Experimental Research On COD And Ammonia Nitrogen Removal Form Cooking Wastewater By The A~2/O~2 Biofilm Process

As we all know Coke Plant wastewater is a typlcal,containing high COD and concentration ammonia nitrogen,and difficult biodegradeational industry wastewater.Because coke sewage contains lots of hard-biodegraded and toxicant substances,It is considered to be one of the most difficult industrial wastewater to purify.Drainage of coke sewage without purify could result in the serious pollution inwaterbody,and the purified coke sewage that could not reach standard would also do harm to waterbody.This is large incompatible with our country now strongly advocated the implementation of energysaving emission reduction policies although with the physical or chemical process,which could meet the request of drainage for the environmental protection,the cost would be very expensive.Coking wastewater is usually treated by activated sludge proeesses such as A/O and/or A~2/O,however,which are difficult to realize simultaneous removals for both COD and NH3-N to the standards mentioned above.The reasons are analyzed,for first drpressed nitrifying bacteria by high influent COD concentrations and baeteria-inhibited organics in influent;Second a small part of degradable COD,a short HRT and Less carbon source in anoxic reactor.As the capacity of COD removal by denitrification is not fully utilized,the effect of denitrifieation is poor so that the A/O and A~2/O processes can not make use of the whole process for COD removal. In the thesis according to water quality and characteristics of cooking wastewater of a coking plant in taiyuan, the paper studied the nitrogen removal mechanism and effect in detail by A~2/O~2 process in the process system to remove high concentrations of COD and NH3-N was relatively system study.The experimental results show that : the removal of COD can reach more than 90%,and NH3-N removal can reach more than 95% in the A~2/O~2 biofilm process in the case of a stable system operation which COD in raw water is between 1200mg/L-2200mg/L, NH3-N is between 200mg/L一1000mg/L,pH is between 7.1—8.3 and the average return ratio is 3.2.