Lestari, Yuliza FujiAhmad AdriantoChairul2012-10-232012-10-232012-10-23nurasmihttp://repository.unri.ac.id:80/handle/123456789/222In producing sago flour takes 20,000 liters of water per ton of starch, where 94% of the water would be liquid waste, so about 19,000 liters of wastewater generated sago starch per ton When directly discharged into the water on a continuous basis it could lead to pollution of the waters. The way of handling the problem of wastewater treatment can be done by using a hybrid anaerobic bioreactor mediated stones. One of the factors that influence of the anaerobic process success is pH and alkalinity. The purpose of this research to determine the effect of feed flow rate on pH and alkalinity in anaerobic hybrid bioreactor at steady state by looking at the pH and alkalinity parameters and determine the optimum conditions for anaerobic processes. Process variables measured were feed flow rate of 2.5 L / day, 3.3 L / day, 5 L / day, and 10 L / day operating conditions at room temperature and the bioreactor working volume 10 L. The results showed that the optimum feed flow rate obtained on 2.5 L / day with an average pH of 6.8 and alkalinity of 2280 mg / L.otherAlkalinityanaerobesHybrid BioreactorSago EffluentArticle