title: Nitrogen dynamics of the aquatic system is an important driving force for efficient sewage purification in single pond natural treatment wetlands at East Kolkata Wetland.
abstract: At East Kolkata Wetlands, though the domestic city sewage is purified very rapidly, the mechanisms of treatment remains inadequately explored. In this context, the present study investigated nitrogen dynamics of the single pond treatment systems during purification and explored its potential role in sewage treatment. For this purpose the concentrations of different forms of nitrogen present both in water and soil at different time points of purification were measured. The organic nitrogen content decreased sharply, in the early phase, with an increase in ammonium concentration. Notably the reduction in organic nitrogen was significantly higher than the increase in NH4+which can be attributed to the volatilization of NH4+under alkaline pH. This volatilization results in reduced oxygen demand. The nitrate-N concentration decreased sharply from soil with a concomitant increase in water column. However the reduction of nitrate in soil was significantly higher than the increase in water column. It indicated the occurrence of denitrification under anoxic condition wherein nitrate serves as terminal electron acceptor. Additionally a part of the nitrate supported planktonic growth. Thus it describes another mechanism of reducing oxygen demand. The initial NH4+-N concentration in the soil was very low and it increased gradually during purification due to increasing soil cation exchange capacity. Thus by trapping NH4+ion soil contributes towards preventing contamination of water. Thus at EKW, the cumulative activities in water and soil involved in nitrogen dynamics lead to overall reduction of the oxygen demand and contribute towards efficient sewage purification.
authors.affiliation: Department of Microbiology, University of Calcutta, 35BC Road, Kolkata, PIN 700019, India; Institute of Environmental Studies and Wetland Management, DD24, Sector I, Saltlake, Kolkata, PIN 700064, India. Electronic address: joy.dasgupta1987@gmail.com.
authors.forename: Anirban
authors.initials: A
authors.lastname: Das Gupta
authors.affiliation: Department of Microbiology, University of Calcutta, 35BC Road, Kolkata, PIN 700019, India; Institute of Environmental Studies and Wetland Management, DD24, Sector I, Saltlake, Kolkata, PIN 700064, India. Electronic address: cusubhasis@gmail.com.
authors.forename: Subhasis
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Institute of Environmental Studies and Wetland Management, DD24, Sector I, Saltlake, Kolkata, PIN 700064, India. Electronic address: singhj13@mail.montclair.edu.
authors.forename: Jayprakash
authors.initials: J
authors.lastname: Singh
authors.affiliation: Institute of Environmental Studies and Wetland Management, DD24, Sector I, Saltlake, Kolkata, PIN 700064, India. Electronic address: tsaha1958@gmail.com.
authors.forename: Tapan
authors.initials: T
authors.lastname: Saha
authors.affiliation: Department of Microbiology, University of Calcutta, 35BC Road, Kolkata, PIN 700019, India. Electronic address: alokksil7@gmail.com.
authors.forename: Alok Kumar
authors.initials: AK
authors.lastname: Sil
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis*; D058440:Denitrification; D007194:India; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis*; D061005:Ponds / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D012722:Sewage; D012987:Soil; D014874:Water Pollutants, Chemical; D014867:Water; D009584:Nitrogen
keywords: Cation exchange capacity; Domestic city sewage; East Kolkata Wetlands; Nitrogen dynamics