach to reducing the costs ofwater purchase, and operational use including effluent disposal. In this way, companies canrealise bottom-line benefits from reduced operating costs, compliance with legislation andregulation, improved product quality and productivity, and good environmental impactmanagement.

The Guide contains plenty of practical advice and examples to reinforce the possibilities and Icommend it to your attention.

Tony ScottDirectorSpecialised Organic Chemicals Sector Association

Summary

Water is used during many stages of the manufacture of speciality chemicals. Water is arelatively cheap commodity, but most of the water used becomes effluent. Combinedwater and effluent costs are between 1.5% and 4% of production costs in mostspeciality chemical companies. However, water supply and trade effluent charges areonly the tip of the iceberg. Hidden costs include on-site water treatment, water heatingand distribution, and effluent treatment, in addition to the value of materials andproduct lost to effluent.

Adopting a systematic approach to water management can help speciality chemical companies to:

■ reduce operating costs;

■ comply with stricter environmental legislation and standards;

■ improve productivity and product quality;

■ improve working conditions;

■ improve their public image.

This Good Practice Guide is intended to help speciality chemical companies save money byreducing their water and effluent costs. The Guide:

■ describes a systematic approach to minimising water use and effluent generation;

■ presents benchmark data on specific water consumption and effluent strength in theindustry;

■ provides practical advice on how to reduce water and effluent costs;

■ gives industry examples illustrating the cost and other benefits of taking action toreduce water use;

■ contains checklists and a cost savings worksheet for companies to use at their sites tohelp them identify cost-effective opportunities to reduce water and effluent costs;

■ signposts to further, more detailed information in other Envirowise publications andfrom other authoritative sources such as the Environment Agency.

Many speciality chemical companies have already implemented measures that have reduced theirwater consumption by between 5% and 50%. Could your company do the same?

Section Page

1 Introduction 11.1 Water and effluent costs 21.2 Benefits of reducing water use and effluent generation 21.3 Water use in the chemical industry 41.4 How to use this Guide 7

2 Taking a systematic approach 92.1 Step 1: Win support and carry out an initial review 92.2 Step 2: Appoint a champion and establish a team 102.3 Step 3: Gather information 102.4 Step 4: Analyse the data and investigate potential problems 132.5 Step 5: Consider improvement options 152.6 Step 6: Produce an action plan 162.7 Step 7: Implement the action plan 172.8 Step 8: Review progress 17

3 Employee training, motivation and accountability 18

4 Water monitoring and supply 194.1 Measuring water and effluent 194.2 Using alternative water supplies 20

5 Maintenance and related issues 21

6 General cleaning and domestic use 236.1 Cleaning practices 236.2 Cleaning devices 236.3 Domestic uses 25

7 Materials management 277.1 Materials delivery, storage and distribution 277.2 Drainage and pollution prevention 28

8 Vessel washing 298.1 Procedural issues 298.2 Equipment issues 30

9 Equipment cooling and vacuum pumps 32

10 Effluent treatment and re-use 3510.1 Types of effluent treatment 3510.2 Improving effluent treatment 3510.3 Effluent/wash water re-use 3710.4 Sludge management 37

11 Further information 3911.1 Help from Envirowise 3911.2 Other sources 40

Appendix Checklists 41

Contents

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Introduction

This Good Practice Guide is intended to help speciality chemical companies save moneyby managing their use of water more effectively. The Guide:

■ presents benchmark data on water use and COD1 levels to allow companies to compare theirperformance with that achieved by others;

■ describes a systematic approach to reducing water and effluent costs;

■ provides practical advice on how to reduce water and effluent costs;

■ gives industry examples illustrating the cost and other benefits of taking action to reducewater use;

■ contains checklists and a cost savings worksheet for companies to use at their sites.

The Guide is aimed at companies of all sizes and all sub-sectors producing products such as:

■ detergents;

■ surfactants;

■ paints;

■ inks;

■ dyes and pigments;

■ cosmetics;

■ agri-chemicals;

■ pharmaceutical intermediates;

■ water/effluent treatment chemicals;

■ surface finishing chemicals;

■ polymers;

■ resins;

■ photographic chemicals.

The Guide is intended to be used by managers looking for practical ways to reduce waste andhence costs. The Guide will help companies seeking to comply with the waste/waterminimisation requirements of Integrated Pollution Prevention and Control (IPPC). It complementsthe chemical industry’s Responsible Care programme and environmental reporting initiatives, andgoes hand-in-hand with quality management systems (eg the ISO 9000 series) andenvironmental management systems such as ISO 14001 and EMAS2.

Being part of a waste minimisation initiative can save companies over £100 000/year. There aremany waste minimisation schemes and clubs all over the country which can provide further help.For information on these and any aspect of waste minimisation, contact the Environment andEnergy Helpline on freephone 0800 585794.

1 Chemical oxygen demand - used in determining effluent charges.2 Eco-Management and Audit Scheme.

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1.1 Water and effluent costs

Water is used during many stages of the manufacture of speciality chemicals. Water is a relativelycheap commodity, typically costing 50 - 90 pence/m3 (2000/2001 prices). However, most of thewater used becomes effluent.

Effluent treatment costs are typically £3 - £5/m3, while sludge disposal costs can be over£20/tonne. In addition, there are the trade effluent charges, which can be as low as 40 - 50 pence/m3 but are often much more. For example, typical charges for an effluent with aCOD content of 5 000 mg/litre and a suspended solids content of 1 000 mg/litre are £2.50/m3

(2000/2001 prices). Results from the survey reported in Water use in the manufacture ofspeciality chemicals (EG105)3 suggested that combined water and effluent costs are between1.5% and 4% of production costs in most speciality chemical companies.

However, these supply and discharge costs are only the tip of the iceberg. Valuable materials andproduct are often lost to effluent. For example, a loss of just 1% of product to effluent by acompany producing 40 000 tonnes/year of product worth £1 000/tonne equates to a loss of£400 000/year. Research carried out by Envirowise suggests that sites lose material to effluentworth around £250 000/year on average and around £600 000/year maximum. This is all lostprofit as manufacturing costs have already been incurred.

The true costs of water use are discussed in more detail in Water use in the manufacture ofspeciality chemicals (EG105).

1.2 Benefits of reducing water use and effluentgeneration

The many benefits of taking action to reduce water use and the amount/concentration ofeffluent generated include:

■ reduced operating costs, eg materials, water, disposal, and thus increased profits;

■ improved productivity, eg due to quicker vessel washing practices;

■ less wasted labour and energy associated with making product that is lost and treating effluent;

■ higher product quality due to better process control, better cleaning practices, etc;

■ easier compliance with consent conditions and environmental standards;

■ reduced health, safety and environmental risks leading to lower insurance premiums;

■ improved employee working conditions leading to potentially less absenteeism and betterstaff retention;

■ enhanced image/reputation with customers, helping you stay as an approved supplier, eg staying on approved supplier lists;

■ better image with the local community leading to easier recruitment, less opposition toplanning applications, etc;

■ improved environmental performance.

There are clear and strong commercial reasons to take water and effluent minimisation andmanagement seriously - as many of the industry examples in this Guide show, it is simply goodbusiness practice.

Table 1 shows the water and cost savings associated with a range of measures introduced bycompanies. The individual measures are not mutually exclusive and most companies haveimplemented between three and seven. Details of these measures are given in sections 4 - 10.

3 Published by the Environmental Technology Best Practice Programme (now Envirowise) in 1997. Available freeof charge through the Environment and Energy Helpline on freephone 0800 585794 or via the Envirowisewebsite (www.envirowise.gov.uk).

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* As reported in Water use in the manufacture of speciality chemicals (Envirowise publicationEG105).

Measures introduced Reduction in Net costwater use (%) saving (£)

Procedural/good housekeeping measures

Metering individual product areas and setting 30 96 000reduction targets

Production scheduling, improvements in plant 50 24 000wash-downs and the use of triggered hoses

Improved pipework to reduce leaks 10 6 000

Good housekeeping, trigger hoses, etc 8 3 400

Better housekeeping to avoid cleaning 3 1 000

Storm water prevented from entering effluent system 7 3 000

Leak detection and reduction 30 70 000

Flow restrictors on vessel cooling lines 5 5 000

Plant and process modifications

Cooling water re-use 21 8 400

Installation of improved cooling towers 50 30 000

Re-use of wash-water for batch dilution 25 29 000

Installation of high pressure washers for cleaning 5 1 000blending tanks

Recirculation of water in liquid ring vacuum pumps 50 19 000

Replacement of water seal vacuum pumps with 24 6 300dry versions

Installation of air chillers 5 3 000

Replacement of laboratory sample coolers with 31 8 500refrigerators

Table 1 Water saving measures and reported savings (1996 costs)*

Clariant UK Ltd is a speciality chemicals company producing chemicals, dyestuffs andpigments. A water savings project implemented during the 1990s led to significantvolume and cost reductions. The project is on-going and continues to be extended.It has involved water minimisation measures and the use of treated borehole waterinstead of mains water.

Between 1990 and 1999, water consumption fell by over 1 000 m3/day and water useper tonne of product by over 80%. Estimated net savings are £440/day, whichequates to overall net cost savings of around £150 000/year.

Key measures included:

■ reducing site water distribution pressures;

■ installing a borehole water treatment plant to produce water to potablestandards (referred to as factory water);

■ substituting factory water for mains water for boiler feed, toilets, vessel cleaning,laboratory equipment cooling and general cleaning;

Water savings programme at Clariant UK Ltd

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1.3 Water use in the chemical industry

The data in this section are taken from the Chemical Industries Association (CIA) Indicators ofPerformance (IoP) survey 2000. Speciality chemical companies are spread across four of the sub-sector categories used by the survey. These benchmark data can be used to compare yourperformance with that of your competitors.

While the data presented here are based on a relatively small sample, the ERA 2000 tool availableon the Envirowise website (www.envirowise.gov.uk) provides a growing set of benchmark data,and allows you to characterise and analyse your own water and effluent data.

Figs 2 and 3 show the average and maximum values for companies in the four categories. Whileyour aim is to achieve the average or below, you need to bear in mind that a particular aspector aspects of your products and processes may make your company different to the majority ofspeciality chemical companies in your category.

1.3.1 Water sources

Fig 1 shows that most companies rely predominantly on mains water, although many useborehole, river and canal abstraction. This generally reduces costs, but may not reduce thecompany’s impact on the environment.

■ using collected rainwater for effluent tank cleaning;

■ modifying and extending the water cooling plant system to reduce waterconsumption;

■ recovering and recycling water from mechanical seals and packed gland coolingsystems;

■ installing isolator valves linked to a building management system (BMS);

■ improving the condensate return system to reduce boiler water make-uprequirements;

■ installing visual flow indicators in condenser cooling return lines to ‘remind’operators to shut them down when not in use;

■ installing tap restrictors in washrooms, etc.

Factory water treatment plant at Clariant UK Ltd

Water savings programme at Clariant UK Ltd (continued)

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*Source: CIA Indicators of Performance survey 2000.

1.3.2 Specific water consumption

Specific water consumption (m3/tonne of product) in the chemical industry varies widely due todifferences in processes, products and plant operations. These variations also reflect differinglevels of efficiency in water management and the extent to which water saving measures havebeen implemented.

Fig 2 shows the range and average for respondents in the CIA survey. In general, unless yourcompany’s processes by their nature are very water intensive, you should have the scope to makereductions if you have average or above average water consumption.

*Derived from CIA Indicators of Performance survey 2000.

100

90

80

70

60

50

40

30

20

10

0Mains River Borehole Canal Other

Tota

l wat

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%)

Water source

Inorganic chemicalsOrganic chemicalsPharmaceutical chemicalsOther chemicals

Fig 1 Water sources used by chemical companies*

15840

1137351

0 100 200 300 400 500

0 20001000 3000 50004000 6000 7000 8000

Inorganicchemicals

Organicchemicals

Pharmaceuticalchemicals

Otherchemicals

m3 of water/tonne of product

m3 of water/tonne of product

MaximumAverage

Fig 2 Specific water consumption of CIA survey respondents*

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The survey conducted for Water use in the manufacture of speciality chemicals (EG105) reportedvalues for 20 speciality chemicals sites. Of these sites, 80% used less than 10 m3/tonne of product,over 60% used less than 5 m3/tonne and almost 40% used less than 2 m3/tonne of product.Details of the product types associated with the different levels of specific water consumption aregiven in Table 1 of EG105. This shows that low rates of water use are often associated withproducts requiring little water as an ingredient, or for cooling or steam production.

Example savingsFrom Fig 2, an ‘average’ company producing organic chemicals has a specific water consumptionof 40 m3/tonne of product. If the company produces 20 000 tonnes/year, it will use 800 000 m3

of water in a year. The company has combined water and effluent treatment/discharge costs of£2.50/m3. A 20% reduction in water use will, therefore, reduce water consumption by 160 000 m3/year and operating costs by around £400 000/year.

1.3.3 Effluent COD

Effluent comes from various sources including:

■ surface run-off;

■ vessel washing and other equipment cleaning;

■ cooling (including blowdown/purge);

■ liquid ring vacuum pumps.

The CIA survey found that COD levels in discharged effluent also vary significantly, againreflecting the wide range of products and processes. Fig 3 shows this range in terms of kg/tonneof product and not as a concentration.

*Source: CIA Indicators of Performance survey 2000.

Water use in the manufacture of speciality chemicals (EG105) reports on effluent discharge ratesfor speciality chemical companies (see its Fig 11 and Table 2). Companies with high levels ofwater use tend to have high effluent discharge rates and thus pay twice for not managing theirwater more efficiently. As described later in this Guide, simple and low-cost measures can betaken to reduce both the volume and concentration of effluent.

20

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0 100 200 300 400 500 600 700

0 20001000 3000 50004000 6000 7000

Inorganicchemicals

Organicchemicals

Pharmaceuticalchemicals

Otherchemicals

kg COD/tonne of product

kg COD/tonne of product

MaximumAverage

Fig 3 Effluent discharge rates reported by CIA survey respondents*

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1.4 How to use this Guide

This Guide provides practical advice to help you reduce water and effluent costs, and signpostsyou to further information available in publications from Envirowise and other organisations.

Section 2 of this Guide describes a systematic approach to minimising water use and effluentgeneration - an approach that has already been used successfully by many companies, both inthe speciality chemicals sector and in other industries.

The importance of involving all employees in your water minimisation programme is stressed insection 3, which deals with training and motivation.

Sections 4 - 10 describe key issues and good practice designed to reduce water use and effluentgeneration. These sections cover:

■ water monitoring and supply;

■ maintenance and related issues;

■ general cleaning and domestic use;

■ materials management;

■ vessel washing;

■ equipment cooling and vacuum pumps;

■ effluent treatment and re-use.

1.4.1 Checklists

Checklists for these different areas of water management are provided in the back pocket of theGuide. A list is given in the appendix, which also contains notes on how to use them.

The checklists are intended to help you identify and prioritise opportunities to increase yourprofits by reducing water, effluent and material costs. The back pocket also contains a costsavings spreadsheet to help you calculate the cost-effectiveness of different measures to reducewater use.

1.4.2 Help from Envirowise

Free publications containing a wealth of practical advice are signposted throughout the Guideand are listed in section 11. All Envirowise publications can be obtained free of charge throughthe Environment and Energy Helpline on freephone 0800 585794 or via the Envirowise website(www.envirowise.gov.uk).

The Effluent Online Club (EOC) on the Envirowise website (www.envirowise.gov.uk/effluentonlineclub) provides:

■ information on best practice, including water minimisation and re-use;

■ news items including new technology, events, etc;

■ a discussion forum.

A benchmarking tool for the sector called Eco-efficient Resource Assessment (ERA 2000) is alsoavailable on the Envirowise website (go to the chemical industry page to download the softwarefree of charge). ERA 2000 is an interactive spreadsheet developed with support from the CIA. Itenables chemical companies to measure their environmental performance routinely across arange of performance indicators.

✓

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Akcros Chemicals, part of Akzo Nobel, is a manufacturer of plastics and processingadditives based in north-west England. Membership of the Environet 2000 wasteminimisation project encouraged the company to prepare a water mass balance (seesection 2.3.3) and implement a variety of cost-effective improvements.

■ Leakage. A number of underground water leaks were identified and repaired.

■ Vacuum systems. Water is now recirculated on vacuum systems in the acrylatesplant, rather than once-through use, and steam ejectors have been replaced withdry vacuum pumps in other areas.

■ Steam condensate recovery. Improved monitoring using energy managementsoftware led to refined steam trap management. This allowed increasedcondensate return and reduced the use of make-up water.

■ Better practices. Management and operators are more aware of the true cost ofwater and how to minimise its use through good practice.

Switching to the dry vacuum pumps has reduced water use by 7 200 m3/year alone.Overall water use has been reduced by 40% since 1997, with estimated savings ofover £10 000/year. In most cases, the payback period was less than a year.

Water savings at Akcros Chemicals

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Taking a systematic approach

The best way to make things happen is to take a systematic approach (see Fig 4) thataims for continual improvement. Your water minimisation programme can be either aseparate initiative or part of a wider programme to reduce waste and improve yourcompany’s environmental performance, eg through the implementation of anenvironmental management system (EMS).

2.1 Step 1: Win support and carry out an initialreview

The first step is to convince senior management, eg the production director or managing director,that the company would benefit from a systematic approach to reducing water use and effluentgeneration. This may be difficult without some supporting evidence gained in an initial review.

■ Walk around the site to identify areas where water is wasted and opportunities for saving orre-using water. Use the checklists in the back pocket of this Guide to help you.

■ Estimate the savings associated with a few of the more promising measures. Use the costsavings worksheet in the back pocket to help you to demonstrate the potential cost savings.

■ Use the industry examples in this Guide and Envirowise case studies to help you make your case.

■ Present the potential savings to senior managers to gain their full support for further work.

Step 1:Win support and carryout an initial review

Step 2:Appoint a championand establish a team

Step 3:Gather information

Step 4:Analyse the data andinvestigate potential

problemsStep 5:

Consider improvementoptions

Step 6:Produce anaction plan

Step 7:Implement the

action plan

Step 8:Review progress

Fig 4 Systematic approach to water minimisation

Further information

■ Profiting from reducing water use: running a workshop to stimulate action (GG229) -includes a slide presentation on water uses and why saving water is important.

■ Reduce your water use and collect the savings (EN339) - gives examples of thesavings that can be achieved and explains how to reduce water and effluent costs.

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2.2 Step 2: Appoint a champion and establish ateam

It is useful to have one overall project co-ordinator or champion to lead and facilitate the work.The champion should preferably be someone with:

■ sufficient authority to make things happen or direct access to someone with that authority;

■ a good understanding of how the company operates in all areas and, preferably, personalcontacts in these areas;

■ an ability to listen to the views of others and make objective decisions;

■ enthusiasm and a belief in waste minimisation.

The champion is likely to have to fit in the new responsibilities alongside existing ones, and it isimportant that time is set aside to allow this.

In most companies, the responsibilities for using water and the impact of waste are spread overa number of departments. It is, therefore, essential to establish a team that includes:

■ environmental, health and safety staff;

■ manufacturing/production managers;

■ shop-floor staff.

Not all of these people will need to be involved at all stages of the process, but they should beidentified at the start and called upon as necessary. In some cases, it may be necessary toestablish more than one team, eg where there is more than one site or division.

2.3 Step 3: Gather information

Understanding where water is used and why effluent is generated is essential to allow improvementsto be targeted carefully. In simple terms, if you don’t measure it, you can’t manage it!

2.3.1 Site meter readings

Overall site use of mains water can be determined by looking at your meter readings. Even wherewater is abstracted from a borehole, canal or watercourse, you should still monitor volumes to:

■ ensure you do not exceed your abstraction consent;

■ allow accurate analysis of water use.

The discharge to sewer from the effluent plant should also be monitored using an appropriatemeter (see section 4.1). Be wary of water company bills as they may be inaccurate - particularlyin relation to effluent volumes, which are often based on estimates (eg taking some account ofevaporation and water in product), historical data and spot readings.

Further information

■ Saving money through waste minimisation: teams and champions (GG27) -explains how to choose a champion and use teams to organise a wasteminimisation programme.

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2.3.2 Process measurements

While site-level data can be helpful, water use and effluent generation should be monitored inrelation to key processes and particular products. This allows you to identify and deal with thecauses of waste and makes departments more accountable. Simple meters can be installed forjust a few hundred pounds each. A portable non-invasive meter can be used to help conduct anaudit of water use.

In addition to metering, water auditing can be carried out by estimating individual flows.

■ In some cases, approximate values for pump flow rates will be known. If not, estimates canbe made for low-pressure flows using a ‘bucket and stop watch’, ie by disconnecting pipesor opening valves to allow a container of known volume to fill up.

■ The flow rate can be estimated by recording the rate of change of levels in tanks.

■ A total value for water consumption can be derived by recording the number of hours thatthe supply is in use - perhaps over a couple of days.

■ Evaporative losses can be estimated, eg by comparison with similar processes where steam iscondensed and recovered.

2.3.3 Mass balance

Water that comes into a process must leave in one way or another, ie inputs must equal outputsin what is known as a ‘mass balance’ (see Fig 5).

Knowing some of the information allows certain ‘unknowns’ (typically leaks and evaporativelosses) to be estimated. The use and movement of various aqueous materials around the site,evaporation from the product at various stages etc, can make this approach quite complicated

Further information

■ Cost-effective water saving devices and practices (GG67) - describes how tomeasure water use and flow, and how to estimate pumping, energy andtreatment costs.

Evaporation

Leaks toground

Effluent

Product

Waterin

Fig 5 Mass balance concept

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when dealing with the site overall. However, a mass balance can be very useful in certaincircumstances and for certain ‘contained’ areas (see the example below).

When recording data, either for the site as a whole or for parts of it, it is important to stick toregular intervals of time. If possible, it is best to record data every four weeks and to produceannual summaries covering 13 periods. This makes period-to-period comparisons easier thanwith calendar months.

Mass balance exampleA fictitious company has a production area with:

■ a daily flow of cooling water (Ia);

■ water used in vessel washing (Ib);

■ one hose which is used for occasional cleaning (Ic).

A water audit of the area suggested that on average: Ia + Ib + Ic = 21 m3/day.

Once it has been used, all of this water goes to drain and then directly to the effluent treatmentplant where the average daily flow is measured at 12 m3/day. Evaporation is thought to bearound 10% overall, say 2 m3/day.

Therefore, only 14 m3/day (12 + 2) of the input water can be accounted for. This simple massbalance suggests that there is a loss of 7 m3/day. It, therefore, appears that 33% of the inputwater is being lost, probably due to a leak from a drain or perhaps through seepage from thefloor into the ground or across to other areas.

Further information

■ Tracking water use to cut costs (GG152) - takes you through the process ofconstructing a water balance for your site.

Akcros Chemicals (part of Akzo Nobel) conducted a thorough water mass balance togain a better understanding of water use and waste at its site. The water balanceinvolved measuring the following key parameters:

■ Water inputs to the site:

- Mains water (from the main meter).

- Borehole water (on-site borehole and meter).

- Rainfall from a rain gauge. Effluent flow is measured as it discharges fromsite. Rainfall volumes are subtracted from the discharged volumes to give theprocess effluent reading.

■ Water outputs from the site:

- Water in products (from sales records).

- Effluent (from meter readings).

- Evaporation rates (estimated).

While this overall water mass balance proved useful, Akcros wanted more information.Water use was, therefore, broken down by plant by using the 20 water meters on-site.The need for further breakdowns to individual items of equipment was then assessed.Areas for improvement were identified and priorities for action agreed.

Akcros Chemicals targets improvements with a water balance

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2.4 Step 4: Analyse the data and investigatepotential problems

Examine and analyse the data you have gathered on water use and effluent generation with aview to improving efficiency and saving money.

Start by relating the data to production throughput during the period used for data collection.Recording water use and effluent generation per tonne of product (see section 1.3) is best as iteliminates variations caused by changes in production.

2.4.1 Taking account of product changes

Care is needed when the product/process varies significantly as water use will also changeaccordingly. The range of products may even out over a year, but over shorter periods you mayhave to take account of the types of product produced and the processes used. The examplebelow from Robinson Brothers demonstrates a practical approach to this problem.

2.4.2 Making comparisons

When analysing the key stages of the production process, it can be useful to look at changes inwater use on a month-by-month basis and to compare a process with another similar one, egmaking similar products on similar plant.

Robinson Brothers Limited makes a wide variety of batch speciality organic chemicals(mainly rubber chemicals and pharmaceutical intermediates) at its plant in WestBromwich in the West Midlands. As part of its certification to ISO 14001, thecompany has focused on substituting hazardous materials, increasing material yield(ie reducing waste) and reducing energy and water use.

To track reduction in water consumption accurately, the company sought to establisha clear and ‘specific’ measure that took production output into account. However,the product mix was varied and ever changing. As a result, a simple ‘water use perproduct tonne’ merely reflected the nature of the products and particular processesrather than how efficiently water was being used. A similar problem wasencountered with other measures such as energy consumption (in relation to theClimate Change Levy) and waste generation.

A universal scoring system was, therefore, devised based on three key factors:

■ Batch time, eg 2 hours = 1; 24 hours = 5; over 48 hours = 10.

■ Reactor utilisation, eg 1 000 kg of product/m3 = 1; 100 kg/m3 = 5; 10 kg/m3 = 10.

■ Any process stage which involves an energy-intensive piece of equipment, iereactor, centrifuge, mill or oven/drier, counts as one, including any step involvingheating or cooling.

For example, process A has a batch time of 2 hours, yields 1 tonne of product froma 1 m3 reactor and involves only the reactor step at 20°C without further processing.It, therefore, scores 1 + 1 + 1 = 3. Process B has a batch time of 50 hours, yields 10kg/m3 of reactor space and requires a reaction step at 20°C and one at 5°C before theproduct is centrifuged, dried and milled. This process scores 10 + 10 + 5 = 25. Overthis period, Robinsons counts this as 25 + 3 = 28 ‘process tonnes’ of production.Water use, energy use and material yield are related to this figure. For example, if56 m3 of water had been used during the same period, the specific waterconsumption is 2 m3 per ‘process tonne’. By taking account of production in this way,the company has been able to track the efficiency of water use effectively.

Monitoring specific water consumption at Robinson Brothers

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■ Is water use per tonne of product falling with time?

■ Is there potential for further improvement?

■ How does water use per tonne compare from one production area to another? Should theybe similar (eg same process/equipment)? Is the variation normal or is there a problem?

■ Can you identify the good practices that result in reduced waste?

One of the best ways of considering this type of question is to use graphs. Fig 6 shows how wateruse per tonne of product changes over 13 four-week periods for two similar production areas.

In this case, plant 1 has a significantly higher specific water consumption than plant 2 - thedifference perhaps being caused by a leaking water pipe or different cleaning procedures. Thevariation in use is also far greater on plant 1 than plant 2, indicating that the process is less wellcontrolled, although this improves as the year goes by. Another point worthy of note is that plant1 uses a particularly large quantity of water in periods 2 and 6 - perhaps due to a problem thatwas dealt with at the time. The graphs demonstrate the need to investigate the causes of boththe higher overall water consumption and the significant variations. If the problems can beidentified and rectified, plant 1’s specific water consumption could be brought to around thesame levels as those for plant 2.

2.4.3 Identifying causes and effects

A systematic investigation will help to establish the real issues and problems. Useful tools at thisstage include:

■ brainstorming sessions;

■ use of cause and effect or ‘fishbone’ diagrams (see Fig 7).

Cause and effect diagrams help to set out the possibilities and record the suggestions made atthe brainstorming session. Often, most of the ‘effect’ is caused by only a handful of causes.

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Period

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Fig 6 Water use analysis for two similar production areas

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2.4.4 Involve everyone

Make sure you involve all relevant staff in these investigations so as to cover all possibilities andimprove motivation and ownership of the problem. It is particularly important to include theshop-floor staff as they are often in the best position to help with constructive comments andsuggestions.

Problems that do not appear to relate to any obvious causes or which have proved difficult tosolve in the past may be the result of a complex mixture of causes. Such problems may requirea more detailed investigation using additional information and statistical methods.

2.4.5 Value each ‘effect’

Once the causes of the various problems have been investigated, convert each major ‘effect’ (iewater waste) into a financial value. As a minimum, consider:

■ the material costs (water, lost product);

■ disposal costs (effluent discharge and sludge/filter cake disposal);

■ productivity costs (ie downtime).

This type of cost data is useful in setting priorities and provides useful ‘ammunition’ whenpersuading senior managers to implement improvements.

2.5 Step 5: Consider improvement options

Having established the areas with a problem and the probable cause(s), the next stage is toidentify and evaluate possible improvement options.

StaffProcess

equipmentCleaning

equipment

Procedure Processcontrol

Design ofprocess area

Effect (effluent)

Causes

Fig 7 Example cause and effect diagram

Further information

■ Saving money through waste minimisation: raw material use (GG25) - outlines arange of tools and techniques for identifying opportunities to reduce waste.

Further information

■ Preventing waste in production: practical methods for process control (GG224) -describes a method known as statistical process control (SPC), which allows amore detailed analysis.

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■ Follow the waste hierarchy. This will achieve the greatest cost and environmental benefits.

– Eliminate - remove the need to use water entirely, eg by replacing a liquid ring pumpwith a dry vacuum system.

– Reduce - tackle the root cause of water and material waste by optimising the process,ie get it right first time with minimum losses.

– Re-use - the next priority is to re-use water and effluent (eg for cooling and cleaning),with or without processing to purify water and recover materials.

– Dispose - effluent discharge to sewer and sludge disposal must be considered as a lastresort. However, even then, steps can be taken to reduce volumes and costs.

■ Use the cost savings worksheet provided in the back pocket of this Guide to record the costsand potential savings from possible water-saving measures.

■ Involve all team members to ensure that all opportunities are considered.

■ Hold brainstorming sessions to draw out key improvement measures.

■ Implement a staff suggestion scheme linked to some sort of reward to help generateimprovement ideas.

■ Don’t be put off by people who insist “That’s the way we’ve always done it” or “We triedthat and it didn’t work”. Technology and costs change - so what was not possible oruneconomic a few years ago may well be viable now.

■ Consider each improvement option in terms of:

– Its cost to the company.

– Its likely benefit (ie the potential saving identified in step 4).

– The level of difficulty that may be faced in implementing it. This is linked to the timeand effort that will need to be expended.

■ Use all the potential costs and savings to calculate the payback period. This will help you toprioritise opportunities for improvement.

Payback period (months) = Capital cost x 12Annual savings

■ Implement no-cost and low-cost measures first to obtain quick savings. This will help tomotivate everyone concerned and give them confidence to tackle the more difficult and,perhaps, more costly measures.

■ If necessary, carry out trials to ensure that suggested changes are feasible.

2.6 Step 6: Produce an action plan

Having considered the various options, prepare an action plan setting out:

■ the various problem areas;

■ the proposed priority improvement measures (together with information about costs andbenefits);

■ ambitious, but achievable targets and timescales.

Further information

■ Investing to increase profits and reduce wastes (GG82) - explains how to assessthe financial benefits of improvement options and the use of investmentappraisal techniques.

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In some cases, you may want to use ‘best’ performance from the past as a reference for targets.It is important that targets relate to parameters that are being measured so that progress can beassessed. Typical targets might include, for example:

■ to reduce overall site water use to below 2 m3/tonne of product;

■ to increase effluent re-use by 50%.

Ask as many people as possible for their comments on the practicality of the plan and thepotential barriers to it. This will help to give them ownership of the project.

It is also important to make everyone aware of the potential benefits of the measures (improvedprofitability, better job security, etc). This can be achieved through presentations, newsletters andnotice-boards. It is also worth considering incentive schemes.

Obtain comments on your draft action plan from senior management and then seek theirapproval for the final modified plan. Without full management commitment, implementationwill be difficult, if not impossible.

2.7 Step 7: Implement the action plan

Implementing the action plan involves detailed teamwork. However, the previous steps shouldmake it easier and more productive. Again, it is important to involve everyone in implementingthe plan from senior managers down to those on the shop floor.

To maintain interest and motivation, it is vital to keep people informed of the measures beingtaken and the progress being made through newsletters, notice-boards, team briefings, etc.

2.8 Step 8: Review progress

Review progress against targets regularly - perhaps first on a six-monthly basis and later on ayearly basis. It may also be helpful to review:

■ the effectiveness of process monitoring and data gathering;

■ how successful the team(s) have been, eg the composition of the team(s) may need tochange as the work progresses.

To maintain momentum and continual improvement, go back to the checklists in the back pocketof this Guide and consider whether you could now implement more cost-saving measures.

Use Checklist 1 to help you implement a systematic water minimisation programme.

Further information

■ Workforce partnerships to reduce waste and save energy (ET228) - explains howto form partnerships with colleagues to introduce effective waste minimisationinitiatives.

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Employee training, motivation andaccountability

Staff at all levels can play an important role in reducing water consumption and effluentgeneration.

■ Train process operators and supervisors in:

– the correct use of machinery;

– procedures;

– the correct handling of materials;

– the early identification of problems.

■ Emphasise the cost of wasted water and the impact that improvements can have on profits(and hence salaries), job security and working conditions.

■ Provide and display written procedures to ensure that everyone knows exactly what isexpected of them.

■ Use separate water meters for different process stages/departments to make staff moreaccountable and hence more likely to take inefficient use of water seriously.

■ Include operators and supervisors in improvement projects. They are often aware of particularissues and the practicality of possible improvement measures.

■ Consider setting up a suggestion and/or incentive scheme related to improvements - not leastto make people feel more involved and motivated.

■ Provide feedback on progress through team briefings, newsletters, notice-boards, etc.

Use Checklist 1 to help you identify and prioritise improvement opportunities at your site relatingto training and awareness.

Further information

■ Profiting from reducing water use: running a workshop to stimulate action(GG229) - contains all you need to run a workshop on water management andincludes a slide presentation, speakers’ notes, exercises and delegate handouts.

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Water monitoring and supply

4.1 Measuring water and effluent

Monitoring water consumption and effluent volumes is essential to control and reduce costs. Itcan also help to detect leaks and thus achieve significant benefits for a minimal cost.

■ Where possible, fit sub-meters to monitor consumption for each department/productionarea.

■ Check water use during ‘silent’ periods such as overnight and during shutdowns. If it is notclose to zero, find out why. There may be a leak or plant left running unnecessarily.

■ Measure flows (instantaneous and cumulative) using simple mechanical meters or moreexpensive (but more accurate and non-invasive) electromagnetic and ultrasound meters. Thelatter are also low maintenance as there is no build-up of deposits and no wear. Ultrasoundmeters can be ‘portable’ (strap-on) and thus useful during water audits.

■ Monitor effluent streams in pipelines using meters (some work better than others with dirtywater) and in channels (eg from the effluent treatment plant before discharge to sewer) usingsimple weirs.

■ Where possible, use electronic devices that can send flow rate or cumulative flow (logged)information to a control panel or computer.

■ Use other methods to fill data gaps, eg flow rates can be estimated using ‘bucket and stopwatch’ techniques or observing the rate of change of water level in a tank.

Use Checklist 2 to help you identify and prioritise improvement opportunities at your site relatingto monitoring.

A company in Worcestershire realised that its water consumption had been risingsteadily over the last few years and at a much faster rate than production.Investigations revealed a large leak. Once the leak was fixed, water consumption fellby around 50%. The company believes it is saving around 25 000 m3/year, wortharound £18 500/year.

Metering identifies leaks

Further information

■ Cost-effective water saving devices and practices (GG67) - gives details ofcommonly used flow measurement techniques.

■ Tracking water use to cut costs (GG152) - explains how to calculate water flowsfor cooling towers/steam relief valves.

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4.2 Using alternative water supplies

Most companies use high quality, treated mains water for all purposes including cleaning. Whilehigh quality water is required for certain process applications, lower quality water can be usedfor certain types of cleaning and for certain other applications, eg in wet air pollution controlequipment and toilets.

■ Consider capturing and using rainwater for cleaning, toilet flushing, etc.

■ Where possible, use borehole and other abstracted waters (eg from a canal or river) forcleaning, boiler feed water, etc. Little or no treatment may be necessary to achieve theappropriate water quality, so costs will normally be lower than those for mains water.

■ Meter alternative supplies to ensure compliance with your abstraction licence and to monitoruse. Be careful that people don’t use more water than necessary just because it is cheaperthan mains water.

■ Consider conditioning and softening water using a physical method (eg magnetic treatment)rather than ion exchange. This eliminates the brine waste produced during regeneration ofthe ion exchange resin.

■ Where possible, use wash waters, cooling water and condensate for lower grade cleaning,eg first/second rinse. Analyse the level of contamination (eg using a total dissolvedsolids/conductivity probe) and identify appropriate uses.

■ Consider simple local treatment, eg settlement or filtration, to allow re-use.

■ Ensure that the availability of low-cost supplies does not increase overall waste - particularlywhen mains water is a significant element of the supply - and effluent generation. Rememberthat discharge costs are generally higher than supply costs and are increasing.

Use Checklist 2 to help you identify and prioritise improvement opportunities at your site relatingto the use of lower grade water supplies.

Further information

■ Cost-effective water saving devices and practices (GG67) - suggests a range of cost-effective devices and practices to reduce water consumption at industrial sites.

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Maintenance and related issues

Leaks are a significant cause of wasted water. Most leaks can be avoided with regularand appropriate maintenance.

■ Locate pipes and tanks above ground to allow easier maintenance and detection of leaks.

■ Pay particular attention to potential leaks from pumps, valves, joints, tanks (eg where a ballvalve is not operating properly) and from corroded areas of pipes and tanks.

■ Set up a scheduled maintenance programme involving pro-active (rather than just reactive)maintenance combined with resetting and recalibration of process equipment, eg flowcontrol valves, metering devices on mixing vessels and thermostats on cooling equipment.

■ Reduce the water supply pressure to reduce flow rates and the possibility of leaks (highpressure seeks out weaknesses).

■ Consider peristaltic pumps (hose pumps) for abrasive/corrosive applications. In these pumps,a cam acts on the outside of a pipe and hence the material does not come into direct contactwith the mechanical parts of the pump. This reduces pump wear and the risk of leaks, airentrainment and contamination. Such pumps can achieve flow rates of 80 m3/hour andpressures up to 16 bar. While they typically cost at least twice as much as conventional(centrifugal and diaphragm) pumps, they need less maintenance and use far less energy.

■ Fit electronic leak detectors to allow the supply to be shut down when a leak is detected.

■ If gate valves used to control flow rates are also used for isolation purposes, avoid thepotential for them to be reset incorrectly by fitting a separate ‘quarter turn’ isolation valve inthe supply line and removing the handle/hand wheel from the gate valve.

■ Fit tamper prevention devices such as locks and straps to regulator valves. When fitted tosafety critical valves, straps must be easy to break or cut in the event of an emergency.

■ Where the flow rate is higher than required, fit a flow restrictor (check) valve on the watersupply to limit the maximum flow, eg to 10 litres/minute. These valves generally cost only tensof pounds but can reduce water use from the supply by 25%. When used on several supplypipes, flow restrictors even out the flow and ensure an adequate supply from each.

The cost of small-scale leakage

Drops breaking to a streamLoss = 30 m3/yearCost = over £30/year

Leaking valve (0.2 litre/minute)Loss = 100 m3/yearCost = over £100/year

A weeping joint, dripping tap or valve can cost a lot more over a year than you mightimagine given that you will be paying for both the water and the effluent.

A trickle can equate to 50 - 100 m3/year. With just 20 minor leaks averaging 0.1 litre/minute each, a site would lose over 1 000 m3/year. This loss would cost thecompany at least £1 100/year in water and effluent discharge costs alone.

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■ Shut off the water supply automatically when it is not needed by fitting solenoid valves inpipelines etc, and interlocking them to equipment such as pumps, lights, passive infrared (PIR)occupancy sensors and building management systems.

Use Checklist 3 to help you identify and prioritise improvement opportunities at your site relatingto maintenance.

One of the main sites operated by Avecia, a speciality chemicals company, is atGrangemouth in Scotland. The company’s continuous improvement culture allowedone of the major plants on site to reduce water consumption by over 30% during2001. This reduction equated to a cost saving of £62 500/year.

The company adopted a structured approach involving a detailed analysis of wateruse within the plant. Opportunities for improvements were identified andprioritised, with cost benefit calculations being performed where necessary.Worthwhile measures were then implemented. The project has mainly involvedsimple no-cost and low-cost measures including:

■ switching off equipment when not needed;

■ repairing defective overflow devices;

■ providing ‘triggered’ water hoses (rather than ‘tap’ valves that can be leftrunning);

■ recirculating hot water, which was previously sent to drain, to heat vessels;

■ optimising scrubber operations.

Most of the improvements have been implemented at minimum cost using existingresources. For example, the in-plant engineering team designed and installed thehot water recirculation system by modifying redundant pipework from anotherplant. The plant now has a comprehensive water monitoring system to measure theeffect of changes and efforts are continuing to look for further reductionopportunities, eg in terms of clean-downs.

No-cost and low-cost water savings at Avecia, Grangemouth

Further information

■ Cost-effective water saving devices and practices (GG67) - describes a range ofdevices and practices to reduce water consumption at industrial sites and givesmore information about the costs of water losses from open taps and leakingvalves, joints, pipes, pump seals and hoses.

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General cleaning and domestic use

6.1 Cleaning practices

Shop-floor cleanliness is crucial for high product quality. Floors and equipment, therefore, needto be washed or vacuumed regularly. However, cleaning uses large quantities of water andsignificant reductions can be made by improving cleaning practices and equipment. Manymeasures are low-cost and have a quick payback.

■ Clean ‘as you go’. Cleaning is less intensive and less water is required if residues, spillages,etc are cleaned before they dry and stick.

■ Mechanical methods. When cleaning off sticky and viscous materials, use mechanicalmethods such as scrapers, shovels and brushes before hosing down with water.

■ Cleaning water quality. Match the quality to the application, ie use slightly contaminatedwater to wash floors and moderately contaminated water to wash very contaminated areas.

■ Water use ‘hierarchy’. Use clean water only for the final rinse or for almost cleanequipment. The wash water can then be re-used for earlier rinses or dirtier equipment. Fig 8 illustrates how you can increase water re-use by cascading water from the cleanest to‘dirtier’ uses.

6.2 Cleaning devices

■ Spillage kits, squeegees and brushes. Use spillage kits and squeegees to soak upspillages, and brushes to sweep spillages down drains. All are preferable to hosing spillagesto drain in terms of water use.

■ Pressurised spraying. This is generally more water efficient than merely ‘filling and swilling’or boil-outs. High-pressure cleaning systems are usually the best option when dealing withsticky and viscous materials. They are generally much quicker and use less water overall.

When using high-pressure systems, ensure that the pressure is optimum (ie not so high as toincrease overall water use) and that the nozzle/spray ball provides the optimum jet/fan ofwater (ie covering the ‘target area’ only) for the optimum period of time.

Cleanwater

Process 1Fairly clean

Process 2Slightly dirty

Process 3Quite dirty

Process 4Very dirty

Drain

Fig 8 Cascading of cleaning water

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■ Pumps. Choose one that gives the appropriate flow rate. Flow rate is proportional to thesquare root of pressure, so doubling the pressure only increases flow rate by around 41%.

■ Trigger guns/nozzles. Triggers attached to hoses are a low-cost way of ensuring water isnot wasted when it is not required.

A regular 2.5 cm mains pressure hose that is left running constantly typically loses 2 - 6 m3/hour of water. If a site has 20 hoses each discharging at 3 m3/hour and these areleft running unnecessarily for an average of only one hour/day, the total loss would be 60 m3/day. Over a year, the loss would be over 15 000 m3 of water at a cost of at least£16 500/year in direct water supply and effluent charges alone.

■ Portable scrubber driers. These devices use a high-pressure water jet/scrubber disk to washthe floor. They then suck up and recirculate the water via a water tank. This uses less waterand time than general hosing down. Units typically cost around £3 000.

■ Portable high-pressure jetting units. Portable units, including a pump set (electric orpetrol/diesel) and jet lance, can spray at up to 130 bar and cost around £500.

■ Cleaning-in-place (CIP). Process plant can use automated or semi-automated CIP systems,which usually involve a permanent, in-situ high-pressure sprayball or nozzle. The CIP systemtakes the equipment through a wash cycle (eg involving set times, pressures, temperaturesand/or additives) and optimises cleaning. The final rinse water is generally re-used forsubsequent first rinses. Cleaning chemicals are also re-used. Check that the cleaningprogramme is appropriate to the application and does not ‘over clean’.

■ Pigging. Pushing a ‘pig’ (an engineered plug) through pipelines to clean them reduces wateruse and recovers usable raw materials and product. Effluent volumes are also reduced. Thepig (typically a rubber bung) is propelled through the pipe by compressed air, pushing residualmaterial out at the other end before a final rinse with water. Such systems involve a simplepig launcher and catcher, and the appropriate valve gear. They can cost less than £10 000and often pay for themselves within a few weeks or months depending on the value of therecovered material.

AH Marks in Bradford makes a variety of batch products mainly for the agriculturalsector. The company has implemented a wide range of water minimisation measuresand has gained certification to ISO 14001.

One of the simpler water-saving measures involved hoses. Until 1998, all operatorsused hoses to wash down their work areas and any spillages. Water audits suggestedthat hose clean-down accounted for 5 - 10% of total effluent volumes. The regularhoses used 94 litres/minute (5.6 m3/hour) in a wide, low-pressure jet.

The company realised that trigger spray guns would use far less water whileproducing a finer, more directional and higher velocity jet. Trials with two spray gunsshowed that they cleaned more effectively while using only 20 litres/minute (1.2 m3/hour), a 79% saving over the conventional hoses. Faster cleaning andautomatic shut-off through the trigger resulted in even more savings.

Following the successful trials, 50 new trigger spray guns were bought at a total costof £2 800 (£56/gun). At a water supply cost of 68 pence/m3, the cost of using thespray guns was £0.82/hour compared with £3.81/hour with the conventional hoses,ie a saving of £2.99/hour of use. This gave a payback period of around 19 hours ofuse. This calculation ignores the savings from the reduced effluent, which wouldreduce the payback period even further. Water costs have since dropped, but thepayback is still only one day.

Trigger spray guns reduce clean-down costs at AH Marks

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Use Checklist 4 to help you identify and prioritise improvement opportunities at your site relatingto general cleaning.

6.3 Domestic uses

While ‘domestic’ uses at speciality chemical companies are relatively small compared with mainprocess uses, they are not negligible (see Table 2) and the potential reduction with water-savingdevices can be significant. For example, sites can typically achieve a 40% reduction in water useby installing water-efficient toilets, showers and taps.

Various low-cost devices can be installed to reduce domestic use. These include:

■ fitting tap controls:

– spray tap heads;

– single lever mixer taps;

– self-closing percussion (push top) taps;

– passive infrared (PIR) sensors to detect hands and, hence, switch taps on and off (via asolenoid valve);

■ fitting flow restrictors in pipes, taps and shower heads to limit the maximum flow rate;

■ specifying small washbasins to eliminate excessive bowl filling;

Further information

■ Cost-effective water saving devices and practices (GG67) - describes a range ofwater-saving devices and practices for general cleaning.

■ Cost-effective vessel washing (GG120) - describes technical improvement optionsincluding high-pressure wash systems and CIP.

■ Batch chemical manufacturer saves with CIP (CS273) - describes the cost andenvironmental benefits of installing a CIP system at Ciba Specialty Chemicals.

■ Pigging cuts costs, recovers product and reduces effluent (GC261) - describes thecost and environmental benefits of using line pigging at Nelsons of Aintree (apreserves manufacturer).

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Item Average water use

Toilets 7.5 - 9 litres/flush

Sinks 3 - 6 litres/event

Showers 30 - 60 litres/event

Baths 50 - 170 litres/event

Dishwasher 20 - 40 litres/event

Hose 8 - 10 litres/minute

Laundry (washing machine) 60 - 100 litres/event

Vehicle washing 50 - 100 litres/vehicle (bucket)400 - 900 litres/vehicle (hose)

Employee (full-time, no canteen) 25 - 50 litres/day/person

Employee (full-time, with canteen) 40 - 90 litres/day/person

Table 2 Typical rates of domestic water use

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■ reducing water use for WC flushing:

– delayed action inlet valves on cisterns (which stay closed while the syphon valve isopen);

– low volume flush cisterns (maximum 6 litres and dual flush);

– cistern volume adjusters (cistern bags that reduce the volume used for each flush);

■ reducing water use for urinal flushing:

– flush control devices, eg PIR sensors to detect occupancy;

– individual urinal push flushes or infrared flush controls on the urinal itself (where onlyused by a few people);

– waterless urinals (these use chemicals to maintain hygiene - see industry example below).

Water-saving practices include:

■ Locate hot water tanks/boilers close to the main areas where hot water is used. This reducesrun off of cold water in the supply pipe.

■ Ensure showers have heads that give a high velocity but a low flow. ‘Power showers’ use farmore water than conventional mixer showers or electric showers.

■ Ensure that taps and showers are not left dripping by replacing washers as necessary.

■ Use on-site water-recirculating vehicle wash systems if the size of the fleet warrants it.Alternatively, use a combination of hand soaping/waxing and high-pressure ‘jet-spraying’rather than low-pressure hosing which can take longer and use more water.

Use Checklist 4 to help you identify and prioritise improvement opportunities at your site relatingto domestic water use.

The domestic urinals at one company in the Midlands previously used around 318 m3/month of water (around 3 500 m3/year) at a cost of some £4 200/year. Newwaterless urinals have been installed which use a small quantity of spray cleaner,applied occasionally, and ‘bio-sticks’ (dropped in the urinal U-bend). These cost£2.90/week and £7.70/week, respectively - a total of around £500/year. The netsavings are, therefore, around £3 700/year.

Benefiting from waterless urinals

Further information

■ Cost-effective water saving devices and practices (GG67) - describes a range ofsimple measures to reduce the amount of water used in toilets, sinks, showers,gardening and garages.

■ Conserving water in buildings - 11 fact cards produced by the EnvironmentAgency on the different types of water-efficiency technology available in Englandand Wales. Available from the Environment Agency’s Water DemandManagement Centre (Tel: 01903 832073) or the website (www.environment-agency.gov.uk/savewater).

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Materials management

Materials handling and storage practices have a major impact on the risk of spillagesand the consequent use of clean-up water and generation of effluent. Proper drainagearrangements are also essential to minimise the risk of polluting groundwater and localwatercourses.

7.1 Materials delivery, storage and distribution

■ Ensure areas where materials are delivered and where vehicle refuelling and washing takeplace are either bunded or connected to the foul sewer (with interceptors installed ifnecessary).

■ Arrange for materials to be delivered in bulk straight into tanks or in returnable containers,eg intermediate bulk containers (IBCs) or drums. This reduces the need for container washingand hence water use and effluent generation. It also reduces packaging waste.

■ Make more tank space available by switching slow-moving materials from bulk delivery todelivery in IBCs, drums and bags and by having deliveries made ‘just-in-time’.

■ Ask your supplier to use plastic bag inserts in drums and rigid IBCs for containing high valuematerials. The bag can be wrung out to reduce material residues and the need for washing.

■ Empty containers of viscous materials in a warm environment to reduce residues. Drum andIBC ‘warmers’ can be used if necessary.

■ Stack IBCs and containers on pallets singly or no more than two high or on proper rackingsystems to reduce the risk of spillage. Keep the containers clear of marked fork-lift routes andwalkways.

■ Fit storage tanks and vessels with overflow warning and prevention devices.

■ Store tanks, IBCs and drums above ground and within bunds:

– with 110% of the capacity of the largest container or 25% of the combined capacity(whichever is the larger);

– with an impervious floor and impervious walls with no drain points (to contain anyspills);

– with walls that are sufficiently high or far enough away from the vessel to stop liquids‘jetting’ over them;

– pumped free of rainwater (to maintain the bund’s capacity).

■ Pump dry and liquid materials (pneumatically/hydraulically) via piped systems tomixing/reaction vessels. This reduces the risk of material spillage and loss.

■ If piping is not possible or practical, use large containers such as IBCs rather than numeroussmaller containers for distribution. This reduces residue losses and the need to cleancontainers.

Use Checklist 5 to help you identify and prioritise improvement opportunities at your site relatingto materials delivery, storage and distribution.

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7.2 Drainage and pollution prevention

To prevent pollution incidents, it is essential to know where your drains go and have proper andpractised procedures for dealing with emergencies.

■ Draw up a drain plan that shows which drains go to the effluent treatment plant or foulsewer and which go to other outlets such as streams, rivers and canals.

■ Colour-code the drains on the plan and the drain covers on site, eg use red for foulsewer/effluent treatment plant connections and blue for surface water drains. Make sure thatstaff are aware of the difference.

■ Ensure that only surface water (rainwater) run-off and other uncontaminated water entersurface water drains.

■ If you cannot establish the destination of a drain, block off this drain to eliminate the risk ofpolluting local watercourses.

■ Develop contingency plans to cover any serious spillages.

■ Provide spillage kits at appropriate locations around the site to mop up any large spills.

■ Ensure you have the means to isolate surface water drains. The simplest and cheapest optionis to have drain covers/bungs available for use during certain procedures or in the event ofan accident. Alternatively, install extra valves to allow flows to be diverted into emergencyholding tanks.

Use Checklist 5 to help you identify and prioritise improvement opportunities at your site relatingto drainage and pollution prevention.

Further information

■ Pollution Prevention Guidance Notes (PPGs). The Environment Agency offers aseries of leaflets dealing with the prevention of pollution to watercourses andgroundwater from different operations and activities. These leaflets can be eitherdownloaded from the business area of the Environment Agency website(www.environment-agency.gov.uk) or obtained as printed copies from theAgency’s general enquiry line on 0845 933 3111.

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Vessel washing

Vessel washing is a major area of water consumption in the speciality chemicals sector.Washing procedures and techniques that are not optimal (eg fill-and-flush and boil-out)often increase production costs and reduce productivity. Many speciality chemicalcompanies have made significant improvements in vessel washing leading to costsavings of 25 - 95%. This section provides hints and tips on the key aspects of vesselwashing to target to minimise water and effluent costs.

8.1 Procedural issues

■ Batch formulation. Review the impact of batch formulation on water use for vessel cleaningand, if possible, alter procedures to reduce water use.

■ Instruction cards. Develop vessel washing instruction/procedure cards to inform staff of themost effective washing methods. Include details of manual inspections, wash times, rinsevolumes, effluent sampling and difficult areas.

■ Mixing outside the vessel. Mixing base products and adding specific ingredients outsidethe vessel may reduce the need for vessel washing.

■ Equipment dedication. Where possible, dedicate mixing vessels, pipe runs, etc to specificproducts so that less cleaning is required.

■ Compatible products. Some products may be compatible and, thus, not require a ‘clean’vessel. Using the same base chemicals for products increases compatibility.

■ Production scheduling. Plan the sequence of production batches so that compatibleproducts follow each other, thus minimising the washing needed between them. If necessary,extend product storage time slightly. Release tank space by storing small volume, slowerturnover product in IBCs or drums.

■ Vessel washing matrix. Using one wash procedure irrespective of the batch sequence isgenerally inefficient. Identify the levels of cleanliness required between different products anddevise the optimum washing requirements between product batches. You may find that nowashing is required or that wash liquor can be re-used. Present this information in a matrix(see Fig 9) for operators to refer to.

Precedingproduct

A

A B

Subsequent product

C

B

C

No washingrequired.

Two rinses withcleaning fluid.Flush with productA base solvent.

No washingrequired.

No washingrequired.

No washingrequired.

No washingrequired.

One rinse withcleaning fluid.Flush with productC base solvent.

Two rinses withcleaning fluid.Flush with productC base solvent.

No washingrequired.

Fig 9 Example vessel washing matrix

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■ Selection of solvent/cleaning agent. Use different solvents/cleaning agents for differentstages in the vessel wash where this allows reduced overall use and does not compromisewash liquor re-use.

■ Wash liquor re-use in product. Wash liquor can be re-used directly in subsequentcompatible product batches where dilution is required (see the industry example below).

■ Material recovery. Where wash liquors cannot be re-used directly, use membrane systemsto recover high value materials/product from effluent. Segregate these effluent streams - ifnecessary, installing extra drains/pipework, valves and tanks.

■ Wash liquor re-use for cleaning. Store and re-use wash liquor for cleaning vessels ofcompatible batches until it becomes too heavily contaminated.

■ Inspection and monitoring. Sample rinse water during a new or trial wash cycle toestablish when a vessel is clean (within set tolerances).

8.2 Equipment issues

■ Vessel design.

– Position valves at the lowest point of the vessel to improve drainage.

– Replace flat-bottomed vessels with vessels with smooth contours and a cone-shapedbottom to assist drainage and cleaning.

– Use fully enclosed vessels to reduce evaporation and, hence, reduce the need forcleaning.

– Use polished stainless steel or plastic-lined vessels (where appropriate) to make cleaningand maintenance easier.

■ Online monitoring. Check the wash liquor to ensure cleanliness standards are met withoutusing excessive amounts of water.

■ High-pressure spray wash and CIP systems.

– Faster washing time means less downtime and increased vessel productivity.

– Spray nozzles/balls provide an alternative to fill-and-flush and boil-out, and can reducewater use by up to 90%.

– Brush systems can be used in conjunction with high-pressure water.

– Automatic and semi-automatic CIP systems allow optimised control.

– Capital costs typically range from £50 for triggered hose/spray equipment to over£20 000 for high-pressure washing systems.

■ Closed-loop wash systems. Make it easier to re-use wash liquor by linking vessels andwash/holding tanks to form a closed system. Closed systems also help to reduce odours,volatile organic compound (VOC) and other gaseous emissions.

MacDermid makes specialist surface finishing chemicals at its site in Birmingham. Thecompany recently redesigned part of its batch chemical plant to meet increasedproduction demands. The new mixing facility is fully computerised and has virtuallyzero discharge. Vessel wash waters are stored in IBCs on a racked system next to themixing plant, which allocates them to subsequent batches of compatible product.

The new plant has allowed the company to save at least £168 000/year in terms ofreduced product losses, around £27 000/year in reduced effluent treatment costs,around £7 000/year in reduced water costs and around £21 000/year in reducedenergy costs - a total of £223 000/year. The payback period on the investment wasaround two years. The technology is now being applied to the other mixing vesselson site.

Re-use of wash waters in product at MacDermid

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Use Checklist 6 to help you identify and prioritise improvement opportunities at your site relatingto vessel washing.

Ciba Specialty Chemicals used to clean the vessels in one of the batch plants at itsBradford site using caustic boil-outs. This took around eight hours/vessel, and wasexpensive in terms of energy and chemicals. It also produced a highly alkalineeffluent that had to be neutralised with acid.

The company now uses a single high-pressure wash system (a lance and rotatingnozzle) that can be moved from one vessel to another. This is far faster (it takes onlyaround 2.5 hours/wash), uses 77% less energy, does not need any chemicals andproduces a far less difficult effluent with a lower COD content. Overall, the changehas saved the company over £2 million/year - mainly due to productivity gains.

Benefiting from mobile CIP

Further information

■ Cost-effective vessel washing (GG120) - explains how to improve vessel washingand reduce washing costs by 20 - 50% without affecting product quality. It coversimproved vessel washing management techniques and technical improvementssuch as spray systems, wash liquor recovery, high-pressure wash systems, CIP andclosed-loop systems.

■ Batch chemical manufacturer saves with CIP (CS273) - describes how CibaSpecialty Chemicals benefited from installing a high-pressure CIP system toremove a sticky additive from stainless steel reaction vessels.

■ Cleaner technology brings cost savings and environmental improvements (NC260)- describes how MacDermid Canning met increased production by installing anew mixing facility with virtually no effluent discharge.

✓

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Equipment cooling and vacuumpumps

Cooling water and seal water from liquid ring vacuum pumps are often used only oncebefore being sent to drain. This relatively uncontaminated water can be recirculated orre-used. A number of other options for reducing water use are available.

■ Control cooling water use. Fit thermostats to water-cooling circuits that reduce/stop theflow when the equipment is sufficiently cool and increase it when the equipment heats up.

■ Recirculate cooling water. Include a heat exchanger (linked to an appropriate coolingtower) in the cooling circuit so that water can be recirculated directly. Fig 10 shows anexample circuit for an air compressor.

■ Control cooling water composition.

– Optimise the bleed and make-up on all water recirculation systems (for vacuum pumps,cooling towers, wet scrubbers, etc) to prevent the build-up of solids and chemicalswhile keeping water use to a minimum. If possible, fit an automated system, eg a totaldissolved solids (TDS) controller, as in the industry example opposite.

– Use an appropriate settlement or other treatment stage in the cooling circuit to reducesuspended and dissolved solids. This will reduce the need for make-up water additions.

A company in the Midlands cooled a piece of equipment using a constant flow ofclean water that was then passed straight to drain. To reduce water use,thermostatic valves were fitted so that coolant only ran when necessary. This reducedflows by 70% from 2 m3/hour to around 0.6 m3/hour. The cooling water is nowdirected back to a holding tank for re-use as cleaning water. This has reduced wateruse by around 3 000 m3/year and saved the company some £3 300/year.

Thermostats control cooling water

Watermain

Drain

Fan-assistedcooling tower

Recirculation

Before After

Fig 10 Cooling system for air compressor

99

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33

■ Condensate. Improve the recovery of condensate from condensers and steam traps. Therecovered water can be treated (if necessary) and re-used, eg for certain cleaning purposes.

■ Liquid ring vacuum pumps.

– Interlock the seal and cooling water supply to the pump via a solenoid valve. This willshut off the water supply when the pump is not operating.

– Use alternative seal liquids in vacuum pumps. In some cases, high boiling point organicsolvents are more effective than water as they keep solids carried over from the processin solution without the heavy purge required with a water seal.

■ Dry vacuum technology. Various types of dry vacuum pump are available including lobepumps, screw pumps and claw mechanism pumps.

Ciba Specialty Chemicals makes a variety of water and effluent treatment chemicalsat its site near Bradford. The site has several cooling towers to deal with excessprocess heat. Until recently, these towers were operated using a typical ‘bleed andfeed’ arrangement. Constant chemical dosing, water bleeding and addition of make-up water limited solids build-up. While effective at stopping corrosion and the build-up of scale, this approach was expensive.

The company has moved to a ‘smarter’ system on one of its towers that ensuresoptimum control irrespective of changes in the circulating cooling water. The newapproach uses conductivity and redox potential probes to monitor TDS and additivelevels in the circulating water. These data are fed into a programmable, computer-controlled unit which provides optimum control of water bleed, make-up additionsand treatment chemical dosing. This approach has reduced bleeding by 50% andsignificantly reduced make-up water use, chemical use and trade effluent costs. Theoverall saving is around £10 000/year.

The company plans to install similar equipment on another cooling tower in the nearfuture. Similar cost savings are expected.

Cooling tower improvements at Ciba Specialty Chemicals

Ciba Specialty Chemicals’ Grimsby site manufactures water treatment chemicals. Anenvironmental, health and safety project highlighted effluent generation as a keyissue. A survey identified sources of process effluent and areas where improvementscould be made.

Condensate from driers was targeted as a potential area for reducing both waterand effluent costs. A number of steps were taken:

■ A suitable condensate stream was identified for re-use.

■ The plant needed for condensate re-use was built and installed. It uses in-housedesigned pipework and control systems.

■ Computer software was modified to allow condensate to transfer back to theprocess for re-use instead of to the effluent stream.

The project has many benefits. The potential reduction in effluent charges is over£25 000/year and the potential water saving is over 2 000 m3/year. The capital outlaywas less than £10 000, giving a payback period of less than six months. A furtherbenefit has been the reduction in process energy consumption due to the warmth ofthe recovered condensate. More improvements are under way to further reducewater use and effluent generation in cooling applications.

Condensate re-use at Ciba Specialty Chemicals

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Use Checklist 7 to help you identify and prioritise improvement opportunities at your site relatingto equipment cooling and vacuum pumps.

Between 1996 and 1998, Ciba Specialty Chemicals switched from oil-lubricatedrotary-vane vacuum pumps to dry vacuum technology at its Bradford site. This issaving the company over £600 000/year in reduced process downtime, maintenancerequirements, oil use and disposal costs. While not saving water, the change hasproved the technology’s suitability for Ciba’s particular applications and dry vacuumtechnology is now used at other Ciba sites.

Use of dry vacuum pumps at Ciba Specialty Chemicals

Further information

■ Reducing vacuum costs (GG101) - explains how to optimise vacuum use in thespeciality chemicals sector and describes the characteristics of different types ofvacuum system, including dry vacuum technology.

■ Profiting from dry-vacuum technology (GC235) - describes how Ciba SpecialtyChemicals achieved cost and other benefits from replacing oil-lubricated pumpswith dry vacuum pumps.

✓

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Effluent treatment and re-use

Effluent treatment plants (ETP) are used to:

■ treat aqueous wastes to a suitable standard for discharge (to meet your company’s consentlimits) and re-use;

■ recover valuable raw materials and product.

Anything you can do to reduce effluent volumes and/or strength (suspended solids, COD, BOD4)will reduce your trade effluent charges and sludge removal costs.

Effective management and control of the processes used for effluent treatment will help you to:

■ reduce your operating costs and thus increase profits;

■ achieve more effective compliance with legislation;

■ improve your company’s public image.

Before reviewing the operation of your ETP, take action to minimise the amount and strength ofthe effluent created by production processes. Producing less effluent in the first place will reducethe demands made on your ETP and thus save both money and effort.

10.1 Types of effluent treatment

The range of effluent treatment processes used in the speciality chemicals sector are summarisedin Table 3 overleaf.

10.2 Improving effluent treatment

Good practice generally involves semi-automation, routine monitoring and effective control ofthe ETP.

Detailed practical advice on improving the performance and thus reducing the cost of your ETPis given in Improving the performance of effluent treatment plant (GG175), which covers:

■ diversion;

■ equalisation/balancing;

■ neutralisation;

■ sedimentation;

■ dissolved air flotation;

■ activated sludge.

Information about anaerobic digestion is given in Industrial wastewater and effluent treatment:a review of anaerobic digestion technology, published by BIO-WISE5.

4 Biochemical oxygen demand.5 Available free from the BIO-WISE Helpline on 0800 432100 or via the BIO-WISE website

(www.dti.gov.uk/biowise).

1010se

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36

Tab

le 3

M

ain

eff

luen

t tr

eatm

ent

met

ho

ds

use

d b

y sp

ecia

lity

chem

ical

co

mp

anie

s

Typ

e o

f p

roce

ssTe

chn

olo

gy

Co

mm

ents

Pret

reat

men

tD

iver

sio

nD

iver

sio

n f

acili

ties

su

ch a

s h

old

ing

tan

ks a

re e

ssen

tial

to

co

pe

wit

h u

nex

pec

ted

vo

lum

es o

rst

ren

gth

s, t

ank

ove

rflo

ws

or

fire

wat

er r

un

-off

. Div

ersi

on

can

be

man

ual

or

auto

mat

ic.

Equ

alis

atio

n/b

alan

cin

gR

equ

ired

to

co

ntr

ol

effl

uen

t fl

uct

uat

ion

s (p

H,

tem

per

atu

re,

CO

D,

etc)

an

d p

reve

nt

sho

cklo

adin

g.

Neu

tral

isat

ion

Aci

dic

an

d a

lkal

ine

effl

uen

t st

ream

s o

ften

nee

d c

hem

ical

ad

dit

ion

s to

ad

just

pH

. W

her

e b

oth

are

pre

sen

t, t

hey

can

be

mix

ed t

o n

eutr

alis

e ea

ch o

ther

.

Phys

ical

/ch

emic

alSe

dim

enta

tio

nW

idel

y u

sed

to

rem

ove

su

spen

ded

so

lids.

Can

rem

ove

met

als,

ph

osp

hat

es a

nd

so

me

org

anic

s.

Dis

solv

ed a

ir f

lota

tio

n (

DA

F)W

idel

y u

sed

to

rem

ove

su

spen

ded

so

lids

and

so

me

org

anic

s. S

olid

s b

eco

me

enm

esh

ed i

n f

ine

air

bu

bb

les

inje

cted

into

th

e ef

flu

ent,

flo

atin

g t

o t

he

surf

ace

wh

ere

they

are

ski

mm

ed o

ff.

Wet

air

oxi

dat

ion

Use

d t

o o

xid

ise

effl

uen

ts w

ith

a h

igh

CO

D c

on

ten

t. I

nvo

lves

air,

pu

re o

xyg

en o

r h

ydro

gen

per

oxi

de

at h

igh

tem

per

atu

res

and

pre

ssu

res.

Ad

sorp

tio

n a

nd

filt

rati

on

Use

d t

o p

olis

h e

fflu

ent

to a

llow

dis

char

ge/

re-u

se o

r to

sep

arat

e ra

w m

ater

ials

fo

r re

-use

.C

om

mo

n f

ilter

med

ia in

clu

de

san

d, p

last

ic g

ran

ule

s an

d g

ran

ula

r ac

tiva

ted

car

bo

n.

Mem

bra

ne

filt

rati

on

M

emb

ran

e sy

stem

s (u

ltra

filt

rati

on

, n

ano

filt

rati

on

, re

vers

e o

smo

sis,

ele

ctro

dia

lysi

s, e

tc)

allo

wef

fect

ive

reco

very

an

d r

e-u

se o

f w

ater

an

d m

ater

ials

, g

ener

ally

wit

ho

ut

the

use

of

chem

ical

add

itiv

es s

uch

as

flo

ccu

lan

ts a

nd

co

agu

lan

ts.

Bio

log

ical

Act

ivat

ed s

lud

ge

Aer

ob

ic t

reat

men

t is

wid

ely

use

d t

o r

edu

ce B

OD

/CO

D a

nd

am

mo

nia

(n

itri

fica

tio

n).

Su

ch p

lan

tsar

e su

itab

le f

or

effl

uen

ts w

ith

CO

D v

alu

es o

f ar

ou

nd

10

000

mg

/litr

e an

d a

CO

D:B

OD

rat

io o

fu

p t

o 3

:1.

An

aero

bic

dig

esti

on

An

aero

bic

tre

atm

ent

is c

arri

ed o

ut

in t

he

abse

nce

of

oxy

gen

at

tem

per

atu

res

typ

ical

ly a

rou

nd

35°C

. Th

e b

iog

as (

mai

nly

met

han

e an

d c

arb

on

dio

xid

e) p

rod

uce

d c

an b

e u

sed

to

gen

erat

ep

ow

er.

In U

K c

on

dit

ion

s, a

nae

rob

ic t

reat

men

t is

mo

st c

ost

-eff

ecti

ve a

bo

ve C

OD

val

ues

of

aro

un

d 5

000

mg

/litr

e, a

nd

can

be

use

d f

or

CO

D c

on

cen

trat

ion

s u

p t

o 5

000

0 m

g/li

tre.

1010

sect

ion

37

10.2.1 Membrane technology

The principles of membrane separation, potential applications, membrane selection and thedifferent technologies are described in Cost-effective membrane technologies for minimisingwastes and effluents (GG54). For effective use of membrane systems:

■ Ensure that the membrane system is protected properly by an upstream treatment processsuch as neutralisation or sedimentation. The removal of larger solids reduces the risk ofblockage/fouling and the need for backwashing.

■ Monitor permeate quality continuously and replace membranes when necessary.

■ Clean the membranes regularly through backwashing and, where necessary, hightemperature cleaning at low and high pH to remove fouling.

■ Maintain the plant regularly, eg look for leaking end seals.

10.3 Effluent/wash water re-use

Cooling waters and most effluents (treated and, in some cases, untreated) can be used aroundthe site, eg in toilet flushing, for cleaning and in some cases in the product itself. Simpletreatment methods such as settlement and filtration increase opportunities for re-use.

■ Match the quality of the effluent to the application. If possible, re-use more than once in acascade (see section 6.1).

■ Re-use locally to avoid the need for long pipe runs and higher pumping costs.

■ For re-use of wash waters and treated effluents in more sensitive areas, monitor dissolvedsolids using a conductivity probe and then bleed off effluent and feed in make-up water asappropriate.

■ Use a technique called water pinch analysis to look at opportunities to minimise water useacross the site as a whole. Water pinch analysis is a systematic approach that takes intoaccount the permissible contaminant concentrations at the inlet and outlet of each processto calculate the minimum overall water flow rate required.

10.4 Sludge management

Most effluent treatment processes used in the speciality chemicals sector generate a sludge.Sludge treatment and disposal costs often represent most of the operating costs of the ETP.Sludge treatment to reduce the volume of sludge requiring disposal will produce savings throughreduced transport and other costs, eg landfill charges. However, sites that take action to reducethe amount of sludge produced in the first place will save much more money.

■ Thickening. Thicken sludge to reduce its volume as sludge from settlement tanks is oftenonly 1% or less dry solids and from DAF only 4% dry solids.

■ Dewatering. Even after thickening, sludges are usually only a few per cent dry solids.Dewatering using centrifuges and belt and plate presses increases the solids contentdramatically (often to 50% or more). Flocculants are usually added to help retain more of thesolids in the press. The resulting filter cake has a much lower weight and volume, and is,therefore, much cheaper to dispose of.

1010se

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Use Checklist 8 to help you identify and prioritise improvement opportunities at your site toimprove effluent treatment, effluent re-use and sludge management.

A company in the Midlands produces around 20 tonnes/week of sludge from its ETP,giving a total of 970 tonnes/year. This was costing over £27 000/year to dispose of at£28/tonne. The company is now using a filter press to dewater this sludge,producing around 55 tonnes/year of filter cake. This costs around £1 300/year todispose of, saving £25 700/year. The new filter press cost about £12 000, giving apayback period of less than six months.

Benefits of sludge filter pressing

Further information

■ Improving the performance of effluent treatment plant (GG175) - describes fivesteps to effective effluent management and gives detailed practical advice on themain effluent treatment methods used by speciality chemical companies in the UK.

■ Cost-effective membrane technologies for minimising wastes and effluents(GG54) - explains the principles of membrane systems (ultrafiltration, reverseosmosis, nanofiltration and microfiltration) and discusses appropriateapplications.

■ Cost-effective separation technologies for minimising wastes and effluents(GG37) - describes proven techniques and technologies (including adsorption, ionexchange, precipitation and dissolved air flotation) for separating dissolvedsubstances from liquids and ways of separating gases from liquids.

■ Choosing cost-effective pollution control (GG109) - gives advice on how to selectthe most appropriate process or effluent treatment plant.

■ Water pinch study pays major dividends (NC55) - describes how Monsanto plcused water pinch analysis to minimise water and wastewater at its Newport site.

■ Ultrafiltration puts an attractive face on cosmetics production (NC138) - describeshow The Body Shop made use of membrane technology to treat a complexprocess wastewater.

■ Effluent Online Club (www.envirowise.gov.uk/effluentonlineclub) is a web-basedforum that shares best practice on effluent management and provides free,expert help.

■ Industrial wastewater and effluent treatment: a review of anaerobic digestiontechnology is produced by the DTI-funded BIO-WISE Programme. It explains howanaerobic digestion works, describes the different types of anaerobic digestionsystem and indicates typical costs. Copies are available free of charge from the BIO-WISE Helpline on 0800 432100 or via the BIO-WISE website(www.dti.gov.uk/biowise).

✓

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Further information

11.1 Help from Envirowise

Envirowise offers a range of free services including:

■ advice from Envirowise experts through the Environment and Energy Helpline on cleanertechnology, waste minimisation, environmental issues and environmental legislation;

■ a variety of publications that provide up-to-date information on water minimisation issues,methods and successes;

■ on-site reviews (a FastTrack visit) from an independent Envirowise advisor to identifyopportunities for reducing waste6;

■ best practice seminars and practical workshops that offer an ideal way to examine wasteminimisation issues and learn about ways of reducing waste;

■ guidance on waste minimisation clubs and other partnerships across the UK that provide achance for companies to share best practice on waste minimisation.

To contact Envirowise:

■ phone the Environment and Energy Helpline on freephone 0800 585794;

■ send an e-mail to: helpline@envirowise.gov.uk;

■ visit the Envirowise website (www.envirowise.gov.uk).

11.1.1 Relevant Envirowise publications

All Envirowise publications are available free of charge through the Environment and EnergyHelpline or via the Envirowise website (www.envirowise.gov.uk).

Guides■ Water use in the manufacture of speciality chemicals (EG105)

■ Cost-effective water saving devices and practices (GG67)

■ Tracking water use to cut costs (GG152)

■ Profiting from reducing water use: running a workshop to stimulate action (GG229)

■ Cost-effective vessel washing (GG120)

■ Reducing vacuum costs (GG101)

■ Improving the performance of effluent treatment plant (GG175)

■ Cost-effective membrane technologies for minimising wastes and effluents (GG54)

■ Cost-effective separation technologies for minimising wastes and effluents (GG37)

■ Choosing cost-effective pollution control (GG109)

■ Reduce your water use and collect the savings (EN339)

■ Saving money through waste minimisation: teams and champions (GG27)

■ Workforce partnerships to reduce waste and save energy (ET228)

6 Available if you employ fewer than 250 people.

1111

40

sect

ion

sect

ion

■ Saving money through waste minimisation: raw material use (GG25)

■ Preventing waste in production: practical methods for process control (GG224)

■ Investing to increase profits and reduce wastes (GG82)

Case studies■ Batch chemical manufacturer saves with CIP (CS273)

■ Profiting from dry-vacuum technology (GC235)

■ Pigging cuts costs, recovers product and reduces effluent (GC261)

■ Cleaner technology brings cost savings and environmental improvements (NC260)

■ Water pinch study pays major dividends (NC55)

■ Ultrafiltration puts an attractive face on cosmetics production (NC138)

Web-based tools■ ERA 2000 is an interactive spreadsheet that enables chemical companies to measure their

environmental performance across a range of performance indicators. To download thesoftware, go to the chemical industry page of the Envirowise website(www.envirowise.gov.uk).

■ Effluent Online Club (www.envirowise.gov.uk/effluentonlineclub) is a web-based forum thatshares best practice on effluent management and provides free, expert help.

11.2 Other sources

■ Conserving water in buildings - 11 fact cards produced by the Environment Agency on thedifferent types of water-efficiency technology available in England and Wales. Available fromthe Environment Agency’s Water Demand Management Centre (Tel: 01903 832073) or thewebsite (www.environment-agency.gov.uk/savewater).

■ Pollution Prevention Guidance Notes (PPGs) from the Environment Agency on the preventionof pollution to watercourses and groundwater from different operations and activities. Canbe downloaded from the business area of the Environment Agency website(www.environment-agency.gov.uk) or obtained as printed copies from the Agency’s generalenquiry line on 0845 933 3111.

■ Industrial wastewater and effluent treatment: a review of anaerobic digestion technology.Available free from the BIO-WISE Helpline on 0800 432100 or via the BIO-WISE website(www.dti.gov.uk/biowise).

■ Sustainable Water Environment in Lancashire (SWEL) - offers advice to companies onimproving water management with the aim of reducing water supply, treatment and disposalcosts. The project is run by Groundwork Blackburn in partnership with the EnvironmentAgency. For more information, visit the SWEL website (www.SWEL.org.uk).

■ Rainwater and greywater use in buildings. Best practice guidance. C539. ConstructionIndustry Research and Information Association (CIRIA). ISBN 860175391. £90.00 for non-members (£45.00 to members). To obtain a copy, phone 020 7222 8891 or visit the CIRIAwebsite (www.ciria.org.uk).

app

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41

Checklists

The back pocket of this Guide contains eight checklists designed to help you manageyour water use more effectively. A cost savings worksheet is also included.

The practical measures in the checklists are suggestions to help you identify and prioritiseopportunities to increase your profits by reducing water, effluent and material costs.

Tick the columns headed ‘implement’ and ‘investigate’ as appropriate - and then take action.

See the appropriate section of the Guide for further information and signposts to relevant freepublications.

Please photocopy the checklists as required.

The checklists cover:

1 Management issuesTaking a systematic approach to water minimisationEmployee training, motivation and accountability

2 Water monitoring and supplyMonitoring water useUsing lower grade water supplies

3 Maintenance and related issues

4 General cleaning and domestic useGeneral cleaning practices and equipmentDomestic water use

5 Materials managementMaterials delivery, storage and distribution Drainage and pollution prevention

6 Vessel washing

7 Equipment cooling and vacuum pumps

8 Effluent treatment and re-useEffluent treatmentEffluent re-useSludge management

For further informationplease contact the

Environmentand EnergyHelpline0800 585794

Envirowise - Practical Environmental Advice for Business - is a Government programmethat offers free, independent and practical advice to UK businesses to reduce waste atsource and increase profits. It is managed by AEA Technology Environment and NPLManagement Limited.

Envirowise offers a range of free services including:

Free advice from Envirowise experts through the Environment and EnergyHelpline.

A variety of publications that provide up-to-date information on wasteminimisation issues, methods and successes.

Free, on-site waste reviews from Envirowise consultants, called FastTrack visits,that help businesses identify and realise savings.

Guidance on Waste Minimisation Clubs across the UK that provide a chance forlocal companies to meet regularly and share best practices in waste minimisation.

Best practice seminars and practical workshops that offer an ideal way toexamine waste minimisation issues and discuss opportunities and methodologies.

© Crown copyright. First printed February 2003. Printed on paper containing a minimum of 75% post-consumer waste.This material may be freely reproduced in its original form except for sale or advertising purposes.

Harwell International Business Centre | Didcot | Oxfordshire | OX11 0QJE-mail: helpline@envirowise.gov.uk Internet: www.envirowise.gov.uk

Practical Environmental Advice for Business