Research And Design On An Equipment For Coking Waste Water From Small And Medium Coking Plants

In recent years,with the rapid development of Chinese economy and industry,the number of industrial enterprises such as petrochemical,steel and gas,has also increased.The prosperity in the number and scale of factories has brought convenience to people’s daily life.Once their by-products such as solid waste,wastewater and waste gas leak outside into the environment,they will not only do harm to the environment,but people’s health simultaneously.With China’s industrialization further developing,the total amount of industrial waste water has increased rapidly.And wastewater’s destruction of the human body and the environment has continued to intensify,especially during the productive process such as steel and gas purification.With the help of our country’s emphasis on coking wastewater hazards and the increasing awareness of people’s environment protection,the ministry of environmental protection in June 2012 promulgated the coking wastewater discharge standards,which proposed "Coking Chemical Industry Pollutant Discharge Standard"(GB16171-2012).There are a series of detailed changes on the basis of the original.For example,the unit of product displacement,direct emissions and indirect emissions of CODcr,ammonia,cyanide and other indicators are added to the stringent standard.Although the studies on treating coking wastewater have made some progress,there is still a great lack of integrated equipments for small and medium enterprises to deal with coking wastewater which could meet the discharge standards after being treated.It is an important factor which restricts the development of the small and medium-sized coking wastewater enterprises with a little money and small-scale.This study proposed and designed a set of integrated equipment for treating small and medium-sized coking wastewater.Firstly,the effect of the experiment on the removal efficiency of coking wastewater was researched from the mass fraction of clay,the ratio of Mn mixed and the ratio of iron to carbon.The author treated coking wastewater respectively by means of the electrochemical-assisted-microelectrolysis process,ozone oxidation process,activated carbon adsorption process and the combination process of electrochemical-assisted-microelectrolysis process-ozone oxidation process-activated carbon adsorption process,and investigated the changes of removal rate of wastewater’s CODcr and NH3-N.The optimum mass ratio of modified microelectrolytic filler was that 20% clay mass fraction”,10% Mn mass fraction,and 3: 1 of the ratio iron to carbon(Fe: C).By electrochemical assisted microelectrolysis process,the highest removal rate of the CODcr and NH3-N was 75.3% and 65.4% respectively.By direct ozone oxidation process,the removal rate of CODcr and NH3-N was low,and the peak of CODcr was 43.5%.The best reaction time of CODcr was 5h,and the removal rate of NH3-N was 36.9%.After 3h,the removal rate of CODcr was reduced to 12%.By comparing activated carbon,coconut shell activated carbon and activated carbon in coal,the saturated adsorption time of wood activated carbon was longer than that of the other two kinds of activated carbon.The removal rate of CODcr and NH3-N was 65% and 62.4% respectively,and the optimum hydraulic retention time was 2h.The optimum removal rate of CODcr and NH3-N was 65% and 62.4% respectively,and the optimum hydraulic retention time changed from 2h to 4h.The design and operation of the equipment were on the basis of small laboratory experiments.The pilot test was carried out,and the results indicated that when the flow rate of treated water was 60 L/h,the effluent concentration was stable after 8 hours of continuous operation,and the removal rate of CODcr and NH3-N could reach 66.2 % and 61%.The equipment showed good results.