Sustainable wastewater treatment – what has gone wrong and how do we get back

on track?

Heidi G. SnymanAM van Niekerk N Rajasakran

Overview of the wastewater treatment industry in SA

• Most WWTPs in SA are relatively small systems

< 0.5 Ml/day50%

0.5 - 2 Ml/day11%

2 - 10 Ml/day21%

10 - 25 Ml/day10%

> 25 Ml/day7%

No. of Plants: 986

Introduction• Metros typically have a few large WWTPs and

are generally well equipped and operated• Specific challenges exist for smaller and poorer

communities• The challenges relate to the small scale of

operation and having to establish new skills and competencies

• The infrastructural, mechanical and electrical maintenance of the plants also present challenges

National survey• 51 plants in eight Provinces.

– micro plants (< 500 m3/day);– small plants (500 – 2 000 m3/day);– medium plants (2 000 – 10 000 m3/day) plant

• The technology utilized, resources deployed for operations and maintenance and overall performance was assessed at each plant.

Location of plants included in the survey

Generic evaluation protocol

Capital infrastructure

Human resources

Financial resources

Information resources

Flow and loads Unit process performance Effluent quality Sludge

handling

Environmental Legal Socio-economic Health

Resources deployed

Plant performance

Stakeholder requirements

Resources deployed on wastewater treatment plants

7

5

9

1

5

11

20

19

9

25

18

18

18

36

14

0

2

4

2

4

13

5

0

0

0

2

0

0

0

0

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Capital infrastructure

Human resources (Operational)

Human resources (Maintenance)

Financial resources

Information resources

Major intervention required Intervention required Adequate Ideal situation Over resourced Significantly over resourced

Resources deployed

• The data shows that some form of intervention is required with regards to the following:– Capital infrastructure investment is required at 35 % of

the plants– Additional skilled operational staff is required to

operate the plant efficiently at 50 % of the plants– Additional skilled maintenance staff is required to

adequately maintain the installed mechanical/electrical equipment and instrumentation at 56 % of the plants

– Supplemental financial resources are required to support the routine operation and maintenance at 21 % of the plants

– Additional information resources are required to properly operate the facilities at 63 % of the plants

Resources deployed on wastewater treatment plants

• The need for additional or upgraded plant infrastructure or the need for additional funding is not the root cause of the poor performance at the majority of surveyed plants

• The most pressing need is the critical shortage of trained, skilled and experienced process controllers and mechanical/electrical maintenance staff

• Most plants operate with insufficient information to guide optimised operations, but this shortcoming can be partially overcome by trained and skilled process controllers

Plant wastewater flow and loads• 16 % are hydraulically overloaded• 22 % are overloaded in terms of the organic/nutrient load• >35 % of the plants can accommodate higher flows and loads

– depend on the capacity of the operators to operate a plant that is running close to or at design capacity

2

2

6

9

20

21

3

2

18

17

2

0

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Flow received

Load received

Major intervention required Intervention required Adequate Ideal situation Over resourced Significantly over resourced

Treatment Process Performance

• More than half the plants experience problems with the following unit processes:– Flow balancing

• facility is not available on the majority of surveyed plants.

– Secondary treatment• Including oxidation pond treatment, trickling filters

and activated sludge which has different levels of complexity and mechanical/electrical component content

• Poor performance plants were almost equally represented in all the main secondary treatment process technologies

• The complexity of the treatment technology is not a major differentiating factor in plant performance

Treatment Process Performance

– Maturation ponds• Many of the maturation ponds are filled with

sludge and overgrown with reeds. • Many plants bypass the maturation ponds and do

not understand the important polishing and disinfection function of maturation ponds.

– Chlorination• 67 % of the plants that disinfect final effluent are

experiencing operational problems. • Problems include inadequate design of

disinfection systems, inappropriate disinfection technology employed, inadequate operation and management of chlorine stock.

Residue and sludge management• 24 – 25 % of plants experience problems

disposing of screenings and grit • Most plants rely on the either the extended

aeration or long resident time in pond systems. • Most of the plants rely on solar drying in drying

beds or sludge ponds/lagoons• Although these are fairly simple processes, poor

operational practices were observed at 39% of the plants

• Disinfection process for sludge is almost non- existing

• Inadequate disposal and use of sludge were recorded at 81% of the plants

• None of the plants visited would comply with the new SA Sludge Guidelines

Maintenance aspects• Immediate intervention is required at 30 % of the plants• Intervention required at > 60 % of the plants• 10 % of plants are maintained to ensure sustainable functionality

12

8

15

7

11

14

13

22

20

12

12

20

17

16

9

19

19

26

13

14

14

5

3

4

3

3

2

5

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Preventative maintenance

Routine electrical maintenance

Routine mechanical maintenance

Redundancy

Turn around time

Equipment replacement

Availability of qualified staff

Major problems Problematic Adequate Ideal situation

Environmental Impacts and Regulatory Compliance

• The compounding effect of all the operational aspects evaluated as well as the general lack of maintenance:

15

11

19

27

15

9

2

1

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Environmental and healthimpact

Authorization andcompliance

Major problems Problematic Adequate Ideal situation

Environmental Impacts and Regulatory Compliance

• 30 % require immediate intervention to avoid crisis situations such as an outbreak of waterborne diseases

• In the short to medium term intervention would be required at more than 66 % of the plants

• The Department of Water Affairs and Forestry requires a 95 percentile compliance to the conditions stipulated in the authorisation.

• If these performance criteria are strictly enforced, only 4 % of the surveyed plants are adequately operated and maintained.

Status of Operating Staff at South Africa Wastewater Treatment Plants

• Major intervention required and practically no trained and competent operations staff available to plant (10%)

• Intervention required with a limited number of trained and competent operations staff available to plant (40%)

• Plant adequately resourced in terms of operations staff but further training of staff required (36%)

• Staff properly trained, qualified and experienced to competently operate the treatment plant. Ongoing training and education programmes are implemented (4%)

• Plant facility has more trained and qualified operational staff allocated to the entire operation of the plant than is required (10%)

Framework for Intervention Strategies

Spheres of influenceUrgent /

immediate actions

Short term actions

Long term actions

Governance and regulatory aspectsFacility management and ownership aspects

Facility planning and construction aspects

Operations and maintenance of facilities

Key Components of Intervention Strategy

• Regulatory interaction with WWTP owners and operators.

• Institutional arrangements.• Service delivery systems.• Advancement of appropriate treatment

technology.• Capacity of operations staff resources.• Capacity of maintenance staff resources.• Financial support programs.• Information systems.• Collaborative actions.

Estimated number of process controllers required to effectively operate the micro, small and medium

wastewater treatment plants in South Africa

Class operator Number of operators required

Number of registered operators in the DWAF

data base

Shortfall of registered operators

Trainee 838 438 400I 1136 71 1065II 838 153 685III 696 229 467 IV 298 254 44V 76 438 (76)* - 362 (0)*

TOTAL 3882 1583 2299TOTAL (Correction for

Class V)* 3882 1221 2661

Maintenance• It is assumed that any wastewater treatment

plant requires access to a “maintenance team” consisting of at least the following staff and support:– electrician;– fitter and turner;– instrumentation technician;– mode of transport (bakkie);– tool kits and basic spare parts.

• Require at least 105 teams• Job creation opportunities!

SO what can be done to help

the situation?

PURPOSE OF THE GUIDELINEThis guideline document deals with the requirements for

undertaking an inspection at a WWTW.

The purpose of the guideline document is to assist the Process Controller to:

• prepare for an inspection at the WWTW; and• take corrective action where a problem is identified.

Assist the Inspector to:

• undertake an inspection at a WWTW; and• give guidance where a problem is identified.

GUIDELINE FOR THE INSPECTION OF WASTEWATER TREATMENT WORKS

PART I: GUIDELINE

PART II: CHECKLISTS

PROCESS OPERATIONS

PROCESS CONTROL

MAINTEANCE AND SAFETY

LABORATORY

Preliminary Treatment

Primary Treatment

Secondary Treatment

Tertiary Treatment

Sludge Treatment

Management and administration

Checklist 1: The WWTW in a Nutshell

Checklist 2: Primary Assessment

Checklist3: Comprehensive Inspection

Checklist 4: The Quarterly Inspection

Legislative Issues

Records/Reporting

Human Resources

Budget

PROCESSCONFIGURATION

Checklist When should the checklist be used?

1 The WWTW in a nutshell

This checklist will help the person undertaking the inspection to get an understanding of the unit processes making up the WWTW and should be undertaken with the Process Manager. All Process Managers and Process Controllers should complete this checklist when commencing employment at the WWTW and again if any upgrades are done to the works. External Inspectors should complete this checklist prior to undertaking an inspection. Examples of flow diagrams of various configurations are set out in Appendix B and C.

2 Primary Assessment

This checklist gives an overall evaluation of the WWTW. The inspection should be undertaken by an experienced person, preferably external to the WWTW who will make a decision on whether the comprehensive inspection needs to be undertaken or not.

3 Comprehensive Inspection

This checklist includes individual checklists for each unit process. It should be used by the regulators and other Inspectors (both external and internal) when a WWTW has failed the primary assessment i.e all aspects have failed or certain parts of the WWTW have serious failures. This checklist will aid in the identification of the problems and will help to make improvements.

4 Quarterly Inspection

This inspection should be undertaken quarterly once the WWTW has been subjected to a comprehensive inspection and/or primary assessment, and has been deemed to be running optimally. Ideally the regulator should undertake this inspection however, the Process Manager or Process Controller could also undertake this inspection.

PART IGUIDELINES FOR

UNDERTAKING AN INSPECTION AT A WWTW

Performance Area Aspects to consider Notes

1 Mechanical assessment

•

Mechanical equipment•

Maintenance schedule and implementation

2 Final effluent

•

Looks and smells good•

Results are displayed graphicallyNote: take a final effluent sample at this time and send to an

independent laboratory for analysis; do field tests as appropriate (eg. residual chlorine using DPD tablets) and interpret the results once received;

3Biological treatment process

•

Attached growth media (eg. stones, disks) is in good condition and does not have a bad smell;

•

Activated sludge - mixed liquor looks good and smells earthy;

4 Good house- keeping

•

Areas around unit processes are kept clean and tidy;•

Chemical storage areas are bunded;

5 Disposal of solids

•

Screenings, detritus and sludge are correctly disposed of in accordance with relevant authorisations

6 Paper work•

Water use authorisation is in place and conditions stipulated are implemented;

•

Contracts for sludge disposal are in place

7 Safety issues •

Obvious safety hazards

CHECKLIST 2: THE PRIMARY ASSESSMENTCHECKLIST 2: THE PRIMARY ASSESSMENT

Rating Description

Observation of a physical item (eg. a pump; unit process)

Note/comment on an issue (eg. documentation)

3 Major failure No/false

2 Problematic Yes, but inadequate/not applicable (n/a)

1 Ideal performance Yes/true

CHECKLIST 3CHECKLIST 3THE COMPREHENSIVE ASSESSMENTTHE COMPREHENSIVE ASSESSMENT

CHECKLIST 4: THE QUARTERLY ASSESSMENTCHECKLIST 4: THE QUARTERLY ASSESSMENT

APPENDICES:APPENDICES:

••Reference documents that should be on hand at the Reference documents that should be on hand at the WWTWWWTW

••Hand drawn flow diagram exampleHand drawn flow diagram example

••Various configurations of WWTW throughout South Various configurations of WWTW throughout South AfricaAfrica

••A simple method to estimate the flow into a WWTWA simple method to estimate the flow into a WWTW

••Example for recording water quality complianceExample for recording water quality compliance

••NormsNorms

Thank you