Study On The Effect And Coagulation Mechanism Of PAC-PDMDAAC

The coagulant which is widespread used in most water supply plants in ourcountry is Polyaluminium Chloride (PAC), which has undesirable effect on organiccompounds and leads to great consumption of reagent. Therefore, reasonably selectingnovel, cheap and effective coagulants has very important significance for drinkingwater treatment.Using poly dimethyl diallyl ammonium chloride (PDMDAAC) andPolyaluminium Chloride (PAC) as starting materials, a composite flocculant ofPAC-PDMDAAC was prepared by dissolving PDMDAAC in PAC solution.Systematical research on this composite flocculant was conducted: the structures ofsolid composite flocculant were analyzed by using FT-IR; the species distribution andtransformation of aluminum in PAC-PDMDAAC solution were studied by means ofFerron complexation timed spectropHotometry; the morpHology of PAC-PDMDAACwas studied by Scanning Electron Microscope (SEM); the charge characteristics ofPAC-PDMDAAC was measured by Zeta potential measurement. In the meantime, Jartests were used to study the influences of the inorganic coagulant sorts and thecomposite ratios of inorganic coagulants to PDMDAAC on the efficiency of humicacid、diatomite、high algae water、Jialing River and Lake water removal.The experiment results indicated that: the micro appearance, species distributionof aluminum, the charge characteristics of the PAC-PDMDAAC were affected byadding PDMDAAC. PAC-PDMDAAC can improve significantly on coagulationprocess to various kinds of source water. For treating diatomite simulation of sourcewater, in lower drug dosage, the turbidity rate can be as high as99%. For treatinghumic acid simulation of source water, removing effect of humic acid is much higherthan the single coagulants（PAC）.For treating Jialing River source water, in the bestdrug dosage, removing effect of compound coagulant can improve more than40%compared with single coagulants. For treating algae water of Jialing River, theremoving rate of PAC-PDMDAAC can be as high as98%. Meanwhile,PAC-PDMDAAC has a wide range of PH adaptability.Mechanism of coagulation of PAC-PDMDAAC is: Compound coagulant forwater in the material removal is mainly through the electricity and the flocculation role, and adsorption bridges, exclusive adsorption effect such as the flocculation could playa certain role. The mechanism of turbidity removing of PAC-PDMDAAC is theelectricity and neutralizing action, when dealing with diatomite simulation of sourcewater; the mechanism of humic acid removing of PAC-PDMDAAC is the electricityand neutralizing action when dealing with humic acid simulation of source water; themechanism of diatom removing of PAC-PDMDAAC is the electricity and neutralizingaction and adsorption bridges when dealing with diatom simulation of source water;the mechanism of turbidity removing of PAC-PDMDAAC is the electricity andneutralizing action, and the mechanism of organic matter is electricity and neutralizingaction and adsorption bridges when dealing with Jialing River.