A comparison of horizontal roughing filters and vertical roughing filters in wastewater treatment using gravel as a filter media

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.