Untreated sewage discharges

Discuss the sources of coastal water pollution in the Asian region focus your attention on untreated sewage discharge. 

Chemical pollution From a qualitative point of view, an important common issue is the excess of chemicals (fertilisers and pesticides) associated with agrarian and livestock farming diffuse sources and the point-source discharge of (treated and untreated) sewage water. Industrial point-source pollution is not addressed as a relevant issue, but it is assumed that industries operate following the legal rules and only the incomplete elimination of industrial chemicals in urban wastewater treatment plants is perceived as a problem. 

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

Poorly maintained or damaged sewers that leak may also contaminate water resources. Where sewers run close to drinking-water mains there is a danger that more direct contamination through ingress into the water mains may occur. System failures may also lead to the discharge of untreated sewage into water bodies. 

Discharge of untreated sewage of the properties outlined, if permitted, could only be satisfactory if two composite requirements are met (1) There is... 

Similar considerations apply to the discharge of untreated domestic effluent to the sea [32]. Raw sewage discharge into shallow, poorly mixed salt-waters can give the same problems with anaerobic decomposition producing odors and microbial contamination on the shoreline and surrounding air, as would be experienced with a small river or a lake [33]. 

Furthermore, due to high nutrient load at points of direct sewage discharge, it was found that macrophytes like water hyacinth flourish best near shore. Several sites, like the Homa Bay, Hippo Point and River Kisati, receive high loads of untreated sewage and industrial wastes. Water hyacinth also flourishes at the off shore of these sites. 

Attention to the public health challenges posed by CSO sewers focus on control of pathogen dispersion. From NPDES perspectives, CSO systems are restricted from discharging untreated sewage during periods of dry weather. 

In the majority of developed areas, municipal sewage treatment means the purification of wastewaters coming from domestic, institutional, commercial and industrial activities, combined with street and other hard surface run-off, all carried by a sewerage system and delivered to a treatment works owned by the municipality or by a private operator. Its objective is to convert this mixed waste into a treated liquid effluent that may be safely returned to the natural environment. Untreated sewage, on discharge to a watercourse for example, would consume oxygen, thus... 

This stratified estuary has a depth of 40 m, with an upper fresh or brackish water layer of 0.2-4 m, depending on the river flow. The main source of pollution is untreated municipal wastewater, which is discharged into the estuary. Water samples were collected at different distances from these sewage outlets at two water depths from the fresh and the marine water layers. Furthermore, at one location, a vertical profile of the water column was made, including a sample of the water surface micro layer. Total A9PEOn, and individual AgPEOi, A9PEO2 and NP concentrations were determined with normal phase HPLC-FL analysis. 

Phenol has been detected in the effluent discharges of a variety of industries. It was found in petroleum refinery waste water at concentrations of 33.5 ppm (Pfeffer 1979) and 100 ppb (Paterson et al. 1996), in the treated and untreated effluent from a coal conversion plant at 4 and 4,780 ppm, respectively (Parkhurst et al. 1979), and in shale oil waste water at a maximum of 4.5 ppm (Hawthorne and Sievers 1984). It has also been detected in the effluent from a chemical specialties manufacturing plant at 0.01-0.30 ppm (Jungclaus et al. 1978), in effluent from paper mills at 5-8 ppb (Keith 1976 Paterson et al. 1996), and at 0.3 ppm in a 24-hour composite sample from a plant on the Delaware River, 2 and 4 miles downriver from a sewage treatment plant (Sheldon and Hites 1979). 

Even where sewage is supposed to be treated prior to discharge, such as in the industrialized countries of North America and western Europe, untreated effluents are still periodically emitted. These emissions are the result of breaks in sewer lines, pump feilures, and combined sewer overflows (CSOs). CSOs occur in sanitary sewer systems that, intentionally or not, merge wastewaters with stormwater runoff The stormwater flows are usually too large for the treatment plants to handle, leading to the discharge... 

Singh, K.P., Mohan, D., Sinha, S., Dalwani, R., 2004. Impact assessment of treated/untreated wastewater toxicants discharged by sewage treatment plants on health, agricultural, and environmental quality in the wastewater disposal area. Chemosphere 55, 227-255. 

The river waters in the Asian region are often heavily contaminated by municipal sewage, industrial effluent and sediments, which form the most important sources of pollution. Of the estimated total of 13.5 x 10 tons per year of sediment transported by the World s rivers, Asian rivers accounted for nearly 50%, although they constitute only 17% of the World s total drainage area. Basically, this is the result of lack of sanitation, discharge of untreated industrial effluents into the rivers, and sediment... 

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