Treated sewage discharges

Formulating a hypothesis Residual chlorine in treated sewage, discharged into the river, is killing the fish. 

Example 17.1 It is desired to design a bromide chloride contact tank to be used to disinfect a secondary-treated sewage discharge. To determine the contact time, an experiment was conducted producing the following results ... 

Sites with potential for soil and groundwater contamination, due to inadequately treated sewage, discharge of manufactured or agricultural wastes, the dumping of toxic wastes, or even runoff from nearby golf courses, should be considered problematic. 

The widespread use of ABS, mainly in laundry detergents, and their subsequent discharge into the sewer, however, led to the unexpected effect of strong foam formation in sewage water, treated sewage and even in river water [5,6]. This observation was directly related to the physical properties of the surfactant that had originally been responsible for its great success. 

Impact of discharges of treated sewage on surface water quality... 

As pharmaceuticals and their metabolites find their way to the environment primarily via the discharge of raw and treated sewage from residential users or medical facilities, most information on their occurrence and fate is related to WWTPs and the receiving waters. Much less is known about their presence in DWTPs and finished (tap) water. This can be attributed not only to the performances of the analytical technologies to detect a diverse range of low levels... 

Over the last years, a renewed interest on the antibiotic resistance phenotypes in municipal waste water treatment plants became apparent in the scientific literature. The underlying hypothesis of these smdies is that urban sewage treatment plants are potential reservoirs of antibiotic resistance, and, in general, it is aimed at contributing to assess the risks of dissemination, posed by the treated effluents discharged into natural water courses. As a general trend, these studies focus on human/animal commensal and environmental bacteria, frequently disseminated via faecal contamination, and which can survive in waters. The relevance of these bacteria, which may exhibit clinically relevant resistance phenotypes, as possible nosocomial agents seems also to be a motivation behind these smdies. 

The presence of other discharge sources can influence the interpretation of the hazard estimate of both the ZPE and LTF schemes. These discharge sources could be either point (e.g., treated municipal sewage discharge) or non-point (e.g., bark or chip pile runoff), entering the watershed up-stream or within the immediate nearfield zone that receives the industrial effluent. 

Total metal concentrations in the Mississippi River are elevated somewhat over average river waters (Table IV), except for polluted areas. The elevated concentrations of copper, cadmium, and lead at Site 4 compared to Site 3 are in part attributable to the discharge of treated sewage effluent and urban runoff. The Minnesota River may be important for all metals studied with the exception of cadmium. Under low flow conditions, 10 to 50% of the trace metal load to the Mississippi... 

It is useful to be familiar with the treatment process, to monitor the changes that occur after the introduction of the treatment, to characterize chemically and microbiologically the treated efQuent, and to determine its dispersion in the receiving waters. It appears that, at least in the UK, the impact of sewage discharge on the marine environment is relatively minor and the main factor responsible for this is high initial dilution [154]. Without sufficient dilution, eutrophication is the most likely consequence, as demonstrated for example by a case study [155]. 

Wastewater discharged into sanitary sewers includes domestic sewage, commercial wastewater and to some extent industrial wastewater. The waste-water is typically transported by gravity to a municipal wastewater treatment plant, where the waste is treated before discharge into a receiving stream. In communities that do not have separate storm water sewers, the sanitary sewers may also serve to convey storm runoff to the wastewater treatment facility. 

Federal Water Pollution Control Act, as amended by the Water Quality Act of 1965 (3 U.S.C. 466e(g)). Provides for financial assistance to States or municipalities for construction of facilities in connection with the prevention and control of water pollution. This includes projects that will control the discharge into any waters of untreated or inadequately treated sewage. 

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