Wimin, DewiAhmad AdriantoChairul2012-10-242012-10-242012-10-24nurasmihttp://repository.unri.ac.id:80/handle/123456789/257Sago demand continues to rise along with the development of processing industries that use raw sago starch. Today’s national sago production reached 400,000 tons / year. In the production of starch required 20,000 liters of water per ton of sago, so it can be expected that the processing of sago require 21 000 kilolitres of water per day, of which 94% of the water will be liquid waste. Sago wastewater has high organic matter composition, when thrown into water it will degrade water quality and contaminate the environment. One of sago waste water treatment is by using hybrid anaerobic bioreaktor. Acetic acid content and pH is one factor affecting the performance of bioreactor. The purpose of this study was to determine the effect of organic loading rate on pH and the concentration of acetic acid by seeing the parameters of pH and acetic acid as well as determining the optimum loading rate on the formation of acetic acid. The research was conducted by using a hybrid anaerobic bioreaktor mediated the stone as a medium growth of microorganisms. Volume of work used in this study amounted to 10 L by varying the organic loading rate is 12.5: 16.7, 25 and 50 kg COD/m3 day. These results indicate that the optimum organic loading rate of 50 kg COD/m3 days with acetic acid concentration of 76,8 mg / L and pH of 6.13. Thus a hybrid anaerobic bioreaktor with the media of stone is capable to treat sago waste water that contains high organic.otherAnaerobicAcetic acidHybrid anaerobic bioreaktorSago waste waterArticle