Biological Processes Flashcards
Anaerobic decomposition
When organic matter decays under the absence of oxygen
End products include: CH4, CO2, NH3
issues: large land areas required, sludge does not dewater, production of hydrogen sulfide
Mesophilic Bacteria
Convert organic acids to methane, have very slow growth rates, 85-100F
Thermophilic Bacteria
Convert organic acids to methane, have very slow growth rates, 120-135F
Composting
Aerobic
end product is partially decomposed organic fraction
natural process, backyards, good soil conditioner
aerobic microorganisms extract energy from the organic matter through a series of exothermic reactions that break down the material into simpler materials
temperature increases, destroys most bacteria
Composting Organic Wastes
a passively aerated compost system consists of shredded and/or screened source-separated organic wastes placed in windrows
Composting MSW
very little use for compost that has glass, plastic, and potentially toxic materials
metals like Pb can present health concerns
odors are emitted
limited reduction in volume of waste
some feed stocks can be composted
agricultural wastes can be composted
sewage sludges are mixed with wood chips & compost