Ecology, Environment and Conservation Paper

PHYSIO-CHEMICAL CHARACTERIZATION OF SEWAGE SLUDGEGENERATED FROM SEWAGE TREATMENT PLANT AT VARANASI,IN RELATION TO NUTRIENTS AND HEAVY METALS FORAGRICULTURE USE

Pavan Singh, Yadvir Singh, Satish Kumar Singh1, P. Raha, Hanuman Singh Jatav andShurendra Singh Jatav

Abstract

Large amount of sewage sludge is generated during waste water treatment at sewage treatment plant(STP), as a result of the sedimentation and suspension of particles. The safe disposal and management ofthis concentrated sewage sludge posesa major challenge for town and city municipal corporations. However,this could also be used in agriculture as an input to partially replace recommended doses of fertiliser. Thus,the current study was conducted to investigate the physio-chemical and biological characteristics of sewagesludge (SS) and its potential application in agricultural fields as an organic manure. Sewage sludge sampleswere collected from sewage treatment plant (STP) at Bhagwanpur, Varanasi, India and sieved in 2 mm meshbefore being analysed for various physical and chemical characteristics. The processed sewage sludgepossessed both major [total nitrogen (1.76 %), total phosphorous (1.29%), total potassium (1.15%)] andmicro nutrients (Fe, Mn, Zn and Cu) and significant amount of organic carbon (8.67 %). However, thissewage sludge was also containing considerable amount of heavy metals like Cadmium (7.3 mg kg-1),chromium (49.2 mg kg-1), nickel (total 27.43 mg kg-1), and lead (39.53 mg kg-1), which were reported to beharmful to human beings, but these were lower than threshold limit recommended by Council of theEuropean Communities, 1988 for agricultural use. Further, Bulk density and water holding capacity was1.18 g cm-3 and 54.5 % respectively. With respect to microfauna, fungi were found more dominating thanactinomycetes and bacteria in this sewage sludge. Therefore,considering use of this sewage sludge foragriculture may decrease the use of chemical fertilisers and make it more sustainable. However, in order toincrease soil health without posing an environmental risk, sewage sludge must be carefully evaluatedbefore being applied to soil especially for heavy metals and other hazardous pollutants.