THE EFFECT OF SAND TYPE AND GRAIN SIZE IN SLOW SAND FILTER TO UTILIZE BLACK WATER FOR IRRIGATION
PRESI RISHALEHESTY, Ir. Agus Prasetya, M.Eng.Sc., Ph.D.
2011 | Tesis | S2 Mag.Sistem Teknik-
Currently, Indonesia has one of the lowest levels of sewerage connection and sanitation coverage in Asia. Gunung Kidul region in the D.I. Yogyakarta Province is one good example to describe realistic poor sanitation and sewage condition in Indonesia. There are many possibilities to treat wastewater; one of the alternatives is reusing wastewater in agriculture. Wastewater utilization for irrigation water convertion can improve various aspects in the life of Gunung Kidul residence. This study intends to seek for the most suitable method to reuse liquid phase from septic tanks to become acceptable irrigation water. In advance, detailed objectives of this study are to identify the effect of grain size of sand filter on COD, BOD, Ammonia, Nitrate and E-Coli of the filtered black water and to identify the effect of sand type on COD, BOD, Ammonia, Nitrate and E-Coli of the filtered black water. The grain size of the filter media and the filter media type was the independent variables. The dependent variable was BOD and COD level, the ammonia, E-coli, and nitrate containment. Materials in this research are Septic tank effluent taken from IPAL Sewon, volcanic sand classified into three different size, medium, coarse, and very coarse, beach sand classified in two different size, medium, and coarse, gravels. Preparation processes coexist to collect supernatant from the septic tank wastewater. The processes utilize sedimentation principle to settle the suspended solid from the wastewater and separate them from the supernatant. Thus, the supernatant can be collected as the influent for the coconut shell filter before goes to the main treatment processes. The process conducted in a continuous filtration apparatus. The apparatus consist of a large reservoir and five filtration columns located near the reservoir. The fivefiltration columns are connected with the reservoir using standard PVC pipe. Thus, the performance of each column measured comprehensively to obtain the optimum grain size and sand type. The results of this study showed that volcanic sand with medium grain size (-30+50 mesh) is the best sand type and grain size to utilize black water for irrigation. The highest reduction of ammonia, BOD, COD and E-Coli occur on day 4th with percent reduction 99.5%, 92.6%, 90.3%, 87.4%, respectively. The highest nitrate production was 58.45 mg/L and occurs on day 4th as well. In addition, filtered black water can fulfill the requirement.
Kata Kunci : Black water, grain size, sand type, beach sand, volcanic sand, slow sand filtration
