【作者】 马满英；

【导师】 余健；

【作者基本信息】 湖南大学 ， 市政工程， 2005， 硕士

【摘要】 通过实验室试验,全面考察了自然有机物对地下水化学氧化及混凝除铁的影响。选择了腐植酸、单宁酸、胡敏酸和草酸四种有代表性的有机物作为研究对象。对高锰酸钾、二氧化氯和自由氯三种氧化剂的除铁能力进行了评价和对比。重点探讨了有机物的种类、分子量及浓度对除铁的影响;同时探讨了pH值、氧化反应时间及温度等因素对去除有机络合铁的影响;并对预氧化在混凝除铁中的作用进行了研究。 试验结果表明:各种自然有机物对化学氧化除铁有不同程度的阻碍作用。有机物的分子量越大,有机物的浓度越高,对化学氧化除铁的阻碍作用越大。在所采用的三种氧化剂中,高锰酸钾对去除有机络合铁最有效,二氧化氯次之,自由氯的的氧化能力最差。当亚铁与分子量小于4K的有机物络合时,可以用高锰酸钾氧化法除铁,而二氧化氯和自由氯仅对与分子量小于1K的有机物络合的铁有明显的去除效果。pH值在5.5～7.5之间时,pH值升高对化学氧化去除有机络合铁有利。延长氧化反应时间,能提高化学氧化对有机络合铁的去除率。温度对化学氧化除铁没有明显的影响。有机物的分子量分布和浓度对混凝除铁有很大影响。有机物的分子量越大,浓度越高,则溶解性铁和DOC的去除率越高。当有机物的分子量大于10K时,用混凝除铁,水中残余铁的浓度低于0.30mg/L,且DOC的去除率在75%以上。混凝除铁只适宜于有机物分子量大于10K的情形。当有机物的分子量小于4K时,采用预氧化混凝工艺能够达到良好的除铁效果,但预氧化对于去除有机物分子量大于4K的的有机络合铁没有明显的促进作用。pH值在6.0至7.5之间时,降低pH值对混凝除铁有利。pH为6.0时所需的最佳投药量为50mg/L;pH为7.0时的最佳投药量为80mg/L。温度升高有利于铁和DOC的去除,并能减少硫酸铝的投量。更多还原

【Abstract】 By experimenting in the laboratory, the effects of natural organic matter on both oxidative and coagulation removal of iron from groundwater were researched. Organic compounds evaluated included humic acid, tannic acid, fulvic acid and oxalic acid. Oxidants evaluated were potassium permanganate, chlorine dioxide and free chlorine. Some impact factors such as pH, oxidant contact time and solution temperature were studied, with stress on discussing the influence of DOC molecular weight and the concentration on removing iron. Pro-oxidantion followed by alum coagulation was analyzed for affecting the efficiency of soluble iron and DOC removal.The experiments show that various natural organic compounds had negative impacts of different degree on the ability of oxidants to promote effective removal of iron. The greater the molecular weight or the concentration of organic substances was, and the higher the degree of negative impacts was. Potassium permanganate was found to be the most effective oxidant of the three investigated. Free chlorine was the most ineffective for removal of iron complexed by various organic compounds. Potassium permanganate was very effective for promoting iron removal when iron was complexed by the organic matters with molecular weight less than 4000. Chlorine dioxide and free chlorine were only effective for removal of iron complexed by the organic matters with molecular weight less than 1000. pH value increasing was beneficial to oxidative removal of complexed iron over the pH range from 5.5 to 7.5. Prolonging reaction time could improve the removal of complexed iron during chemical oxidation. Solution temperature had little effect on oxidative removal of complexed iron. The relative molecular weight distribution and the concentration of organic matters had significant effect on coagulation removal of iron. The removal of DOC and iron also increased with the increasing of the molecular weight and the concentration of organic matter during alum coagulation.Alum coagulation was very effective for removal of iron complexed by organic matter with molecular weight greater than 10000 and the residual soluble iron concentration decreased to value below 0.3 mg /I, in the meantime, overall DOC removal attained 75% or above. Soluble Fe(II) complexed by organics with molecular weight less than 4000 was amenable to removal by KMnO4 addition followed by alum coagulation . But when Soluble Fe( II) was complexed by organics with molecular weight greater than 4000,更多还原