大型水生植物发酵液用于硫酸盐还原菌去除重金属研究

发布时间：2018-04-10 03:01

  本文选题：大型水生植物　切入点：厌氧发酵　出处：《南京大学》2017年硕士论文

【摘要】：大型水生植物对污染水体有良好的净化效果,被广泛应用于水体富营养化治理和人工湿地污水处理中,其资源化利用问题得到广泛关注。利用硫酸盐还原菌处理重金属废水成本低、无二次污染,难点在于寻找合适且廉价的碳源。本论文探索了大型水生植物厌氧发酵产酸的资源化利用方式,将大型水生植物发酵液作为硫酸盐还原菌的碳源处理重金属废水,并进一步将大型水生植物发酵液用作生物滤池的碳源强化重金属去除能力。主要研究结论如下:(1)以挺水植物圆币草、芦苇和再力花作为发酵原料,圆币草厌氧发酵产酸效果最好,圆币草发酵液中的挥发性脂肪酸总量分别是芦苇和再力花的5.1和8.7倍。不同植物种类对挥发性脂肪酸种类影响不大,乙酸均为主要发酵产物。粉碎预处理和提高温度都可有效提高厌氧发酵产酸速率,缩短发酵周期。碱性条件可以促进圆币草厌氧发酵产酸,pH9时VFAs产量分别是pH5和7时的1.74和1.56倍。圆币草、芦苇和再力花厌氧发酵过程中氮释放率分别为68%、79%和43%,磷释放率分别为47%、43%和48%。碱性条件下发酵的发酵液可形成羟基磷酸钙,可作为磷回收的一种方式。厌氧发酵产酸最优条件为:以圆币草为原料,发酵温度37℃、经粉碎处理在碱性条件下发酵。(2)圆币草发酵液是一种良好的硫酸盐还原菌碳源,效果优于葡萄糖和蔗糖,劣于乙醇和乳酸钠。但圆币草发酵液作为大型水生植物资源化的产物,具有价格低廉的优点。在批次试验反应器中,水生植物发酵液作为硫酸盐还原菌碳源,COD/SO42-为1.2、5、7时硫酸盐最大还原率分别为24.4%、43.6%和60%。(3)批次试验中,硫酸盐还原菌可利用圆币草发酵液,有效去除低浓度的Cd2+、Cu2+、Pb2+和Ni2+4种重金属离子,去除率分别可达到95.2%、98.7%、93.0%和89.6%。同时,硫酸盐还原菌利用圆币草发酵液作为碳源,对10mg/L的Ni2+、Cu2+、Cd2+和Pb2+4种重金属废水仍有良好的处理效果,重金属去除率均超过90%,且硫酸盐还原菌的活性没有受到抑制。(4)为提高生物滤池的重金属去除能力,添加圆币草发酵液作为外加碳源,促进硫酸盐还原菌的生物还原作用。稳定运行后,生物滤池系统对低浓度重金属废水的去除效果良好,Ni2+、Pb2+、Cd2+和Cu2+4种重金属离子均得到有效去除,去除率分别达到90%、75%、92%和87%。同时圆币草发酵液中挥发性脂肪酸等有机物质得到有效利用,进水初始COD为300 mg/L时,去除效率可达84%-98%。COD/SO42-为3和8时硫酸盐最大还原率分别为 18.8%和 42.8%。因此,圆币草等水生植物发酵液是一种有效的碳源,可以被硫酸盐还原菌利用还原硫酸盐去除重金属离子,也可以用于在人工湿地前端设置生物滤池去除重金属离子。
[Abstract]:Macrophytes have good purifying effect on polluted water body and have been widely used in eutrophication treatment and sewage treatment of constructed wetland.The treatment of heavy metal wastewater by sulfate reducing bacteria has low cost and no secondary pollution. The difficulty lies in finding suitable and cheap carbon source.In this paper, the resource utilization of anaerobic fermentation of macroaquatic plants to produce acid was explored. The fermentation broth of large aquatic plants was used as a carbon source of sulfate reducing bacteria to treat heavy metal wastewater.Furthermore, the fermentation broth of large aquatic plants was used as a carbon source in biofilter to enhance the removal capacity of heavy metals.The main results were as follows: (1) the total volatile fatty acids in the fermentation broth were 5.1 and 8.7 times higher than those of Reed and reclaimed flower, respectively.Different plant species had little effect on volatile fatty acids, acetic acid was the main fermentation product.The acid production rate of anaerobic fermentation can be increased effectively and the fermentation period can be shortened by grinding pretreatment and raising temperature.Alkaline conditions could promote the production of VFAs by 1.74 and 1.56 times of pH5 and 7, respectively, at pH 9 of anaerobic fermentation.During anaerobic fermentation, the nitrogen release rates were 68% and 43%, respectively, and the phosphorus release rates were 47% and 48%, respectively.The fermentation broth under alkaline conditions can form calcium hydroxyl phosphate, which can be used as a way of phosphorus recovery.The optimum conditions for acid production by anaerobic fermentation are as follows: the fermentation temperature is 37 鈩，

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