Roughing filter

Abstract: Roughing filtration can be considered as a major pre-treatment process for wastewater, since they efficiently separate fine solids particles over prolonged periods without addition of chemicals. This review article summarizes and evaluates modifications to roughing filtration technology, which may address these limitations without compromising the simplicity of the treatment process. Successful modifications includes broken burnt bricks, charcoal and coconut fibre as filter media. The paper also reviews the design concept and process capabilities for roughing filter and it also discusses recent innovations in roughing filter design that now enable this technology to be applied more widely than would have been appropriate 2 decades ago. Achieved results in this study shows that roughing filtration may be considered as efficient pretreatment process incase surface water is used as water supply. Key words: Roughing filter, sedimentation, absorption, turbidity.

Abstract: This study was aimed at introducing multistage filtration (MSF) (a combination of slow-sand filtration (SSF) and pretreatment system - horizontal flow roughing filter (HRF)) as an alternative water treatment technology to the conventional one. A pilot- plant study was undertaken to achieve this goal. Evaluating the MSF performance vs. the existing conventional system in removing selected physical and chemical drinking water quality parameters together with the biological water quality improvement by the MSF without chemical use was done. Evaluation of the effectiveness of the MSF system utilizing locally available material, i.e. gravel, improved agricultural waste (charcoal maize cobs) and broken burnt bricks as pretreatment filter material was also done The benchmark was the Kenya Bureau of Standards (KEBS) values for the selected parameters. Results showed that with proper design specifications, MSF systems perform better than conventional systems under similar conditions of raw water quality and environmental conditions. The tested locally available materials can also be effectively used as pretreatment media with each allowing a filter run greater than 82 d and therefore could serve as alternatives where natural gravel is not readily available. With special reference to the bacteriological quality improvement, the MSF greatly improved the bacteriological quality of the water recording removal efficiencies of over 99% and 98% respectively for E. coli and total coliforms. Despite the observed performance, MSF should be complemented with chlorination as a final buffer against water-borne diseases. However, in this case, the dosing will be greatly reduced when compared to the conventional system.

Abstract: Roughing filtration can be considered as a major pretreatment process for waste water, since the process efficiently separate fine solid particles over prolonged periods without addition of chemicals. Roughing filters mainly act as physical filters and reduce the solid mass. However, the large filter surface area available for sedimentation and relatively small filtration rates also supports adsorption as well as chemical and biological processes. Therefore besides solid matter separation, roughing filters also partly improve the bacteriological water quality and to a minor extent, change some other water quality parameters such as colour or amount of dissolved organic matter. This article evaluates modifications to roughing filtration technology, which may address these limitations without compromising the simplicity of the treatment process and also compare the efficiency of horizontal roughing filters and vertical roughing filters. Successful modifications include the design concept and process capabilities for roughing filter. Achieved results in this study shows that Horizontal roughing filters perform better than vertical roughing filters due to unlimited filter length, simple layout and less susceptible than vertical-flow filters to solid breakthroughs caused by flow rate changes in the filters. Key words: Roughing filters, horizontal roughing filters, adsorption and vertical roughing filters.