| Eutrophication in water body is one of the most serious environmental problems to be solved in China. As a hot spot in research, treatment and reusing of eutrophic water has been paid close attention to in recent years. In GB8978-1996, maximum amount of phosphor in discharge water is 0.50mg/L and l.0mg/L respectively.Phosphorus removal technology can be divided into chemical system and biologic system. Biologic system is applicable in low phosphorus concentration wastewater with about 70% phosphorus removal. But phosphorus removed in biologic system can be liberated again and secondary pollution will be produced. Through chemical system, phosphorus can be removed steadily with simple operating steps. Up to now, chemical system is the accepted effective technology, which can remove phosphorus from wastewater with ideal and steady efficiency at the same time.There are still some shortages in the application of chemical phosphorus removal system such as expensive chemicals, high operating cost and the production of a large quantity of sludge. In this research, flocculants based on calcium aluminate have been synthesized, within which, introduction of ferrum can reduce the amount of sludge and introduction of organic high polymers can improve its phosphorus removal ability.Raw materials in this research are calcium aluminate, which is a kind of industrial waste, ferric chloride and poly dimethyldiallylammonium chloride (PDMDAAC). Through acid liquefaction, copolymerization and recombination, an inorganic/organic flocculant of PAC-PDMDAAC has been produced. Optimization preparation method of this kind of flocculant has been determined and its phosphorus removal ability has been studied. Experiments in this research including: preparation of PAFC, preparation of inorganic/organic flocculant, study of the flocculating capabilities of PAFC-PDMDAAC and study of the application of PAFC-PDMDAAC.The results of the experiments are listed below:Optimization preparation conditions of PAFC are: l.0g calcium aluminate, 6.0 ml 20% HC1 and measured distilled water, reaction temperature is 100 C, reaction time is 3h and low polymer of calcium aluminate can be produced. Dosage of [Aly, Fe ] is O.Smol/L, [AlT]/[FeT] is 7:3, 0.025mol alkali is added slowly and ageing timeof the reaction system is 24h. PAFC can be produced, which is a kind of brown liquid with ideal stability.PDMDAAC has no apparent phosphorus removal ability; recombination of PAFC and PDMDAAC can improve its phosphorus removal ability; through the recombination of PAPC and PDMDAAC, turbidity removing ability is better than PAFC itself. After the treatment by PAFC-PDMDAAC, pH value of wastewater is steady, which is about 7.0. Applicable pH value range of PAFC-PDMDAAC is 6.5-10.0; temperature flexibility of PAFC-PDMDAAC is ideal, with no obvious difference at 5 C, 25 C and 35 C. Stirring condition of PAFC-PDMDAAC is 200r/min for 3min and 60r/min for lOmin. Sedimentation velocity of PAFC-PDMDAAC is fast and completely sedimentation of these two fiocculants will take 15min.In the treatment of real municipal wastewater, phosphorus removal can meet the discharging standard I in China (GB8978-1996)-not more than 0.50mg/L. At the same time, sludge produced in this process can be reduced and pH value of wastewater has no obvious fluctuation. PAFC-PDMDAAC has better phosphorus removing ability than PAFC.PAFC and PAFC-PDMDAAC has ideal phosphorus removing ability and overcome some shortages of traditional flocculants such as high production of sludge and pH value fluctuation. These two kinds of flocculants have practicability in wastewater treatment.
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