Waste disposal and decomposition

1. Waste disposal and decomposition

2. Options for sewage disposal Landfills: problems with cost, availability, ground-water pollution, liquid content, methane production. Incineration; problems with location, NIMBY, Not In My BackYard Oceans: the “Victoria” solution, Seattle’s Lake Washington and Puget Sound experience.

3. Some developments leading to recycling In the 1950’s demonstration by Professor Tommy Edmondson that the Lake Washington ecosystem had been substantially changed due to discharge of effluent. Nitrogen pollution In 1958 voters in Seattle and King County created Metro, an agency charged with creating a regional wastewater treatment system. In 1966 construction of a primary treatment plant completed at West Point with discharge into Puget Sound. 1972 Federal Clean Water Act In 1972 first biosolids applications at Pack Forest In 1991 Metro begins an expansion of the plant West Point plant

4. Recycling The principle is: (1) to use a treatment plant to remove soluble nitrogen from the effluent and kill pathogens, and (2) to apply the solid processed from bacterial matter to agricultural fields, forests, and land requiring re-medial treatment There are problems associated with: Quantities and collection Biology and engineering of treatment Recycling through biosolids application

5. Quantities and Collection In King County 95% of the wastewater is from homes and businesses, with only 5% from industries At the West Point plant: Total Suspended Solids loading (average annual) 181,000 lbs/day Biosolids produced 53,409 wet tons; 13,277 dry tons per year Reclaimed water used 0.61 mgd Electricity generated 7,437,972 kilowatt hours Outfall 3,600 ft. offshore; 240 ft. deep; 500 ft. diffuser Annual budget for King County: Operating, $82 million; Capital, $96 million

6. Two waste water treatment plants in King County Average daily capacity of the West plant is 133 million gallons per day

7. Biology and engineering of treatment Most organic matter is converted by micro–organisms to inorganic forms. This process is called mineralization. Large molecules will first be broken down to smaller ones by bacterial exo-enzymes, enzymes that bacteria excrete. The most important organisms involved in these conversions are heterotrophic bacteria. It is extremely difficult to identify bacterial genera, let alone species, from water purification systems, but it is obvious that the genera Flavobacterium and Pseudomonas are important.

8. Overview of treatment

9. West Point Treatment Plant Secondary treatment Primary treatment Screen Skim and settle solids Grit chamber High Purity Oxygen activated sludge process Chlorination Settled biomass Puget Sound Methane Blend Centrifuge Thicken Solids processing Anaerobic bacterial digestion Heat O2 + bacteria + dissolved and suspended organic matter Nitrogen removal into biomass

10. Nitrogen metabo;ism mean cell residence times Nitrogen is incorporated into microbial biomass. Two types of bacteria process ammonium to nitrate http://bark214-3.berkeley.edu/MCB290/illana.htm

11. Anaerobic sludge digester http://bark214-3.berkeley.edu/MCB290/illana.htm

12. Anaerobic methane production 30% of power for the plant Electricity sold to Seattle City Light

13. Problems! We do not know the precise composition of bacteria in either the aerobic or anaerobic processes. Plating out and culturing provides micro-organisms with a very different environment than found in the tanks There is some hope to use new DNA/RNA identification techniques to identify bacteria and seek ways of improving processing rates

14. Increased treatment capacity will be needed What will happen in the future? A third plant will be added. But there is resistance to expanding the processing area of existing plants although their current capacity may be exceeded

15. 350 feet deep processor Temp and O2 control systems A 350 feet deep processor is being investigated!!

16. Recycling through biosolids application What we do not have! Some regulations Seattle Biosolids Applications The “Cornell” recommendations

17. What we do not have!

18. What we need to avoid Giardia lamblia trophozoites, as they appear with the scanning electron microscope.  Original image by Arturo Gonzalez, CINVESTAV, Mexico. http://www.biosci.ohio-state.edu/~parasite/giardia_sem.html

19. Some regulations A Plain English Guide to theEPA Part 503 Biosolids Rule http://www.epa.gov/owm/bio/503pe/ The EPA breaks down land application of biosolids into 4 categories: Agricultural lands, Forest lands, Reclamation sites, and Public contact/Home lawns & gardens.  Each land application category has its own set of requirements according to WAC 173-308-210, 220, 230, 240, and 250.  Washington state has adapted the federal EPA rule 40 CFR 503 standards to its own rule, Chapter 173-308 WAC. 

20. Different rules for different classes of biosolids. Class A biosolids contain no detectible levels of pathogens and and meet strict vector attraction reduction requirements and have low levels of metals. Permits are required to ensure that these standards have been met. Class B biosolids are treated but still contain detectible levels of pathogens. There are buffer requirements, public access, and crop harvesting restrictions for virtually all forms of Class B biosolids.

21. Class A Biosolids Class A production processes include irradiation, composting, heat drying, heat treatment, pasteurization, thermophilic aerobic digestion, and alkaline stabilization. Class A biosolids do not contain pathogens in sufficient quantity to warrant restricted access or special precautions and may be applied the same way as commercial fertilizer.

22. Alternative 1: Thermally treated biosolids Biosolids must be subject to one of the following four (4) time-temperature regimes: 7 percent solid or greater biosolids must be heated to 50 degrees Celsius of higher for 20 minutes or longer. 7 percent solid or greater biosolids in the form of small particles and heated by contact with either warmed gases or immiscible liquid must be heated to 50 degrees Celsius or higher for 15 seconds or longer. Biosolids less than 7 percent solid must be heated for at least 15 seconds but less than 30 minutes using the following equation: D=131,700,000/100.14 t Biosolids less than 7 percent solid must be heated to 50 degrees Celsius of higher with at least 30 minutes of longer contact time. There are chemical alternatives for application of alkaline

23. K-S Nara Paddle Dryer/Cooler

24. Class B Biosolids King County biosolids are anaerobically digested at the treatment plant to meet Class B pathogen reduction. Further reduction does take place after application in what King County (and other processors) refer to as a hostile environment for microbes In practice odor is a principal restriction to the location where Class B biosolids can be applied. This can be reduced by chemicals

25. EPA Class B biosolids site restrictions Restricted ActivitySite Restriction Harvest of food crop touching ground 14 months after application Harvest of root crop (see next condition) 20 months after application Harvest of root crop if sludge on surface 38 months after application Harvest of other food, feed, and fiber crops 30 days after application Grazing of animals 30 days after application Harvest of turf for high contact site, 1 year after application e.g., golf course or lawn; or public access to turf Access to sites with high potential for Restrict for 1 year public exposure Access to sites with low potential for Restrict for 30 days public exposure

26. Biosolids Quality from the West Point Plant2000 Average Total Solids 24.8% Ammonia Nitrogen 1.2% Organic Nitrogen 5.5% Phosphorus 1.9% Potassium 0.3% Sulfur 1.1% By weight Organic nitrogen provides a sustained release of N

27. Trace metals in West Point biosolids West Point PlantNational and State Regulatory Standards mg/kg mg/kg Arsenic7.07541 Cadmium3.739 Copper 5291500 Lead 141 300 Mercury 2.7117 Molybdenum11.1under reconsideration Nickel35.1420 Selenium5.9736 Zinc8042800

28. “Dryland” soils program Improved moisture retention Increased growth – sometimes too much N

29. Forest Application

30. Reclamation Bunker Hill Wetland, Idaho Rapid establishment of vegetation Issues – returning to ‘natural’ vegetation may be retarded by high N

31. Four arguments against biosolids application 1. Odor and ‘unpleasantness’ 2. EPA is not doing its job to ensure compliance with its own regulations 3. Treatment and disposal should be local 4. Class B biosolids can cause illness to people applying them

32. Cornell University site management recommendations --Limiting applications to keep soil metals low;--Testing soils before application;--Applying only at agronomic rates;--Supplying all landowners with biosolids quality information;--Monitoring downstream water bodies and wells;--Calibrating application equipment;--Maintaining setbacks and buffers;--Avoiding application to areas prone to runoff;--Imposing access restrictions for the public. In practice most of these items are specified in Washington State and EPA regulations

33. Conclusion According to EPA estimates for 1993, approximately 33% of the 5.4 million dry metric tons of biosolids generated annually in the US is land applied This is increasing due to rising costs and less available space in landfills, regulations banning ocean dumping, and a move away from incineration.  So application to the land will increase and must be placed on a sustainable basis There is likely to be continued discussion as new regions consider biosolids application

34. Courses that deal with this topic ESC518, formerly Microbial Degradation, to Bioremediation Science CIVE 484 On-Site Wastewater Disposal CIVE 482 Water and Wastewater Treatment