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Pathogens and Biosolids

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Pathogens and Biosolids

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    1. Pathogens and Biosolids George A. O’Connor, SWSD, UF with input from Jim Smith, USEPA & Ian Pepper, UA

    3. What are biosolids?

    4. Biosolids characteristics Nutrient-rich, mostly organic material Useful as fertilizer or soil amendment Improve and maintain productive soils. Improves soil biological, chemical, and physical properties modestly Slow-release nutrient source of N, S, P, and micronutrients Harmless to human health or the environment when managed correctly.

    5. Biosolids use 8 million dry tons produced nationally each year: In 1988, 35% land-applied. In 2003, 65% land-applied. In Florida: 300,000 dry tons produced each year. 83% used beneficially. Additional 100,000 dry tons of Class AA pellets imported annually.

    6. Biosolids regulations Federal (EPA) Title 40 CFR Part 503 (came from Clean Water Act). State In Florida, the Fla. Dept. of Environmental Protection enforces Chapter 62-640, Florida Administrative Code.

    7. How do regulations assure safety? Controls are in place to protect public health: Prevent contact with pathogens Limit potential pollutant/metals impacts Limit potential nutrient impacts

    8. Pathogen controls Pathogen reduction: Class B – “PSRP” (significantly reduce) Class A – “PFRP” (undetectable) Vector attraction reduction Site restrictions (Class B): Limited public access, setbacks, harvesting and grazing restrictions, slope, groundwater, etc.

    9. Biosolids classes in Florida

    10. Pathogens of Concern Bacteria Viruses Protozoa Helminth worms

    11. Bacterial Pathogens of Potential Concern in Biosolids Major Concern - Classic Salmonella Shigella enteropathogenic E. coli Yersinia enterocolitica Campylobacter jejuni Vibrio cholera Leptospira New issues - changes E. coli 0157:H7 Listeria Helicobacter Mycobacteria Aeromonas Legionella Burkholderia Endotoxins Antibiotic resistance

    15. Dose Response Data Viruses and Parasites Typically have been most concerned about effects on human health and so approach has been to reduce through some form of management the levels of pathogens to below that needed for infection. Often this has meant reducing the organisms to below the detection level with current analytical capabilities.Typically have been most concerned about effects on human health and so approach has been to reduce through some form of management the levels of pathogens to below that needed for infection. Often this has meant reducing the organisms to below the detection level with current analytical capabilities.

    16. Survival Times of Pathogens on Soils and Plants While some level of treatment may occur for example in: septic tank hog waste lagoon wastewater treatment plant…..etc. Need to think about what happens in the soil or with passage over the soil and through grasses/plants…and on the way to the stream. See here quite a difference for life of microbes in the soil or on the soil / plants.While some level of treatment may occur for example in: septic tank hog waste lagoon wastewater treatment plant…..etc. Need to think about what happens in the soil or with passage over the soil and through grasses/plants…and on the way to the stream. See here quite a difference for life of microbes in the soil or on the soil / plants.

    17. Class A Biosolids Requirements Pathogens Fecal coliform density <103 MPN/g or Salmonella sp. density <3 MPN/4g and Vector Attraction Reduction Treatment Alt. (Table 5-1) Thermal (1 of 4) High pH/ temp/dry Other – demo Unknown – test PFRPs (Table5-4) Equivalent PRFP

    18. Concentration Fecal Coliform vs Probability Detecting Salmonella

    19. A review of the Class A processes… One plot applies when the total solids are > 7%; t > 50ºC and time is > 20 minutes. If the sludge particles are small and are heated by warmed gases or an immiscible liquid, the minimum time is 15 seconds. This equation also applies when the solids <7%, t >50ºC and time is > 15 sec to <30 min. Another plot applies for total solids < 7 %; t > 50ºC and D > 30 minutes. A review of the Class A processes…

    20. Class B Biosolids Requirements Pathogens Fecal coliforms < 2 x 106 MPN/g or <2 x 106 CFU/g and Vector Attraction Reduction and Natural Attenuation Treatment Alternatives (Table 5-5) Monitor indicator organisms PSRPs (Table 5-7) Equivalent PSRP Site Restrictions Crop Time Public access (Table 5-6)

    22. Vector Attraction Reduction Purpose Reduce attractiveness of biosolids and pathogens to vectors (Options 1-8), or Prevent vector contact with biosolids (Options 9-11) Options (Table 5-8) Reduce volatile solids Additional digestion (anaerobic or aerobic) Reduce SOUR Alkali addition Drying Inject/incorporate

    23. Are pathogen requirements protective? Yes Class A – essentially pathogen-free Class B – contain pathogens, but additional site restrictions and management practices provide protection Generally, Class A = Class B + Site restrictions + Management Practices

    31. Definitions “Domestic wastewater residuals.” The solid, cake, or liquid material generated during domestic wastewater treatment. Wastewater treatment produces effluent and residuals (a.k.a. sewage sludge, biosolids).

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