Wastewater Reuse: Selected Applications EnvH 545 Steven Drangsholt, Lesley Leggett, Jennifer Parker, Ching-Yu Peng, Kelly Stumbaugh

Wastewater Plant Standards Some states have guidelines, some have regulations –Washington has guidelines EPA Suggested Guidelines –pH = 6-9 –BOD 5 ≤ 10 mg/L –Turb. ≤ 2 NTU –E. coli = NONE –Res. Cl 2 ≥ 1 mg/L

EPA Guidelines Urban Reuse Restricted-Access-Area Irrigation Agriculture Reuse Recreational Impoundments Landscape Impoundments Construction Uses Industrial Reuse Groundwater Recharge Indirect Potable Reuse Disinfected, Tertiary Treated Effluent can be used in all of these Applications

Secondary Effluent

Complete Treatment Expensive!!!! Filter can be several units Chemical Addition depends on SE

Direct Filtration No clarification – reduces solids production SE should be less than 10 NTU Filtration step may have several units

Contact Filtration No Floc Step, No Clarifier Relies on in-line coagulation Can produce equivalent virus kill with disinfection

How Effective? Constituent After secondary with BNR plus disinfection After secondary with BNR plus depth filtration and disinfection After secondary with BNR plus microfiltration, RO and disinfection TSS ≤ 1 BOD TN 2-12 ≤ 1 NO ≤ 1 Phosphorus ≤ 0.5 Turbidity 2-6≤ Bacteria ≤ 2.2≈ 0 Protozoan 5-10≤ 1≈ 0 Viruses ≤.0001≈ 0

Agricultural Reuse of Wastewater One of the most significant uses of reclaimed wastewater Water needed for irrigation in some states accounts for >80% of demand Regulations and guidelines vary widely from state to state Guidelines for food crop use (21 states) and non-food crop use (40 states)

Benefits of Agricultural Reuse High concentrations of nutrients May eliminate need for fertilizer Long-term soil enrichment Decreases demand on potable water supply Additional treatment in soil Water not discharged to receiving waters

Disadvantages of Agricultural Reuse Health risk from associated pathogens Health risk from other contaminants (e.g. metals, chemicals, pharmaceuticals) Decrease in soil quality from accumulation of metals and acidification Infiltration of groundwater

Agricultural Reuse in Washington Foods consumed raw –surface irrigation: water requires oxidation and disinfection with mean total coliforms < 2.2/100 ml –spray irrigation: water requires oxidation, coagulation, filtration, disinfection and total coliforms < 2.2/100ml Processed foods –only oxidation and disinfection, regardless of irrigation type, and a 7-day mean total coliforms < 240/100 ml

Urban Wastewater Reuse What is recycled urban wastewater or reclaimed water? –Urban wastewater that has undergone additional treatment following secondary treatment in order to be reused rather than discharged into the environment Can reduce strain on potable water supply

Urban Wastewater Reuse What can urban reclaimed water be used for? –Irrigation - public parks, schools, road medians, any landscaped areas, golf courses –Commercial - vehicle washing facilities, laundry facilities, window washing, mixing pesticides and herbicides –Construction - dust control, concrete production –Toilet and urinal flushing –Fire protection –Drinking water?? in Australia, not yet in the U.S.

Urban Wastewater Reuse A reclaimed water system consists of: Water reclamation facility - provides treatment in addition to secondary treatment Distribution system - includes pipelines, storage facilities, pumping facilities

Urban Wastewater Reuse Reclaimed water distribution system is a dual distribution system Network of pipes to deliver reclaimed water to the public Run separate but parallel to potable water pipelines Potential problem???? CROSS CONNECTIONS!!!

Urban Wastewater Reuse Major considerations are public health and reliability of the system –Water must be of acceptable quality for intended uses –System must be maintained and operated properly –Reclaimed water pipes must be clearly marked

Urban Wastewater Reuse Retrofitting reclaimed water system in existing cities can be expensive BUT can be cost-effective if: –Water supply is of poor quality –Water supply does not meet demand –Advanced wastewater treatment already required

Urban Wastewater Reuse St. Petersburg, FL –Using reclaimed water system since 1977 –Provides for residential & commerical properties, baseball stadium, schools San Diego, CA Ponoma, CA –Serves CA Polytechnic Institute, paper mills Austin, TX Tucson, AZ

Urban Wastewater Reuse In the news… California county turns to sewer water to increase drinking supplies International Herald Tribune, Nov. 27, 2007 “ On Friday, the Orange County Water District will turn on what industry experts say is the world's largest plant devoted to purifying sewer water to increase drinking water supplies. They and others hope it serves as a model for authorities worldwide facing persistent drought, predicted water shortages and projected growth.” “San Jose-area water officials announced a study of the issue in September, water managers in southern Florida approved a plan last week calling for abundant use of recycled wastewater in the coming years in part to help restock drinking water supplies, and planners in Texas are giving it serious consideration.”

Residential Wastewater Reuse Why reuse wastewater at home? –Conserve precious drinking water supply Droughts Arid climates Overuse or population overwhelming supply –Save money –Reduce environmental impact associated with wastewater treatment & disposal

Residential Wastewater Reuse Greywater: –Wastewater from sinks, bathtubs, showers, dish washer, laundry (anything except toilets) –May contain pathogens, likely to contain other microbes, detergents, FOGs, bleach, hair, food particles, suspended solids –Not for potable reuse unless tertiary treatment

Residential Wastewater Reuse Simple home water reuse: –Collect warming tap water in bucket –Hose from sink drain to outdoors planter box More complex home water reuse: –Divert greywater to underground lawn/garden irrigation system –Commercial treatment & reuse systems

Residential Wastewater Reuse Commercially available greywater treatment & recycling

Residential Wastewater Reuse Commercially available greywater treatment & recycling

Residential Wastewater Reuse Custom designed system in Sydney, Australia

Residential Wastewater Reuse Healthy Home System in Toronto, Canada

Groundwater Recharge California Florida Source: US EPA. Guidelines for water reuse

Groundwater Recharge - Purposes establish saltwater intrusion barriers provide further treatment for future reuse increase potable or nonpotable aquifers provide storage of reclaimed water for subsequent retrieval and reuse control or prevent ground subsidence

Less cost than equivalent surface water reservoirs The aquifer serves as an eventual natural distribution system No evaporation, taste and odor problems occurred in surface reservoirs Suitable sites for surface water reservoirs may not be available or environmentally acceptable Groundwater Recharge - Advantages

Extensive land areas may be needed for spreading basins Costs for treatment, water quality monitoring, and injection/infiltration facilities operations may be expensive. Recharge may increase the danger of aquifer contamination due to inadequate pretreatment. Groundwater Recharge – Limitations (1)

Not all recharged water may be recoverable Hydrogeologic uncertainties may reduce the effectiveness of the recharge project in meeting water supply demand Inadequate institutional arrangements or groundwater laws may not protect water rights Groundwater Recharge – Limitations (2)

Source: US EPA. Guidelines for water reuse Groundwater Recharge – Techniques

TreatmentOxidized, coagulated, filtered, and disinfected BOD 5 5 mg/l TSS5 mg/l Turbidity2 NTU (Avg); 5 NTU (Max) Total Coliform2.2/100 ml (Avg); 23/100 ml (Max) Total NitrogenNot specified Groundwater Recharge – Guidelines (WA) Source: US EPA. Guidelines for water reuse

Conclusions Many current uses for recycled wastewater Varying levels of treatment required Pros: –Conserve potable water –Reduce effluent to environment Cons: –Health & safety precautions necessary –Careful planning needed Potential for much greater use in future

Questions?