Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
School of Plant and Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Sci Total Environ. 2020 May 10;716:137135. doi: 10.1016/j.scitotenv.2020.137135. Epub 2020 Feb 4.
An integrated photo-bioelectrochemical system (IPB) for wastewater treatment combines a microbial fuel cell with an algal bioreactor, eliminating requirements for aeration, promoting electricity generation, remediating nutrients and producing algal biomass for conversion into biofuel or other bioproducts. To examine strategies for improving IPB functions of electrochemical output and nutrient removal efficiency, this study tested effects of cathode bacterial inoculation and nitrogen loading on cathode microbial community and IPB performance. IPB cathodes were inoculated with the green alga Chlorella vulgaris, in combination with nitrite-oxidizing bacteria (NOB) Nitrobacter winogradskyi, and/or ammonium-oxidizing bacteria (AOB) Nitrosomonas europaea. IPB performance was examined before and after nitrifying bacteria inoculations and under three ammonium loading concentrations in the wastewater medium. Bacterial communities in the cathode suspension and biofilm were examined by 16S rRNA gene sequence analysis. Relative to the algae only control, cathode inoculation with NOB and/or AOB improved net nutrient removal, but resulted in reduced dissolved oxygen availability, which impaired electricity generation. Higher ammonium loading increased electricity production and nutrient removal, possibly by overcoming algal-bacterial competition. Inoculation with nitrifying bacteria resulted in minor changes to total bacterial composition and AOB or NOB comprised <3% of total sequences after 1 month. Community composition changed more dramatically following increase in ammonium-N concentration from 40 to 80 mg L. Manipulation of N loading could be a useful strategy to improve IPB performance, while inoculation of AOB or NOB may be beneficial for treatment of water with high ammonium loading when N removal is the primary system goal.
一种集成光生物电化学系统 (IPB) 结合了微生物燃料电池和藻类生物反应器，消除了曝气的需求，促进了发电，修复了营养物质，并生产藻类生物质以转化为生物燃料或其他生物制品。为了研究提高 IPB 电化学输出和养分去除效率的策略，本研究测试了阴极细菌接种和氮负荷对阴极微生物群落和 IPB 性能的影响。将绿藻小球藻与亚硝化细菌 (NOB) 硝化杆菌和/或氨氧化细菌 (AOB) 欧洲亚硝化单胞菌一起接种到 IPB 阴极。在硝化细菌接种前后以及废水中三种铵负荷浓度下检查了 IPB 的性能。通过 16S rRNA 基因序列分析检查了阴极悬浮液和生物膜中的细菌群落。与仅藻类对照相比，阴极接种 NOB 和/或 AOB 提高了净养分去除率，但导致溶解氧可用性降低，从而损害了发电。更高的铵负荷增加了电力生产和养分去除，这可能是通过克服藻类-细菌竞争来实现的。硝化细菌的接种对总细菌组成的变化很小，接种后 1 个月 AOB 或 NOB 仅占总序列的<3%。随着铵-N 浓度从 40 增加到 80mg/L，群落组成变化更为剧烈。氮负荷的控制可能是提高 IPB 性能的一种有用策略，而接种 AOB 或 NOB 可能有益于处理高铵负荷的水，当氮去除是系统的主要目标时。
