Comparison of different media filtration for rainwater harvesting system

Abstract

In Malaysia, the rapid growth of urbanization, population and industrial has caused the water demand getting higher over a year including Perlis State. So, this study was conducted to treat the rainwater as a water supply by rooftop harvesting technique for non-potable use domestic purposes. Several tests hads been conducted to determine the quality of rainwater after and filtration process which is pH, Total Suspended Solid (TSS), Biochemical Oxygen Demand (BOD), Ammonia nitrogen (NH3N) and Dissolved Oxygen (DO). The rainwater was treated into two type of filtration system which involved rice husk and rice husk ash as filter media. Both of these mediums were compared to ensure the quality of the rooftop rainwater harvesting is improved. The quality of rainwater was tested by using 3 sample from rooftop rainwater, rice husk and rice husk ash filtration. Besides, for the designing of filtration system, each treatment is divided into three layer which from bottom is gravel, sand and treatment (rice husk or rice husk ash). The result from experiment shown that, the pH of rainwater change from 4.16 to 8.33 when using rice husk ash media filter whereas in Ammonia Nitrogen test, rice husk ash able to lower down the Ammonia Nitrogen from 0.26 mg/l to 0.17 mg/l whereas for rice husk is 0.21 mg/l. In the other hand, for Biochemical Oxygen Demand, rice husk reduces the value of BOD from 13.33 mg/l to 9.54 mg/l and the DO is 1.34 mg/l compare to rice husk ash is 1.45 mg/l. In the conclusion, the best system was system that use rice husk and rice husk ash.