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A study of self-purification capacity of Anyim stream

J.I. Obianyo
E.E. Ohazurike
O.O. Onyeike
I. Ije
S. Eboh
L.I. Nwobia


This paper studied the self-purification capacity of Anyim stream to identify the location where pollution load is comparably less for water abstraction and economical treatment and distribution to consumers. Standard methods were used to determine the water quality parameters along the stream reach. Results show that temperature remained constant at 26.60℃, turbidity reduced from 145.4 NTU to 85.0 NTU, average color along the stream were 198.33 PCU, 192.33 PCU, 121.33 PCU and 135.67 PCU, average dissolved oxygen trend were 6.0 mg/l, 8.0 mg/l, 4.0 mg/l and 7.0 mg/l. BOD trend presented 15.0 mg/l, 10.0 mg/l, 30.0 mg/l and 20.0 mg/l. Maximum oxygen deficit of 9.17 mg/l occurred in 4.42 days while maximum oxygen recovery of 31.46 mg/l happened in 21.68 days. Complete self-purification will take place at a distance of 114.57 km downstream of the influent station of Anyim stream. The trend show that water in Anyim stream experienced self-purification from Okosi through Ahaba to Okporo-akanu and increased to Amaokwe because of effluent from confluence station of Anyim and Etu streams. It is recommended that water should be sourced downstream of Okporo-akanu and 114.57 km downstream of Anyim stream for treatment and distribution to consumers since these sources would require less elaborate treatment methods and hence would be cheaper and more economical to manage.