| Flocculation is a kind of method and technique of purifying water in common use.But the conventional flocculants such as polyaluminium chloride (PAC) andpolyacrylamide (PAM) in water treatment are prone to produce secondary pollution,the aluminum ions that is produced from hydrolysis of PAC in water come intohuman body via feed water and cause various diseases such as anaemia, hair-losingand brain dementia etc., crylic acid and amine that are produced from hydrolysis ofPAM would harm human health too. So how to prepare a kind of novelenvironmentally friendly flocculant which is of less pollution and better flocculatingperformance is a very inportant subject and an urgent task in water treatment fieldrecently. Therefor, a kind of novel high-effect environmentally friendly flocculanthad been prepared by using the natural resources in Hubei province such as rectoriteand the red lobster shell which are at low prices and abundant amount. Comparedwith the conventional flocculant, this novel composite flocculant has a moreenvironmentally friendly function, lower price and higher effect by using it to treattypical feed water and wastewater. The main research contents and results of thispaper are included as following:1, By adopting the novel process, the modified rectorite flocculant was prepared fromthe natural rectorite. Compared with the natural rectorite, its removal rate of COD andSS were increased by 25.3％and 35.0％respectively, and its medicament cost wasdecreased by 5％.2, By adopting the novel preparing and clean production process, the chitosanflocculant was prepared. Compared with the conventional process, the cost ofpreparing chitosan was decreased by 19％, the time of preparing chitosan wasshortened by 50％, the total yield of perparing chitosan was increased by 5％, thecontaminating burthen in preparing chitosan was reduced by 54.3％, the value ofrecycling byproduct in preparing a ton of chitosan product was enhanced by 4 times,moreover, the main performance parameters of this chitosan had reached to the ones of the same product made in Sigma Co. of the U.S.3, It's the first time that the compound of modified rectorite and chitosan was used inthe flocculation of water treatment, and the fundamental proportion and optimaltreating process of this composite flocculant were put forward. The fundamentalproportion of treating feed water was the vol.of feed water (cloudy degree=95±10NTU): the vol. of 1% modified rectorite liquor: the vol. of 0.1% chitosanliquor=1000: 1: 0.02, the fundamental proportion of treating wastewater is the vol.of wastewater (COD=500±100mg·L-1): the vol. of 1% modified rectorite liquor:the vol. of 0.5% chitosan liquor=1000: 8: 0.2.4, Compared with conventional flocculants, this composite flocculant is of moreenvironmentally friendly function, lower price and better effect in treating water suchas feed water, petrochemical wastewater, paper-making wastewater, bear wastewater,paint wastewater and sludge dehydrating etc., especially, in treating feed water usingthis flocculant, the concentration of aluminum ions in the water was decreased by56.25%, so that feed water treated by this flocculant is more secure and moreenvironmentally friendly.5, According to the flocculation theory and the structure characteristic of the modifiedrectorite and chitosan, this paper analyzed and researched the flocculating mechanismand properties of this flocculant theoretically. The research results show that thereason why the flocculating performance of the modified rectorite is better thannatural rectorite is that the "inserted function" of linked aluminium reagent inmodified rectorite, this inserted function enable rectorite to produce a larger wideningof the space and a wider opening of the field between the layers of Is, so that themodified rectorite is of a wider adsorptive range and a more bulky adsorptivecapability. On the other hand, there are lots of amino group (-NH2) and hydroxyl(-OH) on the molecule chain of chitosan, chitosan can be protonated with H+ intocationic polyelectrolyte in water. This characteristic of chitosan enable chitosan to beof three kinds of flocculating mechanism in water treatment: chelation, electricneutralization and bridge linking function, in which the main function of chelation isto remove the metal ions, the main function of electric neutralization is to remove theCOD and SS in the treated water, and the main function of bridge linking is to improve the whole flocculating performance of the composite flocculant. So thecombining flocculating by using certain inorganic flocculant and organic flocculantcan come to the goal of cooperating enhancing the flocculating effect, complementingthe other's deficiency mutually, and improving the whole flocculating performanceconsumedly.
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