Modeling the Economic Feasibility of Large‐Scale Net‐Zero Water Management: A Case Study

Abstract

While municipal direct potable water reuse (DPR) has been recommended for consideration by the U.S. National Research Council, it is unclear how to size new closed-loop DPR plants, termed ''net-zero water (NZW) plants'', to minimize cost and energy demand assuming upgradient water distribution. Based on a recent model optimizing the economics of plant scale for generalized conditions, the authors evaluated the feasibility and optimal scale of NZW plants for treatment capacity expansion in Miami-Dade County, Florida. Local data on population distribution and topography were input to compare projected costs for NZW vs the current plan. Total cost was minimized at a scale of 49 NZW plants for the service population of 671,823. Total unit cost for NZW systems, which mineralize chemical oxygen demand to below normal detection limits, is projected at~$10.83 / 1000 gal, approximately 13% above the current plan and less than rates reported for several significant U.S. cities. Water Environ. Res., 88, 811 (2016).

Mineralizing urban net-zero water treatment: Field experience for energy-positive water management

“…The energy for such peroxone mineralization represents a cost of only $0.25/m 3 ($0.96/1000 gal) [assuming 2.11 kWh/m 3 for mineralization of COD in secondary effluent (Wu and Englehardt 2015) and US average $0.12/kWh electricity (US Energy Information Administration, 2013)]. Because other factors may dominate utility expenses, total capital and operating cost for ~2 MGD peroxone-based NZW plants, after hot water energy savings, has been projected lower than combined water/wastewater rates reported for several major U.S. cities (Guo et al, 2016). Presumably, operation of such moderately-sized distributed plants can be facilitated by remote automated process monitoring and control, allowing off-site and mobile technical support.…”

Net-zero water management: achieving energy-positive municipal water supply

“…Moreover, modeling studies indicated that (a) the cost of such a NZW system is Environmental Science: Water Research & Technology Perspective already competitive with conventional water/wastewater technology, 4 at plant sizes as small as 100 households per plant. 3 Finally, it has so far been found that environmental and proscience attitudes, risk-seeking, and past exposure to recycled water are negatively associated with disgust; disgust was the most important predictor of willingness to use recycled water; and participants given information about recycled water reported significantly lower disgust. 21…”

“…Such systems have been shown capable of economically producing potable water from comingled municipal wastewater. [1][2][3][4] Motivations for net-zero municipal water management are compelling: in addition to avoidance of water shortages, it is now projected that a DPR NZW system can be significantly energy-positive, retaining and saving more hot-water thermal energy in the water than is used for treatment. 5 In addition, available data indicate that water conveyance currently requires four times the energy required for treatment, on average in the US.…”

Sustainable Drinking Water Security Strategic Plan: A Case Study of Juba South Sudan

“…International Journal of Scientific Advances ISSN: 2708-7972 will become very difficult [40]. Looped systems are more expensive, both in terms of initial investment and ongoing operating expenses [40,57]. It is a primarily suitable solution for potable water distribution in urban or industrial areas requiring a high system and stability [58].…”