IMPROVING BELT FILTER PRESS PERFORMANCE USING RELIABILITY CENTERED MAINTENANCE

Eastman Chemical Company operates a large organic chemical, plastics, and synthetic fibers (OCPSF) manufacturing complex at its Tennessee Operations site located in Kingsport, Tennessee. Wastewaters generated as a result of the various OCPSF manufacturing activities are treated at a large industrial wastewater treatment plant. The wastewater treatment plant uses conventional activated sludge treatment to process approximately 4,740 m3/hr (30 MGD) of wastewater at an average annual design loading of 100,000 Kg BOD5/day (220,000 pounds BOD5/day). Biological sludge generated during the activated sludge treatment process has produced annual average sludge generation rates of up to 55 dry metric tons/day (60.5 dry tons/day).Belt filter presses are used to thicken and dewater waste activated sludge from the wastewater treatment process prior to on-site thermal treatment in coal fired boilers. The wastewater treatment facility operates seven 1.5-meter and two 2.0-meter width belt filter presses in its sludge dewatering unit operations. Maintenance costs for these belt filter presses comprise one of the largest equipment related maintenance costs in the wastewater treatment operating budget. These costs, both gross and indexed to equipment runtime, had been trending upward for several years and had reached an unacceptable level.Wastewater treatment plant supervisors, engineers, operators and maintenance personnel on a cross-functional problem solving team applied a reliability centered maintenance process to improve operating and maintenance performance in the sludge dewatering operations. Using a systematic and structured approach to equipment maintenance and reliability the upward trend of increasing belt filter press maintenance costs was reversed. Overall failure rates were reduced from approximately 6.2 failures per 1000-hours runtime to approximately 3.2-failures per 1000- hours runtime. The average number of belt filter press failures was also reduced from 247 per year to 127 per year. Overall maintenance costs were reduced in excess of 50% from 8.65-12.00 per hour runtime to approximately 4.20 per hour runtime as a result of improving belt filter press reliability.