Effect of Aeration Rates on Removals of Organic Carbon and Nitrogen in Small Onsite Wastewater Treatment System (Johkasou)

¹ Faculty of Civil Engineering and Planning, Universitas Islam Indonesia, Kaliurang 55584, Indonesia
² Graduate school of Engineering, Gifu University, Yanagido 501-1193, Japan
³ Department of Chemical Engineering of Natural Product, Polytechnic ATI Padang, Adinegoro Bungo Pasang 25586, Indonesia
⁴ River Basin Research Center, Gifu University, Yanagido 501-1193, Japan
⁵ Faculty of Engineering, Gifu University, Yanagido 501-1193, Japan

^* Corresponding author: joni.af@uii.ac.id

Abstract

Onsite application of oxygen supply in domestic wastewater system may be influenced by several factors that can inhibit the oxidation and nitrification processes. In this study, the influence of aeration rate on the Johkasou performance was focused using two Johkasou facilities serving up to five persons household. In the Johkasou A (JO-A) system, we increased the aeration rate from 30 to 63 L.min^-1 whereas, in the Johkasou B (JO-B), it was decreased from 59 to 34 L.min^-1. Water and sludge samples were collected from the anaerobic-anoxic-oxic zones before and after adjustment of the aeration rate measured for organic matters and nitrogen parameters. Increasing the aeration rate in JO-A resulted in a high removal of organic matter (82.5%) and nitrogen (60.3%) compared to decreasing of aeration rate in JO-B (52.0% and 33.0%, respectively). Simultaneous nitrification and denitrification (SND) exhibited a maximum percentage when the aeration rate was increased compared to decreasing of aeration rate. These results indicate that application of a high aeration rate increases removal of organic matter and nitrogen and enhances ammonia transformation. It is therefore recommended to apply high aeration rates in Johkasou system.