Department of Chemical and Petroleum Engineering, The University of Kansas, Lawrence, KS 66045, USA.
J Environ Manage. 2015 Sep 1;160:128-38. doi: 10.1016/j.jenvman.2015.05.033. Epub 2015 Jun 23.
The use of nitrification filters for the removal of ammonium ion from waste-water is an established technology deployed extensively in municipal water treatment, in industrial water treatment and in applications such as fish farming. The process involves the development of immobilized bacterial films on a solid packing support, which is designed to provide a suitable host for the film, and allow supply of oxygen to promote aerobic action. Removal of ammonia and nitrite is increasingly necessary to meet drinking water and discharge standards being applied in the US, Europe and other places. Ion-exchange techniques are also effective for removal of ammonia (as the ammonium ion) from waste water and have the advantage of fast start-up times compared to biological filtration which in some cases may take several weeks to be fully operational. Here we explore the performance of ion exchange columns in which nitrifying bacteria are cultivated, with the goal of a "combined" process involving simultaneous ion-exchange and nitrification, intensified by in-situ aeration with a novel membrane module. There were three experimental goals. Firstly, ion exchange zeolites were characterized and prepared for comparative column breakthrough studies for ammonia removal. Secondly effective in-situ aeration for promotion of nitrifying bacterial growth was studied using a number of different membranes including polyethersulfone (PES), polypropylene (PP), nylon, and polytetra-fluoroethylene (PTFE). Thirdly the breakthrough performance of ion exchange columns filled with zeolite in the presence of aeration and in the presence of nitrifying bacteria was determined to establish the influence of biomass, and aeration upon breakthrough during ammonium ion uptake. The methodology adopted included screening of two types of the naturally occuring zeolite clinoptilolite for effective ammonia removal in continuous ion-exchange columns. Next, the performance of fixed beds of clinoptilolite in the presence of nitrifying bacteria is compared to that in columns in which only ion exchange is occurring. The aeration performance of each of the chosen membranes was compared experimentally using a newly developed membrane support module which is also described. Comparison of ammonia removal in columns equipped with in-situ aeration using each membrane was undertaken and the breakthrough characteristics determined. The results showed that ammonia removal in the presence of the nitrifiers was significantly intensified. Column operation with membrane aeration showed further enhancement of ammonia removal. The greatest enhancement was observed in the case of the polyethersulfone membrane (PES). It is concluded that combined nitrification and ion-exchange is significantly intensified in packed columns by in-situ aeration using a novel membrane module. There is significant potential for extending the ion-exchange cycle time and thus potential cost reduction.
利用硝化滤池从废水中去除铵离子是一项成熟的技术，已广泛应用于城市水处理、工业水处理和养鱼等领域。该工艺涉及在固体填料支撑物上开发固定化细菌膜，其设计旨在为膜提供合适的宿主，并允许供应氧气以促进需氧作用。为了满足美国、欧洲和其他地方正在实施的饮用水和排放标准，越来越需要去除氨和亚硝酸盐。离子交换技术对于从废水中去除氨（作为铵离子）也很有效，与生物过滤相比，其具有快速启动的优势，生物过滤在某些情况下可能需要数周才能完全运行。在这里，我们研究了在硝化细菌培养过程中使用离子交换柱的性能，目的是开发一种“组合”工艺，涉及同时进行离子交换和硝化，通过新型膜模块进行原位曝气来强化。有三个实验目标。首先，对沸石进行了表征，并为氨去除的比较柱穿透研究进行了准备。其次，使用多种不同的膜（包括聚醚砜（PES）、聚丙烯（PP）、尼龙和聚四氟乙烯（PTFE））研究了有效的原位曝气以促进硝化细菌生长。第三，确定了填充沸石的离子交换柱在曝气和硝化细菌存在下的穿透性能，以确定生物量和曝气对铵离子吸收过程中穿透的影响。采用的方法包括筛选两种天然沸石斜发沸石，以在连续离子交换柱中有效去除氨。接下来，比较了含有硝化细菌的固定床斜发沸石的性能与仅发生离子交换的柱中的性能。使用新开发的膜支撑模块对所选每种膜的曝气性能进行了实验比较，并对该模块进行了描述。比较了每个膜配备原位曝气的柱中氨的去除情况，并确定了穿透特性。结果表明，在硝化菌存在下，氨的去除明显得到强化。膜曝气的柱操作进一步提高了氨的去除率。在聚醚砜膜（PES）的情况下观察到最大的增强。结论是，通过使用新型膜模块进行原位曝气，填充柱中的硝化和离子交换的组合得到了显著强化。有可能延长离子交换周期时间，从而降低成本。
