Thermophilic Methane Fermentation of Evaporator Condensate from a Kraft Pulp Mill, 1990 Environmental Conference Proceedings

We have performed a bench scale study of the thermophilic anaerobic digestion of high-concentration wastewater discharged from a kraft pulp production process. The system consisted of pretreatment equipment for oil separation, a stripping system for sulfur compound separation, an anaerobic bioreactor for methane fermentation, membrane module equipment and a gas treatment system. The bioreactor had a fixed-bed constructed of pumice stone with an effective volume of 5 m3. In continuous operation with the membrane module system, the HRT was 12 hours, the maximum ROD loading rate was 35 kg BOD/m3/d and the maximum BOD removal. rate was 93%;. High efficiency of continuous operation was attained with the membrane which

concentrated useful bacteria. Addition of evaporator condensate waste pretreatment by anaerobic digestion, to the conventional aerobic system decreased treatment costs by 26.7% per meter cubed. In order to better maintain bioreactor operations, we studied conditions of low digester efficiency and its causes.