Significant Improvement of Activated Sludge Plant Performance by Pretreatment with Anaerobic Reactor at American Israeli Paper Mills

摘要

American Israeli Paper Mills (AIPM) in Hadera, Israel, is a unique paper mill as it produces different paperrngrades, such as tissue from de-inked fibers, corrugated case materials from recycled paper and fine paper fromrnmarket pulp, all at one site.rnThe annual paper production is over 300,000 ton and the specific all-inclusive water consumption is 8.2 m~3/tonrnof paper. As a result of this low figure, we encountered in the activated sludge plant (ASP) problems of bulkingrnand floating sludge; surplus activated sludge has been unstable and difficult to dewater. The average parametersrnof the treated effluent for TSS, BOD and COD were in the year 2000: 84, 43 and 251 mg/l respectivelyrnIn order to meet strict new environmental demands the site ran a 3-year program that involved all the parts of thernmills and central services:rnPreventive program in the paper mills of more than one hundred improving projects. The goal was minimizingrnloads and disturbances to the biological process.rnInstallation of an anaerobic system (IC from Paques) as a pre-treatment before the ASP. The IC is now removingrn75% of the total incoming COD.rnOptimizing the entire biological treatment to extract the best performance from the system.rnThose actions resulted in significant changes in the existing ASP operation and its performance. The averages ofrnthe TSS, BOD and COD in the effluent today are: 6, 4 and 80 mg/l respectively. The sludge amount was reducedrnby 75% and its stability was raised. In addition we gained other benefits like reduction in energy consumptionrnand nutrient demand.