有机物和硝酸盐对硫自养—电化学氢自养组合工艺还原高氯酸盐性能的影响

发布时间：2018-06-19 09:12

本文选题：高氯酸盐 + 硝酸盐　；参考：《中国海洋大学》2015年硕士论文

【摘要】：本实验主要研究了有机物和硝酸盐的存在对硫自养-电化学氢自养组合工艺还原高氯酸盐性能的影响,并探讨了水力停留时间(HRT)对该工艺可能产生的影响。该工艺以CO2为碳源、以S0和H2为电子供体,在进水ClO4-浓度为30mg/L、HRT为6h、电流强度为35mA的条件下进行高氯酸盐还原菌的培养与驯化。该反应器以硫自养段还原高氯酸盐时产生的H+作为电化学氢自养段还原高氯酸盐的前驱物,这既可以为氢自养高氯酸盐还原菌还原高氯酸盐提供电子供体H2,又可以降低出水的pH值。通过调节水力停留时间可以控制出水中SO42-浓度。反应器对高氯酸盐的去除效果随着进水中NO3--N浓度的逐渐增加而降低,当进水NO3--N从0mg/L增加到50mg/L时,反应器高氯酸盐去除率从99%降至50%以下,硝酸盐的去除率也降至45%以下。由于硝酸根离子的氧化还原电位高于高氯酸盐,它会优先于高氯酸盐结合电子从而对高氯酸盐的还原产生抑制作用。反应过程中存在严重的S0的歧化作用,出水中SO42-浓度的增加量远大于理论值。当进水中有机物浓度从0mg/L增加到150mg/L时,反应器高氯酸的去除率始终保持在99%以上。但当进水COD浓度增加至300mg/L时,反应器高氯酸盐去除率降至97%,出水pH值也大幅降低。在有机物存在的情况下,微生物会优先选择有机物作为电子供体,这会导致出水中S042-浓度随着COD浓度的增加逐渐降低,出水中ORP值也不断下降。反应器出水具有强烈的刺激性气味,这说明反应器在硫酸盐还原菌的作用下产生了H2S。当在进水中同时加入有机物和硝酸盐时,反应器在整个反应过程中都具有很好的高氯酸盐去除率,出水中SO42-浓度有所增加。当进水NO3--N为50mg/L、COD为150 mg/L,HRT由6h缩短至4h时,反应器高氯酸盐的去除率从99%降至97%,硝酸盐的去除率则始终保持在99%以上。当HRT从6h缩短为4h和2h时,反应器硫段出水中的ClO4-浓度稍有增大,但反应器高氯酸盐去除率仍保持在99%以上；继续缩短HRT至1h时,反应器硫段出水和氢段出水中的ClO4-浓度大幅增加,反应器高氯酸盐去除率降至50%。通过调节反应器的HRT,可以控制出水中SO42-浓度。出水中的SO42-浓度随着HRT的减小而不断降低。出水pH值和ORP值则随着HRT的减小而升高。在整个反应过程中,反应器内始终保持着良好的厌氧环境,ClO4-减少量与Cl-增加量的摩尔比接近1：1,被还原的ClO4-全部转化为Cl-,不存在中间产物ClO3-和ClO2-的积累。pH值变化范围为7.3～8.35,可以满足高氯酸盐还原菌正常新陈代谢所需要的条件。
[Abstract]:The effect of organic matter and nitrate on the reduction of perchlorate by the combination of sulfur autotrophic and electrochemical hydrogen autotrophic process was studied, and the possible effect of HRT on the process was discussed. Using CO _ 2 as carbon source and S _ 0 and H _ 2 as electron donors, the culture and acclimation of perchlorate reducing bacteria were carried out under the condition that the influent concentration of CLO _ 4- was 30 mg / L ~ (-1) HRT for 6 h and the current intensity was 35mA. In this reactor, H produced from the reduction of perchlorates in the sulfur autotrophic stage is used as the precursor of the reduction of perchlorates in the electrochemical hydrogen autotrophic section. This can not only provide the electron donor H _ 2 for reducing perchlorate by hydrogen autotrophic perchlorate reducing bacteria, but also reduce the pH value of effluent. The concentration of so _ 4 _ 2-in the effluent can be controlled by adjusting the HRT. The removal efficiency of perchlorate in the reactor decreased with the increasing of the concentration of NO3-N in the influent. When the concentration of NO3-N in the influent increased from 0 mg / L to 50 mg / L, the removal rate of perchlorate in the reactor decreased from 99% to less than 50%, and the removal rate of nitrate decreased to less than 45%. Because the redox potential of nitrate ion is higher than that of perchlorate, it will preferentially inhibit the reduction of perchlorate over perchlorate binding electrons. In the process of reaction, there is a serious disproportionation of S _ 0, and the increase of so _ 4 _ 2-concentration in the effluent is much larger than the theoretical value. When the concentration of organic matter in the influent increased from 0 mg / L to 150 mg / L, the removal rate of perchloric acid remained above 99%. However, when the influent COD concentration increased to 300 mg / L, the removal rate of perchlorate in the reactor decreased to 97%, and the pH value of the effluent decreased significantly. In the presence of organic matter, organic matter is preferred as electron donor, which leads to the decrease of S042- concentration and the decrease of ORP value in effluent with the increase of COD concentration. The effluent of the reactor had a strong irritating odor, which indicated that H _ 2S was produced in the reactor under the action of sulfate reducing bacteria. When organic matter and nitrate were added into the influent at the same time, the reactor had a good removal rate of perchlorate in the whole reaction process, and the concentration of so _ 4 _ 2-- in the effluent increased. When the influent NO3 N is 50 mg / L ~ (-1) COD = 150 mg / L ~ (-1) HRT is shortened from 6 h to 4 h, the removal rate of perchlorate in the reactor decreases from 99% to 97%, and the removal rate of nitrate remains above 99%. When HRT was shortened from 6 h to 4 h and 2 h, the concentration of ClO4- increased slightly, but the removal rate of perchlorate remained above 99%, and when HRT was shortened to 1 h, the removal rate of perchlorate remained above 99%. The concentration of ClO4- in the effluent of sulfur stage and hydrogen stage increased greatly, and the removal rate of perchlorate decreased to 50%. By adjusting HRT of the reactor, the concentration of so _ 4 _ 2-in the effluent can be controlled. The concentration of so _ 4 _ 2-in effluent decreases with the decrease of HRT. The effluent pH and ORP increased with the decrease of HRT. During the whole reaction, In the reactor, the molar ratio of reduction of ClO4- to the increase of Cl-is close to 1: 1, and the reduced ClO4- is converted to Cl-completely. The accumulation of ClO3- and ClO2- does not exist. The pH value of the intermediate products can vary from 7.3 to 8.35. To meet the requirements for the normal metabolism of perchlorate reducing bacteria.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU991.2

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