| With the increasing production of excess sludge in China and the improvement of environmental protection laws and regulations,the requirements for sludge treatment and disposal have become more and more stringent.Traditional sludge treatment and disposal methods have been difficult to meet our country’s current sludge disposal needs.In view of my country’s traditional sludge treatment technologies,such as thermal hydrolysis pretreatment,anaerobic digestion,aerobic biological drying,thermal drying,incineration,etc.,there are key technical difficulties with high input and high energy consumption.The sludge disposal method cannot realize the utilization of sludge as a resource,and is likely to cause secondary pollution of the ecological environment.It is urgent to find a new sludge disposal method to solve the current dilemma of sludge disposal in my country.In recent years,as a new type of sludge disposal method,the sludge carbonization process has the advantages of low energy consumption,simple products,pollution free and broad prospects for resource utilization.It is of great help to solve the dilemma of large sludge production,high disposal cost,and low utilization rate of resources in China,and it has attracted more and more attention from many domestic scholars.This paper mainly uses municipal sludge as raw material through high-temperature carbonization process to make sludge charcoal as raw material,to study the chemical and physical properties of the residual sludge after high-temperature carbonization and use it in-situ for sewage treatment and residual sludge.In the treatment process,the enhanced effect of the activated sludge method in removing pollutants and the conditioning effect of the remaining sludge in sewage treatment are studied and analyzed.In the study of its in-situ application for sewage treatment in sewage plants,the sludge charcoal powder prepared by high-temperature carbonization process was liquefied under vacuum and then added to the SBR pilot plant.The enhancement effect of different adding ways and proportions of carbonization on the removal of pollutants by activated sludge process was studied.When it is used in sewage treatment,the results show that the sludge carbonization is added into the activated sludge SBR pilot test equipment at the addition ratio of 0.5 g/L,1g/L,2 g/L and 3 g/L at one time.Compared with the experimental control group,the average removal rate of CODcr increased by 1.23%,1.25,1.08%,0.62%.The average removal rate of NH3-N increased by 7.75%,8.19%,9.05%and 8.58%.The average removal rate of TN was increased by 9.11%,7.88%,9.83%and 8.31%.The average removal rate of TP increased by9.51%,10.73%,10.99%and 7.62%.The sludge carbonized matter was added into the acclimated activated sludge SBR test equipment with the addition ratio of 0 g/L,0.02 g/L,0.04g/L,0.06 g/L and 0.08 g/L with each influent.Compared with the experimental control group,the average CODcr removal rate was improved by 0.54%,0.69%,0.82%and 0.69%.The average removal rates of NH3-N were improved by 3.31%,4.94%,5.59%and 5.25%.The average removal rates of TN were improved by 3.08%,7.33%,8.88%and 7.98%.The average removal rates of TP were improved by 2.73%,4.1%,4.39%and 3.67%.Through the analysis of the physical and chemical properties of sludge char and the effects of adding activated char on the properties of activated sludge,dehydrogenase activity and microbial diversity,it can be found that the enhanced removal effect of sludge char on pollutants in wastewater treatment process mainly depends on the physical adsorption and enhanced biodegradation of sludge char,which complement and promote each other.When the domestic wastewater is treated,the treatment effect is significantly improved.Due to its large specific surface area and physical adsorption capacity,sludge carbonization has an adsorption effect on pollutants in sewage at the initial stage of influent,which can reduce the impact of high concentration pollutants on microorganisms in activated sludge.At the same time,the carbonized material has a relatively high specific surface area,which can provide attachment points for the microorganisms of the activated sludge,increase the density of the micells in the sludge,and make the activated sludge system maintain a higher biomass.In the study of its in-situ application in excess sludge dewatering conditioning experiment,the carbonized powder was added to the excess sludge according to different proportions for conditioning and stirring,and the sedimentation rate of excess sludge and the change of supernatant liquid volume with time were observed.The results showed that the sludge sedimentation and dewatering performance were greatly improved after the carbonized powder conditioning.When the dosage of carbonization was 50 g/L,the sedimentation rate of excess sludge increased from 0.4 m L/min to 2.25 m L/min,the volume of supernatant increased from15 m L to 36.5 m L,the moisture content of sludge cake decreased from 89.62%to 77.67%,and the specific resistance of sludge decreased from 1.99×109 S2/g to 0.73×109 S2/g.Based on the analysis of the microscopic photos,zeta potential and infrared spectrum of the sludge before and after conditioning,the mechanism of sludge conditioning with carbonized sludge powder is mainly through physical adsorption to build the skeleton structure with carbonized sludge powder as the core in the sludge,so that the strength of the flocs in the remaining sludge is increased,thereby maintaining the high permeability of the mud cake.At the same time,the addition of carbonized sludge can be added in the sludge.To a certain extent,reduce the hydrophilicity of sludge,strengthen the hydrophobicity of sludge to achieve the purpose of reducing the water content of sludge. |
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