Design And Operation Of A High Nitrogen Containing Wastewater Treatment Engineering

With the rapid development of economic,many dye chemical plants are being built and put into production all over the country,producing amounts of wastewater.Dye chemical wastewater has the characteristics of high concentration,high nitrogen content and high biological toxicity.The discharge of industrial effluent at will can cause extremely serious environmental pollution and ecological perniciousness,and threaten the health of residents.In this paper,various denitrification processes were firstly summarized,including physical and chemical methods such as air stripping,magnesium ammonium phosphate(MAP)precipitation and chemical oxidation,and biochemical methods such as A/O,single reactor system for high activity ammonium removal over nitrite(SHARON),anaerobic ammonium oxidation(ANAMMOX),oxygen-limited autotrophic nitrification-denitrification(OLAND)and completely autotrophic nitrogen-removal over nitrite(CANON).The wastewater from a dye chemical plant was then analyzed,with the main characteristics including:(1)Wastewater quality changes.The wastewater quality varies during producing different products,and the indexes of major pollutants fluctuate greatly.(2)High level of nitrogen content in the wastewater detected by Kjeldahl.(3)Low carbon-nitrogen ratio(C/N)in the wastewater.According to the analysis of the wastewater from the dye chemical plant,several schemes were developed,and finally membrane bioreactor(MBR)based CANON process was used.The main conclusions were presented as follows:(1)The CANON process is very effective in treating high nitrogen content wastewater.During operation,the average removal efficiency of CODCr was 95.5%and the average removal efficiency of total nitrogen was 88.2%.This process is feasible for the treatment of wastewater from dye chemical plants.(2)The operating cost is low.The treatment cost is 5.28 RMB per ton of wastewater.It is of great significance for popularizing this process with a low operating cost.(3)The system loading is low.During steady operation,the average volumetric loading of CODCr was 0.265 kg/m3.d,and that of ammonia nitrogen was 0.042 kg/m3.d.