Study On Three-stage Biological Treatment Technology Of Slaughterhouse Wastewater

In recent years,water pollution caused by nitrogen,phosphorus and organic matter has been widely concerned around the world.Slaughterhouse wastewater is one of the main sources.If it is discharged without proper treatment,it will cause serious harm to the water environment.In view of the high concentration of nitrogen,phosphorus and organic matter in the effluent of conventional secondary biological treatment of slaughterhouse wastewater,this study carried out the research on advanced treatment technology based on the secondary biological treatment process.Based on the study of nitrogen,phosphorus and carbon removal performance and mechanism of natural zeolite,a natural zeolite sulfur oxidation denitrification reactor?Z-SOD?was constructed with natural zeolite as the main biological carrier,elemental sulfur particles as the electronic donor and solid waste oyster shell as the alkali source,to explore the removal effect of pollutants and micro growth in the sulfur autotrophic denitrification reactor by adding natural zeolite The community effect of biomass and the mechanism of enhanced denitrification nitrogen and phosphorus removal and carbon removal were analyzed.First of all,in the study of nitrogen,phosphorus and carbon removal technology of natural zeolite,through its static experiment,it is determined that the process of ammonia nitrogen removal?NH₄⁺-N?of natural zeolite conforms to Freundlich isotherm adsorption equation?R²>0.90?;the main cations exchanged with NH₄⁺are Na⁺and Ca²⁺.At the same time,the removal rate of phosphate(PO₄^3-)by natural zeolite is stable at 8%¹0%,and the removal rate of COD is about 60%.The results show that the best desorption efficiency is 50%for NH₄⁺at pH 12,45%for PO₄^3-at pH 2,and 20%-30%for COD at all pH values.Thermodynamics study shows that the removal of NH₄⁺-N by natural zeolite is a spontaneous process and exothermic reaction.Based on the above conclusion,the influence of the modification on the physical and chemical adsorption of nitrogen,phosphorus and organic compounds was further studied.The results of dynamic experiment show that the modified zeolite can improve the NH₄⁺-N removal ability.The reaction rates of the two dynamic experiments were in accordance with the logistic model?R²>0.995?.Based on the study of natural zeolite denitrification,a Z-SOD reactor for nitrogen,phosphorus and organic matter advanced treatment based on sulfur autotrophic denitrification was constructed,and its performance was compared with that of traditional sod.The results show that the EBCT is 8.1 hours The removal rate of NO₃^-?NO₃^-removal rate is 90%-95%?,PO₄^3-removal rate is 30%-60%,and COD concentration is in a state of continuous growth,but the by-product production in Z-SOD reactor is significantly lower than that in SOD.The EBCT value is 6.3 h by detecting the concentration of NO₃^-and sulfate(SO₄^2-)and calculating the reaction kinetics.The utilization rate of Z-SOD reactor is the highest and the pollutant concentration of the effluent can meet the discharge requirements;the results of the treatment of the secondary biological treatment effluent of the actual slaughterhouse wastewater show that Z-SOD can still effectively remove NO₃^-?NO₃^-removal rate is90%?,PO₄^3-removal rate is 30%-70%,and COD concentration is stable.According to the study of microbial community structure,the dominant bacteria in denitrification system include Thiobacillus,Acetobacter and denitrisoma.Aerobic bacteria and denitrifying bacteria coexist,so as to achieve the continuous and effective removal of NO₃^-.In conclusion,the Z-SOD reactor designed and constructed in this study can effectively adsorb and remove nitrogen,phosphorus and organics in the water,and is suitable for the secondary biological treatment of slaughter wastewater.It is a low-cost,simple and efficient advanced treatment method of wastewater.