Preparation Of Polytitanium Slicate And Its Application In Coking Wastewater Treatment

Coking wastewater is a kind of industry sewage with high COD,high concentration of NH3-N and high organic pollutants.Earlier showed that coking wastewater pretreatment is generally unable to effectively remove organic pollutants.And so it may have an inhibitory effect on microorganisms in biochemical treatment.Titanium salt flocculant has attracted much attention in recent years due to its non-biological toxicity and excellent coagulation effect.In this paper,the preparation of polytitanium silicate flocculant(PTSC)and its application in coking wastewater coagulation treatment were studied,in order to effectively reduce the concentration of organic pollutants and to further improve the biodegradability of coking wastewater.(1)PTSC flocculant was prepared by composite polymerization method using sodium silicate and titanium tetrachloride as raw materials.The effect of Si/Ti molar ratio(A),alkalinity(B)and activation time(C)on the coagulation treatment of kaolin-humic acid simulated wastewater were investigated by response surface methodology.The obtained optimized preparation conditions of PTSC are: Si/Ti(A)= 0.51,alkalinity value(B)= 0.39,activation time(C)=17.70 h.The turbidity and UV254 removal rate of simulated wastewater by PTSC prepared under these conditions could reach 98.3% and 96.2%,respectively.The analysis of FTIR and XRD results showed that the molecule of PTSC flocculant had Si-O-Ti and Ti-OH structures.(2)The coagulation performances and sedimentation performances of PTSC,PAC and CPAM with different flocculant dosages for kaolin-humic acid simulated wastewater were studied by six-point stirring and static observation.The results showed that PTSC had better coagulation and sedimentation behaviors than CAPM and PAC in the same dosage range.The PTSC flocculant was applied to the raw water and biochemical effluent of coking wastewater.The results showed that,when the dosage was 300 mg/L,the removal rate of turbidity,UV254,COD and DOC in the raw water of coking wastewater could reach 98%,11 %,30%,25%,respectively,while the removal rate of turbidity,UV254,COD,DOC in biochemical effluent can reach 92%,28.5%,59%,64.5%,respectively.Through GC-MS analysis,it was found that the raw water and biochemical effluent of coking wastewater treated by PTSC flocculant significantly decreased the concentration of organic matter and significantly reduced the species.(3)PT-AP flocculant was prepared by the composite method using APDES and titanium tetrachloride as raw materials.The Si/Ti molar ratio,alkalinity B value and activation time were investigated by kaolin-humic acid simulated wastewater by single factor experiment.The influence of coagulation performance optimizes the preparation conditions.Through the treatment experiment of kaolin-humic acid simulated wastewater,the results show that the PT-AP flocculant has a Si/Ti molar ratio of 0.5,an alkalinity B value of 0.5,and an activation time of 0.5-60 days.The removal efficiency of turbidity and UV254 can reach 98% and 98.7% at 50 mg/L.Compared with the treatment effect of inorganic flocculant PTSC on simulated wastewater,the dosage is reduced by 10 mg/L,but the turbidity removal rate And UV254 removal efficiency is higher,coagulation effect is better.PTC and PT-AP were characterized by attenuated total reflectance Fourier transform infrared spectroscopy(ATR-FTIR).It was found that Ti-O-Ti structure existed in PTC,and Si-O-Ti and Ti-O-Ti structure existed in PT-AP flocculant.