Primary sewage treatment

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. 

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As a result of several studies, the following conclusions regarding viruses in sewage warrant consideration (1) primary sewage treatment has little effect on enteric viruses (2) secondary treatment with trickling filters removes only about 40 percent of the enteroviruses (3) secondary treatment by activated sludge treatment effectively removes 90 percent to 98 percent of the viruses and (4) chlorination of treated sewage effluents may reduce, but may not eliminate, the number of viruses present. 

Primary sewage treatment (settleable-solids ramoval) 0.4 2... 

The water is brought in from a lake, stream, or reservoir and initially filtered to remove sticks, leaves, dead fish, and such. The turbidity (haziness) that s commonly present in river or lake water is removed through treatment with a mixture of alum (aluminum sulfate) and lime (calcium hydroxide), which forms gelatinous aluminum hydroxide and traps the suspended solids. This is basically the same treatment used in wastewater treatment plants (see Primary sewage treatment . ... 

Secondary Emissions from Basic Oxygen Process Steelmaking Facilities for Which Construction Commenced after January 20, 1983 Sewage Treatment Plants Primary Copper Smelters Primary Zinc Smelters... 

Sewage treatment plants Primary copper smelters... 

The primary biodegradation grades of secondary alkanesulfonates measured by different tests are distinctly above 90%. In the OECD Confirmatory Test (sewage treatment plant simulation test), the biodegradability is 99% (decrease in MBAS, the methylene blue active substance). 

Fig. 2.1.3. Selected ion chromatograms for C14-C17-SAS homologues in (a) primary effluent and (b) secondary effluent collected from a sewage treatment plant. Reproduced with permission from Ref. [35]. 1994 by American Chemical Society.

Static die-away tests were performed by Potter et al. with an A9PEO7 24 mixture in water from a vertically well-mixed estuary in Florida [36]. Lag times of 0—12 days were observed, and after 4—24 days, primary degradation was complete. These rates are similar to those reported by Kvestak and Ahel [6]. It is likely that the microorganisms in these experiments were pre-acclimated to biodegrade nonionic surfactants, as a municipal sewage treatment plant discharge is present a few kilometres upstream. 

Raw primary sewage sludge (municipal treatment plant, Kogalim) 0.75 2.6 4.2 25 Low hazard... 

Watershed types are based on the primary sources of N to each estuary. Watersheds dominated by urban N sources (e.g., point, septic, and non-point source runoff) were classified as urban, watersheds dominated by agricultural N sources (e.g., fertilization, fixation, and manure) were classified as agriculture, and watersheds dominated by atmospheric N deposition were classified as atmospheric. Effluent from sewage treatment plants in the Barnegat Bay watershed is discharged offshore sewage inputs to the Barnegat Bay estuary are from septic systems in the watershed. Modified from Castro et al. (2003). 

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