Research On Deep Denitrification Technology For Slaughterhouse Wastewater Based On Tire And Elemental Sulfur Particles

Slaughtering wastewater is one of the most harmful agricultural and food industrial wastewater,which is rich in nitrogen,phosphorus and other nutrients that can induce water eutrophication.At present,the removal capacity of TN and TP in most of the secondary treatment processes of slaughterhouse wastewater is limited,which is difficult to meet the increasingly strict discharge requirements in China.Therefore,on the basis of ensuring the existing treatment capacity,it is urgent to strengthen the performance of advanced removal of nitrogen and phosphorus,develop new processes or upgrade the existing processes.In order to solve the problem of insufficient available carbon source in the secondary effluent of slaughterhouse wastewater,waste tire particles?T?were used as the organic carbon source of heterotrophic denitrification in batch experiments,and elemental sulfur particles?S⁰?were used as the electronic donor of sulfur autotrophic denitrification to explore the denitrification effect of different nutrient denitrifying microorganisms,the results of microbial batch experiments show that:?1?The slow-release organic carbon from T particles can be utilized by heterotrophic denitrifying microorganisms,at the same time,it was observed that T particle had good adsorption effect on nitrate nitrogen?NO3^--N?,and its adsorption capacity could reach 3.83mg/g.?2?Compared with the pure heterotrophic denitrification system,there is a more efficient denitrification capacity in the mixed nutrient denitrification system with T particles as carbon source.?3?Compared with the pure sulfur autotrophic denitrification system,the sulfate(SO4^2--S)production in the mixed nutrient denitrification system is lower,and the change of p H is closer to neutral.Based on the theoretical research of batch experiments,two kinds of up flow packed bed reactors,namely,tire sulfur mixotrophic denitrification?T-SMD?and sulfur oxidizing denitrification?SOD?,were constructed,at the same time,in order to ensure the stability of the p H value of the effluent,the broken oyster shell?OS?were added to the reaction column as the source of alkalinity.This experiment focuses on the removal of NO3^--N and TN from simulated slaughterhouse wastewater by a new mixed biological carrier packing combination?T+S+OS?,the accumulation of by-product SO4^2--S and the change of p H value in the reaction were observed.The denitrification performance of T-SMD and SOD was compared and analyzed,the results of column experiments show that:?1?Compared with SOD,the removal rate of TN and NO3^--N by T-SMD is higher,91.2%and 99.0%respectively,and the domestication time of microorganism is shortened by nearly half,which shows that the denitrification system with T particle as carbon source donor has more efficient denitrification performance.?2?The concentration of SO4^2--S in T-SMD is lower,and the concentration of SO4^2--S in effluent is much lower than that in drinking water?GB5749-2006??83 mg/L?,and the concentration of SO4^2--S is much lower than that in effluent of SOD?93.21±2.71 mg/L?.Therefore,compared with sulfur autotrophic denitrification alone,the denitrification efficiency of mixed nutrient denitrification is higher and the accumulation of SO4^2--S is lower.?3?The COD concentration?28.27±1.67 mg/L?in the effluent of T-SMD added with T particle as organic carbon source is far lower than the requirement of the discharge standard of water pollutants for meat processing industry?second draft?for the direct discharge of sewage by new enterprises?60 mg/L?,indicating that the organic carbon released by T particles can be fully and efficiently utilized by heterotrophic denitrifying microorganisms,and will not cause secondary pollution of the effluent.During the operation of T-SMD,the change of p H value is about 6.70-7.67,which is more stable and more suitable for the growth of denitrifying microorganisms compared with SOD?about 6.30-7.60?.Compared with the results of the batch of experiments,it can be seen that the addition of OS particles makes the alkalinity consumed in the system timely supplement.This study is applicable to the situation that the effluent organic carbon concentration of slaughterhouse wastewater after secondary treatment is low and TN concentration is not up to standard,and further treatment is still needed.It can provide a new idea for the reconstruction and design of the existing and new slaughterhouse wastewater advanced treatment process,and provide a certain data reference for the revision of the"wastewater discharge standard of meat processing industry"?second draft for comments?.The innovation of this paper lies in the advanced treatment of slaughterhouse wastewater with T+S+OS packing combination and sulfur autotrophic denitrification technology,which has the advantages of energy saving,environmental protection,no secondary pollution and high denitrification efficiency.