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推动了对更清洁的水和廉价的能源、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，公用事业必须处理这些废物。目前的废水处理方法耗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，废水处理可以通过微生物将废有机碳漏斗到它们的细胞中形成聚羟基丁酸盐（PHB）颗粒来完成。然后，PHBs可以从产生的废物中分离出来，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整合，废水处理过程可以被改造为“生物精炼厂”，生产清洁的水只是许多产品中的一种。这种水基础设施的重新发明也将使可持续废物处理和资源管理概念能够向各级学生的更广泛受众传播。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转变。在新兴生物炼制技术发展的推动下，该项目旨在通过处理富含phb的生物质，实现并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化合物燃料。实验将进行：(1)制定有效的策略，从微生物生物量中分离PHB，并促进PHB在水环境中的解聚；(2)确定phb衍生单体的最佳脱水脱羧反应条件和催化剂；(3)示范将废有机碳综合转化为汽油级燃料，并建立该系统的技术经济分析（TEA）框架。从生物质中分离PHB和随后的解聚将侧重于只使用水的策略，以尽量减少化学投入和副产品废物。催化剂的开发将侧重于低成本的固体酸催化剂（SACs），如沸石。最具前景的催化剂将在连续流反应器中进行评估，并对维持催化剂活性的预防和再生策略进行测试。这项研究将为市政、农业和工业部门增加有机碳丰富的废物流的增值提供支持，可能会改变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推广活动将支持向更多受众传播可持续废物处理和可再生能源生产方法。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.