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Forward Osmosis Membrane Bioreactor Performance for Wastewater Treatment Applications.

机译：废水处理应用中正渗透膜生物反应器的性能。

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摘要

Global water shortage and scarcity has spurred worldwide efforts to explore alternative approaches to augment the existing water supply. Recent consideration for the utilization of wastewater as a viable water source has been adopted in several efforts to develop advanced treatment methods capable of providing adequate treatment for water reuse. The forward osmosis membrane bioreactor (OMBR) offers one such alternative, coupling conventional wastewater treatment processes with the promising high rejection properties of the forward osmosis (FO) membrane. The OMBR offers a low-energy alternative to conventional wastewater treatment and other energy intensive membrane processes (i.e., reverse osmosis), while still achieving advantageous wastewater treatment as well as high-quality salty product water obtained through the FO membrane. This preliminary FO process serves as a high-quality pretreatment step that has far-reaching expansion potential, as the product water may be further treated through an additional membrane treatment process to produce a potable and recyclable water source. This makes the OMBR an effective pretreatment device for recycled water applications.;The single-stage reactor design employed here combines anoxic and aerobic processes to reduce the footprint and decrease energy costs of continuous aeration. The aeration cycling, solids and hydraulic retention times, and membrane cleaning strategies were examined for adequate wastewater treatment with optimal flux through the FO process. One of the major challenges facing the continuous operation of the OMBR system was maintaining adequate biomass concentrations to achieve denitrification when treating primary effluent from a local wastewater treatment facility. Efforts to address this focused on having sufficient carbon substrate present to facilitate microbial growth and denitrification. Spiking the primary effluent with an additional 300 mg/L glucose resulted in a noticeable decrease in NOx species, consistent with enhanced denitrification, and the reactor MLSS concentrations stabilized. Subsequent batch experiments using three subset reactor configurations with OMBR mixed liquor, OMBR mixed liquor spiked with 30 mg/L NO3 -, and OMBR mixed liquor spiked with 30 mg/L NO3 - and 60 mg/L glucose validated the carbon limited status, as the denitrification rate increased from 0.102 to 0.214 to 0.523 mg-N/L-hr, respectively. The fivefold increase in denitrification observed in the reactor spiked with both NO3- and glucose further confirmed the influence additional carbon and nitrogen substrates have on increased reactor performance. A high-strength wastewater was eventually implemented in the continuously operating OMBR system to increase both carbon and nitrogen loading. Higher MLSS levels and denitrification rates were observed; however, the FO membrane flux decreased more rapidly and required more frequent membrane cleaning. These results demonstrate the complexity and interconnectedness of the operational parameters and the need for a fine-tuned balance when combining the two treatment processes.;The fate of solute transport into the draw solution from the OMBR was also investigated. Solute behavior and fate in the draw solution stream is important because this draw solution will serve as the feed stream for the secondary membrane process. This coupled membrane system utilizes the OMBR as a pretreatment step, whose product water serves as the feed solution for the final treatment process to produce potable quality water while reconcentrating the FO draw solution in the process. Examining solute transport from the OMBR to the draw solution, and whether the secondary membrane process provides near complete rejection, gives insight into whether draw solution treatment or replacement will be required for optimal water quality production in the coupled membrane system. A series of abiotic studies examined the behavior of several solutes relevant to OMBR systems in an effort to determine the implications solute passage and buildup have for long-term and continuously operated OMBR systems.
机译：全球水资源短缺和稀缺刺激了世界范围内探索替代方法以增加现有水供应的努力。在开发可为水再利用提供适当处理的先进处理方法的数项努力中，最近已考虑将废水作为一种可行的水源加以利用。正向渗透膜生物反应器（OMBR）提供了一种这样的替代方案，将常规废水处理工艺与正向渗透（FO）膜的有前途的高截留性能结合在一起。 OMBR为常规废水处理和其他高能耗膜工艺（即反渗透）提供了低能耗的替代品，同时仍实现了有利的废水处理以及通过FO膜获得的高质量咸水。初步的FO工艺可作为高质量的预处理步骤，具有广泛的扩展潜力，因为可以通过附加的膜处理工艺进一步处理产品水，以生产饮用水和可循环利用的水源。这使OMBR成为用于循环水应用的有效预处理设备。此处采用的单级反应器设计结合了缺氧和好氧工艺，以减少占地面积并降低连续曝气的能源成本。检查了曝气循环，固体和水力停留时间以及膜清洁策略，以通过FO工艺以最佳通量对废水进行充分处理。 OMBR系统连续运行面临的主要挑战之一是，在处理当地废水处理设施的主要出水时，要保持足够的生物质浓度以实现反硝化。解决该问题的努力集中在具有足够的碳底物以促进微生物生长和反硝化上。用额外的300 mg / L葡萄糖加标初级流出物会导致NOx种类明显减少，这与反硝化作用增强相一致，并且反应器MLSS浓度稳定。随后的分批实验使用了三个子反应器配置，分别为OMBR混合液，掺有30 mg / L NO3-的OMBR混合液和掺有30 mg / L NO3-和60 mg / L葡萄糖的OMBR混合液，验证了碳限制状态，如下反硝化率分别从0.102增加至0.214至0.523 mg-N / L-hr。在掺有NO3-和葡萄糖的反应器中观察到的反硝化提高了五倍，这进一步证实了额外的碳和氮底物对提高反应器性能的影响。最终在连续运行的OMBR系统中实施了高强度废水处理，以增加碳和氮的负载量。观察到更高的MLSS水平和反硝化率；但是，FO膜通量下降得更快，需要更频繁的膜清洁。这些结果证明了操作参数的复杂性和相互联系以及组合两种处理方法时需要微调的平衡。;还研究了溶质从OMBR进入抽提溶液的命运。汲取溶液物流中的溶质行为和命运很重要，因为该汲取溶液将用作二级膜工艺的进料流。该耦合膜系统利用OMBR作为预处理步骤，其产物水用作最终处理过程的进料溶液，以生产饮用水质量的水，同时在过程中浓缩FO汲取溶液。检查从OMBR到溶质溶液的溶质传输，以及次级膜工艺是否提供接近完全的排斥，可以深入了解是否需要对溶质液进行处理或更换，才能在耦合膜系统中获得最佳水质。一系列非生物研究检查了与OMBR系统有关的几种溶质的行为，以测定溶质的通过和积累对长期连续运行的OMBR系统的影响。

著录项

  • 作者

    Freitas, Ally M.;

  • 作者单位

    University of Nevada, Reno.;

  • 授予单位 University of Nevada, Reno.;
  • 学科 Civil engineering.;Environmental engineering.
  • 学位 M.E.
  • 年度 2016
  • 页码 116 p.
  • 总页数 116
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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