Biological Adsorbent Containing Cr (vi) In Basic Research Of Wastewater

Due to the rapid development of industrial production, The environmental pollution problem, caused by chromium(Ⅵ), is becoming more and more seriously, especially the emission of wastewater containing chromium(Ⅵ) in metallurgy, working, electroplating, tannery, Dyeing and printing industry etc, has become the primary pollution. Chromium(Ⅵ), high toxicity, they can enter the water with the water movement, which seriously threat the surrounding environment and the quality of people's life. The existing approach to removing Cr (Ⅵ) in wastewater often has big investment, high operating costs, the yield large amount of mud and secondary pollution on the environment.Immobilized Microbial Technology which can get the microbial intensive can maintain a high biomass concentration in reactor and easy to solid-liquid separation. It particularly applies to poisonous materials and has become a new, efficient and economic technology. Therefore, this thesis uses Immobilized Microbial Technology to make biological adsorben treating low concentration of Cr (Ⅵ) wastewater.This thesis uses the activated sludge in city sewage treatment plant as biological adsorption materials to study calcium alginate biological adsorbent and polyurethane foam biological adsorbent. Study the effection factors, adsorption properties and adsorption mechanism.Calcium alginate biological adsorbent removing Cr (Ⅵ) is mianly affected by pH and dosage.At the condition of sludge dry weight is 0.6 g, wastewater pH is 2 and adsorption temperature is 25℃.To the initial concentration of 10 mg/L containing Cr (Ⅵ), the removal rate is 97.95 percent, the average adsorption capacity is 1.63 mg (Cr (Ⅵ))/g (dry sludge weight).Breakthrough adsorption capacity is 5.35mg/g, and the corresponding rate of adsorption is 0.206mg.g-l.h.Depletion adsorption capacity is 7.27mg/g, the corresponding rate of adsorption is 0.145mg.g^-1h^-1. The analysis of adsorption process showed that: The main adsorption role on removing Cr (Ⅵ) of calcium alginate biological adsorbent is sludge. The adsorption proces is a multi-molecular layer of physical adsorption process. Calcium alginate biological adsorbent has better affinity ability and adsorption ability than suspension activated sludge. Polyurethane foam biological adsorbent removing Cr (Ⅵ) is mianly affected by pH and dosage.At the condition of sludge dry weight is 0.92 g, wastewater pH is 1 and adsorption temperature is 25℃.To the initial concentration of 10 mg/L containing Cr (Ⅵ), the removal rate is 97 percent, the average adsorption capacity is 1 mg (Cr(Ⅵ)/g (dry sludge weight).Breakthrough adsorption capacity is 7.35mg/g, and the corresponding rate of adsorption is 0.377mg.g-1.h^-1.Depletion adsorption capacity is 14.37mg/g, the corresponding rate of adsorption is 0.23g.g^-1.h^-1. The analysis of adsorption process showed that: The main adsorption role on removing Cr (Ⅵ) of polyurethane foam biological adsorbent is sludge. The adsorption proces is a multi-molecular layer of physical adsorption process.Polyurethane foam biological adsorbent has better affinity ability and adsorption ability than suspension activated sludge..Calcium alginate biological adsorbent and polyurethane foam biological adsorbent to Cr (Ⅵ) adsorption kinetics can be described by Lagergren second order kinetic model. In this experiment operation conditions, calcium alginate biological adsorbent and polyurethane foam biological adsorbent to Cr (Ⅵ) instantaneous adsorption capacity and adsorption time following the two equations:Qt=1.9615t/0.194+t Qt=2.5284t/0.7067+tCalcium alginate biological adsorbent and polyurethane foam biological adsorbent to Cr (Ⅵ) isotherm adsorption can be described by Freundlich isotherms. In this experiment operation conditions, calcium alginate biological adsorbent and polyurethane foam immobilized activated sludge to Cr (Ⅵ) isotherms following the two equations:IgQ_e=0.4589lgc_e+0.1382 lgQ_e=0.41491gc_e+0.1959In this experiment operation conditions, polyurethane foam biological adsorbent has big Qe, affinity ability, breakthrough adsorption capacity and depletion adsorption capacity than polyurethane foam biological adsorbentActivated sludge is a kind of ideal adsorption materials, which has the advantages of big adsorption capacity, high efficiency, good selectivity, wide scope of pH and temperature. Through immobilized microbial technology into its preparation, can not only increase the intensity of microorganisms, the adsorption capacity, and make adsorption process stable, but also can particularly applied in treating contain poisonous materials. The technology can also study the effective use of activated sludge from city sewage treatment plant and make use of it.