Environmental Technology Wastewater Management Module 6.0

Historically... u In 1848 in London, England 14,600 people died of cholera and dysentery u In 1856 in London, England 10,675 people died of cholera and dysentery..a pattern maybe? u human wastes were contaminating the city’s water supply

Obj 6.1: Wastewater defined......is used water, or…...is used water, or… u the water supply of a person and/or community that has been used for a variety of purposes

Obj 6.1: Wastewater “Strength” u BOD u TSS u Nitrogen u Phosphorus u Pathogens u Untreated sewage is about 99.9% water and only 0.1% impurities and solids

Wastewater “Strength” u Biochemical Oxygen Demand: high demand indicates lots of organics and micro-organisms u Total Suspended Solids: typically only 0.1% of total sewage u BOD u TSS

Wastewater “Strength” u compounds of Nitrogen such as ammonia, nitrites, and nitrates (~35mg/L) u Phosphor compounds such as phosphates (~10mg/L) u Nitrogen u Phosphorus

Wastewater “Strength” u Protozoa, bacteria, and other disease causing organisms u E.coli indicative of human waste u detected by Coliform test u Pathogens

Obj 6.2: Contributors to Sewage Flow u residential land uses (sanitary sewage) u commercial/institutional land uses (sanitary sewage) u industrial/manufacturing land uses (industrial sewage) u infiltration into sewer system u stormwater (for combined sewers)

Sanitary Obj 6.4: Storm vs Sanitary Sewers? Similarities u both are converging systems u both use pipes and manholes u both use Manning’s Equation to examine flow characteristics

Sanitary Obj 6.4: Storm vs Sanitary Sewers? Differences u Inflow: storm sewers open to air; sanitary sewers are closed to air. u Outflow: storm sewers are fragmented and with several discharge points; sanitary sewers are continuous leading to a sewage treatment plant

Combined Systems u Some cities still have combined storm and sanitary sewers u if system overflows during heavy rains, raw sewage gets into natural watercourses u combined sewer overflow u combined sewer overflow (CSO) storage tanks u (Figure 8.1 Nathanson)