Elucidating Novel Algal-Sludge Granules for Wastewater Treatment and Biomethane Feedstock Generation

马萨诸塞州阿默斯特大学目前美国大部分城市都使用活性污泥法处理废水。该工艺实现了二级处理，但能源密集，主要是由于其需要曝气以处理有机物和营养物。近年来，人们对藻类废水处理的兴趣有所增加，因为它能够通过光合藻类和细菌的共生生长在不曝气的情况下处理废水，并产生生物燃料原料。尽管有这些益处，但由于微藻生物絮凝的缺乏（其导致难以将生物质与水分离）以及不能控制废水环境中的藻类物种，阻碍了用于废水处理的藻类方法的发展。本研究的目的是阐明微藻和细菌的颗粒化，产生新的藻类污泥颗粒。这些颗粒是由微藻和细菌组成的大的、致密的和球形的生物聚集体。初步研究发现，藻类-污泥颗粒可以在废水环境中自然形成，并用于在流通式生物反应器中处理废水。由于其物理特性，颗粒很容易从水中分离出来，克服了藻类工艺的主要挑战之一。此外，藻类和细菌在同一颗粒生物质内的共生促进了用于废水和营养物处理的藻类工艺的工程化。为了揭示微藻和细菌颗粒化的机制，本研究将采用一系列的批处理和流通反应器的研究，并调查光，温度和生长速率对藻类细菌颗粒化的影响。为了确定藻类污泥颗粒的微生物性质和表征其理化特性，研究人员将通过本研究对藻类颗粒进行遗传、显微镜和理化分析。该项目还将使用微传感器方法来记录关键代谢化学物质在颗粒中的运输，从而研究颗粒的微生物活性和功能及其与废水处理性能的联系。最后，通过对收获的藻类颗粒进行厌氧消化研究，特别是与污水污泥和藻类生物质纯培养物等其他原料进行比较，研究其归宿、消化率和厌氧消化的甲烷生物能产量。本研究的贡献将揭示新型藻类污泥颗粒开发及其在真实的废水处理背景下生长的基础科学。该研究具有重要意义，因为藻类和细菌的微颗粒将导致可控和有效的藻类废水处理工艺。此外，藻类和细菌的共生生长将导致有意义的生物质产量，用于从废水处理中产生生物原料。总的来说，这项研究的成果不仅将推动废水处理领域的发展，还将通过减少废水处理过程中消耗的能源，增加以生物能源原料和生物甲烷的形式回收废水化学能的机会，对社会产生广泛的影响和效益。

CBET - 1335816Chul ParkUniversity of Massachusetts AmherstMost municipalities in the US currently use the activated sludge process to treat wastewater. The process achieves secondary treatment but is energy intensive, mainly due to its need of aeration for organic matter and nutrient treatment. Interest in algae-based wastewater treatment has increased in recent years because of its ability to treat wastewater without aeration through the symbiotic growth of photosynthetic algae and bacteria and generate biofuel feedstock. Despite these benefits, the lack of microalgae bioflocculation, which accounts for the difficulty in separating biomass from water, and an inability to control algal species in the wastewater environment have hindered the development of algae processes for wastewater treatment. The objective of this research is to elucidate biogranulation of microalgae and bacteria that yields novel algal-sludge granules. These granules are large, dense, and spherical bioaggregates composed of both microalgae and bacteria. Preliminary research has found that algal-sludge granules can be naturally formed in the wastewater environment and be used for treating wastewater in a flow-through bioreactor. Due to physical characteristics, granules readily separate out from water, overcoming one of the major challenges of algae processes. In addition, symbiosis of algae and bacteria within the same granular biomass facilitates the engineering of an algae process for wastewater and nutrient treatment. To unveil the mechanisms of biogranulation of microalgae and bacteria this research will employ a series of batch and a flow-through reactor studies and investigate the effect of light, temperature, and growth rates on algal-bacterial granulation. To determine the microbiological nature and characterize physiochemical properties of algal-sludge granules, the investigators will conduct genetic, microscopic, and physicochemical analyses on the biogranules through this research. The project will also use a compliment of microsensor approaches to document the transport of key metabolic chemicals across the granules, thus studying microbial activity and function of the granules and their link to wastewater treatment performances. Finally, the research will conduct anaerobic digestion study on harvested biogranules to investigate its fate, digestibility, and methane bioenergy yield by anaerobic digestion, especially compared to other feedstock, such as sewage sludge and pure cultures of algal biomass.The contribution of this research will reveal the fundamental science behind the development of novel algal-sludge granules and their growth in the context of real wastewater treatment. This research is significant, because biogranules of algae and bacteria will result in a controllable and effective algae-based wastewater treatment process. Additionally, the symbiotic growth of algae and bacteria will lead to meaningful biomass yield for biofeedstock generation from wastewater treatment. Collectively, the outcome of this research will not only advance the field of wastewater treatment, it will also have a substantially broad impact and benefit to society by reducing the energy consumed during wastewater treatment and increasing opportunity to recover chemical energy of wastewater in the form of bioenergy feedstock and biomethane through its anaerobic digestion.