Secondary sewage treatment

Both the primary and secondary processes produce a material called sludge, which is a mixture of particulate matter and living and dead microorganisms. The sludge is dried and disposed of by incineration or in a landfill. It can even be spread on certain types of cropland, where it acts as a fertilizer. 

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Other appHcations of firefly hioluminescence include measurement of the activity of bacteria in secondary sewage treatment activated sludge (296,297), detection of bacteria in clean rooms and operating rooms, measurement of bacteria in bottled foods, beverages (298), and pharmaceuticals (299), determination of the antimicrobial activity of potential dmgs (300), determination of the viabiHty of seeds (301), and measuring marine biomass concentrations as a function of ocean depth or geographical location (302). 

Secondary sewage treatment (final clarifiers—activated sludge and trickling filters) 0.55-0.7 1.5-2... 

Secondary sewage treatment (final clarifiers—activated sludge and ... 

Activated sludge aeration stage for a smallscale secondary sewage treatment plant operating at Central Saanich, British, Columbia. 

The Mill Cove plant is a conventional secondary sewage treatment plant with preliminary treatment, primary settling, activated sludge treatment, secondary settling and finally UV. Biosolids are treated by anaerobic digestion and transported to a lagoon. It has been in operation since 1969 and expanded in 1981, to treat 22.5 million litres per day. It is now capable of treating more than 31.5 million litres per day. 

The Lancaster sample is from the Lancaster secondary sewage treatment plant of the city of Saint John, New Brunswick, but the plant treats only a fraction of the generated sewage. The Strawberry Marsh sample is from a similar plant of the city of the Miramichi in northern New Brunswick (previously called Newcastle). 

Total suspended solids, pH, temperature, flow, and oils and grease are typical measures that must be reported. In the case of a secondary sewage treatment, the minimum stemdmds for BODj, suspended solids, and pH over a 30-day averaging period are 30 mg/L, 30 mg/L, and 6-9 pH, respectively. In practice, these limits wUl be more stringent, and in many cases there will be separate conditions for summer and winter conditions as well as case-by-case limitations. 

Carbon adsorption m. Secondary sewage treatment process... 

If primary treatment is all that the wastewater undergoes, then sometimes chlorine is added to kill a majority of the bacteria before the wastewater is returned to the waterways. It still contains a high BOD, though. So if the waterway is a lake or slow-moving stream, then the high BOD causes problems — especially if a number of towns use the same type of sewage treatment. The problems can be prevented with secondary sewage treatment. 

FIG. E-22 Motor-driven aeration pumps in secondary sewage treatment operation. (Source Reliance Electric.)... 

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