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T19+notes - Waste Disposal (Topic 19) Biosolids are the...

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Waste Disposal (Topic 19) Biosolids are the byproduct of municipal wastewater treatment and are also known as sewage sludge. Approximately 10 million tons of municipal sewage sludge are produced each year in the U.S.; about 75 lbs/person/yr. Sewage sludge is generally termed a biosolid to lessen the negative connotation. Sludge at a sewage treatment plant contains about 5% solids and 95% liquid and thus has the consistency of a slurry – a viscous liquid. How is it disposed of? 1. Reuse - Land application (50%) 2. Incineration (27%) ~$200 per ton 3. Landfill (19%) ~$100 per ton 4. Distribution and Marketing (4%) 5. Ocean dumping Concerns with sludge use 1. Pathogens 2. Heavy metals ( e.g., chromium, nickel, cadmium, lead, copper, zinc) 3. Nutrients ( e.g., nitrate and phosphate) 4. Toxic organic compounds ( e.g., PCBs, industrial wastes) 5. Soluble salts - a problem primarily in arid and semi-arid climates 6. Odor - can be minimized by deordorization or injection/incorporation into soil What is the role of soil in sludge disposal? Because of the ability of soil to act as a "living filter", land application of sludge is often the safest, most economical, and easiest method for disposal of sludge: 1. Decomposition/transformation by microorganisms 2. Plant and microbial uptake of nutrients
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This note was uploaded on 01/27/2011 for the course SSO 10 taught by Professor Randydahlgren during the Fall '10 term at UC Davis.

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T19+notes - Waste Disposal (Topic 19) Biosolids are the...

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