Overall Performance of Specific Household Water Filtration Techniques on Turbid Water and Effects of Selected Factors

Abstract

Turbid surface water remains an important source of household water in many low-resource communities, particularly where piped drinking-water supplies are inadequate or unreliable. It is well known that Household filtration techniques (HFT), which include fibre or cartridge filters, ceramic filters, activated-carbon filters and bio-sand filters, can substantially or significantly improve water quality. The performance of these techniques depends on several operational factors. This paper presents a report on performance evaluation of selected HFT (fibre or cartridge filters, ceramic filters, activated-carbon filters) with particular attention to removal of selected health-related water quality parameters (Alkalinity, Electrical conductivity, Chromium, Iron, pH, and Mercury). Effects of selected operational parameters (Settling time or treatment time, Alum dose or coagulant dose, Turbidity of the raw water, and number of Filter units) on the performance were evaluated using Analysis of variance and Taguchi techniques. The study revealed that raw-water turbidity, filter configuration, coagulant dose, and settling time have effects of the performance of these techniques. The overall best performance was 98.26% using one filter unit; turbidity of 1500 NTU; alum dose of 120 mg/l and settling time of 10 minutes, and the lowest overall performance was 67.57% with operational conditions of three filter units; turbidity of 2000 NTU; alum dose of 80 mg/l and settling time of 15 minutes for Activated Carbon Filter. In the case of the Ceramic Filter, the overall best performance was 97.29% using three filter units; turbidity of 1500 NTU; alum dose of 80 mg/l and settling time of 5 minutes and the lowest overall performance was 77.46% with operational conditions of one filter unit; turbidity of 500 NTU; alum dose of 200 mg/l and settling time of 5 minutes. The overall best performance was 92.83% using two filter units; turbidity of 1500 NTU; alum dose of 80 mg/l and settling time of 10 minutes, and the lowest overall performance was 78.96% with operational conditions of one filter unit; turbidity of 1500 NTU; alum dose of 120 mg/l and settling time of 10 minutes for fibre filter. It was concluded that the most reliable treatment of highly turbid water is therefore obtained through a multi-barrier arrangement comprising coagulation, sedimentation, particle filtration, adsorption and final disinfection.