Department of Civil and Environmental Engineering, University of California, Davis, CA, USA.
Trussell Technologies, Inc., Oakland, CA, USA.
Water Environ Res. 2021 Aug;93(8):1231-1242. doi: 10.1002/wer.1531. Epub 2021 Feb 15.
Population growth, the impacts of climate change, and the need for greater water security have made the reuse of wastewater, including potable use, increasingly desirable. As interest in potable reuse of wastewater increases, a variety of processes have been proposed for advanced water treatment following conventional wastewater treatment. In all cases, the operation and performance of advanced water treatment facilities (AWTFs) is improved when the treated wastewater feed is of the highest quality that can be achieved and the advanced water treatment (AWT) processes are operated at a constant flow. One proven method of optimizing the performance of wastewater treatment facilities (WWTFs) is constant flow operation with no extraneous return flows other than internal process recycle flows, such as return settled solids. A number of approaches can be used to achieve constant flow including flow equalization, divided treatment trains, and satellite treatment. The ways in which constant flow wastewater treatment benefits both WWTFs as well as the AWTFs are considered with special emphasis on the ability to achieve predictable log removal credits (LRCs) for specific microorganisms. Actual performance data from constant flow WWTFs are used to illustrate how LRCs are determined. PRACTITIONER POINTS: Constant flow WWTFs should be considered to produce the highest quality secondary effluent for AWT. Flow equalization, divided treatment trains, and satellite treatment can be used to achieve constant flow to optimize wastewater treatment in small and medium size WWTFs. Flow equalization can be used to maximize the amount of wastewater that can be recovered for potable reuse. Important benefits of constant flow for wastewater treatment facilities include economic and operational savings, stable and predictable treatment performance, energy savings, ability to optimize performance for the removal of specific constituents, and the ability to assign pathogen log removal credits (LRCs). Important benefits of constant flow and optimized WWT for AWTFs include economic and operational savings; less pretreatment needed, including energy and chemical usage; elimination of the need to cycle treatment processes; and added factor of safety with respect to the required pathogen LRCs. In large WWTFs, constant flow for AWTFs will typically be achieved by effluent diversion; depending on the effluent quality additional pretreatment may be needed. The design and implementation of WWTFs and AWTFs for potable reuse should be integrated for optimal performance and protection of public health.
人口增长、气候变化的影响以及对更大水安全保障的需求，使得废水再利用（包括饮用水用途）变得越来越可取。随着人们对废水再利用（包括饮用水用途）的兴趣日益增加，各种先进的水处理工艺已经被提议在传统废水处理之后使用。在所有情况下，当处理后的废水进料达到最高质量时，并且先进的水处理（AWT）工艺以恒定流量运行时，先进的水处理设施（AWTFs）的运行和性能都会得到改善。优化废水处理设施（WWTFs）性能的一种经过验证的方法是恒流运行，除了内部工艺循环流（例如返回的沉淀固体）之外，没有其他额外的回流。有几种方法可以实现恒流，包括流量均衡、分处理列车和卫星处理。恒流废水处理对 WWTFs 和 AWTFs 的好处都将被考虑，特别强调实现特定微生物可预测对数去除信用（LRCs）的能力。使用恒流 WWTFs 的实际性能数据来说明如何确定 LRCs。从业者要点：应考虑恒流 WWTFs 以生产用于 AWT 的最高质量二级出水。流量均衡、分处理列车和卫星处理可用于实现恒流，以优化中小规模 WWTFs 的废水处理。流量均衡可用于最大限度地回收可用于饮用水再利用的废水量。恒流对废水处理设施的重要好处包括经济和运营节省、稳定和可预测的处理性能、节能、优化特定成分去除性能的能力以及分配病原体对数去除信用（LRCs）的能力。恒流和优化的 WWT 对 AWTFs 的重要好处包括经济和运营节省；预处理所需的能源和化学品用量减少；无需循环处理过程；以及在所需病原体 LRCs 方面增加了安全系数。在大型 WWTFs 中，AWTF 的恒流通常通过出水分流来实现；根据出水质量，可能需要额外的预处理。为了实现最佳性能和保护公众健康，应将饮用水再利用的 WWTFs 和 AWTFs 的设计和实施集成在一起。
