Survey of Chitosan with Polyaluminum Chloride in turbidity removal from Ahwaz water treatment plant

The water that has been contaminated by human or naturally for changing into drinkable water it should go through different process of refinement. The current water treatment process include: screening, coagulation, making the clot treatment, sedimentary, water treatment and disinfection. Coagulation is a process that in the course of it the little non_settling particles that called colloidal and are an important factor in appearing the turbidity sticking together and format the bigger particles which can be settle. The process of water treatment without the use of materials which increase the precipitation of intensely particles seems to be impossible[1].In the process of coagulation, we use different coagulant and coagulant aids materials. The coagulant materials include the materials which are used for unstabling the particles and sticking them together. while using of coagulant aids materials is a help for faster sedimentary and increase the density of Adherent particles [2].Aluminum salts and iron are the most are the most current coagulants which are used for water treatment and waste water. But in recent years a new kind materials called inorganic polymeric flocculants (IPFS)1 are provided with the use of ordinary iron salts and aluminum. Poly aluminum chloride(PAC) is one of the most important kinds of (IPFS) that is more useful than the other kinds [3,4].Serious detriments had been obtained because of using aluminum salts and remaining it in the water and producing a big quantity of sludge and they way of disposal it in the environment[5].According to Mack Dermot (1987) and his colleagues survey, there is a meaningful connection between increasing the aluminum law, average and high turbidities are 10 and 1mg/l and the maximum turbidity elimination for 73.4 percent is 5 and 0.5 mg/l and the maximum turbidity elimination for96 percent is 5 and 0.5 mg/l and the maximum turbidity elimination for 98.2 percent had been obtained[13]. Bing-tao and his colleagues at 2008 worked onstudying the effect and the mechanism of chitosans coagulant aids to eliminate the turbidity of organic materials in the drinkable water. The poly aluminum chlorides optimum concentration had been obtained at 35mg/l and for chitosan 0.15mg/l and 7.5 optimumpH[14].Wang and his colleagues at 2009, worked on studying the effect of chitosan as a coagulant aids on the Floces shape and firmness. According to optimum condition to eliminate the turbidity, chloride ferrics optimum doses had been obtained at 29mg/l and0.1mg/l for chitosan. The formed Floces by chitosan were bigger and had a high precipitation and caused the floces not to be broken easily [15]. Roussy and hiscolleagues at 2005, worked on studying the effect of concentration of brain tissues in the seven sick people who are suffering from encephalopathy dialysis with the concentration of this element in the dialysis liquid[6].For minimizing each kind of potential riskarising from the aluminum remaining in the watertreatment that in it flocculants aluminum has been used, water treatment process should be optimized forreducing the rate of remaining aluminum to the lowest possible level. with the purpose of solving the problems related to chemical flocculants, a lot of researches hasbeen done in the recent years about natural flocculants that in this respect we can mention chitosans application[7].Chitosan