Study On Flocculation System For Dewatering Of Environmental Dredged Sediment And Its Temperature Interference Mechanism

At present,in the dredging industry,the treatment of dredged sediment is mainly based on the conventional methods of reduction,stabilization and harmlessness.Among them,the reduction of dredged sediment is the most important link in the whole treatment process of dredged sediment,and the pharmaceuticals used in the reduction process become an important factor affecting its efficiency.However,in practical engineering practice,the flocculant is relatively single,and due to the lack of corresponding theoretical support,there are many problems in the use of flocculants,environmental factors will also have a great impact on the flocculation effect.Taking the sediment of Baiyangdian Lake as the research object,this paper studied the flocculation effect of the flocculation system based on single flocculant and compound flocculant,and explored the influence of temperature on the flocculation effect of flocculant and its mechanism.This paper systematically studied the composite flocculant with single flocculant and various single flocculant.The degree of flocculation reaction was characterized by measuring the time of flocculation reaction,the amount of flocculant residual water,the turbidity of flocculant residual water and the floc grade.The flocculation mechanism was explored by measuring the Zeta potential of residual water.The flocculating effects of organic,inorganic and biological single flocculants were compared,and the flocculating effects of single flocculant were improved by using organic-inorganic and organic-biological composite flocculants.At the same time,surfactants and small molecule salts were added to the flocculation system to improve the flocculation effect of flocculants.The experimental results show that when inorganic flocculant PSAF is mixed with organic flocculant CPAM,the dosage of organic flocculant can be reduced by about 30%and the floc grade can be raised to 4.When organic flocculant CPAM is mixed with biological flocculant,the dosage of CPAM can be reduced by 30%when the same flocculation effect is achieved.Right,and the remaining water turbidity can reach below 5NTU.When the flocculation auxiliaries was mixed with APAM,the turbidity of residual water could be reduced to 40?50%of the blank group.The flocculation kinetics was also studied by changing the water content of sediment.The results show that the flocculation settling process accords with the second-order kinetics.In addition,the influence of temperature on flocculation effect was investigated by changing different environmental temperatures(5-40 C).The results showed that at high temperature(35-40 C)and low temperature(5-15 C),the flocculation reaction time doubled and the residual water turbidity increased by 2-3 times.In addition,this paper also analyzed the flocculant screening test of the pollution sediment dredging and disposal project of Xingyun Lake in Yunnan Province.The whole test tested 14 kinds of organic flocculants provided by six factories,and finally selected two kinds of flocculants suitable for dewatering and volume reduction of Xingyun Lake sediment.