Study On The Removal Of Phenol In Coking Wastewater By Coagulation With Composite Flocculants

As a typical high-concentration organic wastewater,if the coking wastewater is directly subjected to biochemical treatment,the high concentration of organic matter will increase the biological load and even poison the microorganisms,which is not conducive to the normal operation of the biological treatment,the coking wastewater must be pretreatment before the biological treatment.Therefore,it is important to realize the enhanced coagulation pretreatment of coking wastewater and improve the biodegradability of the wastewater after pretreatment,so as to explore or develop an efficient flocculant suitable for coking wastewater.This research provides the theoretical basis for coagulation pretreatment of coking wastewater through the preparation of aluminum polysilicate flocculant and the research on its coagulation performance of simulated wastewater and actual coking wastewater.The main findings are as follows:?1?Polysilicate aluminum coagulant?PASiC?with different molar ratio of aluminum and silicon was prepared by using sodium silicate and aluminum chloride.The morphological structure was analyzed by a series of characterization methods.Combined with FTIR and XRD analysis,it was proved that polysilicic acid reacted with aluminum to form new compounds.The SEM analysis showed that the PASiC with Al/Si molar ratio of 1.0 exhibited a dense porous structure.This kind of structure is favorable for the flocculatio n agent's adsorption and bridging of the tiny colloidal particles in the water.The experimental results of simulated wastewater coagulation showed that the PASiC₁?molar ratio of Al to Si is 1.0?has the best effect on the co-removal of turbidity and phenol,and the removal rate of turbidity can reach 99%,the removal efficiency of phenol is also have 4.6%.?2?The coagulation performance of simulated wastewater was compared among CPAM?cationic polyacrylamide?,PASiC₁ and PAC.PASiC₁ and PAC showed excellent removal of wastewater turbidity,and CPAM had the best effect on the removal of phenol in wastewater.Under different PASiC₁ mass concentrations,different dosages of CPAM to study the effect on coagulation performance.The results showed that when the CPAM dosage was 5 mg/L,the turbidity removal rate was up to 99%and the phenol removal rate was 10.3%.In the pH range of 4 to 9,the Composite flocculant PASiC₁-CPAM has a good removal effect on the turbidity of wastewater,but the removal of phenol is greatly affected by the pH value,and the removal of phenol is better under alkaline conditions.?3?Comparison of coagulation performance of PASiC₁ with three organic flocculants CPAM,GG?guar?and CGG?cationic guar?in simulated wastewater.The coagulation effect of CGG is best.When the dosage ws 125 mg/L,the removal rate of turbidity is 93%,and the removal rate of phenol can reach 18.1%.PASiC was used in combination with GG and CGG,respectively.It was found that the composite flocculant PASiC₁-CGG of the coagulation performance for wastewater is better than that of PASiC₁-GG.When the addition amount of CGG was 20 mg/L,the highest removal rate of turbidity was more than 99%,and the highest removal rate of phenol was 17%.Under alkaline conditions,PASiC₁-GG and PASiC₁-CGG all has a better removal of turbidity and phenol from waste water.?4?Taking the actual coking wastewater as the research object,PASiC ₁,PASiC₁-CPAM,PASiC₁-GG,and PASiC₁-CGG were respectively used for coagulation treatment of coking wastewater.The research showed that the three kinds of composite flocculants had significantly better effect on the removal of turbidity,COD_Cr and volatile phenol from waste water than PASiC.PASiC₁ was compounded with 5 mg/L CPAM,the highest removal rates of turbidity,COD_Cr and volatile phenol were 90%,27%,and 35%;After PASiC₁ was mixted with 25 mg/L GG,the highest removal rates of turbidity,COD_Cr,and volatile phenol were63%,32.8%,and 38.2%;PASiC₁ was compounded with 20 mg/L CGG,the highest removal rates of turbidity,COD_Cr,and volatile phenol were 95%,37.7%,and 42%.