Assessing cost‐effective nutrient removal solutions in the urban water system

Abstract

Many states are adopting more stringent nutrient load restrictions, requiring utilities to invest in costly improvements. To date, substantial research has been done to independently assess the nutrient removal efficacy of wastewater treatment technologies and stormwater control measures. The analysis presented here provides a unique assessment by evaluating combinations of nutrient load reduction strategies across water supply, wastewater, and stormwater sectors. A demonstration study was conducted evaluating 7812 cross-sector removal strategies in the urban water system using empirical models to quantify efficacy of common wastewater treatment, water management, and stormwater control measures (SCMs). Pareto optimal solutions were evaluated to identify the most cost-effective strategies. To meet stringent nutrient requirements, wastewater treatment facilities (WWTFs) will likely require advanced biological nutrient removal with carbon and ferric addition. Even with these technologies, WWTFs may still be unable to obtain target nutrient requirements. In addition, municipalities can consider water management practices and SCMs to further reduce nutrient loading or provide a more cost-effective nutrient removal strategy. For water management practices, source separation and effluent reuse were frequently identified as part of the most effective nutrient strategies but face engineering, political, and social adoption barriers. Similarly, SCMs were frequently part of effective nutrient removal strategies compared to only adopting nutrient removal practices at WWTFs. This research provides the framework and demonstrates the value in using an urban water system approach to identify optimal nutrient removal strategies that can be easily applied to other urban areas.

Nutrient control in water bodies: A systems approach

“…A comprehensive study of traditional and emerging nutrient recovery and removal technologies was conducted at the municipal scale (Hodgson et al, 2020;Hodgson & Sharvelle, 2019). The assessment was conducted at four wastewater treatment facilities (WWTFs).…”

“…Metrics within life cycle cost assessment, triple bottom line, and other assessment frameworks may vastly vary by facility or location due to heterogeneous climatic, hydrologic, and other physical and social factors. Moreover, optimal (or least‐cost) solutions for a component of the system may not be optimal at the watershed level (Arabi, Govindaraju, & Hantush, 2006; Hodgson et al., 2020; Lammers et al., 2020; Osmond, Shober, Sharpley, Duncan, & Hoag, 2019). To ensure integration on a watershed scale, a set of consistent sustainability indicators or metrics may be considered, including, but not limited to, minimization of nutrient loads and costs, maximization of the likelihood of adoption, equity to all groups, reliability in meeting water quality targets, and resiliency to changes in driving forces and pressures.…”

“…A systems view can involve technological, environmental, and societal considerations or also consider valuation of monetized and nonmonetized co‐benefits and the inherent consequences that make up a nutrient management program. These studies evaluate several promising nutrient control technologies for stormwater or domestic wastewater (Hodgson, Dell, Sharvelle, & Arabi, 2020; Xu et al., 2020). Similarly, the effects of agricultural conservation practices (Hirt, Veith, Collick, Yetter, & Brooks, 2020) and stream restoration strategies (Lammers, Dell, & Bledsoe, 2020) on nutrient loads are investigated.…”