Study On The Preparation And Flocculation Effect Of Montmorillonite Flocculant

At present,the more widely used flocculant is polyaluminium chloride(PAC).Because of its losse flocs structure,easy to float,poor sedimentation performance,certain residues in the water and other shortcomings,study and development of safe,non-toxic,high-efficient and low-cost coagulants has been an important research field at home and abroad,and also,such research work which is of great significance.In order to reduce the bio-toxicity and increase the settling effect of floc,the montmorillonite flocculant(MTSF)was prepared by acid modification with inorganic mineral montmorillonite(MTS)as a raw material,and was used to treat the simulated wastewater by comparing with Poly Aluminium Chloride(PAC).The experimental results showed that MTS had no flocculation performance,while MTSF had a good flocculation performance with the removal efficiency of turbidity reaching 96.73%.Importantly,regarding with the settling volume and settling velocity of floc,MTSF performed much better than PAC.The flocculation mechanism of MTSF was attributed to the function of adsorption and electrification,caused by a synergistic effect between solid particles and soluble salts,showing better settling performance and compressive properties of floc.After the equilibrium of settling,the floc volume of MTSF was less than one third of that of PAC.Moreover,the mix of MTSF and PAC flocculant could effectively reduce the floc volume and improve the settling performance.Overall,MTSF has similar flocculation effect to PAC,while its settling and compressive properties are much better than PAC,regarding with superior comprehensive performance.The montmorillonite flocculant(MTSF)was prepared to treat high concentrated swine wastewater,by comparing with traditional flocculant polyaluminium chloride(PAC).The effect of flocculant's dosage on the treatment performance was studied,and the settling characteristics of flocculation were also discussed.The results show that MTSF performed better than traditional flocculant PAC.Under the optimum MTSF's dosage of 12000 mg L-1,the removal efficiency of turbidity,SS,CODcr,NH4+-N and TP reached 85.7%,96.8%,60.7%,16.3%and 97.7%,respectively.Although MTSF's dosage was higher than that of PAC,but the settled floc volume of MTSF accounted for 12%of the total volume,which was less than 1/5 of PAC.The synergistic effect of soluble salts and insoluble particles in MTSF contributed to the outstanding flocculation and settling performance.Importantly,heavy metals of Cd,Cr,Ni,Cu and Pb were not detected in the supernatant.Although the As concentration increased from 0.16 mg L-1 to 0.34 mg L"1,it was still less than the maximum value of 0.50 mg L-1 according to?the standard of wastewater discharge?(GB8978-2002).Therefore,the supernatant after flocculantion by MTSF can meet the standard of discharge or be used for subsequent biological treatment.