Characterizing manufacturing wastewater in the United States for the purpose of analyzing energy requirements for reuse

Abstract

This paper seeks to inform an improved understanding of the energy tradeoff associated with on-site manufacturing water reuse in the U.S. from a lifecycle perspective, in part by developing an analytical framework for understanding when this tradeoff for reuse is beneficial. We survey the literature to assess the current state of reuse and its motives and barriers in the U.S., before synthesizing information from publicly available EPA data on contaminants in U.S. manufacturing wastewaters and technologies for treating them. Using the available data, we derive a set of "ubiquitous contaminants" among the top ten in terms of mass discharged in more than half of U.S. manufacturing subsectors (NAICS 31-33) according to EPA permit data. We also present information on proven treatment trains and their energy requirements. We then compare water quality requirements for specific contaminants in reclaimed water to those characteristic of wastewater streams currently being discharged from manufacturing plants into surface waters to highlight sectors with reuse opportunities that could require little cost to realize, such as primary metals and, to a lesser extent, petroleum and coal products. We conclude by highlighting data limitations that need to be rectified before applying the framework more broadly and discussing how these data gaps could be filled. Better understanding the relationship between energy and water in the context of on-site manufacturing water reuse would allow manufacturers to improve resiliency by reducing regulatory, physical, and reputational risks while lessening their footprint on local watersheds.

Survey of Available Information on U.S. Manufacturing Wastewater and Energy Requirements for Reuse

“…Finally, note that this report complements a recently published journal article by the same authors (Fuchs and Rao 2021); this longer report can be viewed as a supplement to that work. In the interest of providing sufficient context to understand the information contained in this report, it is necessary to include some figures, equations, and text from the journal article here.…”

Opportunities and Challenges for Industrial Water Treatment and Reuse

“…In a recent characterization of manufacturing wastewater in the U.S., Fuchs and Rao found that some contaminants in the chemical industry wastewater are already being treated to sufficient levels for reuse. 162 Wastewater treatment in the chemical industry generally follows a three-stage process. The primary treatment stage is mostly mechanical, aimed at the separation of suspended solids, and often includes American Petroleum Institute (API) oily water separators, corrugated plate interceptors (CPI), sour water strippers, or buffer tanks.…”

National Alliance for Water Innovation (NAWI) Industrial Sector Technology Roadmap 2021

“…The primary sources of water for industry are withdrawn from surface or ground water; other sources include municipal water and or treatment effluent (secondary or tertiary), followed by seawater. 28,29 This is largely driven by cost and generalized water quality requirements that surface waters often meet and include: chloride concentration limitations temperature (generally less than 75-85 degrees F) neutral pH (6.8-7.0) low hardness (<50 mg/L), low suspended matter (<25 mg/L), and low organic matter content low dissolved metals 30 Costs of water withdrawals are generally limited to infrastructure, pretreatment, and permitting and management costs, since in many cases there is currently no direct purchase price for the water. Municipal water usually is the first alternative source…”

“…Moreover, in numerous industries, wastewater effluent being discharged is already of high enough quality for on-site reuse. 30 In current practice, seawater is generally a last resort as a source for many industrial non-cooling applications because it requires a higher investment in treatment technology (desalination in particular) and access is geographically limited due to infrastructure and transportation costs required to convey seawater inland any considerable distance.…”