Study On Preparation And Properties Of Attapulgite/Polyvinyl-alcohol Immobilized Carrier

Nitrogen pollution is the most difficult pollution indicator to deal with organic pollution in water bodies,and the environmental problems caused in my country are the most prominent.Microbial biochemical treatment technology is a vital way to remove nitrogen pollution in water.The interface and pore structure of the immobilized carrier directly affect the attachment and growth of microorganisms.Therefore,designing carrier materials with corresponding functions and enhancing the long-term effect of microbial biochemical reactions has become a crucial research direction of sewage treatment materials.This work systematically studied the modification process of attapulgite collected from Mingguang,Anhui province and Linze,Gansu province,which performance in purifying dye wastewater,and then used it to prepare attapulgite/polyvinyl alcohol microbial immobilized carrier materials.The performance of the carrier,the adhesion,growth of microorganisms and the removal efficiency of ammonia nitrogen in the water body were included.The main conclusions are as follows:(1)Organic modification of attapulgite from Anhui Mingguang(MG)and Gansu Linze(LZ)was carried out using KH550.The modified solution formulation was optimized based on response surface methodology and used to adsorb Congo Red(CR)and Methylene Blue(MB).The research results showed that the best modified formula of MG was: attapulgite 10 g,water 50 g,ethanol 50 g,KH550 5 g;the best modified formula of LZ was: attapulgite 10 g,water 100 g,KH550 10 g.Meanwhile the origin of the attapulgite was different,and the modified solvent formula should be adjusted accordingly.The maximum adsorption capacity of MG-5 and LZ-9 for CR in the modified samples were 148.27 mg/g and 123.12 mg/g,respectively,which were 1.9 times and 2.1 times of the adsorption capacity of MG and LZ.The adsorption kinetics fitted the pseudo-secondary model,and the adsorption thermodynamics fitted the Langmuir model,indicating that the adsorption process was dominated by chemical adsorption and monolayer adsorption.The measurement of Zeta potential indicated that electrostatic attraction was the main driving force for the adsorption of CR on organically modified attapulgite.The increase in specific surface area and the micropore structure provided more sites for adsorption.(2)MG/PVFM and KH550-MG/PVFM composite materials were prepared by using MG and KH550-MG as the inorganic phase and polyvinyl formal(PVFM)as the matrix,while constructing PVFM,MG/PVFM and KH550-MG/PVFM.Four reactors for ordinary activated sludge,systematically investigated the performance of the carrier and the effect of microorganism immobilization in sewage purification.The study found that MG and KH550-MG were evenly dispersed in the PVFM matrix,especially KH550-MG and PVFM matrix formed a strong chemical bond.The addition of the inorganic phase increases the porosity of the carrier,forming a large-pore interpenetrating structure,the apparent density and the water absorption rate increases.The three carriers of PVFM,MG/PVFM,and KH550-MG/PVFM all had excellent microbial affinity.Among them,the KH550-MG/PVFM carrier had the highest amount of microbial film when the reactor run for 20 days,reaching 165.55 mg/g;COD average removal rate and the total nitrogen reached 94.37% and 85.73%,respectively,and the turbidity value was reduced to 1.11 NTU.The performance was higher than that of ordinary activated sludge reactor,showing superior microorganism immobilization performance.(3)LZ/PVFM,KH550-LZ/PVFM composite materials were prepared with LZ,KH550-LZ as the inorganic phase,and PVFM as the matrix.Four reactors of PVFM,LZ/PVFM,KH550-LZ/PVFM,and ordinary activated sludge were constructed simultaneously,that performance of the carrier and the immobilization effect of microorganisms in sewage purification were systematically investigated.The study found that: LZ and KH550-LZ were evenly dispersed in the PVFM matrix,and KH550-LZ forms a strong chemical bond with the PVFM matrix.The carbonate associated minerals in LZ had obvious chemical pore-forming effect in the preparation of PVFM.Adding an inorganic phase increases the porosity of the carrier,forming a large-pore and small-pore interpenetrating structure,the apparent density and the water absorption rate increased.The three carriers of PVFM,LZ/PVFM and KH550-LZ/PVFM all have marvelous microbial affinity.Among them,KH550-LZ/PVFM carrier had a maximum microbial film amount of 159.51 mg/g when the reactor was operated for 20 days,which was PVFM.2.39 times.The average removal rate of COD reached 93.87%,the average removal rate of total nitrogen reached 82.27%,the turbidity equivalent value was reduced to 1.94 NTU,and the microbial immobilization performance was excellent.