| Acid mine drainage (AMD) is a worldwide problem. Based on the principle of sulfur recycle biological treatment of AMD is a hot spot and the treatment of AMD by sulfate reducing bacteria (SRB) and insitu permeable reactive barrier (PRB) is paid attention. Carbon resource, SRB’s growing energy and electron donor, is an important factor that influences the treatment of AMD by SRB and the feasibility of easy-obtained sludge and biomass for SRB’s energy was explored home and abroad. However the treatment of AMD by immobilized SRB and Sustained-release law of biomass in PRB and PRB filled with sludge and biomass, the effects of contaminated water’s temperature, pH and hydraulic retention time (HRT) on the carbon resource’s availability and activity evaluation of biomass immobilization product, optimization of solid-state fermentation conditions and biochemical performance evaluation of PRB are rarely reported.In this paper solid wastes (sludge produced in wastewater treatment, biomass such as corncob and sawdust) were used as the slow-released carbon resource to study PRB, and to explore pretreatment of sludge, optimization of sludge fermentation parameters and to build indicator system for assessing the activity of biomass immobilized SRB products by SiR and to study the release law and conversion of biomass in the wastewater treatment and to build new process system that can transform solid waste to high quality carbon resource and to improve the use efficiency of solid waste and biochemical performance evaluation of SRB immobilized PRB. Experiments and results are as follow:(1) Building the detection of biomass immobilized SRB:the effects of immersion medium, soaking time, ultrasonic power, ultrasonic time, and pretreatment, Preparation Conditions for Solid-state fermentation product of crude enzyme solution, on the enzyme were studied to determine the feasibility of sulfite reductase taken as the extracellular enzyme of SRB in characterizing the biomass. The results indicated that enzyme activity values treated through both lixiviate and supersonic treatment were significantly higher than those only treated by lixiviate and supersonic treatment, but heating by ultrasound is difficult to control. The best conditions determined in the experiment were as follows: phosphate buffer of25mL,2g fermentation product immersion for60min and enzyme activity value of1.0799/(U/g). The establishment of the detection methods of biomass immobilized SRB enzyme activity may provide a theoretical basis for the assessment of immobilized SRB product activity and the biochemical performance evaluation of PRB.(2) Pretreatment of sludge and optimization of acid produced from anaerobic fermentation:studies are conducted to explore the effect of mechanical agitation, pH (adding acid or alkalis), surfactant and ultrasound on the lysis of sludge and the optimal condition was determined by Orthogonal. The anaerobic fermentation of anaerobic bacteria planted pretreated sludge was studied to explore the effect of different factors on Fermentation products of sludge and the availability of SRB on VFAs. The results indicated that methanoic acid forms at pH of2-3or pH of6, ethanoic acid forms at pH of2-5; tropic acid forms at the temperature of10-20, butyric acid forms at the temperature of20-35; based on the enzyme activity of SRB utilizing VFAs and the removal efficiency of sulfate, the descending availability of SRB on VFAs is tropic acid, butyric acid, ethanoic acid, which is the same with Ren.(3) Sustained-release law of biomass and its influence factors:in order to solve the carbon resource problem of insitu treatment of AMD by PRB, three biomass (corncob, sawdust and cane trash) are emerged in simulated wastewater to study the effect of various factors on Sustained-release law of biomass and to build biomass hydrolysis kinetic model and to provide basis of carbon resources at low costs for the treatment of AMD by SRB. The results indicated COD produced from corncob was nearly linear with sugar and the ratio of soluble COD and sugar was some240and the equation between sugar concentration and adding concentration was y=0.0425x+0.1491, which can be used to calculate C/S. The hydrolytic kinetic model of corncob was built based on the experimental data of the corncob and the sugar field was CG=k1·(e-k1t-e-k2t)/(k2-ki),mg/g; the reducing sugar formation rate and degradation rate constant at various temperatures were determined. The hydrolysis activation energy of corncob Ea was33342.213kJ/mol and the pre-exponential factor was3.068×105. These results illustrated that, as the sustained-release carbon source, corncob was easy to hydrolyze at room temperature and provided theoretical basis for the treatment of acid mine drainage by sulphate-reducing bacteria.(4) Preparation of SRB immobilized products:immobilized SRB by solid-state fermentation was explored to solve the problem of inculcation and enlarging cultivation in PRB. The preparations of SRB immobilized products by solid fermentation process were studied to solve the amplification culture, preservation and inoculation of bacteria in biological treatment of AMD.The single factor experiments of biomass particle biomass particle size, initial moisture content and inoculation quantity were investigated using SiR as the testing index of bacteria activity, the optimal conditions for the solid fermentation of biomass carrier were examined and verified by response surface methodology. The kinetic equation of SO42-removal by SRB was built using the data of immobilized products for the treatment of AMD by the graphing of Lineweaver-Burk. The results indicate that the optimal fermentation conditions for the following carriers were as follows:corncob (particle size of8-20mesh, moisture content of70%, inoculation quantity of10%, the optimized SiR of2.7385U/g); sawdust(particle size of1-8mesh, moisture content of80%, inoculation quantity of5%, the optimized SiR of2.4863U/g); bagasse(particle size of8-20mesh moisture content of75%, inoculation quantity of10%, the optimized SiR of4.2960U/g). In the treatment of SO42-from AMD by immobilized products, SRB immobilized corncob products shows the best fitting solution (y=1176.9x+0.6034, R2=0.9199) by the plot of1/v against1/[s]. The kinetics model of SO42-treatment by SRB immobilized corncob products can be described as the function: V=1.657[s]/(1950.45+[s]). |
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