Synergistic Treatment Of Microwave Chemistry Hydrolysis Acidification For Removal Of Heavy Metals From Sludge

Land use has always been an important direction for sludge resource utilization.However,the heavy metals in sludge severely limit its land use.Biological methods can be used to extract heavy metals from sludge at low cost,but its relative chemical reagent extraction time Longer,this experiment is based on the previous research results of the research group,with sludge hydrolysis acidification as the leading leaching method,combined with the auxiliary effect of microwave chemistry to improve the efficiency of hydrolysis and acidification leaching of heavy metals.The main research results are as follows:1.Through domestication of inoculated sludge,inoculated sludge with a stable p H value of about 3.5 is obtained.The settling performance of successfully domesticated inoculated sludge becomes better,the p H value is stable,the color becomes yellow-brown,and the sludge becomes granular.The culture temperature is 37°C constant temperature,the nutrient dosage ratio is C:N:P=200:5:1,and the dosage of methanogenesis inhibitor2-bromoethanesulfonate（BES）is 106mg/L.2.Through different inoculation rate,temperature,sludge moisture content,reaction time,reflux ratio,the optimal process conditions for sludge hydrolysis and acidification are determined.The optimal inoculation rate is determined to be 20%.The temperature should be selected for the purpose of lowering the p H value.35°C is more economical.If both a lower p H and better sludge dewatering performance are considered,the appropriate temperature is 45°C,the sludge moisture content is determined to be 97%,the reflux ratio is200%,and the reaction time is preferably 36h.Continue to study the removal rate of heavy metals by hydrolysis and acidification under the optimal process conditions.It is found that the removal efficiency of heavy metals does not change much after a certain period of time.After 15 hours of reaction,the removal rates of As,Cd,Cr,Cu,Ni,Pb,and Zn in the sludge reach 78.46%,48.92%,56.22%,50.93%,70.33%,70.37%,67.49%.3.By adding GLDA in the hydrolysis and acidification reaction,adjusting the p H of the sludge to 3 with CA,shaking assist,and pretreating the sludge with microwave,the reaction rate was significantly increased.The final reaction conditions were determined as follows:microwave power P1,heating to 60°C,9m L 0.1mol/L GLDA,0.69m L 2mol/L CA solution,shake the reaction.The average removal rate of heavy metals in sludge reached 82.93%.4.Through analysis of the heavy metal forms of concentrated sludge,hydrolysis acidified sludge and microwave chemical synergistic hydrolysis and acidification sludge,the results show that the exchangeable state,the carbonate bound state,the iron manganese oxide bound state,the organic matter bound state and the residue state are in the After hydrolysis and acidification,there have been changes to different degrees.The content of various forms of each heavy metal is very different,the stability of heavy metals in various forms is different,and the content of various forms of the final mud after the reaction is also different.5.By comparing the properties of thickened sludge,hydrolyzed acidified sludge and microwave chemical synergistic hydrolytic acidified sludge,the results show that the p H is reduced from 7.01 to 3.65,until the final sludge drops to 3.0,and the SV₃₀is reduced from96%to 83.%,until the final sludge drops to 81.5%,the sludge moisture content is reduced from 97.1%to 94%,until the final sludge drops to 93.2%,the organic matter in the sludge rises from 319 to 346g/kg,until the final sludge rises to 350g/kg,the change in the properties of sludge helps the land use of sludge.