Low Cost Filtration of Domestic Wastewater for Irrigation Purpose

Abstract

Water scarcity in developing countries has forced farmers to use sewage as an alternative source of irrigation water. However, the usage of sewage for vegetable production has been known to cause excessive and often-unbalanced addition of nutrients hence posing a threat to food safety. The objective of this study was to determine the efficacy of slow sand filter and wetland plant in domestic wastewater treatment. To achieve this objective, samples were collected from the domestic wastewater collection pond within Jomo Kenyatta University of Agriculture and Technology (JKUAT). Laboratory tests were conducted on the collected samples and they revealed the presence of BOD, DO, pH, TDS, Sulfates, Chloride, Turbidity, Salinity, Conductivity, Alkalinity and Coliform; whose values varied when compared with that of the parameters for standard irrigation water. This gave insight to the kind of treatments and filtration medium that were required to transform domestic wastewater into water fit for irrigation. A slow sand filter bed was designed and constructed using precisely six samples materials; sand, sand and wetland plants, gravel, gravel and wetland plants, mixture of gravel and sand, mixture of gravel and sand with wetland plants. These materials were used to identify the chemical and biological changes in domestic wastewater within a seven-day period. The water collected from the slow sand filter was tested, results showed that, of all six samples, slow sand filter using the mixture of gravel, sand with wetland plants had an average percentage efficient of 90% in removing all impurities from domestic wastewater thereby turning it into water suitable for irrigation. It is hoped that this study will provide a safe, easy, eco-friendly and cheap method of wastewater treatment while ensuring the sustainability of wastewater for irrigation and the expansion of green spaces in urban and peri-urban areas.