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this presentation is about the reuse of treated wastewater.Different application and technologies involved. I have also put four case studies taken from some journals mentioned.
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Reuse of Treated wastewater
PULKIT SHUKLA
SIDDHARTH KATIYAR
ROBIN AJMERA
Page 1 of 34
What is Wastewater Reuse
The U.S. Environmental Protection Agency (EPA) defines wastewater reuse as, “using wastewater or reclaimed water from one application for another application. A common type of recycled water is water that has been reclaimed from municipal wastewater (sewage).”
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Reasons for Wastewater Reuse
The most common reasons for establishing a wastewater reuse program is to identify new water sources for increased water demand and to find economical ways to meet increasingly more stringent discharge standards
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Types of Reuse
• Urban reuse-the irrigation of public parks, school yards , highway medians, and residential landscapes, as well as for fire protection and toilet flushing in commercial and industrial buildings.
• Agricultural reuse-irrigation of non food crops, such as fodder and fiber , commercial nurseries, and pasture lands. High-quality reclaimed water is used to irrigate food crops.
• Recreational impoundments-such as pond sand lakes.
• Environmental reuse-creating artificial wetlands, enhancing natural wetlands, and sustaining stream flows.
• Industrial reuse-process or makeup water and cooling tower water.
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Technical Description
One of the most critical steps in any reuse program is to protect the public health, especially that of workers and consumers. To this end, it is most important to neutralize or eliminate any infectious agents or pathogenic organisms that may be present in the wastewater. For some reuse applications, such as irrigation of non-food crop plants, secondary treatment may be acceptable. For other applications, further disinfection, by such methods as chlorination or ozonation, may be necessary. Table 18 presents a range of typical survival times for potential pathogens in water and other media
Table 18
Page 5 of 34
Application of Treated Wastewater
Agricultural Irrigation
Crop irrigation
Commercial nurseries
Landscape Irrigation
Parks
School yards
Highway medians
Golf courses
Cemeteries
Residential
Industrial Recycling and Reuse
Cooling water
Boiler feed
Process water
Heavy construction
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Groundwater Recharge
Groundwater replenishment
Saltwater intrusion control
Subsidence control
Recreational / Environmental Uses
Lakes & ponds
Marsh enhancement
Stream-flow augmentation
Fisheries
Non-Potable Urban Uses
Fire protection
Air conditioning
Toilet flushing
Potable Reuse
Blending in water supply reservoirs
Pipe-to-pipe water supply
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Historical Examples 3000 BC – Crete (Minoan culture)
Collection of rainwater and sand “filtration” for reuse
1890 – Mexico
Agricultural irrigation
1912 – Europe & US
Landscape irrigation
1926 – US & Europe
Industrial uses: cooling processes & boilers
1960 – US; Europe; Africa; Australia
Landscape Irrigation (including golf-courses)
Groundwater Recharge
Advanced WW reclamation for potable water supply augmentation
1980 – US; Europe; Japan
Water recycling for toilet flushing in urban areas
Agricultural irrigation of food crops eaten uncooked
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Constituents to be checked in Reclaimed Water
Conventional (measured in mg/L; used in designing conventional WWTPs)
TSS
BOD; COD
TOC
Nitrogen (Ammonia; Nitrate; Nitrite)
Phosphorus
Microorganisms: Bacteria; Viruses ; Protozoan cysts & oocysts
Non-conventional (to be removed or reduced by advanced treatment processes)
Refractory organics
VOC
Surfactants
Metals
TDS
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Problems associated with Wastewater Reuse
Heavy Elements
Public Health – nervous system disorders, mutagenesis, teratogenesis, carcinogenesis
Bioaccumulation (food chain on crops and animals)
Surface water pollution
Environmental Impact – acute and chronic toxicity for plant and animal life, chronic degradation effect on soil
Nutrients (N & P)
Public Health – blue-baby syndrome (from NO3-)
infiltration into potable water supplies
Environmental Health – Eutrophication, crop yield effects (+ive & -ive)
Surface water pollution
Irrigation practices
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Problems associated with Wastewater Reuse
Dissolved Solids (salinity)
Environmental Health
Induce problems for the crops’ yield selection and quantity
Accumulation in soil
Effect on soil permeability
Clogging drip-irrigation systems
Emerging Pollutants
Public Health
Acute and chronic health effects – effect on growth, reproduction problems
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Problems associated with Wastewater Reuse
Groundwater contamination Nitrate contamination on private drinking wells
Antibiotics lower effectiveness of antibiotics if irrigation of fodder is involved
Odor Public health of neighboring communities
Aesthetic concern - Reduced land values
Concerns with industrial processesScaling
Corrosion
Biological growth & fouling
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Reclaimed wastewater can be safe for agricultural irrigation
Reduce the pathogen levels
Avoid direct contact of crops with reclaimed wastewater
Restrict the type of crops irrigated
Different treatment for safe irrigation of different crops: For tree nurseries, pastures, industrial crops
Secondary treatment & detention in surface reservoirs
For fruits to be canned, vegetables for cooking and fruits with non-edible peels
Tertiary treatment (i.e. AS & Sand Filtration)
For edible crops (uncooked)
Tertiary treatment followed by soil aquifer treatment (or advanced)
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Guidelines and RegulationsTYPE OF REUSE TREATMENT RECLAIMED WATER
QUALITYRECLAIMED WATER MONITORING
SETBACK DISTANCES
Urban Reuse
Landscape irrigation,
vehicle washing, toilet
flushing, fire protection,
commercial air
conditioners, and other
uses with similar access
or exposure to the water.
SecondaryFiltrationDisinfection
pH = 6–9<10 mg/L biochemicaloxygen demand (BOD)< 2 turbidity units (NTU)5No detectable faecalcoliform/100 mL41 mg/L chlorine (Cl2)residual (min.)
pH – weeklyBOD – weeklyTurbidity – continuousColiform – dailyCl2 residual –continuous
50 ft (15 m) topotable watersupply wells
Agricultural Reuse
For Non-Food Crops
Pasture for milking
animals; fodder, fiber and
seed crops.
SecondaryDisinfection
pH = 6–9< 30 mg/L BOD< 30 mg/L totalsuspended solids (TSS)< 200 faecal coliform/100 mL51 mg/L Cl2 residual(min.)
pH – weeklyBOD – weeklyTSS – dailyColiform – dailyCl2 residual –continuous
300 feet (90 m)to potable watersupply wells
Indirect Potable Reuse
Groundwater recharge by
spreading into potable
aquifers.
Site Specific Secondary and Disinfection. May also need Filtration and/or advanced waste water treatment
Site specificMeet drinking waterstandards afterpercolation throughvadose zone.
pH – dailyTurbidity – continuousColiform – dailyCl2 residual – continuousDrinking water standards– quarterlyOther – depends onconstituent
100 ft (30 m) toareas accessibleto the public (ifspray irrigation)site specific
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Some Wastewater Reuse Advantages and Disadvantages
• This technology reduces the demands o potable sources of freshwater.
• It may reduce the need for large wastewater treatment systems, if significant portions of the waste stream are reused or recycled.
• The technology may diminish the volume of wastewater discharged, resulting in a beneficial impact on the aquatic environment.
• Capital costs are low to medium for most systems and are recoverable in a very short time; this excludes systems designed for direct reuse of sewage water.
• Operation and maintenance are relatively simple except in direct reuse systems where more extensive technology and quality control are required.
• Provision of nutrient-rich wastewaters can increase agricultural production in water-poor areas.
• Pollution of rivers and groundwater may be reduced.
• Lawn maintenance and golf course irrigation is facilitated in resort areas.
• In most cases, the quality of the wastewater, as an irrigation water supply, is superior to that of well water.
Advantages
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If implemented on a large scale, revenues to water supply and wastewater utilities may fall as the demand for potable water for non-potable uses and the discharge of wastewaters is reduced.
• Reuse of wastewater may be seasonal in nature, resulting in the overloading of treatment and disposal facilities during the rainy season; if the wet season is of long duration and/or high intensity, the seasonal discharge of raw wastewaters may occur.
• Health problems, such as water-borne diseases and skin irritations, may occur in people coming into direct contact with reused wastewater.
• Gases, such as sulphuric acid, produced during the treatment process can result in chronic health problems.
• In some cases, reuse of wastewater is not economically feasible because of the requirement for an additional distribution system.
• Application of untreated wastewater as irrigation water or as injected recharge water may result in ground
Disadvantages
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New Technologies and Approaches Used In Wastewater Reuse
Page 17 of 34
Membrane Filtration Systems
Nanotechnology
Microbial Fuel cells
Natural Treatment Systems
Urine Separating Toilets
Membrane Filtration Systems
For wastewater treatment applications, membranes are currently being used as a tertiary advanced treatment for the removal of dissolved species; organic compounds; phosphorus; nitrogen species; colloidal and suspended solids; and human pathogens, including bacteria, protozoan cysts, and viruses.
Membrane bioreactors—usually microfiltration (MF) or ultrafiltration (UF) membranes immersed in aeration tanks (vacuum system), or implemented in external pressure-driven membrane units..
Low-pressure membranes—usually MF or UF membranes, either as a pressure system or an immersed system, providing a higher degree of suspended . UF membranes are effective for virus removal.
High-pressure membranes—nanofiltration or reverse osmosis pressure systems for treatment and production of high-quality product water suitable for indirect potable reuse and high-purity industrial process water. Also, recent research has shown that microconstituents, such as pharmaceuticals and personal care products, can be removed by high-pressure membranes.
Page18 of 34
Nanotechnology
Further dramatic improvements are feasible in the near future (Shannon et al., 2008). Nanotechnology concepts are being investigated for higher performing membranes with fewer fouling characteristics, improved hydraulic conductivity, and more selective rejection/transport characteristics. Advances in RO technology include improved membranes and configurations, more efficient pumping and energy-recovery systems, and the development of process technology, such as membrane distillation (Kim et al., 2008).
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Microbial Fuel Cells
With microbial fuel cells, a potential breakthrough technology, electrical energy could be extracted directly from organic matter present in the waste stream by using electron transfer to capture the energy produced by microorganisms for metabolic processes (Logan et al., 2006). First, microorganisms are grown as a biofilm on an electrode; the electron donor is separated from the electron acceptor by a proton exchange membrane, which establishes an electrical current. Electrical energy is then generated through the oxidation of organic matter (BOD5).
Although this technology is still in the early stages of development and significant advances in process efficiency and economics will be necessary, it has the potential to produce electrical energy directly from organic matter in the waste stream.
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Natural Treatment Systems
Our fundamental understanding and characterization of processes in natural treatment systems (NTSs) is also improving, enabling us to take advantage of natural processes to improve water quality (Kadlec and Knight, 1996). In NTSs, a variety of physical, chemical, and biological processes function simultaneously to remove a broad range of contaminants.
For example, NTSs are increasingly being used to capture, retain, and treat storm water, thereby converting this “nuisance” into a valuable source of water. These natural systems have the advantage of being able to remove a wide variety of contaminants, including nutrients, pathogens, and micro-constituents (e.g., pharmaceuticals and endocrine-disrupting chemicals). Long proven effective for treatment of potable water, NTSs are increasingly being used for water reclamation.
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Urine Separating Toilets
The development of urine-separating toilets and technologies for treating urine to produce hygienic fertilizer products is a key to managing nutrients with minimal requirements for outside resources, such as additional energy (Larsen et al., 2001; Maurer et al., 2006). Urine-separating toilets have already been developed and continue to be refined, and research on using them for waste management is ongoing. Struvite precipitation and other processes are already available for producing usable fertilizer products from separated urine, and efforts are ongoing to improve the established approaches.
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Case Studies-1Wastewater Reuse in Europe
In Europe the last two decades has witnessed growing water stress, both in terms of water scarcity and quality deterioration, which has prompted many municipalities to look for a more efficient use of water resources, including a more widespread acceptance of water reuse practices.
The study identified more than 200 water reuse projects as well as many others in an advanced planning phase.
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Identifable Water reuse projects in Europe,including their size and intended use
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Conclusion
Almost all medium- and large-scale schemes have been designed as add-on technology to conventional secondary treatment processes.
Despite the fact that water reuse is already becoming an essential and reliable water supply option for many municipalities, there is still significant potential for an increased utilisation of reclaimed wastewater.
The water sector in Europe is in a transitional phase with unique opportunities for water reuse to be implemented on a larger scale as a sustainable practice within a framework of integrated water management.
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Case Study-2Waste water quality and reuse in irrigation in Kuwaitusing microfiltration technology in treatment
Micro filtration (MF) unit has been tested in Kuwait Institute for Scientific Research to treat the secondary wastewater effeulant from Riqqawastewater treatment plant.
There was a consistent reduction in biological oxygen demand (BOD), Chemical oxygen demand (COD), Total bacterial count (TBC) and total suspended solid (TSS).
The comparison is based on calculation sodium absorption ratio (SAR), residual sodium carbonate (RSC), adjusted SAR, sodium hazards (SSP), and measured parameters such as the electrical conductivity (EC), chloride, calcium and potassium concentration, total suspended solids, trace metal analysis and other parameters of health significance.
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Conclusion
Mf filtrate water will not cause any clogging problem related to its EC, SAR, and ESP.
Only chloride potential might causes a moderate potential problem
The MF product water satisfied all the microbiological and organic matter restrictions and standards
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Case Study-3The risks associated with wastewater reuse and xenobiotics in the agroecological environment
The technological progress in respect to analytical chromatographic methods has enabled the identification and quantitation of a number of organic xenobiotic compounds in treated wastewater.
It is also widely accepted that the currently applied treatment processes for urban wastewater abatement fail to completely remove such contaminants and this lead to their subsequent release in the terrestrial and aquatic environment through disposal and reuse applications.
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Conclusion
Since the traditional wastewater treatment methods are not capable of fully removing recalcitrant xenobiotic compounds, advanced technologies must be applied such as Advanced Oxidation Processes (AOPs) and membrane-separation technologies, which are effective in simultaneously removing, both pathogens and xenobiotics, and perhaps their combined application may constitute today, the best option for wastewater treatment and reuse schemes.
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Case Study-4Ultrafiltration for the reuse of spent filter backwash waterfrom drinking water treatment
During most water treatment processes, spent filter backwash water (SFBW) is generated.Innovations in membrane technology, especially in micro- and ultrafiltration processes, offer a suitable treatment for SFBW in order to guarantee a water quality necessary for reuse.
Experiments were performed with SFBW from a full-scale water treatment plant. The plant was operated with high fluxes of more than 40 L/(m2·h) using clarified and non-clarified SFBW. Best membrane performance was obtained using non-clarified SFBW.
As a result, no space- and time consuming sedimentation processes are necessary.Results confirmed that the filtrate can be used as an additional and safe water source. When a continuous maintenance disinfection was provided, filtrate was free of microbial contamination and could be reused without any safety concerns.
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Listing of References
1. U.S. Environmental Protection Agency, Process Design Manual: Guidelines/or Water Reuse.Cincinnati, Ohio, 1992 (Report No. EPA-625/R-92-004).
2. US Environment Protection Agency ,1992. Guidelines for Water Reuse
3. http://cdmsmith.com/en/Insights/Viewpoints/Membrane-Technology-Advances-Wastewater-Treatment-and-Water-Reuse.aspx
4. D Bixtio, C. Thoeye, J. De Koning, D Joksimovic, D. Savic, T Wintgens, T. Melin:Wastewater Reuse in Europe;Desalination 187(2006) 89-101
5. M. Al-Shammiri*, A. Al-Saffar, S. Bohamad, M. Ahmed; Waste water quality and reuse in irrigation in Kuwait using microfiltration technology in treatment; Desalination 185 (2005) 213–225
6. D. Fatta-Kassinosa, , , , I.K. Kalavrouziotisb, P.H. Koukoulakisc, M.I. Vasqueza The risks associated with wastewater reuse and xenobiotics in the agroecologicalenvironment Volume 409, Issue 19, 1 September 2011, Pages 3555–3563
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7. Florian G. Reissmanna*, Wolfgang Uhlb; Ultrafiltration for the reuse of spent filter backwash water from drinking water treatment;Desalination 198 (2006) 225–235
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TITLE SLIDE Reuse of Treated wastewater
What is Wastewater Reuse
Reasons for Wastewater Reuse
Types of Reuse
Technical Description
Application of Treated Wastewater
Historical Examples
Constituents to be checked in Reclaimed Water
Problems associated with Wastewater Reuse
Reclaimed wastewater can be safe for agricultural irrigation
Guidelines and Regulations
Page 33 of 34
Some Wastewater Reuse Advantages and Disadvantages
New Technologies and Approaches Used In Wastewater Reuse
Membrane Filtration Systems
Nanotechnology
Microbial Fuel Cells
Natural Treatment Systems
Urine Separating Toilets
Case Studies-1 Wastewater Reuse in Europe
Case Study-2 Waste water quality and reuse in irrigation ...
Case Study-3 The risks associated with wastewater reuse a...
Listing of References
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