Study On The Engineering Application Of Anoxic Aerobic Pond + Hydrolytic Acidification Pond + Ozone Oxidation + A/O Process In Treating Pig Wastewater

With the rapid development of large-scale livestock and poultry breeding,the environmental problems are becoming more and more serious.Intensive livestock and poultry breeding can not avoid the massive concentration of pollutants such as feces,resulting in an increase in the emission density of pollutants such as livestock and poultry feces,a serious disjunction between agriculture and animal husbandry,seriously affecting the surrounding environment,restricting the sustainable development of social economy and endangering the country's ecological security.With the continuous expansion of livestock and poultry breeding enterprises,the traditional returning mode and natural treatment mode have not been able to meet the needs of large-scale pig farm wastewater treatment,and efficient industrial treatment mode has emerged as the times require.According to the characteristics of high concentration of organic pollutants,suspended solids,ammonia nitrogen and total phosphorus in pig-raising wastewater,this paper integrates a set of reliable technology,high treatment efficiency,stable operation,economical and applicable combination process-anoxic aerobic pond+hydrolytic acidification pond+ozone oxidation+A/Ocombination process.Based on the new construction project of a large intensive pig farm wastewater treatment station in Wannian,Jiangxi Province,the pig wastewater treatment process design and equipment selection were carried out on the basis of the combined process,and the technical feasibility of the combined process was discussed through the commissioning and operation of the actual project to ensure the stable operation of the wastewater treatment system and the discharge of effluent up to standard.The anoxic aerobic pond and hydrolytic acidification pond were used as the first-class biological treatment process for pig farm wastewater.After nearly 60 days of commissioning,the volume load of the anoxic aerobic pond reached the design requirements and the operation was stable.During stable operation,SV_30%was maintained at 35%?40%,MLSS was measured at 3500?4000 mg/L,sludge reflux ratio was controlled at 100%,CODCr removal rate was above 60%,NH₃-N removal rate was above 75%,PO₄³⁺removal rate was stable at about 70%.The hydrolytic acidification pond was started in a low-load way.After nearly 3 months of debugging,the hydrolytic acidification bacteria with high activity were successfully cultured in the hydrolytic acidification pond.The COD_cr in the effluent was stable at 300?350mg/L,the removal rate reached about 45%,and the treatment system had a certain impact resistance.The ozone oxidation process is adopted to carry out advanced oxidation treatment on the wastewater after primary biochemical treatment to degrade refractory organic matters and improve the biodegradability of the wastewater.After stable operation,when the COD_cr in the influent is about 350 mg/L,the COD_crr in the effluent is 180-200 mg/L,the COD_cr removal rate is stable at 45-50%,the chroma of the effluent can be reduced to less than 30 times,and the removal rate can reach 90-95%.The A/O process was used as the secondary biological treatment process.The A/O pool was started by low-load aeration for 10 days,and then the load was gradually increased for continuous operation.After the stable operation of the A/O tank,COD_cr of the influent water is stable at about 200,and the effluent water is kept near 80 mg/L,with the removal rate above 60%.The NH₃-N in the influent is150-200 mg/L,the NH3-N in the effluent is below 15 mg/L,and the NH₃-N removal rate is stable above 90%.The removal rate of PO₄³⁺is more than 50%when the influent PO₄³⁺is about 20 mg/L and the effluent PO₄³⁺is less than 10 mg/L."anoxic Aerobic pond+hydrolysis acidification pond+ozone oxidation+A/O"After the completion of the combined processing process,formally put into operation,the units run Stably.During stable operation,the average daily treatment of biogas slurry 1500m³,pig farm wastewater removal rate of the main pollutants are more than 90%,of which,COD_cr removal rate of more than 93%,NH₃-N removal rate stabilized at more than 97%,PO₄³⁺removal rate of more than 99%.In contrast to the requirements of the primary discharge standard in the GB8978-1996 of the comprehensive effluent discharge standard,wastewater achieves standard Discharge.The operating cost of the combined treatment process is 3.17 yuan/t wastewater,which has remarkable environmental economic benefits.