Study On The Start-upand Adsorption Performance Of Anaerobic Granular Sludge System Based On Livestock And Poulry Breeding Wastewater Treatment

Along with the development of society and economy,China has successively built large-scale intensive livestock and poultry farms,which discharge huge amount of wastewater with the characteristics of high concentration of pollutants,resulting in considerable economic damage.With thin margins of livestock and poultry breeding industry,economic and efficient removal of chemical oxygen demand?COD?emissions from wastewater and ammonia nitrogen?NH₄⁺-N?in discharge water quality to meet the national standards is the main problem in the process of aquaculture wastewater treatment.Combining the biosorption concept with anaerobic granular sludge adsorption characteristics,this research explored the rapid forming process of anaerobic granular sludge in different carbon source in Anaerobic Sequencing Batch Reactor?ASBR?.COD quick adsorption ability and the main influence factors were also investigated in the presence of ammonia nitrogen,in order to remove ammonia nitrogen by ANAMMOX later smoothly.Rapidly increase the organic load by increasing the influent COD concentration and shortening the Hydraulic retention time?HRT?to achieve rapid start-up of the reactor,successfully cultivating anaerobic granules with sludge particle size of 1.1 mm;when the volumetric load was reached 6 g/?L?d?,the COD removal rate was 95%.The mature particulate sludge was used to study the influencing factors of rapid adsorption of organic matter.The results showed that the optimal pH range for the adsorption of organics by anaerobic granular sludge was 6.8 to 7.2 and the optimal temperature range was 35±2?.The optimal regeneration time was 6h;the best idle time was 4 h;the optimal sludge particle size was 0.4¹.2 mm.By comparing batch stirring,upflow stirring and continuous stirring,it was found that the intermittent stirring was best.At the same time,the experimental results show that the stirring frequency was 20 s/?2 min?during the adsorption period,the adsorption equilibrium can be achieved within 8 min,and the maximum adsorption rate was 73.5%.In addition,the influent COD concentration can affect the adsorption sites on the surface of anaerobic granular sludge adsorbed the amount of organic matter,thus affecting the adsorption performance of anaerobic granular sludge for organic matter;the content of extracellular polymer was directly proportional to the adsorption rate of organic matter by anaerobic granular sludge.The gibbs free energy change?G^?obtained from the adsorption thermodynamics were all negative,indicating that the process of anaerobic granular sludge adsorption for organic pollutants was spontaneous,the range of values suggested that the adsorption process was mainly based on physical adsorption.The enthalpy change?H^?<0 indicates that the whole adsorption process was exothermic;the entropy change?S^?>0 indicates that the degree of disorder in the entire adsorption system was increasing.When the influent COD concentration was 3000mg/L,according to the change of COD in the adsorption period of the reactor after 30 days cultivation,the correlation coefficient R² of the first-order reaction of anaerobic granular sludge was 0.6289 and the R² of the intraparticle linear diffusion fit was 0.8275under the condition of sodium acetate as the substrate,bio-adsorption interparticle diffusion dominated the rate-limiting stage;the correlation coefficient R² of the first-order reaction of anaerobic granular sludge was 0.9260and the R² of the intraparticle linear diffusion fit was 0.9362 under the condition of sodium acetate:soluble starch 2:1 as the substrate,bio-adsorption interparticle diffusion dominated the rate-limiting stage;the correlation coefficient R² of the first-order reaction of anaerobic granular sludge was 0.9781 and the R² of the intraparticle linear diffusion fit was 0.9531 under the condition of sodium acetate:soluble starch 1:1 as the substrate,the membrane mass transfer was the dominant rate-limiting stage.When sodium acetate:soluble starch was 1:1?COD concentration was 3000mg/L?,the adsorption performance of granular sludge after 30 days cultivation can be well fitted by the pseudo first-order and pseudo second-order reaction equations and has good correlation.The pseudo second-order reaction equation R² was 0.9998;the pseudo first-order reaction equation R² was only 0.9744,indicating that the adsorption kinetics of anaerobic granular sludge was more suitable to be described by pseudo-second order kinetic equations.