Bioelectrochemistry applications for recovery and production of valuable resources from wastewater and organic waste

这项工作的长期目标是展示将不需要的废物（废水污泥，食物垃圾和烟道气）可持续地转化为有价值的产品（NH 4+和生物塑料）。这种转换需要密集的能量消耗和其它资源（例如，用于生物塑料生产的有机酸）。为了使这种转化可行，我们将研究微生物电解池（MEC），双极膜电渗析（BMED）和微生物PHA（生物塑料的聚羟基链烷酸酯原料）积累，短期目标如下。1.从有机废物中分离NH 4+和挥发性脂肪酸（VFA）的节能 *2.选择性富集高容量PHA积累微生物 *3.用于微生物CO2转化为PHA**BMED的可持续H2供应由双极膜（BPM）和离子交换膜（IEM）组成，以通过阴离子交换膜（AEM）分离VFA（乙酸盐、丙酸盐）的共轭碱和通过阳离子交换膜（CEM）分离NH 4+来产生酸和碱溶液（在本工作中为VFA和NH 4+溶液）。将在BMED中处理液态水（本工作中从嗜热预处理的废水污泥和食物垃圾中分离的液态废水）以产生VFA和NH 4+溶液。为了减少电能消耗，BMED将被整合到MEC中，在MEC中，产电细菌通过VFA氧化产生电流。**真养罗尔斯通氏菌是一种高效的PHA富集菌（占干细胞的80-90%），然而，目前还没有选择性富集罗尔斯通氏菌的方法。混合培养的真养型。因此，它们不适合于使用生物活性废水中的有机物（例如，液态）。在这项工作中，我们将利用R的另一个独特功能。可以异养（有机碳作为碳源）或自养（CO2作为碳源）生长的真养生物。通过反复交替的自养和异养条件，我们假设R。可从混合培养物中选择性地富集真养生物，而其它异养生物和自养生物显示出有限的生长。来自BMED的不含NH 4+的VFA溶液将用于在R期间诱导PHA积累。真养生物富集。我们将进一步证明使用富集的R将烟道气中的CO2自养转化为PHA。真养型培养MEC将用于供应H2，从而降低PHA生产的成本。来自BMED的VFA溶液将为MEC中的外生产电菌提供有机底物，并且VFA溶液中不存在NH 4+将触发CO2转化为PHA。**我们的研究成果将使利用有机废物和烟道气生产NH 4+和PHA的成本降低成为可能。从有机废物中回收的NH 4+可用于土地肥料制造。从烟气中生产PHA将减少GHG（温室气体）排放，因为煤炭/天然气发电厂占加拿大GHG排放量的约10%。**

The long-term objective of this work is to demonstrate sustainable conversion of unwanted wastes (wastewater sludge, food waste, and the flue gas) into valuable products (NH4+ and bioplastics). Such conversions require intensive energy consumption and other resources (e.g., organic acids for bioplastics production). To make such conversions feasible, we will research microbial electrolysis cells (MEC), bipolar membrane electrodialysis (BMED), and microbial PHA (polyhydroxyalkanoateraw material of bioplastics) accumulation with the following short-term objectives.******1. Energy reduction in NH4+ and volatile fatty acid (VFA) separation from organic waste***2. Selective enrichment of a high-capacity PHA-accumulating microorganism***3. Sustainable H2 supply for microbial CO2 conversion into PHA******BMED consists of bipolar membranes (BPMs) and ion exchange membranes (IEMs) to produce an acid and base solutions (VFA and NH4+ solutions in this work) by separating conjugate bases of VFAs (acetate, propionate) through anion exchange membranes (AEMs) and NH4+ through cation exchange membranes (CEMs). Liquid digestate (liquid wastewater separated from thermophilically pretreated wastewater sludge and food waste in this work) will be treated in BMED to produce the VFA and NH4+ solutions. To reduce electric energy consumption, BMED will be integrated in MECs where exoelectrogenic bacteria generate electric current from VFA oxidation.******Ralstonia eutropha is high-capacity PHA-accumulating bacteria (80-90% of dry cells); however, there are no methods for selective enrichment of R. eutropha from a mixed culture. As a result, they are not suitable for PHA production using organics in biologically active wastewater (e.g., liquid digestate). In this work, we will utilize another unique capability of R. eutropha that can grow either heterotrophically (organic carbon as carbon source) or autotrophically (CO2 as carbon source). By alternating autotrophic and heterotrophic conditions repetitively, we hypothesize that R. eutropha can be selectively enriched from a mixed culture while other heterotrophs and autotrophs show limited growth. The VFA solution without NH4+ from BMED will be used to induce PHA accumulation during R. eutropha enrichment.******We will further demonstrate autotrophic conversion of CO2 in the flue gas into PHA using the enriched R. eutropha culture. MECs will be used to supply H2, reducing the cost for PHA production. The VFA solution from BMED will provide organic substrates to exoelectrogens in the MECs and the absence of NH4+ in the VFA solution will trigger conversion of CO2 into PHA.******Our research outcomes will make it feasible to utilize organic waste and the flue gas for NH4+ and PHA production at reduced costs. NH4+ recovered from organic waste can be used for land fertilizer manufacturing. PHA production from the flue gas will reduce GHG (greenhouse gas) emission as coal/natural gas power plants are responsible for ~10% of GHG emission in Canada.**