Preparation Technique Of Snow-melting Agent By Using Calcium Based Waste And Organic Acid

In this paper,the lime mud from paper-making process?LMP?is a kind of calcium-based inorganic waste,which is used to react with organic acids to produce snow-melting agent.The technique can obtain the high value-added utilizations of LMP and organic acids from bio-hydrogen process.The LMP mainly consists of calcium carbonate?CaCO₃?and a small amount of sodium sulfide?Na₂S?.Its pH is10-13,often being land filled.This treatment technology can cause a series of environmental pollution of air,water and soil.In addition,the residual liquid from anaerobic fermentation of acid and hydrogen production has plenty of organic acids,which will cause secondary pollution if it discharges into the environment directly.Therefore,try the best to achieve the resource utilization of the lime mud from paper-making process and residual liquid by anaerobic fermentation are particularly important task.The contents of this paper are as follows.For accessing hydrogen-producing bacteria?HPB?cell cultivation and H₂evolution,iron?Fe?and calcium?Ca?elements are inorganic trace elements are essential supplements for carbohydrate based substrates?e.g.,glucose?,which can help to produce volatile fatty acids?VFAs?in H₂ fermentation process.The results indicated that along with the increase concentration of CaO,the accumulated hydrogen production has increased when the concentration of CaO in the range of 12-28 mg/L.However,the excessive concentration of CaO could lower the production yields of H₂and VFAs.Besides,the effect of Fe²⁺on hydrogen production in medium temperature fermentation was evaluated.The results showed that as the increase concentration of Fe²⁺,the accumulate H₂ yield has increased when the concentration of Fe²⁺in the range of less than 200 mg/L.Nevertheless,further increasing Fe²⁺concentration could inhibit the activity of HPB,resulting in the decreases in H₂ and VFAs yields.This study provides some preparation methods of solid and liquid snow-melting agent by using LMP and residual liquid from anaerobic fermentation,which are used as raw material.The experiment results showed that the solid snow-melting agent prepared by using LMP and the mixed organic acids of formic and acetic acids,has batter performance when the formic acid/acetic acid ratio is 3:7,which is 1.2 times as much as that of sodium chloride?NaCl?.In order to overcome the drawbacks of the nonuniform caused by mechanical throwing techniques and the low performance of snow melting agent,LMP and VFAs generated from bio-hydrogen of glucose were utilized to produce liquid snow-melting agent.The better results were obtained to be1.3 times as much as NaCl solution.The corrosion tests of carbon steel by different snow-melting agents showed that compared with conventional snow-melting agents?e.g.,NaCl?,the corrosion degree?0.13-0.15 g/m²·h?of Ca-based waste snow-melting agents to carbon steel was lower than that?0.41-0.45 g/m²·h?of NaCl agent.During bio-hydrogen process,fruit and vegetable wastes can be converted intoVFAs,CO₂ and H₂.The VFAs are high concentration of chemical oxygen demand?COD?,which can react with alkaline wastes to produce snow-melting agents.This can obtain zero discharge of wastewater,and recover Ca²⁺?Mg²⁺?Na⁺and S^2-from LMP.In addition,the characteristics of LMP,VFAs and snow-melting agents were determined by using Fourier transform-infrared spectroscopy?FT-IR?and other conventional methods.