Preparation And Application Of Natural Polymer Vegetable Gum Flocculant

Flocculation is the most widely adopted method in wastewater treatment. Flocculation efect concerns with the flocculant property directly. Based on the analysis and generalization of the existent organic macromolecular flocculants preparation and flocculation property researches, a new natural organic product named natural polymer vegetable gum flocculant, which belongs to a kind of green (or called environment-protecting) flocculants, was prepared by vegetable gum which was extracted from an easily-got and low-priced farm crop called taro and yam. Its preparation was to modify the raw material with cationic reagent. Preparation experiment conditions and parameters were optimized through a lot of orthogonal experimental studies, with a research for the function of flocculant being the first step and the analysis of the flocculant mechanism of flocculant.In my research, took taro and yam as raw material, extracted vegetable gum from the ram material by organism melting agent precipitates. The optimal extract conditions from taro were determined: water～bath temperature 80℃, water～bath time 2h, precipitant dosage ( physical volume ratio) as 1:1.2;at this time the extraction rate of vegetable gum was 4.34%;the influence turn of each factor was: Water-bath temperature > water^bath time> precipitant dosage. The optimal extract conditions from yam were determined: water-bath temperature 40℃, water-bath time 2.5h, precipitant dosage ( physical volume ratio) as 1:4;at this time the extraction rate of vegetable gum was 7.60%;the influence turn of each factor was: Water-bath temperature > precipitant dosage > water-bath time.In its preparation vegetable gum was used as the matrix, H₂O₂-FeSO₄ was utilized as the initiator and the copolymer product of triethylamine and epichlorohydrin wasused as the cationic reagent-----M. 2.0 g vegetable gum was mixed with 8 ml M. Theoptimized reactions included two steps: Firstly, vegetable gum was alkalifred at 42℃ for 30min under the condition of H₂O 8 ml, NaOH 1.2g and NaCl (as depressor) 0.1%(in total mass). Then it was etherified at 75℃ for 3.5h using H₂O₂-FeSO₄ 0.01% (in total mass) as initiator.Natural polymer vegetable gum flocculant was applied in the flocculation process of several kinds of water, and the experimental results indicate /naturalpolymer vegetable gum flocculant has a wide optimal dosage and pH value in the flocculation process of kaolinite suspension and wastewater. The optimal removal efficiency of CODcr for the wastingwater following 10mg/L natural polymer vegetable gum +40mg/L PAC was 58.7%, which is superior to that of Praestol 855.Natural polymer vegetable gum flocculant was applied in the sludge sedimentation, and the experimental results indicate: when the dosage of vegetable gum flocculant was 2mg/L, the minimun sludge hingh could reach 65ml, and the average sedimentation rate of sludge was 0.35ml/s> which was 1.17 times of 2mg/L GPAM, and 1.46times of 10mg/L CPAM;when the dosage of vegetable gum flocculant was 10mg/L, the minimun sludge hingh could reach 62ml, and the average sedimentation rate of sludge was 0.38mL/s, which was 1.27 times of 2mg/L GPAM, and 1.58 times of 10mg/L CPAM;those all indicate that vegetable gum flocculant was good for accelerating the sedimentation rate of sludge speed, and was superior to CPAM.In the case of decreasing moister content of sludge, vegetable gum flocculant is also superior CPAM. In the Natural filtrated process, with the dosage of vegetable gum flocculant in 2¹0mg/L, filtrated volume increasing with the dosage increase, the maxmiun reach 15.6mL, which is 1.53 times of blank;in the press decreasing process, when the dosage was 4mg/L, vegetable gum floccultant's flocculat was sperior to CPAM, and the filtrated volume could reach 34.3ml in 4mins.