Experimental study on pH adjustment combined with composite flocculation vacuum dewatering of sludge
The traditional vacuum preloading method is time-consuming and has poor dewatering effects in the treatment of sludge,making it crucial to efficiently dewater the sludge and enhance resource utilization.Therefore,a composite treatment method combining pH adjustment,compound flocculation and vacuum preloading was proposed.The treatment scheme of pH adjustment combined with compound flocculation is obtained through sludge specific resistance tests and settling column tests.Subsequently,vacuum dewatering model experiments are conducted for application to validate the effectiveness of the proposed method.The mechanism and treatment effects of this composite technology are evaluated and analyzed in terms of specific resistance,drainage volume,pore water pressure and shear strength.The results indicate a significant improvement in sludge dewatering performance with appropriate acidic adjustment.When the pH value of the sludge is adjusted to 4.2,the stimulating effect of the coagulant is more significant,and the treatment effect of compound flocculation is much higher than that of single flocculation.In addition,the addition of coagulants can improve the sedimentation performance of sludge in a short period.Compared with the traditional vacuum preloading method,this composite treatment method exhibits remarkable improvements in drainage volume,water content,and soil strength.The water content of the treated soil is reduced to below 60％,resulting in denser soil and a 2.7-fold increase in shear strength,highlighting the excellent volume reduction and reinforcement effects of this composite treatment technology.
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