Using Intermittent Sand Filters of Various Depths to Remove NH3-N, NO3N and NO2N from the Wastewater of Sugar Milling Factory

Abstract

Intermittent sand filter systems have been used in wastewater treatment according to Selecky (2012) especially their application for on-site wastewater management. Intermittent sand filters have not been used to treat effluent from sugar factories in Kenya. There is very limited information on how to optimize their application in treating effluent from sugar factory in Kenya. This study focused on optimization of intermittent sand filter used in treatment of wastewater from sugar factory. Samples of wastewater were randomly taken from Kibos Sugar and Allied factories. These samples were loaded into sand filters with different sand depths of 0.30, 0.45 and 0.60m. Different loading rates, volumes and frequencies were applied for each depth. Samples from the filtrate were collected and analyzed in the laboratory for NH₃-N, NO₃-N and NO₂-N values. The data was subjected to analysis of variance for fractional factorial (ANOVA) using the GenStat Version 13.2 computer programme. Wastewater generated from the sugar factories had NH₃-N, NO₃-N and NO₂-N were within the WHO acceptable limits. The sugar factory managers targeting to remove NO₃-N should use a sand filter with a depth of 0.45m by loading it at a rate of 2L/min, volume of 30L and frequency of 12hrs. To remove NO₂N using a sand filter of 0.45 m deep, they should use a loading rate of 4L/min, loading volume of 10L and loading frequency of 12hrs.

Keywords: Effluent, factory, filter, intermittent, sand, sugar, wastewater.