Application Research Of Organic-Al-Zn-Fe Coagulant On Wastewater Treatment

A new inorganic-organic polymeric coagulant named organic-Al-Zn-Fe (PPAZF)was prepared by adding polyacrylamide (PAM) as organic modified additives inpoly-Al-Zn-Fe (PAZF) which had been successfully developed. The structure andsurface morphology of PPAZF were carried out by a variety of analytical technologies,such as infra-red spectrum (IR), X-ray diffraction (XRD) and scanning electronmicroscope (SEM) and so on. The coagulation performance of PPAZF was studied bycoagulation experiment on simulating humic acid wastewater, sewage and severalindustrial wastewaters, and the coagulation mechanism of PPAZF was also discussedpreliminarily.The experimental results indicated that the preparation of PPAZF comprises acidleaching stage (same to PAZF) and polymerization stage. The microscopiccharacterization experimental results expressed that PPAZF was a sort of polymericcoagulant containing multi-hydroxyl poly-aluminum, zinc, iron and organicingredients, and also was the coexistence of amorphous polymer and crystalline.There were a lot of globular materials connected to form a long chain-like structure,which then formed an internal dense mesh-block structure. Therefore, PPAZF had sobetter adsorption and netting capacity that its settlement was faster, and its treatmenteffect was much excellent.Coagulation effect of PPAZF was significantly better than of the combination ofdosing of PAM and PAZF. A series of experiments showed that the turbidity,chromaticity, COD and total phosphorus removed by PPAZF at the optimum dosagewas higher than that of PAZF and PAC. PPAZF could adapt to a broad range of pHvalue and the optimum pH ranged from7to12. Due to the complex of actualwastewater quality, the effect of treating practical wastewater was not very good;however, PPAZF had certain advantages compared with PAZF and PAC. For the studyof the flocs of sewage sedimentation performance, the flocs that PPAZF producedsank fast, large and dense, and had a good coagulation effect. Finally, PPAZF hadbetter capacity on phosphorus removal. PPAZF had better coagulation performance. It was because that the free ions ofaluminium, zinc and iron or mononuclear hydroxyl complexes and polynuclearhydroxyl complex ions in PPAZF gave full play to its role and power, which includedelectrical neutralization, adsorption bridging and roll sweeping role. Meanwhile，PAMalso enhanced the adsorption bridging effect between colloidal particles.