ABSTRACT
The feasibility of operating intermittent sand filters for upgrading the effluent parameters from waste stabilization pond was investigated. Samples of the effluent were colleeted from the outlet of the Waste Stabilization Pond of the Ahmadu Bello University Zaria (A.B.U.) and were subjected to sand filtration. The filter system, of which there were two, consisted of 150mm diameter perspex columns filled to a depth of 2.0 meters with sand obtained from the bed of Kubani River at A.B.U.. The sand had effective sizes of 0.25mm and 0.33mm, Uniformity Coefficient of 2.64 and 1.39 and porosity of of 0.435 and 0564 for filters 1 and 2 respectively. Both the samples and the corresponding effluent samples from the filters were collected and analysed for some physical, chemical and biological parameters. The results show some reductions in the concentrations of suspended solids (SS), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), algae, helminths and water fleas. For a filter bed 2.0m deep consisting of sand with effective size 0.25mm, porosity of 0.435 and uniformity coefficient of 2.64, an average removal of 87.85%, 90.5% and 84.52% were obtained for S.S, BOD and COD respectively while complete removal of algae, helminths and water fleas were obtained at the same depth. However, the concentrations of some metallic elements such as Bo, Mg, Ca and Cu whose original concentrations in effluent samples were low, did not show any appreciable reduction. Also an increase in the numbers of faecal coliforms (MPN) in the filtrate was observed contrary to expectation. However, this observation is not conclusive and is subject to further investigations.