The Preparation Of Flocculant By Modified Shell Powder And Wheat Bran With The Research Of Floc Fractal Simulation

In this paper,the shell powder and wheat bran were used as raw materials to prepare the modified shell powder-bran coagulant(Whb-sp)through different processing.After that,the removal effect of turbidity and phosphorus of these coagulants were investiagted in simulated wastewater and actual wastewater;Besides that,fractal dimension was introduced to study the structure of the coagulant.The correlation between the coagulation effect and the flocs fractal structure of the coagulants were also investiagted.In order to discuss the mechanism of coagulation and phosphorus removal,some related samples had been tested.In the end,fractal theory was applied to water treatment by the DLA model "the simulation software of Whb-sp coagulation based on the finite diffusion model" to compare the actual fractal flocs with simulated floc fractal in dimension values and verify the feasibility of this software in wastewater treatment.The main contents of this paper are as follows:(1)Based on the analysis of obtained data,the best alkalization conditions of wheat bran were determined.Reaction temperature 50?,reaction time 1h,dosing quantity 0.5 ml and bran dosing quantity 0.3 g.The obtained optimum etherification conditions of wheat bran were also affirmed.Reaction temperature 70?,etherification time 1h,etherification dose 3ml and 1.5 ml initiator dose.The best Whb-sp synthetic experimental conditions were determined by single factor experiments.(2)The Whb-sp was used to the treatment of simulated wastewater.The raw water of101~122 NTU and 9.8~11.6 mg/l phosphorus content was treated.The best removal effect the Whb-sp coagulant appeared under the following conditions: of dosing quantity 7ml,coagulation sedimentation time 25 min,raw water PH value of 6~8 and slow speed 40 r/min.The maximum removal rate of turbility and phosphorous were 94.39% and 66.03%,respectively.The Whb-sp was also adopted to treat the real wastewater with the raw water turbidity 95.3~148NTU,4.07~6.35 mg/l phosphorus content and PH value in 7.39~7.92.The obtained best conditions were as following: Whb-sp coagulant dosing quantity in 7 ml,coagulation sedimentation time 20 min,slow speed of 40 r/min.The maximum removal rate of turbility and phosphorous were 96.57% and 85.84%,respectively.The value of fractal dimension value and the target pollutants removal rate of the flocculation body are quitesimilar.The treatment effect of flocculation body was better than that of aluminum sulfate.(3)Some samples were characterized by advanced equipment and modern analysis techniques.Results show that the prepared flocculant was the hybrid of many different formation of crystal material and organic high polymer complex materials.The mechanism analysis show that the coagulation process involves adsorption-electricity neutralization and adsorption bridging,the compression process of electric double layer effects coexist,at the same time.Phosphorus was removed through chemical bonds inter-atomic forces,molecular inter-atomic forces and other forces with phosphate in bridging role,adsorption,electricity neutralization and precipitation.(4)Compared with the real flocs and analog flocs in image and fractal dimension,combined with polynomial model,the mathematical model of sewage turbidity raw water with initial particles number,raw water PH value with the movement of step length,radius of raw water with the release of phosphorus content was ascertained.After that,the relationship of fractal dimension with Whb-sp additive amount was determined.Using MATLAB GUI to programme,optimizing the factors of slow stirring speed,settling time by BBD experiments,the application and feasibility in wastewater treatment of the synthesized flocs were discussed.