| With the rapid development of economy,the scale of sludge treatment plant is increasing,and sludge production is also increasing.As the composition of sludge is complicated and the water content is huge,the treatment and disposal of sludge has become an important environmental problem.A lot of waste pickling liquor(WPL)has been produced with the rapid development of steel industry,which is rich in waste acid and some other substances such as metals,the environment will be polluted seriously with improper treatment,but also a great waste of resources.The aim of this paper is to apply the WPL to the sludge conditioning,which can realize the resource utilization of the WPL and solve the problem of sludge treatment,to achieve the purpose of waste control by waste.The WPL will be used as agents for improving the sludge dewatering performance,and use the agents of polyacrylamide(PAM),FeCl3,AlCl3,aluminium polychlorid(PAC)in sludge conditioning,with the evaluation index of specific resistance to filtration(SRF),capillary suction time(CST),filter cake moisture content and sludge dewatering rate,and the effects of single conditioning and combined conditioning on sludge dewatering performance are studied,the mechanism of their action is expounded,the sludge settling performance,floc morphology and benefit are analyzed under the optimum conditions.The main methods and results are listed as follows:(1)Conditioning sludge with PAM agent alone,the PAM molecular weight,concentration and species were screened and found that cationic polyacrylamide(CPAM)had smallest SRF and the effect of sludge conditioning was the best with the molecular weight of 12 million and mass fraction of 0.1%.CPAM had the best dosage of 70 mg/L that the sludge dewatering performance was the highest.When FeCl3,AlCl3,PAC and WPL were used alone to conditioning the sludge,the best dosage was 3.5 g/L,4 g/L,6 g/L,7 g/L respectively,which theevaluation indexes of sludge were the best and the sludge dewatering performance was improved obviously.(2)It is focused on the effect of factors on sludge dewatering such as dosage and the order of adding with conditioning of WPL and CPAM,which was compared with the compound conditioning of CPAM and FeCl3,AlCl3,PAC,based on the fact of sludge conditioning of single,orthogonal test proved that the effect of the combined conditioning was better than the single conditioning,and the order of adding had a great influence on the sludge dewatering performance.When CPAM and FeCl3 were combined to conditioning sludge with the dosage of 50 mg/L,1.5 g/L respectively,the effect was the best;When CPAM and AlCl3 were combined to conditioning sludge with the dosage of 60 mg/L,1.0 g/L respectively,the effect was the best;When CPAM and PAC were combined to conditioning sludge with the dosage of 60 mg/L,1.0 g/L respectively,the effect was the best;When CPAM and WPL were combined to conditioning sludge with the dosage of 60 mg/L,1.1 g/L respectively,the effect was the best,and all evaluation index were the best,the sludge improvement rate was the highest.With the order of dosage was added first and then the dosage of CPAM When CPAM and other agents were used to conditioning the sludge can have a higher improvement rate and better dehydration effect.(3)Take raw sludge,CPAM of the optimum condition and the combined conditioning results of all agents to make analysis of the sludge settling performance,floc morphology and the estimation of economic cost,found that the sludge settling performance was obvious improved,floc structure was better than the original sludge,dehydration performance was better with the conditioning sludge of CPAM.After combined conditioning,the sludge was easier to settle,the floc was more compact and stable,and the dewatering performance was further improved.WPL and CPAM in sludge combined conditioning with the best effect had the a good economic and environmental benefits.Based on the above results,we know that it is feasible and effective to apply waste pickling liquor to sludge conditioning research by comparing the waste pickling liquor and other agents in sludge conditioning,which can realize the availability and utilization of the sludge and the waste pickling liquor. |
