CHEESE WHEY AND CHEESE FACTORY WASTE-WATER TREATMENT WITH A BIOLOGICAL ANAEROBIC-AEROBIC PROCESS

Research on the anaerobic treatment of raw cheese whey started in 1990 with the objective of developing a technology suitable for medium siz e cheese factories that have growing disposal problems and cannot affo rd high investment costs for whey valorisation technologies (such as w hey protein and lactose recovery, spray drying, etc.). In order to cou ple process stability and high loans, a new downflow-upflow hybrid rea ctor (DUHR) has been designed. The reactor was able to reach B-v value s around 10 g COD . 1(-1). d(-1), with 98% COD converted to gas and ef fluent soluble COD values close to 1,000 ppm; no external addition of alkalinity is required to maintain a stable pH that was constantly aro und 6.5-6.7 in the downflow pre-acidification chamber and around 7.5 i n the bio-methanation upflow chamber. The high strength of the cheese whey treated gives an effluent that still contains high amounts of GOD , ammonia nitrogen and phosphorus and therefore a post treatment is re quired in order to meet standard limits. Tests of post treatment were carried out during two years with a Sequencing Batch Reactor (SBR). Th e SBR was tested at various F/M values with different durations of ano xic-anaerobic-oxic cycles, obtaining, under certain conditions, more t han 90% removal of GOD, nitrogen and phosphorus. Copyright (C) 1996 IA WQ. Published by Elsevier Science Ltd.