Research On The Whole Process Of Duck Breeding Wastewater Treatment And Resource Recovery

Duck farming wastewater has the characteristics of high solluted chemical oxygen demand（SCOD）,high nitrogen and phosphorus,and poor biodegradability.It is a high-concentration refractory organic wastewater.Improper disposal will threaten the ecological environment and human health.This subject takes the production wastewater of a duck farm in Shandong Province as the research object.The average SCOD concentration in the wastewater is above 60000 mg/L,the average ammonia nitrogen concentration is above 4000mg/L,and the average total phosphorus concentration is about 1300 mg/L,the raw water B/C=0.134,the wastewater has poor biodegradability,and it is difficult for conventional biological treatment.In view of the characteristics of wastewater,experimental research finally determined the use of coagulation sedimentation-Fenton oxidation-blowing-continuous stirred tank reactor（CSTR）-two-stage sequencing batch reactor（SBR）combined process,and at the same time,the ammonia nitrogen and biogas generated during the treatment process were recovered.The effects of coagulation sedimentation method,Fenton oxidation method and stripping method to pretreat wastewater and optimized the operating parameters was studied in the thesis.Experimental results show,the best operating parameters of coagulation sedimentation:p H=8,the dosage of ferric chloride 80 mg/L,the dosage of polyacrylamide6 mg/L;the best operating parameters of Fenton oxidation:p H=3,The dosage of H₂O₂ 30mmol/L,the dosing ratio of H₂O₂ and Fe²⁺is 2:1;the best operating parameters for stripping:p H=11,reaction temperature at 45℃,stripping time 120 min,aeration intensity 4 L/min.After the preliminary physical and chemical pretreatment,SCOD,ammonia nitrogen,and total phosphorus were reduced by 25.3%,89.7%and 98.8%respectively,antibiotics in wastewater were effectively removed,and the biodegradability of wastewater was significantly improved.CSTR-two-stage SBR as the follow-up biological treatment unit was used in the thesis.The CSTR anaerobic reactor has the best operating effect under the conditions of 37℃,sludge retention time（SRT）=30 d and volumetric load of 1.32 kg/m³●d,and the best effect on wastewater treatment.After CSTR process treatment can remove 87.5%of SCOD and 56%of ammonia nitrogen.At the same time,the influence of different aeration time and sedimentation time of SBR process on the treatment effect was studied,and the best aeration time was determined to be 5 h,and the best sedimentation time was 0.5 h,finally it is determined that SBR runs 3 cycles per day,and the operation cycle is 8 h.Water inflow for0.5 h,stirring while water inflow,anoxic section for a total of 2 h（including water inflow section 0.5 h）,aeration section for 5 h,precipitation for 0.5 h,drainage section for 0.5 h;two-stage SBR treatment,the removal rates of SCOD,ammonia nitrogen,total phosphorus and5-day biochemical oxygen demand（BOD₅）were 91%,92.3%,91.3%,94.6%,respectively,and the effluent quality was significantly improved.Long-term experimental results show that the combined process of coagulation sedimentation-Fenton oxidation-stripping-CSTR-two-stage SBR treats duck farming wastewater under optimal operating conditions.The average concentrations of effluent SCOD,ammonia nitrogen,total phosphorus and BOD₅ are 353 mg/L,28 mg/L,6 mg/L and83 mg/L,all have reached the"Emission Standard of Pollutants for Livestock and Poultry Farming"（GB18596-2001）,the recovery rate of ammonia nitrogen can reach more than 90%,and the anaerobic unit volume production the gas ratio is 1.2 L●（m³●d）^-1,and the CH₄ content is 58.9%.