Evaluation of the Decentralized Wastewater Treatment Plants in Four Provinces in Indonesia

In Indonesia there is a number of Decentralized Wastewater Treatment Plant or Community-based Sanitation (called SANIMAS) locations. In this study, the survey locations included Tangerang – Serang Province, Surabaya – East Java Province, Yogyakarta Province and Bali Province. These locations were selected for the following considerations: variation of influent into the SANIMAS system, ease of access to the SANIMAS manager, availability of resources and data completeness of the system and the distance to the available wastewater laboratory. Most of the SANIMAS, systems applied in Indonesia were developed by BORDA having a similar shape and size.

The study found that the typical BORDA biodigester (with a diameter of 3 meter) could work well at the loading rate of 1 kg-COD/day/m3 of biodigester, and it could reduce COD up to 3.5 kg-COD/day. If all of the removed COD was converted into biogas, it would produce 1,850 L of biogas/day, with the concentration of CH4 in biogas of about 75%. Moreover, the SANIMAS system operation was very simple; in general, there were no obstacles in the operation of SANIMAS system, neither in communal, tofu-tempe industries, nor in treating cattle dung. However, there were several constraints/problems associated with the system performance and SANIMAS system as a whole found in this study.