A REEEP-funded project with the Environment Technology Center at the Agency for the Assessment and Application of Technology (BPPT) is just completing a first report on the existing use of renewable technologies in the Indonesian tofu sector. Based on this report, the project will go on to make recommendations on policies to support the wide-scale production of RE biogas from the wastewater of tofu SMEs.

Tofu production itself is a water-intensive process.  It begins with washing soy beans and soaking them in water for 6 hours. After soaking, the beans are ground and mixed with more water to form slurry.  This mixture is then boiled and filtered to separate the liquid starch from its dregs.  Acetic acid solution is then added into the liquid starch, where it forms clumps of tofu. Using pressing equipment, these clumps of tofu are then pressed out, yielding liquid wastewater and tofu itself as a product.

In the end, about 60 kg of soybeans and 2700 litres of water are required to produce 80 kg of tofu. The vast majority of the water – in this example approximately 2610 litres of it -- ends up as wastewater. Its main components include reductive sugar, sucrose, starch and volatile acid, making tofu wastewater a serious environmental pollutant.

Treating this wastewater with methane bacteria to produce biogas can provide a much cleaner environment and at the same time unlocks a major new source of renewable energy - for the tofu industry itself and for the benefit of surrounding communities, as many tofu producers are located directly in and around small villages.

BPPT has developed a pilot plant in the Banyumas tofu industrial cluster where wastewater is in fact being used to produce biogas. The REEEP-funded project is evaluating a wide variety of anaerobic digester types used here and in other areas of Indonesia, including Chinese, fixed bed and baffled reactor types, and is weighing up the relative advantages of each.

Looking ahead, this project will develop an enabling framework and policy recommendations for the wide-scale use of RE biogas in the tofu industry.  A workshop will also be organised to disseminate all findings, case studies and recommendations.

“This project is interesting for several reasons,” says Dr. Ridwan Djamaluddin as Deputy of Natural Resources Technology Development of BPPT. “It lays out the groundwork for a wider roll-out of RE biogas in an industry with huge wastewater production. We think that more than 56,000 tonnes of fossil fuels could be substituted each year with biogas produced from tofu industry waste water in Indonesia. Beyond that, it will also be able to be a model for other types of industry clusters, in considering the integration of the funding sources potential for investment, including the potency of carbon market as a source of investment funding.”