Heavy Metal Removal from Municipal Raw Sewage by Activated Sludge
Treatment Process and Effects of Sewage on the Metal Contents of Buckingham
Canal Water across Different Seasons at Kalpakkam (India)
Abstract: Removal of heavy metals (Zn, Pb, Cu, Ni and Cr) from municipal raw
sewage by extended aeration activated sludge treatment process and the effects
of the treated effluent in relation to the raw sewage on the heavy metal
contents of water of the receiving water body, Buckingham canal at Kalpakkam
was monitored seasonally during pre-monsoon, monsoon, winter and summer. It was
found that the concentrations of Zn, Pb, Cu, Ni and Cr were 0.12, 0.063, 0.57,
0.63 and 0.019 ppm, respectively in the raw sewage, which were reduced
considerably at each phase of the treatment, at aeration tank with a removal
efficiency (RE) of 17, 13, 14, 33 and 31%, respectively, and in secondary
clarifier with RE of 67, 73, 72, 87 and 47%, respectively. The concentrations
of these heavy metals have increased in the downstream compared to that of its
upstream of the canal in both treated as well as untreated sewage outfall
zones, and were higher in the later zone. The concentrations of these heavy
metals were higher during pre-monsoon and monsoon seasons followed by that of
summer and winter in the canal water.
Keywords: Municipal sewage, heavy metals, Zn, Pb, Cu, Ni, Cr, Buckingham canal, activated sludge treatment process
