Removal Of Sulfate From Bio-fuel Wastewater And Its Resource Utilization

In order to solve the problem of the waste water in the production of bio-fuel with straw aqueous phase catalytic depolymerization,a method for optimal utilization of bio-fuel wastewater is proposed.By adding straw and other biomass to the joint anaerobic fermentation,biogas and bog fertilizer were obtained.It is not only beneficial to ecological and environmental protection,but also reduces the cost of preparing bio-fuel.As the high concentration of sulfate has inhibitory effect on anaerobic fermentation,and the low concentration of sulfate is beneficial to the anaerobic fermentation,therefore,it is necessary to remove the sulphate root to a certain extent.Combined with the existing wastewater removal technology,this paper discusses the relationship between the ratio of calcium to sulfur and the rate of sulfate removed,by using calcium oxide method to remove sulfuric acid from bio-fuel wastewater.The quadratic orthogonal rotation combined experimental design method and the response surface were used to optimize technological parameters of removing the sulfate radical from biofuel oil wastewater by the calcium oxide method with temperature,rotary speed and reaction time as the control factors,.Through experiments,comparing and analyzing the gas,liquid and solid indexes in anaerobic fermentation of bio-fuel oil wastewaters with the different degree of removal of sulfate ion combined with corn stalks,this calcium-sulfur ratio is selected,with which,the wastewater is most suitable for anaerobic fermentation combined with corn stalks Further experiments were carried out to explore the performance of anaerobic fermentation combined with bio-fuel wastewater,after removing sulfate ions,and corn stalks with different TS ratio.Through experiment and analysis,the following conclusions can be drawn:(1)The results showed that the calcium oxide method to remove biofuels wastewater sulfuric acid root ion to fit with straw biomass for anaerobic fermentation of the best calcium sulfur mole ratio is about 1.6.According to the results of single factor test,the relationship between the ratio of calcium sulfide and the removal rate of sulfate is proposed.The optimum ratio of calcium to sulfur is about 1.6.After the desulfurization pH value of wastewater is about 7.04,RES removal rate of sulfate is 95.52%.(2)The optimum technological conditions were optimized,with temperature ranging from 30 to 50 degrees,the rotational speed was 190 ~ 210 r/min,and the time was 3h,under the condition of optimum ratio of calcium to sulfur.The significance of the influence factors on the biological fuel desulfurization were determined as the stirring speed,time and temperature,by using quadratic orthogonal rotating center combination test.The result of response surface shows that,when the rotational speed is 180 ~ 227.6 r/min,the precipitation efficiency of calcium oxide is very high,and the temperature has little effect on the reaction efficiency,and the reaction equilibrium is reached within 3 h.With the optimum technological conditions above,it can achieve a best level of removal sulfate for anaerobic fermenting with a lower energy costs in a short time.(3)It has different effects on the gas production performance of anaerobic fermentation as biological fuel wastewater with different treatment degree combined with corn stover for anaerobic fermentation.In this experiment,when the concentration of sulfuric acid root was higher than 2.01g/L,the inhibition effect was strong and the combined anaerobic fermentation with maize straw could not be started.When the concentration of sulfuric acid root is lower than 1.27g/L,the treated wastewater can be combined with corn straw to produce anaerobic fermentation gas.Moreover,when the concentration of sulfuric acid is about 0.6g/L,the wastewater can also promote the combined anaerobic fermentation to produce gas and increase the methane production rate,and promote the degradation of organic matter of substrate such as straw.(4)The different proportions of corn straw and desulfurization processed wastewater combined anaerobic fermentation,producing gas performance have certain differences When the concentration of sulfuric acid root is about 0.6 g/L,mixed with corn stalk with different proportion of TS,as initial TS concentration rang from 6.44 to 8.93%,the combined anaerobic fermentation can be started and normal operation of the gas,the lower the initial TS,straw substrate degradation rate is higher.But when the initial TS was 7.71%,produce gas combined anaerobic performance is best,so it is to the methane production rate.Using optimization techniques to remove biofuels wastewater sulfuric acid root partly with calcium oxide,and then mixed with corn stalks to a certain proportion,combined anaerobic fermentation,can promote the system into the anaerobic fermentation gas production.The full utilization of organic matter and heat of waste water not only reduces the pollution of waste water to the environment,but also reduces the production cost of bio-fuel.