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 paper grades, such as tissue from de-inked fibers, corrugated case materials from recycled paper and fine paper from market pulp, all at one site. The annual paper production is over 300,000 ton and the specific all-inclusive water consumption is 8.2 m~3/ton of paper. As a result of this low figure, we encountered in the activated sludge plant (ASP) problems of bulking and floating sludge; surplus activated sludge has been unstable and difficult to dewater. The average parameters of the treated effluent for TSS, BOD and COD were in the year 2000: 84, 43 and 251 mg/l respectively In order to meet strict new environmental demands the site ran a 3-year program that involved all the parts of the mills and central services: Preventive program in the paper mills of more than one hundred improving projects. The goal was minimizing loads and disturbances to the biological process. Installation of an anaerobic system (IC from Paques) as a pre-treatment before the ASP. The IC is now removing 75% of the total incoming COD. Optimizing the entire biological treatment to extract the best performance from the system. Those actions resulted in significant changes in the existing ASP operation and its performance. The averages of the TSS, BOD and COD in the effluent today are: 6, 4 and 80 mg/l respectively. The sludge amount was reduced by 75% and its stability was raised. In addition we gained other benefits like reduction in energy consumption and nutrient demand.