THERMOPHILIC ANAEROBIC TREATMENT OF INDUSTRIAL-PROCESS WATERS AND WASTEWATERS

In many water-intensive industries, high manufacturing temperatures ge nerate hot and concentrated process waters and wastewater fractions. T hermophilic anaerobic treatment offers an attractive alternative to th e treatment of these hot streams. Thermophilic treatment could be appl ied as an external treatment system or as an internal purification uni t in closed water circuits combined, e.g., with membranes. The benefit s of the thermophilic anaerobic process as compared to the mesophilic one would be an increased loading rate and the avoidance of cooling be fore treatment and reheating if the water is recirculated. We have con ducted laboratory- and pilot-scale studies on thermophilic anaerobic t reatment of hot process waters and wastewater streams from the pulp an d paper industry and from vegetable processing. These studies have dem onstrated a successful startup of thermophilic processes using mesophi lic inocula. The performance of the anaerobic processes was stable at 55 degrees C as well as at 70 degrees C. At 55 degrees C, the COD remo vals were comparable to those in mesophilic processes, while at 70 deg rees C the removals were slightly lower. Higher loading rates were ach ieved at 55 degrees C than at 70 degrees C. Acetate was utilized at te mperatures as high as 80 degrees C, while propionate conversion was se verely limited or completely inhibited at temperatures greater than or equal to 70 degrees C. Sulfate reduction occurred readily with acetat e both at 55 and 70 degrees C.