From Wastewater to Gasoline - Aqueous Biorefining of Polyhydroxybutyrate (PHB)-Enriched Biosolids

不断增长的人口和不断提高的生活水平正在推动对更多清洁水以及廉价能源、材料和食品的需求。与此同时，这种需求产生了越来越多的固体和液体废物，公共事业公司必须对其进行管理。目前的废水处理方法需要花费大量的能量来去除水中的有机碳、营养物质和病原体。然而，在废水处理过程中，这些相同的“废物”成分可能会被回收为能源或其他有价值的产品。最近的研究表明，废水处理可以利用微生物将废弃的有机碳输送到细胞中形成聚羟基丁酸酯(PHB)颗粒来完成。然后，可以从产生的废物中分离出PHBs，并将其转化为高价值产品，如可再生汽油、工业化学品和生物塑料。通过生物和催化技术的集成，废水处理过程可以被改造成一个“生物精炼厂”，只生产许多产品中的一个清洁水。这种水基础设施的重新发明还将使可持续废物处理和资源管理的概念传播到更广泛的各级学生受众中。最终，需要这样的研究和教育努力来支持国家向更可持续的基础设施的转变。在新兴生物炼油技术的推动下，该项目旨在通过加工富含PHB的生物质来实现和优化将废弃有机碳流转化为有价值的工业化学品和汽油级碳氢燃料。将进行以下实验：(1)开发从微生物生物质中分离PHB的有效策略，并促进PHB在水环境中的解聚；(2)确定反应条件和催化剂，以优化生成的PHB衍生单体的脱水和脱羧基；以及(3)展示将废有机碳集成转化为汽油级燃料，并为该系统建立技术经济分析(TEA)框架。PHB与生物质的分离和随后的解聚将侧重于仅含水的策略，以最大限度地减少化学投入和副产品废物。催化剂的开发将集中在沸石等低成本固体酸催化剂(SACS)上。最有希望的催化剂将在连续流动反应器中进行评估，并将测试保持催化剂活性的预防和再生策略。这项研究将支持在市政、农业和工业部门增加有机碳丰富的废物流的价格化，潜在地颠覆污水处理设施的能源平衡和成本模式。此外，该项目支持研究生和本科生参与者的职业发展，为K-12学生和教师设计的教育和外展活动将支持向更多的受众传播可持续废物处理和可再生能源生产方法。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Increasing population and rising living standards are driving the demand for more clean water and inexpensive energy, materials, and food. At the same time, this demand produces growing volumes of solid and liquid wastes that public utilities must manage. Current approaches to wastewater treatment expend large amounts of energy to remove organic carbon, nutrients, and pathogens from the water. However, these same "waste" constituents can potentially be recovered as energy or other valuable products during the wastewater treatment process. Recent research demonstrates that wastewater treatment can be accomplished using microorganisms that funnel waste organic carbon into their cells to form polyhydroxybutyrate (PHB) granules. The PHBs can then be separated from the resulting waste and converted to high-value products such as renewable gasoline, industrial chemicals, and bioplastics. Through integration of biological and catalytic technologies, the wastewater treatment processe can be reinvented as a "bio-refinery" that yields clean water as just one product of many. This re-invention of water infrastructure will also allow the diffusion of sustainable waste treatment and resource management concepts to a broader audience of students at all levels. Ultimately, such research and educational efforts are needed to support the Nation's shift towards more sustainable infrastructure.Motivated by developments in nascent biorefinery technologies, this project aims to realize and optimize the conversion of waste organic carbon streams to valuable industrial chemicals and gasoline-grade hydrocarbon fuels through the processing of PHB-enriched biomass. Experiments will be conducted to: (1) develop effective strategies for separating PHB from microbial biomass and promoting PHB depolymerization in an aqueous environment; (2) identify reaction conditions and catalysts for optimal dehydration and decarboxylation of the resultant PHB-derived monomers; and (3) demonstrate integrated conversion of waste organic carbon to gasoline-grade fuels and establish a techno-economic analysis (TEA) framework for the system. PHB separation from biomass and subsequent depolymerization will focus on aqueous-only strategies to minimize chemical inputs and byproduct wastes. Catalyst development will focus on low-cost solid acid catalysts (SACs) such as zeolites. The most promising catalysts will be evaluated in continuous flow reactors, and both preventative and regenerative strategies for maintaining catalyst activity will be tested. This research will support a path forward towards increased valorization of organic carbon-rich waste streams in municipal, agricultural, and industrial sectors, potentially flipping the energy balance and cost model for wastewater utilities. In addition, this project supports the career development of graduate and undergraduate student participants, and educational and outreach activities designed for K-12 students and teachers will support the diffusion of sustainable waste treatment and renewable energy production methods to a larger audience.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.