Study On Advanced Treatment Of First Grade A Effluent By Biological Active Coke Combination Process

The advanced treatment of the effluent of the first grade A standard of urban sewage is an important means to reduce the pollution of water environment,and the advanced treatment of low concentration sewage is one of the research hotspots in the field of water treatment.In this paper,the ozone aerobic anoxic combined process(O3+OA,packed with activated coke filler,referred to as ozone biological activated coke combination process)was used to treat the effluent up to the first grade A standard,and the ozone aerobic anoxic combined process(O3+OA,containing suspended plastic filler,referred to as ozone biofilm combination process)was used as the control to study the effect of COD and nitrogen removal in the ozonation,aerobic and anoxic reaction stages,and determine the optimal operation conditions of each process unit in the ozone biological active coke combination process,achieving the best treatment effect.Headspace solid phase microextraction and GC-MS were used to determine the change of organic matter in the effluent of each process unit of the combined process of ozonactive coke,and the mechanism of degradation of organic matter in each process unit was studied and analyzed.Through research,the following conclusions are obtained:(1)Ozonation can degrade organics in water and improve their biodegradability.With the extension of ozone contact time,the removal rate of COD in the effluent increased continuously.The removal rate of COD in the first 60 min increased obviously,reaching 23.06%,at 60 min,and then the removal rate of COD in the last 60 min tended to be stable;Adjust the pH value of the influent water from weak acid to slightly alkaline,the COD concentration of the effluent water decreases gradually.The alkaline reaction conditions are more conducive to the decomposition of organic matters in the water by ozonation,and the pH value of the effluent water decreases after ozonation;With the increase of ozone generation,the COD concentration of effluent decreased rapidly.When the generation was 9mg/min,the COD removal rate reached 23.58%.After 9mg/min,the COD concentration of effluent changed little;Adding H2O2 and powdered activated carbon had no significant effect on COD removal;The first grade A effluent is ozonized under the operating conditions of contact time 60min,ozone generation 9mg/min and pH value of influent 9.0.The biochemical property of organic matter in effluent is high;At the stage of ozonation,the nitrogen content in water can not be removed,but the existing form of nitrogen in water can be transformed(2)The aerobic bio active coke method is better than the aerobic bio membrane method in removing the organic matter content in the effluent.With the increase of HRT in aerobic reaction stage,the concentration of COD and nitrogen in the effluent of bio activated coke reactor column decreased.The hydraulic retention time is shortened to 4h,and the COD concentration of the effluent is less than 30mg/L,which meets the COD standard of class ?surface water quality;The ammonia nitrogen in the effluent is basically zero,and the removal rate is up to 97%;It is easy to form the DO concentration gradient from the surface to the inside in the porous structure of the biofilm cultured with the active coke as the biological carrier,so as to create the growth space and conditions of denitrifying bacteria,which has a certain denitrification efficiency and the TN removal rate is about 38%,reflecting the advantages of the active coke as the filler(3)Compared with the anoxic biofilm method,the anoxic bio active coke method can further remove the total nitrogen content in the effluent.With the increase of the dosage of sodium acetate,the TN concentration in the effluent decreased gradually,on this basis,the hydraulic retention time is continuously shortened,and the TN concentration in the effluent is increased,when the hydraulic retention time of the control anoxic reaction stage is 3h and the influent is added with 20mg/L sodium acetate,the TN concentration of the effluent can be reduced to 1.46mg/L,reaching the TN standard of class ? surface water,the TN removal rate is as high as 81.09%,the COD of the effluent is stable below 30mg/L of the COD standard of class IV surface water,and the added carbon source is fully used for denitrification reaction,with high denitrification efficiency(4)After advanced treatment by ozone biological active coke combination process,the effluent of the municipal sewage reaching the first grade A standard has ammonia nitrogen<1.5mg/L,TN<1.5mg/L,COD<30mg/L,all of which meet the class ? water quality standard of surface water.The combination process of ozone biological active coke can give full play to the synergistic effect of chemical oxidation,adsorption of active coke and microorganism The special structure of the surface pore diameter of active coke can keep the biofilm with high activity and biodiversity,and it is easy to adsorb low concentration organic matter and nitrogen in the water.It has a good treatment effect on the organic matter and nitrogen in the effluent of level a standard.(5)The ozone bioactive coke combination process is used to deeply treat the first grade A standard effluent.The content and types of organic matter in the effluent are significantly reduced,and new substances are produced.Before the first grade A effluent treatment,the main organic matter is alkane,acid,alcohol,phenol,ester,ketone,aldehyde,benzoquinone,benzene series,glycoside,furan,quinidine,hormone and pigment.The main organic substances in the treated water are alkanes,acids,alcohols,esters,aldehydes,glycosides,benzenes,phenols,benzoquinones,ketones and hormones.Among them,esters are removed the most,furans,quinolines and pigments are completely removed,and no new organic substances are generated.In the ozone oxidation stage,the macromolecular organic substances in the effluent of grade A are oxidized by hydroxyl radicals to easily biodegradable alkanes and acids such as pentadecane and tetradecane,which are used as electronic donors to be decomposed and utilized by microorganisms in the subsequent biochemical treatment process to synthesize new substances and produce metabolites.Dodecanal,nonanal,and aescin-l-ol were not completely removed in the effluent.