MCA - Exploring Algal Carbon Capture Potential in High pH Laboratory- and Field-Scale Systems

需要创造性的策略来管理大气中的二氧化碳（CO2），以减轻气候变化的后果。本研究通过实验和建模，考察了高pH藻类培养的潜力，以最大限度地提高无机碳（通过来自大气二氧化碳的溶解碳物种）的量，这些无机碳可用于将二氧化碳转化为藻类生物量。然后，这种生物质可以用于其他目的，例如生物柴油燃料。到目前为止，高pH值的藻类生长系统还没有得到充分的探索，即使在这些条件下，二氧化碳在空气-水推理中被化学消耗。为了更好地了解高pH/藻类系统的潜力，实验和数据的数学建模将用于探索高pH/藻类碳捕获过程，可行性和性能。研究人员和实践者可以使用该模型来估计旨在生产高价值产品（例如生物燃料）的大规模养殖的碳抵消。通过模型开发，研究将阐明碳酸盐的作用，并描述藻类生长过程中总溶解无机碳物种的动力学相互作用。氮源循环作为一种自然的、具有成本效益的策略来管理pH值和改善碳捕获的影响也将被探索。这项工作的更广泛影响包括通过设计最大限度地去除大气二氧化碳的藻类生产系统，支持气候变化管理和劳动力发展，从而造福社会。这可以作为综合碳管理计划的一部分，以尽量减少由于高浓度温室气体导致的气温上升所带来的无数经济、生态和社会后果。为了开展这项工作，将积极招募来自科学领域代表性不足群体的学生。这项研究需要进行混合藻培养实验，主要产品将是一个扩展的、经过验证的藻类生长模型，用于预测藻类生物量的生产和碳捕获，这是一个相互关联的参数的函数，包括水溶性总溶解无机碳、氮源类型和培养pH。高pH值正在研究中，因为在高pH值下，大多数溶解的总无机碳转化为溶解的碳酸盐。其作为无机碳源的适宜性很少受到关注。因此，本研究旨在扩展和验证一个数学模型，以量化高pH系统中混合淡水藻类的生长，为未来的碳捕获实验提供信息。实验将在克莱姆森大学的分区水产养殖系统进行。项目目标是通过以下四个目标来描述和模拟间歇反应器中总溶解无机碳的限制生长：第一个是确定和量化高ph下测量无机碳种类的分析方法的准确性。第二个和第三个是确定碳酸盐对藻类生长的动力学影响程度，并确定适当的monod -总溶解无机碳的配方，限制混合培养藻类的生长速度。第四个目标将是定量测量开放式间歇反应器中藻类培养物的碳捕获，这些数据将用于支持模型验证。另一个目标将是探索如何利用氮源循环来管理培养反应器中碳捕获的pH值，从而可以估计氮对pH值和生物量生产的影响，并根据几种营养负荷情景提供碳捕获的估计。在这个项目中，一名研究生和其他几名学生将参与其中。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。

Creative strategies are needed to manage atmospheric carbon dioxide (CO2) to mitigate the consequences of climate change. This research examines, through experiment and modeling, the potential of high pH algal cultures to maximize the amount of inorganic carbon (through dissolved carbon species derived from atmospheric CO2) available for conversion of CO2 to algal biomass. This biomass can then be used for other purposes, such as bio-diesel fuel. To date, high pH algal growth systems have not been adequately explored even though, at these conditions, carbon dioxide is chemically consumed at the air-water inference. To better understand the potential of the high pH/algal system, experiments and mathematical modeling of the data will be used to explore high pH/algal carbon capture processes, feasibility, and performance. The model can be used by researchers and practitioners to estimate the carbon offsets of large-scale cultures aimed at production of high-value produces (e.g., biofuels). Through model development, the research will clarify the role of carbonate and describe how total dissolved inorganic carbon species kinetically interact during algal growth. The impacts of nitrogen-source cycling as a natural, cost-effective strategy to manage pH and improve carbon capture will also be explored. Broader impacts of the work include benefits to society by supporting climate change management and workforce development through designing algal production systems that maximize atmospheric carbon dioxide removal. This can serve as part of an integrated carbon management plan to minimize a myriad of economic, ecological and social consequences of rising temperatures due to high concentrations of greenhouse gases. To carry out the work, students from underrepresented groups in the sciences will be actively recruited. This research entails experiments with mixed algal cultures and the primary product will be an expanded, validated, algal growth model for predicting algal biomass production and carbon capture as a function of interconnected parameters of total dissolved inorganic carbon aqueous species availability, nitrogen source type, and culture pH. High pH is being investigated because at high pH most dissolved total inorganic carbon is converted to dissolved carbonate, whose suitability as an inorganic carbon source has received little attention. Thus, this research seeks to expand and validate a mathematical model to quantify mixed freshwater algal growth in high pH systems to inform future carbon capture experiments. The experiments will be conducted at the Clemson University's Partitioned Aquaculture System. Project goals are to characterize and model total dissolved inorganic carbon-limited growth in batch reactors through the lens of four objectives, the first being to identify and quantify the accuracy of analytical methods for measuring inorganic carbon species at high pH. The second and third are to determine to what extent carbonate kinetically impacts algal growth and determine an appropriate formulation of the Monod-total dissolved inorganic carbon-limited growth rate of mixed culture algae. The fourth goal will be to quantitatively measure carbon capture by the algal cultures in open batch reactors, data that will be used to support model validation. An additional objective will be to explore how nitrogen source cycling could be used to manage pH for carbon capture in the culturing reactor so impacts of nitrogen on pH and biomass production can be estimated and to deliver estimates of carbon capture based on several nutrient loading scenarios. During the project, a graduate student and several additional students will be engaged.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.