纤维素载体预处理及其强化MBR脱氮效果研究

发布时间：2018-05-02 18:17

本文选题：纤维素载体 + 预处理　；参考：《东南大学》2015年硕士论文

【摘要】：投加碳源是提高低C/N比污水脱氮效率的有效方法。常见甲醇、乙醇、乙酸等外加碳源,具有成本高且投加量难控制的缺点。因此,新型纤维素类农作物废弃物固态碳源应运而生,但未处理农作物废弃物因碳源利用效率低、反硝化速率低、出水有机物浓度高等不足而制约了其大规模应用。鉴于此,本研究采用超声波辐射、微波辐射和碱浸泡处理对丝瓜络、玉米芯、稻草这3种纤维素类废弃物进行预处理,制备成纤维素载体,研究其释碳能力、反硝化能力及反硝化规律等,并将其运用于MBR中,以考察其强化脱氮的效果。通过研究得出以下主要结论：(1)对丝瓜络、玉米芯、稻草3种木质纤维素废弃物原料进行超声波辐射、微波辐射和碱浸泡预处理,比较其COD释放能力、还原糖释放能力和反硝化潜力(DP),最终确定碱浸泡为最佳预处理方式。经2%NaOH浸泡24h,3种材料的COD释放能力和反硝化潜力分别从136mg/gCOD178mg/g,112.04mg/gDP157.94mg/g提高到250mg/gCOD323mg/g,233.82mg/gDP50.69mg/g。纤维素载体组分分析、扫描电镜分析和红外光谱分析表明,碱处理有效地去除了难生物降解的木质素,使纤维素组分含量提高,增强了其对酶的可及度。综合考虑,纤维素载体能够作为良好的缓释固体碳源。(2)传统MBR对TN的去除率有限。对照组、投加聚丙烯载体、投加0.4g/(L·d)乙醇碳源3组MBR的TN平均去除率分别为26.81%、36.05%、72.96%。这表明碳源是MBR工艺脱氮过程中的限制因素。当投加量为1.42g/d时,碱-稻草组MBR对TN的去除率达63.46%,TN平均出水低于城镇污水处理厂污染物排放标准(GB18918-2002)一级A标准的控制浓度15mg/L。经动力学分析,碱-稻草组MBR中硝酸盐饱和常数为0.21,低于空白组MBR的1.82,更接近于单级反硝化进程。(3)合适的稻草投加量不仅不会增加出水COD浓度,反而促进了活性污泥的脱氢酶活性,碱-稻草组MBR污泥的脱氢酶活性为144.60 mgTF/(L·h),远高于对照组MBR的78.17 mgTF/(L-h)。在连续110d不排泥的实验条件下,碱-稻草组MBR中MLSS从初始7865mg/L上升到9466mg/L,并无发现堵塞、膜通量下降等不良反应。
[Abstract]:Adding carbon source is an effective method to improve nitrogen removal efficiency of low C / N ratio wastewater. Methanol, ethanol, acetic acid and other external carbon sources have the disadvantages of high cost and difficult to control the dosage. Therefore, a new type of cellulose crop waste solid carbon source emerged as the times require, but the untreated crop waste is limited to its large-scale application because of the low efficiency of carbon source, low denitrification rate and high concentration of organic matter in effluent. In view of this, ultrasonic radiation, microwave radiation and alkali soaking were used to pretreat three kinds of cellulose wastes, such as luffon, corncob and straw, to prepare cellulose carrier, and to study its carbon releasing ability. Denitrification ability and denitrification law were applied to MBR to investigate the effect of denitrification. The main conclusions are as follows: (1) Ultrasonic radiation, microwave radiation and alkali soaking were used to pretreat three kinds of lignocellulosic waste materials, such as luffa, corncob and straw, and their COD release ability was compared. The release ability of reducing sugar and denitrification potential were determined as the best pretreatment method. The COD release ability and denitrification potential of the three materials were increased from 136mg / gCOD178mg / g / g 112.04mg / g / g ~ 157.94 mg / g / g to 250mg / g / g = 233.82 mg / g / g ~ 233.82 mg / g / g respectively. The analysis of cellulose carrier components, scanning electron microscopy and infrared spectroscopy showed that alkali treatment could effectively remove the lignin, increase the content of cellulose components and enhance the accessibility of cellulose to enzymes. Taken into account, cellulose carrier can be used as a good slow release solid carbon source. 2) the removal rate of TN by conventional MBR is limited. In the control group, adding polypropylene carrier and adding 0.4g/(L d, the average removal rate of TN in the three groups was 26.81 and 36.05, respectively. This indicates that carbon source is the limiting factor in the denitrification process of MBR process. When the dosage of 1.42g/d was added, the removal rate of TN by MBR of alkali straw group reached 63.46%. The average effluent concentration of TN was lower than that of the first class A standard (GB18918-2002) of the municipal wastewater treatment plant (GB18918-2002). The kinetic analysis showed that the saturation constant of nitrate in MBR of alkali-straw group was 0.21, which was lower than that of MBR in blank group (1.82%), which was closer to the process of single-stage denitrification. The suitable dosage of rice straw did not increase the concentration of COD in effluent. On the contrary, the dehydrogenase activity of the activated sludge was promoted. The dehydrogenase activity of MBR sludge in alkali-straw group was 144.60 mgTF/(L / h, which was much higher than that in the control group (78.17 mg TFR / L ~ (-1) hh ~ (-1). Under the condition of no sludge excretion for 110 days, the MLSS in MBR of alkali-straw group increased from initial 7865mg/L to 9466 mg / L, and no adverse reactions such as blockage and decrease of membrane flux were found.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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