Collaborative Research: A Novel Biological Valorization of Hydrothermal Liquefaction Wastewater with Marine Protist and its Granulated Phenotype

水热液化(HTL)被认为是一种很有前途的热处理方法，可以从包括农业废物生物质、城市固体废物和藻类在内的多种有机物中生产生物燃料。美国能源部最近的一份报告称，利用HTL技术，美国每年可以从可用的废弃有机物中生产多达59亿加仑的生物原油；这种生物原油可以进一步提炼成液体运输燃料，使用类似于传统石油精炼的工艺，取代目前由不可再生原料生产的燃料。然而，目前的HTL工艺产生了大量的高浓度有机化合物和营养物质的废水，这些废水的可持续处理是HTL规模化和商业化的最大瓶颈之一。这项研究将通过从HTL废水中回收有机碳和营养物质，从环境和能源转换效率的角度解决HTL的问题。这是提高HTL工艺的净能源产量、增强经济可行性和环境可持续性的关键一步。在实施该项目的过程中，研究人员将在生物燃料生产、生物技术/生物加工和环境管理方面培训下一代科学家和工程师，同时教育公众可持续的生物燃料生产以及能源消耗对经济、环境和社会可持续发展的影响。该提案的研究团队最近发现，海洋原生生物纹状体螺旋藻HB可以在没有补充营养的情况下在HTL处理城市固体废物产生的废水中生存和生长，同时去除大约80%的总有机碳、100%的总氮和80%的磷。此外，研究发现，这些微生物在较宽的pH和盐度范围内(与海水相当)代谢HTL废水中的有机化合物，同时能够在恶劣条件下形成细胞聚集体。因此，海洋原生生物有望成为HTL废水处理和有价物处理的一类新的优势微生物。该项目的总体目标是建立一个纹状体HB促进的HTL废水评估平台，以实现可持续的HTL生物燃料生产。本研究的具体目标是：(1)阐明生物产量与HTL废水组成之间的关系；(2)揭示纹状体HB对新的废水环境的代谢适应，以提高总体能量回报和生物粗品产量；(3)由于与分散细胞相比，生物颗粒在废水评价中更有效，因此本研究的具体目标是：(3)探索纹状体HB生物颗粒的形成机理及其对HTL废水评价的影响。海洋原生生物可能是一类很有前途的新型微生物，可用于其他类型的高浓度废水的有价化处理。拟议研究的跨学科性质将促进研究和教育计划的整合，以加强参与该项目的三个研究所的教育计划。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。

Hydrothermal liquefaction (HTL) has been considered as a promising thermal processing approach to biofuel production from a broad range of organic matter, including agricultural waste biomass, municipal solid waste, and algae. A recent U.S. Department of Energy report stated that as much as 5.9 billion gallons of biocrude could be produced each year in the U.S. from the available waste organic matter using HTL technology; this biocrude can be further refined to liquid transportation fuels using processes similar to conventional petroleum refining, replacing those fuels currently produced from non-renewable feedstocks. However, current HTL processes produce a large amount of wastewater containing high concentrations of organic compounds and nutrients; the sustainable disposal of this wastewater is one of the most significant bottlenecks to the scale-up and commercialization of HTL. This research will address concerns from both environmental and energy conversion efficiency perspectives of HTL by recovering organic carbon and nutrients from HTL wastewater. This is a critical step to increasing the net energy yield and enhancing the economic viability and environmental sustainability of HTL processes. In the course of carrying out this project, the researchers will train the next generation of scientists and engineers in biofuel production, biotechnology/bioprocessing, and environmental stewardship, all while educating the public about sustainable biofuel production and the impact of energy consumption on economic, environmental and societal sustainability.The research team of this proposal has recently found that a marine protist Thraustochytrium striatum HB can survive and grow in wastewater produced from HTL processing of municipal solid waste without supplemental nutrients while removing approximately 80% total organic carbon, 100% total nitrogen, and 80% phosphorus. Additionally, the microbes were found to be tolerant of wide pH and salinity ranges (comparable to sea water) in metabolizing organic compounds in HTL wastewater while being able to form cell aggregates under harsh conditions. Therefore, marine protists hold promise to be a new class of superior microorganisms for HTL wastewater treatment and valorization. The overarching goal of this project is to establish a T. striatum HB-facilitated platform for HTL wastewater valorization to enable sustainable HTL for biofuel production. The specific objectives of this research are to: (1) elucidate the correlation between biocrude yield and the HTL wastewater composition; (2) reveal the metabolic adaptation of T. striatum HB to the new wastewater environments to enhance overall energy return and biocrude yield; and (3) explore the formation mechanisms of T. striatum HB biogranules and the resulting performance impact on HTL wastewater valorization since biogranules are more efficient in wastewater valorization compared to dispersed cells. The marine protists could be a new class of promising microorganisms for valorization of other types of high-strength wastewater. The interdisciplinary nature of the proposed research will facilitate the integration of research and educational plans to enhance the education programs of three institutes involved in this project.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.