Research On Treatment Of Model Biogas Slurry By Heavy Metal Chelating Agent-BCO-SBBR-MAP Precipitation Method

With intensive of intensification and the trend of scale in pig industry,swine farm in recent years,wastewater treatment has became more more difficult,preliminary study based on an engineering project indicate that heavy metals exists in biogas slurry in pig farms,which can inhibit aerobic biological treatment in the next stage.Emissions index of pHospHorus in the wastewater will exceed the standard at the same time.Therefore,this research adds removal of heavy metals before biogasslurry come into aerobic biological treatment process and adds removal of denitrification and pHospHorus at the end,put forward a technology named“heavy metal chelating agent-BCO-SBBR-MAP precipitation method”to treat swine farm wastewater treatment(biogas slurry),this research include heavy metal removal experiments aimed at model biogas slurry,BCO-SBBR series experiments,removal of denitrification and pHospHorus by the MAP crystallization experiment,the conclusion is as follows.(1)TMT-10 filtered is the most suitable heavy metal chelating agent for processing piggerywastewater of low concentration of heavy metal,to treat 250 m L swine farm wastewater which contains 2.8mg/L Zn(?)and 1.3mg/L Cu(?),under the additive amount of 0.6 mL,the removal rate of Zn(?)and Cu(?)is 92.61% and 90.77% respectively.TMT-10 treat 250 mL swine farm wastewater which contains 2.8mg/L Zn(?)and 1.3 mg/L Cu(?),the optimized conditions were determined as follows:don't adjust pH value,reaction time is 3min,20 mins precipitation time,1m% of PAC and PAM dosing is 1.5mL.Under this condition,Zn(?)and Cu(?)removal rate were 98.22% and 92.65% respectively,the residual concentration is 0.05mg/L and 0.096 mg/L respectively.COD and NH3-N and TP fell to 1485.8mg/L,379.7mg/L,25mg/L respectively.(2)In the condition of wastewater index:COD and NH3-N and TP is 1493mg/L,416.50mg/L,26.55mg/L,the optimized BCO operating condition is as follows.HRT is 12 h,gas water ratio is 12:1.Under this condition,effluent COD,NH3-N and TP come to 544mg/L,181.35mg/L,18.07mg/L respectively,the removal rate is 63.53%,56.45% and 31.95% respectively.(3)In the condition of wastewater index:COD and NH3-N and TP is 614 mg/L,218.38 mg/L,20.89mg/L,the optimized SBBR operating condition is as follows..In The aeration quantity 3.0L/h,the average DO in aerobiotic stage is 3.56mg/L.In this condition,effluent COD,NH3-N and TP come to 153.67mg/L,52.86mg/L,16.20mg/L respectively,the removal rate is 74.98%,75.79% and 22.43% respectively.(4)The experiment about BCO-SBBR reactor running effect found that heavy metal`s inhibiting impact on COD is not obvious,but can obviously inhibit NH3-N and TP,and inhibiting impact cannot recover in a short time.In the condition of 2.8 mg/L Zn(?)and 1.3 mg/L Cu(?)concentrations,average effluent COD and NH3-N and TP concentration were 183.76mg/L,81.81 mg/L,17.55mg/L,the average removal rate is 87.89%,80.20% and 36.47% respectively.After remove heavy metals by heavy metal chelating agent,the average index of effluent water from BCO-SBBR is as follow,COD,NH3-N and TP concentration were 127.92 mg/L,38.62 mg/L,13.33 mg/L,the average removal rate were 91.57%,90.65%,51.75% respectively,and TP cannot achieve claim in ?Livestock and poultry breeding industry pollutant discharge standards?.(5)The best conditions of MAP crystallization is as follows.pH=8.5,Mg:P=1.3:1,total reaction time is 15 minutes,for the water that TP and NH3-N were 13.33 Mg/L and 38.6 Mg/L,after processing,the residual concentration of TP and NH3-N were 0.80 mg/L and 29.04 mg/L,removal rate were 94.02%and 24.77% respectively,and TP can achieve claim in ?Livestock and poultry breeding industry pollutant discharge standards?.