COMPARISON OF BELT PRESS VS. CENTRIFUGE DEWATERING CHARACTERISTICS FOR ANAEROBIC DIGESTION

A full-scale, side-by-side comparison study of filter belt press and centrifuge dewatering was started in January 2002 at Inland Empire Utilities Agency's Regional Water Recycling Plant No. 2. The duration of the testing in this study is four months. The full-scale, side-by-side comparison study was conducted at sludge feed rates of 80 – 100 gpm (1,000 – 1,200 lb/hr). The study did an evaluation of the two dewatering processes based on the quality of the dewatered biosolids, the filtrate/centrate quality, polymer dosage, energy consumption, odors, and ease of operation. With the use of centrifuge, the dewatered biosolids improved in cake and centrate quality by 33% and 58%, respectively, compared to the dewatered biosolids from the filter belt presses. Polymer dosage had to be increased by approximately 50% to achieve optimum operation with the centrifuge. Electrical cost of operation also increased by 120% with the centrifuge compared to the filter belt press. In addition, the centrifuge also appeared to be much more flexible in handling the various stage and temperature phased sludge feeds. In all the different scenarios, the centrifuge cake yielded higher cake solids at a higher energy cost. Significant timesavings were also realized due to the 24 hr/day operation and the reduced shutdown and cleanup time of the centrifuge. The total annual cost of operation of the centrifuge, at 473,000 was considerably lower than that of the filter belt presses at 509,000.