Retooling Green Wastewater Treatment Infrastucture to Support Edible Crop Growth

Howard Weinberg北卡罗来纳大学教堂山分校随着人口的增长和美国乃至世界大部分地区的周期性干旱，必须考虑利用再生废水来保持淡水质量。经处理的废水在陆地上的应用，例如用于作物灌溉，可以同时保护饮用水水源的质量，因为经过处理的废水可以从敏感的水生生态系统中转移出来，同时减少对饮用水的需求。该项目将优化绿色基础设施设计，包括好氧植被砂过滤（VSF）与地下流（SSF）人工湿地相结合，以去除废水中人为来源的化学物质，并调查再生水中残留的化学物质在多大程度上积聚在用这种水灌溉的作物的可食用部分。该项目将系统地评估VSF和SSF操作的变化如何优化微量有机污染物和病原体的去除，以最大限度地减少用这种再生水灌溉的作物与用自来水灌溉的作物之间的可测量差异。这将通过两种方式实现；一项模拟处理设计的实验室柱状研究将研究不同工艺和过滤基质的组合，使用有特征的家庭污水进行优化，然后处理后的水将在温室中用于灌溉各种作物，包括土豆、大豆和叶类蔬菜，这些作物的选择是因为已知的化学吸收或排斥特性与传统自来水生长的对照不同。具体来说，我们将确定用这种水灌溉的作物是否会排斥污染物，使其可供食用，或者作物是否会吸收污染物，如果是这样，它们是否可以用作废水处理的额外修复工具。从实验室研究中确定的绿色基础设施设计过程的操作变化将转移到全面操作中，并在现场评估优化过程对作物生长的可行性。因此，该项目将证明是否可以更广泛地使用类似的设计和以这种方式使用再生水作为污染物补救和作物灌溉的管理办法的一部分，从而节省淡水以供更关键的需要。该项目将使人们更好地了解植被和作物如何对其环境中废水成分的存在作出反应。大多数废水处理系统不是专门为从进水废物中去除人造化学物质而设计的，因此通过在实验室控制的环境中评估基本处理过程，可以更好地优化设计以改善处理后的水质。此外，项目结果将显示废水成分是否被作物吸收（在这种情况下，这种过程对补救技术有影响），或者作物是否对吸收有抵抗力（在这种情况下，可以考虑在作物灌溉中更广泛地使用回收废水）。使用绿色基础设施设计在进入废水的地方有效去除废水污染物，对这些污染物在更广泛的环境中的排放产生了更广泛的影响，这在集中污水处理厂的废水排放中是典型的。升级这些装置以针对单个污染物并防止其排放可能会很昂贵，而现场处理可以分阶段进行，并且可以更有效地针对单个污染物进行处理。该项目还将为决策者提供有价值的信息，以协助确定安全操作做法，并将有助于提高公众对安全使用再生水的认识。

CBET 1336199 Howard Weinberg The University of North Carolina at Chapel HillWith population growth and recurrent drought conditions in much of the United States and across the world, new uses for reclaimed wastewater must be considered to preserve freshwater quality. Terrestrial application of treated wastewater such as for crop irrigation could simultaneously protect drinking water source quality, by diverting treated waste effluents from sensitive aquatic ecosystems while reducing demand for drinking water. This project will optimize green infrastructure designs including aerobic vegetated sand filtration (VSF) in combination with subsurface flow (SSF) constructed wetlands for removal of chemicals of anthropogenic origin in wastewater and investigate the extent to which residual chemicals in the reclaimed water accumulate in the edible portions of crops irrigated with this type of water. The project will systematically evaluate how changes to the operation of VSF and SSF can optimize trace organic contaminant and pathogen removal to minimize measureable differences between crops irrigated with such reclaimed water and those irrigated with tap water. This will be achieved through two approaches; a laboratory column study that simulates the treatment designs will investigate the combination of different processes and filter substrates for this optimization using a characterized domestic effluent, and the treated water will then be used in a greenhouse to irrigate a variety of crops including potatoes, soybeans, and leafy vegetables selected because of differences in known properties of chemical uptake or rejection alongside controls conventionally grown with tap water. Specifically, we will determine whether crops irrigated with such waters reject the pollutants making them viable for consumption or if the crops uptake the pollutants and, if so, might they be used as an additional remediation tool for wastewater treatment. Changes to the operation of the green infrastructure design process determined from the laboratory study will then be transferred to full-scale operation and the viability of the optimized process towards crop growth evaluated onsite. The project will, therefore, demonstrate whether more widespread use of similar designs and the use of reclaimed water in this manner could be part of a managed approach to pollutant remediation and crop irrigation, thereby saving freshwater for more critical needs. The project will provide a better understanding of how vegetation and crops respond to the presence of wastewater constituents in their environment. Most wastewater treatment systems are not specifically designed to remove man-made chemicals from the influent waste and so by evaluating the fundamental treatment processes in a laboratory-controlled environment, design can be better optimized to improve treated water quality. Moreover, the project results will show whether wastewater constituents are taken up by the crops (in which case such a process has implications for a remediation technology) or whether the crops are resistant to uptake (in which case a more widespread use of recycled wastewater in crop irrigation can be considered). The use of green infrastructure design for the effective removal of wastewater contaminants at the site of their entry into wastewater has broader impacts on the disbursal of these contaminants throughout the wider environment as is typical in wastewater discharges from centralized wastewater treatment plants. Upgrading such plants to target individual contaminants and prevent their disbursal will likely prove expensive whereas with on-site treatment, cost can be staged and treatment more effectively targeted to individual pollutants. The project will also provide policymakers with valuable information to assist with determining safe operating practices and will help to improve public perception regarding the safe use of reclaimed water.