title: Assessment of pollutants and gaseous emissions in sewer network in NCT of Delhi.
abstract: The NCT of Delhi in India handles domestic sewage through a long sewerage networks. The network is into eight divisions. The aim of the present study is to arrive at a correlation between sewage quality and gas emissions in the sewer network of various divisions. This will aid in forewarning the sewer workers about the safety precautions. The health effects due to toxic sewer gases exposure and assessment of hazardous conditions and hazard potential are discussed. The study areas were broadly classified as residential, commercial, industrial and mix (combination of residential & commercial) for comparison. Sewage samples were collected from 1020 sites and analyzed for 10 different physicochemical parameters. The analytical data revealed wide variation in the chemical composition of sewage flowing at various sewerage network sites. Based on comparison with the regulatory standard for discharge in sewers, 89 sites with higher values of BOD and sulphate were marked as critical sites. Subsequently, the concentrations of CH4 and H2S in sewer emissions were determined for the 89 critical sites through onsite monitoring. Samples from 22 sites had significantly higher concentration of CH4 than the LEL and those from 40 sites showed concentrations higher than the LFL. On the other hand, samples from 38 locations showed significantly high H2S concentration, more than permissible limit of 10 ppm. The sewer workers in North East, North West and West region of the metropolis were exposed to hazards from excessive CH4 and H2S emissions, whereas those under South and South West regions were more vulnerable to H2S related risks. The sewer network under North, Central and South poses relatively less hazard with regard to gaseous emissions.
authors.forename: P
authors.initials: P
authors.lastname: Aswale
authors.forename: N N
authors.initials: NN
authors.lastname: Rao
authors.forename: M
authors.initials: M
authors.lastname: Karthik
authors.forename: R
authors.initials: R
authors.lastname: Dhodapkar
authors.forename: G
authors.initials: G
authors.lastname: Patkar
authors.forename: T
authors.initials: T
authors.lastname: Nandy
mesh_terms: D002947:Cities; D004323:Drainage, Sanitary; D006801:Humans; D006862:Hydrogen Sulfide / Q000032:analysis; D007194:India; D008697:Methane / Q000032:analysis; D016273:Occupational Exposure; D018570:Risk Assessment
chemical_list: D008697:Methane; D006862:Hydrogen Sulfide