Assessment of seasonal effects of municipal sewage pollution on the water quality of an urban canal—a case study of the Buckingham canal at Kalpakkam (India): NO3, PO4, SO4, BOD, COD and DO

Abstract

The seasonal effects of untreated and treated municipal sewage on the nutrients-nitrate (NO(3)), phosphate (PO(4)), sulphate (SO(4)), and the biochemical oxygen demand (BOD), chemical oxygen demand (COD) and dissolved oxygen (DO) of the receiving urban canal, the Buckingham canal at Kalpakkam (Tamil Nadu, India) was monitored monthly during pre- monsoon-2005 to post-monsoon-2006. The NO(3), PO(4) and SO(4) contents were higher in the downstream than that of the upstream of the outfall points of treated as well as untreated sewage, of the canal. The NO(3) and PO(4) contents were higher during summer than that of monsoon; however the SO(4) was higher during winter and lower during summer in the canal water. The BOD and COD were lower and DO was higher at the upstream than that of downstream of the canal. The concentrations of BOD and COD were higher during summer season, which decreased during monsoon season, while the DO decreased during the summer season and increased in monsoon season in the canal water. Cluster analysis applied to the six sampling points of the canal, has grouped them based on the water quality similarities.

Municipal wastewater can result in a dramatic decline in freshwater fishes: a lesson from a developing country

“…Although lower numbers of individuals and species were observed in downstream sites in 2016 this difference was comparatively smaller from July to September than in other months. This might be due to the rise in water level associated with heavy rains during the rainy season (Galib et al, 2016(Galib et al, , 2018 that may reduce the level of unfavourable physicochemical properties of water through pollutant dilution (Kumar and Reddy, 2009). When the water level began to recede, the impact of wastewater pollution on fish abundance and species richness became much more apparent.…”

“…To minimise this impact, wastewater should be treated through establishing proper treatment plants. However, treated effluents can also be dangerous to the receiving water bodies (Kumar and Reddy, 2009) and thus multiple treatments might be considered before releasing wastewater into natural water bodies.…”

“…The majority of research carried out on wastewater pollution in Asia focuses on changes in the receiving water's physicochemical quality and sediments (e.g. Kumar and Reddy, 2009;Dai et al, 2018;Rajeshkumar et al, 2018;Ramachandra et al, 2018); impacts on invertebrate communities (e.g. Morse et al, 2007 summarised the status of East Asian countries) or impacts on the physiology of individual fish species (e.g.…”

A new weighting factor in combining belief function

“…This result is true and reasonable as the adjacent area of Site 6 and 7 is A6 that discharged untreated sewage directly to those sites [45, 46], that have the worst water quality with very high BOD, nutrients (NO3-N and PO4-P), NH3-N, EC, and TDS with very low dissolved oxygen. Untreated sewage has high BOD, nutrients (NO3-N and PO4-P), NH3-N, EC, and TDS with very low or almost zero dissolved oxygen [47]. However, the combination (A2, A3, & A6) in Site 4 to 5 and the combination (A2, A3, A5, & A6) in Site 5 to 6 also have urban settlement (A6), which contributed insignificantly because urban settlement covered only a smaller land cover, is far from the river, and sewage outfall is absent in Site 4 and lower in Site 5.…”

“…This is because the rivers have low flow in these months with February being winter and March to May being the pre-monsoon season [47]. The low flow in a river results in a high concentration of pollutants due to the lack of dilution.…”