Research And Application Of Advanced Treatment Technology For Biogas Slurry Of Large-Scale Piggery

A large-scale pig farm was built in Qibu Township,Wannian County,Jiangxi Province.It is located at the intersection of Poyang,Yugan and Wannian counties and belongs to Binhu District.In order to protect the water environment of Poyang Lake,Wannian county environmental protection bureau requires the effluent of this pig farm to meet the first grade standard in table 4 of"The Integrated Wastewater Discharge Standard"?GB8978-1996?.Although the biochemical property of swine wastewater is good,it contains a large number of refractory pollutants such as antibiotics,therefore the conventional biochemical treatment can not make the effluent reach the discharge standard.Based on this situation,the process of“anoxia-aerobic-hydrolysis acidification-ozone oxidation-A/O"was adopted to treat the wastewater from the biogas tank.The main research contents are:?1?The effects of experimental conditions on wastewater ozone treatment were studied by orthogonal experiment and single factor experiment.The orthogonal experimental results show that the reaction time is the main influencing factor,the ozone dosage and pH value are secondary influencing factors.The optimal conditions are reaction time 40min,ozone dosage 30g/h,pH 9.6.The results of single factor experiment showed that the higher the ozone dosage,the higher the COD removal rate.When the reaction was 20mins and the dosage of ozone was 18,24,30g/h,the COD removal rate was 31.1%,36.0%,37.5%,respectively;The higher the pH value,the higher the COD removal rate.When the pH value was increased from 5.6 to 10.6,the COD removal rate was increased from 32.5%to 42.2%.However,the removal rate of COD will decrease if the pH value is too high.When the pH value was 11.8,the COD removal rate was only 35.5%.?2?The effect of ozone on the biodegradability of hypoxic-aerobic effluent of biogas slurry was studied.The experimental results show that the B/C of the wastewater after ozone treated increased from 0.12 to 0.42,the biodegradability was significantly enhanced.?3?The concentration of COD,NH₃-N and PO₄^3-of the swine wastewater was about 16500,960 and 90mg/L,respectively.After anaerobic digestion in the biogas tank,the concentration of COD,NH₃-N and PO₄^3-was decreased to 1500,550 and100mg/L.In this paper,"anoxia-aerobic-hydrolysis acidification-ozone oxidation-A/O"process was designed as the main part to treat the biogas slurry.Anoxic-aerobic pond after 50 days of commissioning,the concentration of COD,NH₃-N and PO₄^3-was about 450,198 and 32mg/L,respectively,and the average removal rates was 68.6%,61.3%and 69.0%,respectively.The hydrolytic acidizing pond underwent a month and a half of commissioning,the COD removal rate reached more than 20%,the COD concentration was about 340mg/L.The COD removal rate of ozone oxidation tank was about 30%,chroma removal rate was more than 90%.A/O pool after a month and a half of commissioning,the SV₃₀ was more than 30%,the MLSS was about 3300 mg/L.And the average concentrations of the effluent COD,NH₃-N and PO₄^3-were about 81,10 and 0.3mg/L,the average removal rates were 69.4%,94.9%and 98.8%,respectively.The nitrogen and phosphorus removal effects were remarkable.After integrated process operated,the average removal rates of COD,NH₃-N and PO₄^3-were 94.2%,98.3%and 99.7%,respectively.The effluent indicators were better than the first grade standard in Table 4 of"The Integrated Wastewater Discharge Standard"?GB8978-1996?.The total investment of the project was 7.0539 million yuan,and the operating cost was 3.11 yuan/m³.The project can reduce COD,NH₃-N and PO₄^3-emissions by741.9t,293.2t and 53.5t per year,inspectively.