| With the vigorous development of our country’s economic level and the continuous progress of our country’s industrialization level,our country’s sludge production has increased year by year in recent years.How to reduce the amount of sludge and how to dispose of it properly has been a hot issue in recent years.In the waste water treatment of the lead-acid battery industry,flocculants such as PAC,PAM and Ming staff are often used to precipitate the lead and other elements in the waste water.After the waste water treatment,a large amount of lead-containing sludge will be produced.Lead-containing sludge is a hazardous waste which can cause serious damage to the environment.However,the research on the reduction of lead-containing sludge is still hard to find currently,and the key points of the reduction technology and the reduction mechanism of lead-containing sludge are still unclear.In order to solve the problems above,this paper takes the lead-containing sludge taken from the thickening tank of the lead-acid battery factory as the research object to do some research.The main research contents include:1)The influence of different conditioning methods on the suction filtration process for the reduction of lead-containing sludge.The sludge was pretreated by hydrogen peroxide conditioning,Fenton conditioning,and electrochemical advanced oxidation conditioning respectively,and then mechanical suction filtration was used to dehydrate the sludge.In order to maximize the reduction degree of sludge,it was found that the optimal dosage of30 wt.%H2O2 solution for hydrogen peroxide conditioning should be 5.00 m L/100 m L sludge,the optimal p H value of the sludge that needs to be adjusted in advance should be around 2 under the premise that the dosage of 30 wt.%H2O2 is 3.33 m L/100 m L sludge when Fenton conditioning is used,and the best conditioning condition when using the electrochemical advanced oxidation method is to adjust the p H of the sludge in advance to around 3,the conditioning voltage and the time of electrolysis being 4.5 V and 12 h respectively.In these three conditioning conditions,compared with the unconditioned control group,the reduction degree of sludge cake was 23.56 wt.%,47.18 wt.%,and 74.90wt.%respectively.The moisture content of the sludge cake decreased from 90.11 wt.%in the control group to 88.75 wt.%,83.23 wt.%,and 79.39 wt.%respectively.The viscosity of the sludge decreased from 18 m Pa·s in the control group to 7.2 m Pa·s,2.6 m Pa·s,2.7 m Pa·s respectively.The VSS/TSS of the sludge cake after suction filtration increased from 0.276in the control group to 0.298,0.449,and 0.409.In addition,the morphology and SEM-EDS analysis of the suction filter cake indicate that single hydrogen peroxide conditioning or electrochemical advanced oxidation conditioning cannot completely destroy the flocculation caused by inorganic flocculants such as PAC and alum,while Fenton conditioning or electro-Fenton conditioning has a more powerful effect on the entire floc structure of the sludge.2)The influence of Fenton conditioning on the electro-dewatering process for the reduction of lead-containing sludge.Fenton conditioning is used to pre-treat the sludge,and then the sludge is suction filtered and electro-dewatering is carried out to reduce the mass of the sludge.It is found that in order to have a better reduction effect on the sludge,under the premise that the p H value of the sludge system is adjusted to 3 in advance,the 30 wt.%H2O2 solution that needs to be added is 13.33 m L/100 m L sludge.Under this conditioning condition,compared with the control group where the sludge is not conditioned and directly subjected to suction filtration and electro-dewatering,the reduction degree of the sludge cake after electro-dewatering is 66.20 wt.%,and the moisture content of the mud cake after the electro-dewatering decreases from 80.45 wt.%in the control group to 71.48 wt.%.The viscosity of the sludge decreased from 18 m Pa·s to 4.4 m Pa·s,and the VSS/TSS of the sludge cake increased from 0.306 in the control group to 0.384 after electrolysis.In addition,under the optimal conditioning conditions,the H2O2 concentration and ferrous ion concentration in the sludge were tested during the Fenton reaction,and it was found that the H2O2 consumption accounted for 55.62 wt.%of the total dosage after 30 minutes of reaction,the concentration of ferrous ion was 1.39 mg/m L sludge before the Fenton reaction started,and it could not be detected 5 minutes after the reaction started.The morphology and SEM-EDS analysis of the sludge cake after electro-dewatering showed that single concentrated sulfuric acid conditioning cannot make the aluminum element in the flocculant lost to the filtrate.The surface structure of the electro-dewatering sludge cake of the experimental group after Fenton conditioning is less dense,and the mass of inorganic elements in the sludge cake is less.3)The influence of Electrochemical advanced oxidation conditioning on the electro-dewatering process for the reduction of lead-containing sludge.The sludge is pretreated by the electrochemical advanced oxidation method,and then the sludge is suction filtered and electro-dewatering is carried out.It is found that in order to minimize the mass of the remaining sludge cake after the final reduction,the p H of the sludge system needs to be adjusted to 3 in advance,and conditioning voltage and conditioning duration is 4.5 V and12 h respectively.At this time,compared with the control group where the sludge was not conditioned and directly subjected to suction filtration and electro-dewatering,the reduction degree of the sludge cake after electro-dewatering was 77.08 wt.%,the moisture content of the sludge cake decreased from 80.45 wt.%in the control group to 71.26 wt.%,the viscosity of the sludge decreased from 18 m Pa·s to 2.7 m Pa·s,and the VSS/TSS of the sludge cake after electro-dewatering increased from 0.306 in the control group to 0.452.In addition,only changing the conditioning time in the best conditioning conditions of the best electrochemical advanced oxidation method,it was found that when the conditioning time was further extended to 24 h,the sludge reduction degree decreased to 58.20 wt.%.By adding a small amount of electrolytes such as 3.33 g/L Na2SO4,3.33 g/L Na Cl to enhance the current during electrochemical conditioning,it was found that compared with the control group that was conditioned at 5.0 V for 12 h without adding electrolyte,the sludge reduction degree was changed to 42.06 wt.%and 38.65 wt.%from 39.23 wt.%of the control group respectively.In addition,the SEM-EDS analysis of the sludge cake after electro-dewatering found that the electric Fenton conditioning can cause stronger damage to the surface structure of the sludge cake after electro-dewatering and will cause more inorganic substances to be dissolved in the filtrate. |
