Obrdlick, P


The Chongwe-Ngwerere River System in Zambia: Physico-chemical and Bacteriological Status, by Petr Obrdlik, Zambia Journal of Science & Technology, Vol.7, October 1984, Pg 1-11.


Physico-chemical bacteriological regimes of the Chongwe-Ngwerere River basin east of Lusaka was studied from June 1983 to June 1984. The upper portion of the Ngwerere stream is polluted by crude municipal effluents and wastes from the sewage treatment plants. The pollution level drops rapidly down stream and the Chongwe River, below the confluence, is only slightly polluted. Mean concentrations of D.O. range from 3.10 to 8.39 mg/l. Water was alkaline in nature. Conductivity reached 71 mmhos/cm in undisturbed waters of the Chongwe River and 618mmhos/cm at the head of Ngwerere stream. Concentration of the nutrients NO3-N and PO4-P varied between 0.23 to 1.50 mg/l and 0.15 to 0.81 mg/l, respectively. The maximum mean number of coliform bacteria was 36,230 colonies in 100 ml, taken from the heavily polluted station N1; the minimum mean number of 670 colonies in 100 ml was recorded in the Chongwe Dam. Concentrations of psychrophilic bacteria as plate count at the same localities were 2,090 colonies/ml and 40 colonies/ml, respectively. Water from the major part of the Ngwerere stream and the whole of the study area of the Chongwe River is suitable for irrigation purposes, the watering of cattle and the preparation of drinking water through conventional technologies.

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