Study On Preparation And Application Of Composite Flocculants By Using Bentonite And Red Mud As Raw Materials

Inorganic polymer flocculants(IPF) is a new type of water treatment agent.This subject,by using bentonite from Xinyang of Henan Province,red mud from in Henan Branch China Aluminum Com.,as raw materials,synthesized a series of composite inorganic polymer flocculants.The optimal conditions were determined by the process of dissolution from concentration,temperature,time,respectively;observed morphology by scanning electron microscopy;discussed the flocculant performance, such as dosage,time,pH,respectively,by using it for the coagulation tests to life sewage and industrial wastewater of Kaifeng City.It was analyzed the indexes of heavy metal and nutrition constituent of the sludge after the process of precipitation, and a preliminarily study on the kinetics of flocculation.The research was carried out as following:1) A series of complex flocculants of polymeric aluminum ferric sulfate(PAFS) were prepared by using bentonite as the main raw material,the optimal conditions which affected the extraction efficiency from bentonite were determined by the process of dissolution were the concentration of H₂SO₄,reaction temperature and time,which were 40%,95℃and 3 h,respectively;observed morphology by scanning electron microscopy and found that product is an amorphous material in general,randomly forming aggregates of various sizes and shapes,showing needle or lamellar structure,a small fold;the results from the coagulation tests show that the dosage,settlement time and pH is 0.80mL/L,8min and 6-7,respectively,at the optimum conditions,the value at which the turbidity,chroma and COD reduction is 96%,90%and 45%,respectively.2) A series of complex flocculants of poly aluminum ferric silicate sulfate(PAFSi) were prepared by using bentonite as the main raw material,the optimal conditions which affected the extraction efficiency from bentonite were determined by the process of dissolution were the concentration of NaOH,reaction temperature and time,which were 4mol/L,80℃and 1 h,respectively;observed morphology by scanning electron microscopy and found that product is an amorphous material in general,randomly forming aggregates of various sizes and shapes,showing rich lamellar structure and huge surface area;the results from the coagulation tests show that the dosage, settlement time and pH is 0.50mL/L,8min and 5-10,respectively,at the optimum conditions,the value at which the turbidity,chroma and COD reduction is 97%,100% and 90%,respectively.3) A series of complex flocculants of polymeric aluminum ferric chloride(PAFC) were prepared by using red mud as the main raw material,the optimal conditions which affected the extraction efficiency from red mud were determined by the process of dissolution were the liquid-solid ratio,reaction temperature and time,which were 3.5:1,95℃,1 h,respectively;observed morphology by scanning electron microscopy and found that product is an amorphous material in general,randomly forming aggregates of various sizes and shapes,showing small fold;the results from the coagulation tests show that the dosage,settlement time and pH is 0.80mL/L,30min and 6-7,respectively,at the optimum conditions,the value at which the turbidity, chroma and COD reduction is 69%,85%and 70%,respectively.4)The result showed that the indexes of heavy metal content in sludge,after the coagulation tests from three floccuants,are in line with the national requirement of Standard of agricultural pollutants in sludge control,nutrient content is higher than livestock manure's which used in agricultural commonly.The most appropriate use pattern is to stabilize the sludge compost as a fertilizer after treatment.5) The study on the dynamics of the flocculation process was shown:The orthogonal test indicated that the most important factor which effecting coagulation is the impact of stirring speed,time to secondary factor;The values of Gt are 10⁴～10⁵ in phase of fast and slow.In the composite flocculants of three,PAFSi showed the best settling property,which is expected to increase system capacity.Preparation of three inorganic polymer composite flocculants are safe and highly efficient,a very good development prospects for the development.The study can utilization of bentonite,the cheap,abundant natural resources,the red mud,changing waste into valuables,bringing out the concept of rational use of resources and the green environmentally industry,in accordance with the development of society of "Resource-saving" and "Environmentally-friendly".