LONG TERM APPLICATION OF BIOREACTOR AND MEMBRANETECHNOLOGIES FOR TREATMENT OF METALWORKING FLUIDWASTEWATERS

摘要

In the late 1980s, General Motors (GM) determined that various combinations of bioreactor andrnmembrane technologies were effective for the removal of contaminants originating from the usernof both petroleum and non-petroleum based metalworking fluids. In the early 1990s, GMrnadopted the use of the membrane biological reactor (MBR) process configuration for full scalerntreatment of manufacturing plant wastewaters at selected U.S. and international sites. The MBRrnsystem installed at the GM of Canada Ltd.(GMCL) Windsor plant in Windsor, Ontario, Canadarn(GMCL Windsor) in 1994, represented at the time the largest MBR facility in the world treatingrnindustrial wastewater. Although performance expectations were being met, after approximatelyrnfive years of operation the MBR system flowsheet was modified to incorporate a membranernenhanced aerobic digester. The MBR-aerobic digester configuration has proven optimal tornmaintain treatment system performance while minimizing the costs of disposal of excess biomassrnand non-biodegradable membrane captured solids (i.e., waste solids). This paper reports thernresults from operation of the GMCL Windsor conventional MBR and the MBR-aerobic digesterrntreatment systems, focusing on the 12 year plus operating history of the bioreactors and thernmembrane component.rnThe results from operation of the conventional MBR system from start-up in Januay 1996rnthrough 2000, clearly showed the largest single cost associated with operation was the disposalrnof bioreactor waste solids. In an attempt to address this issue while ensuring the majorrnadvantages of the MBR technology were not compromised, the MBR-aerobic digester processrnconfiguration was developed and implemented in November 2000. The results derived fromrntreatment plant performance and operating audits completed in the early 2000s and most recentlyrnin May of 2007, confirm the advantage of the MBR-aerobic digester flowsheet with respect tornreducing the disposal cost of waste solids. There is no evidence that the modified scheme hasrnnegatively impacted the membrane system efficiency, performance or life expectancy.