Research On Chemical Stabilization Technic For Malodorous Black Water Sediments

In the treatment on malodorous black water,it is very important to treat the malodorous black water sediments which is the endogenous pollution of water,the treatment of malodorous black water sediments includes in-situ remediation and ex-situ remediation.Although the ex-situ remediation has a large scale and high cost,it has obvious advantages and quick effects,and is widely used.The malodorous black water sediments of the general city is usually mechanical dewatered,and then the mud cake is transported or reused.However,in small towns and suburban areas,the sediments is usually treated by natural drying.If the sediments without further stabilization and harmless,which could result in the secondary pollution of the environment.Therefore,this study proposes a sediment stabilization technic by adding chemical reagent.Exploring the stability effect of single reagent and composite reagent for the malodorous black water sediments,and analyze influence factor,development of chemical stabilization technic suitable for the disposal of malodorous black water sediments.Providing a scientific basis for the disposal of malodorous black water sediments.In this study,the stability of malodorous black water sediments using single reagent such as Na2S2O8,CaO and H2O2 was performed.The results showed that,the three single chemical reagents have stable effect on black water sediments.Among these regents,Na₂S₂O₈ showed the best performance,this result may be due to the strong oxidation ability and low loss of Na₂S₂O₈.The optimal dosage of Na₂S₂O₈ was 6 g/L,at which dose the sediment was basically stable after 4 days'reaction,the removal rate of TN,NH₃-N,TP in sediment was 63.09%,66.62%and 68.76%,respectively;and the removal rate of heavy metal Cd,Cr,Ni,Pb is 33.62%,36.61%,38.95%and 19.04%respectively.After 7 days'reaction,sediment moisture content and organic matter content could be reduced from 64.21%and 10.24%to 43.21%and 8.36%respectively.Stirring could promote the removal of various pollutants in the sediment the sediment during the reaction,and the optimal stirring times was 3 times/d.The stability effect of malodorous black water sediments using composite reagent Na₂S₂O₈+H₂O₂ and Na₂S₂O₈+CaO was also determinend.The results show that,the best composite reagent for stabilizing the sediment is Na₂S₂O₈+H₂O₂,with the optimal dosage of Na2S2O8 and H2O2 were 4.5 g/L and 7.5 mL/L respectively.After 4 days'reaction,the sediment is basically stable,the removal rate of TN,NH₃-N,TP in sediment were 69.53%,74.58%and 77.23%respectively;and the removal rate of heavy metal Cd,Cr,Ni,Pb were39.21%,41.01%,43.72%and 21.74%respectively.After 7 days'reaction,sediment moisture content and organic matter content could be reduced from 63.54%and 10.19%to42.21%and 7.79%respectively.Compared with single reagent,the composite reagent showed better performance on the stability of sediment,this result may be due to the synergism between reagents,resulting in the enhanced oxidation ability of reagent.