Comparison of Environmental Efficiency of Domestic Wastewater Treatment Systems in a Factory of Indonesia Based on LCA

Abstract

In Indonesia, a conventional on-site wastewater treatment system which is called septic tank is commonly used to treat domestic wastewater in both of household and industrial sectors. However, it is concerned that its environmental burden is high. Starting from industrial sectors such as major factories, Japanese technology of Johkasou has been adopted as an alternative system of septic tank. The objective of this study is to compare the environmental efficiency between a septic tank and a Johkasou, which is installed in Indonesia but is originally developed in Japan, to discuss the improvement of environmental efficiency of wastewater treatment systems in Indonesia. The environmental efficiency was compared between the two systems by the amount of greenhouse gas （GHG）emissions. Nitrous Oxide （N₂O）and Methane （CH₄）gasses are emitted in wastewater treatment processes, and it is important to grasp the amount of those gasses because the Global Warming Potential （GWP）of N₂O and CH₄ are high. However, there is no helpful measured data available in Indo nesia. In this study, sampling and analyzing gasses from the septic tank and Johkasou were conducted in a factory located in Jakarta. As a result, GHG emissions which are directry emitted from the septic tank are 7.6 times higher than those of Johkasou on the operational stage; 44.8 kg-CO₂eq/person/year and 5.9 kg-CO₂eq/person/year, respectively. Compared with Johkasou, total GHG emissions of the septic tank were 1.8 times higher through the whole lifecycle. As a result of water quality analysis, the amount of BOD removal of the septic tank and Johkasou were 20.4 kg/person/year and 105.3 kg/person/year respectively. In conclusion, this study showed that the environmental efficiency of Johkasou is 10 times higher than that of the septic tank.