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JICA Partnership Program
 "Development of a Model System for Participatory Community Waste Water Treatment in Densely Populated Area of Yogyakarta Special Province"

Appropriate Technology for Industrial Wastewater Treatment and Rotating Biological Contactors

 In the former project (Development and Management of Appropriate Technology Center for Waste Water Treatment in Indonesia), focusing on five kinds of industries, that is, tannery, dye-works, food processing, hospital and hotel, we tried to develop appropriate technology for wastewater treatment by testing totally 9 pilot plants newly installed.

 In these pilot actions, we have repeatedly demonstrated effectiveness of the combined process of anaerobic treatment and aerobic treatment. The wastewater treatment process commonly used in industrialized countries is aerobic process such as activated sludge. However, the aerobic treatment requires power for operation and generates a lot of excess sludge, which has to be further treated. Although the application of anaerobic process is somewhat limited in areas with cold climate, it can be widely used in tropical countries such as Indonesia. Different from aerobic process, anaerobic process has an advantage that it doesn’t require power for the operation. But the quality of treated water from anaerobic process is rather low. Therefore, if we add the aerobic process as post-treatment of anaerobic process, the process that can treat wastewater to satisfactory level of quality but requires only small amount of energy, is realized.

 As anaerobic treatment in the system, we use anaerobic filter, anaerobic baffle reactor or UASB (Upflow Anaerobic Sludge Blanket) depending on the condition. As for aerobic treatment which follows the anaerobic treatment, we usually make use of Rotating Biological Contactors (RBC) as a characteristic technology of PUSTEKLIM. RBC has a series of disk-shaped contactors fixed to a shaft and a vessel with semi-circular cross-section filled with wastewater. About 40% of the contactors surface area is submerged in the water. Then, if we rotate the contactors slowly, every part of the contactors goes into the water and then comes up to the air alternatively. With this condition in which both organic substances from wastewater and oxygen from air are abundantly supplied, aerobic microorganisms grow spontaneously forming layers on the surface of the contactors. These microorganisms absorb and decompose organic matter in the wastewater.

 Compared with activated sludge process, which is commonly used as aerobic treatment, the RBC is characterized by its easiness of operation, small consumption of power and small production of excess sludge. In addition, RBC is less vulnerable to shock load. However it has also some disadvantages such as relatively low quality of treated water, less economic in large scale plants etc. Considering these characteristics, PUSTEKLIM came to regard RBC as a technology which is suitable for small- and medium scale wastewater treatment plant in Asia. So far, we have developed and have been making use of two kinds of RBC, one with contactors made of palm fiber and the other with Three-Dimensional Lattice Contactors.

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