Faculty of Civil and Environmental Engineering, Technion - IIT, Haifa 32000, Israel.
Water Res. 2013 Oct 1;47(15):5911-20. doi: 10.1016/j.watres.2013.07.012. Epub 2013 Jul 20.
Sustainable design and implementation of greywater reuse (GWR) has to achieve an optimum compromise between costs and potable water demand reduction. Studies show that GWR is an efficient tool for reducing potable water demand. This study presents a multi-objective optimization model for estimating the optimal distribution of different types of GWR homes in an existing municipal sewer system. Six types of GWR homes were examined. The model constrains the momentary wastewater (WW) velocity in the sewer pipes (which is responsible for solids movement). The objective functions in the optimization model are the total WW flow at the outlet of the neighborhoods sewer system and the cost of the on-site GWR treatment system. The optimization routing was achieved by an evolutionary multi-objective optimization coupled with hydrodynamic simulations of a representative sewer system of a neighborhood located at the coast of Israel. The two non-dominated best solutions selected were the ones having either the smallest WW flow discharged at the outlet of the neighborhood sewer system or the lowest daily cost. In both solutions most of the GWR types chosen were the types resulting with the smallest water usage. This lead to only a small difference between the two best solutions, regarding the diurnal patterns of the WW flows at the outlet of the neighborhood sewer system. However, in the upstream link a substantial difference was depicted between the diurnal patterns. This difference occurred since to the upstream links only few homes, implementing the same type of GWR, discharge their WW, and in each solution a different type of GWR was implemented in these upstream homes. To the best of our knowledge this is the first multi-objective optimization model aimed at quantitatively trading off the cost of local/onsite GW spatially distributed reuse treatments, and the total amount of WW flow discharged into the municipal sewer system under unsteady flow conditions.
灰水再利用（GWR）的可持续设计和实施必须在成本和减少饮用水需求之间取得最佳折衷。研究表明，GWR 是减少饮用水需求的有效工具。本研究提出了一种多目标优化模型，用于估计现有市政污水系统中不同类型 GWR 住宅的最佳分布。研究考察了六种类型的 GWR 住宅。该模型限制了污水管道中的瞬时废水（WW）速度（这是固体运动的原因）。优化模型的目标函数是居民区污水系统出口的总 WW 流量和现场 GWR 处理系统的成本。优化路由是通过进化多目标优化与以色列沿海一个居民区代表性污水系统的水动力模拟相结合来实现的。选择的两个非支配最佳解决方案是出口 WW 流量最小或每日成本最低的解决方案。在这两种解决方案中，选择的大多数 GWR 类型都是用水量最小的类型。这导致两个最佳解决方案之间，关于居民区污水系统出口处 WW 流量的日变化模式，只有很小的差异。然而，在上游链路中，WW 流量的日变化模式存在很大差异。这种差异是由于只有少数家庭在上游链路中实施相同类型的 GWR，并且在每个解决方案中，这些上游家庭都实施了不同类型的 GWR。据我们所知，这是第一个旨在根据非稳定流条件下空间分布的局部/现场 GW 再利用处理的成本和排入市政污水系统的 WW 总量，定量权衡成本的多目标优化模型。
