阴离子交换树脂生物再生去除硝酸盐氮

阴离子交换树脂可高效去除水体中的硝酸盐,但盐水再生所产生的脱附液处理难度大.生物再生可通过反硝化作用降解吸附于树脂上硝酸盐氮,减少盐的使用,降低处理成本.本文在考察不同碳源(葡萄糖、乙酸钠、乳酸钠、甲醇)对生物再生影响的基础上,利用反硝化细菌对吸附有硝酸盐氮的阴离子交换树脂进行了生物再生研究,考察了微生物浓度和共存Na Cl对生物再生的影响.结果表明,生物再生过程由离子交换脱附过程和反硝化过程构成,整体受反硝化过程限制.微生物浓度的升高可显著降低生物再生所需时间,当微生物接种量高于0.6 g·L-1时,树脂上的硝酸盐可以在10 h内完全降解.再生体系中Na Cl可促进硝酸根的离子交换脱附,造成初始阶段溶液中硝酸盐浓度的快速升高,但生物再生仍受反硝化过程控制.当Na Cl浓度高于20 g·L-1时,反硝化生物活性被抑制,生物再生时间显著增加.而吸附生物再生多批次实验表明,生物再生后的树脂吸附量稳定于30~35 mg·g~(-1).

Bioregeneration of Anion Exchange Resin Used in Nitrate Removal

Anion exchange resin is a feasible adsorbent for nitrate removal because of its high efficiency and cost-effectiveness, but brine regeneration complicates subsequent wastewater procedures. Bioregeneration degrades the nitrate from the nitrate-laden resin, which can decrease brine solution usage and waste discharge. In this study, based on investigation of the effect of carbon source, for example, glucose, sodium acetate, sodium lactate, and methanol, on bioregeneration, nitrate-laden resin was employed to investigate the effects of inoculum amount and salt concentration on bioregeneration with sodium acetate as the carbon source. The results showed that the bioregeneration process comprised chemical desorption and biological denitrification and was limited by the biological process. With increasing inoculum amount, the bioregeneration time was remarkably reduced. Nitrate on the resin could be completely biodegraded within 10 h when the inoculum amount (measured as VSS) was higher than 0.6 g·L^-1. Furthermore, higher NaCl concentrations improved the chemical desorption of nitrate, resulting in a sharp increase in soluble nitrate. However, the denitrification process of bioregeneration was also eventually limited by the biological process. When the concentration of NaCl was higher than 20 g·L^-1, bioactivity of the denitrifying bacteria was limited and the bioregeneration time increased to more than 10 h. The result of multi-cycle adsorption-bioregeneration experiment showed that the NO₃^--N adsorption capacity of bioregenerated resin was stable at 30-35 mg·g^-1.