Sustainable wastewater reuse for agriculture

Nature Portfolio (Springer Nature) | June 6th, 2024

The frontiers of water and sanitation

Nature Portfolio (Springer Nature) | January 19th, 2023

The way in which human society uses water is continuously evolving. The present challenges related to clean water availability require the development of sustainable tech

The way in which human society uses water is continuously evolving. The present challenges related to clean water availability require the development of sustainable technologies and infrastructure. Furthermore, a stronger and wider appreciation of water inequalities and injustice demand an adequate transformation of water governance at local and global scale. We have asked nine experts in various sectors of water-related research to share their views on how water and sanitation science, technology and governance must evolve to meet the requirements of a healthier relationship between water and society.

The implications of drought and water conservation on the reuse of municipal wastewater: Recognizing impacts and identifying mitigation possibilities

Water Research, Elsevier | November 1st, 2017

As water agencies continue to investigate opportunities to increase resilience and local water supply reliability in the face of drought and rising water scarcity, wa

As water agencies continue to investigate opportunities to increase resilience and local water supply reliability in the face of drought and rising water scarcity, water conservation strategies and the reuse of treated municipal wastewater are garnering significant attention and adoption. Yet a simple water balance thought experiment illustrates that drought, and the conservation strategies that are often enacted in response to it, both likely limit the role reuse may play in improving local water supply reliability. For instance, as a particular drought progresses and agencies enact water conservation measures to cope with drought, influent flows likely decrease while influent pollution concentrations increase, particularly salinity, which adversely affects wastewater treatment plant (WWTP) costs and effluent quality and flow. Consequently, downstream uses of this effluent, whether to maintain streamflow and quality, groundwater recharge, or irrigationmay be impacted. This is unfortunate since reuse is often heralded as a drought-proof mechanism to increase resilience. The objectives of this paper are two-fold. First, we illustrate—using a case study from Southern California during its most recent drought— how drought and water conservation strategies combine to reduce influent flow and quality and, subsequently, effluent flow and quality. Second, we use a recently developed regional water reuse decision support model (RWRM) to highlight cost-effective strategies that can be implemented to mitigate the impacts of drought on effluent water quality. While the solutions we identify cannot increase the flow of influent or effluent coming into or out of a treatment plant, they can improve the value of the remaining effluent in a cost-effective manner that takes into account the characteristics of its demand, whether it be for landscaping, golf courses, agricultural irrigation, or surface water augmentation.

The Pulse of the Bay 2019: Pollutant Pathways

San Francisco Estuary Institute (SFEI) | September 26th, 2019

Pollutants make their way to San Francisco Bay from near and far. Some pollutants come from the other side of the world, such as the mercury that is emitted into the atmo

Pollutants make their way to San Francisco Bay from near and far. Some pollutants come from the other side of the world, such as the mercury that is emitted into the atmosphere by coal-fired power plants in Asia, transported across the Pacific Ocean by the wind, and deposited on the surface of the Bay and in the Bay watershed. Some pollutants come from the far corners of the Bay’s watershed, which encompasses 40% of the land surface of California. Mercury used in historic gold mining regions in the Sierra Nevada is still flowing downstream into Central Valley rivers, through the Delta, and into the Bay.  Most pollutants, however, originate from activities closer to home in the small, local watersheds that surround the Bay. Rain that falls onto yards, roofs, parking lots, streets, farms, pastures, and other surfaces in the watersheds picks up pollutants and carries them to the Bay through an intricate network of thousands of miles of storm drain pipes, culverts, and creeks. Most of this stormwater flows to the Bay without any form of pollutant removal.  Another parallel and intricate network of thousands of miles of pipes carries wastewater from homes, business, and industries through sewage collection systems to municipal wastewater treatment plants. These treatment plants are highly effective at removing most pollutants from the wastewater stream, but some are not effectively treated and pass through to the Bay.  Some industrial operations, such as the Bay Area’s petroleum refineries, are large enough to warrant having their own wastewater treatment facilities that remove pollutants so the effluent can be safely discharged into the Bay, reused in plant operations, or applied to land.  Disposal of dredged material at designated sites within the Bay is another activity that introduces pollutants to specific areas in the Bay, but in this case the pollutants are simply transferred from one part of the Bay to another. Much of the pollutant mass in dredged material is also removed from the Bay via disposal in the ocean or beneficial reuse in wetlands and upland sites. This edition of the Pulse of the Bay features articles on the four major pollutant pathways that are the primary focus of Bay water quality managers: municipal wastewater, industrial wastewater, stormwater, and dredging and dredged material disposal.

Treated Wastewater as a Multi-Benefit Groundwater Sustainability Project

Nature Conservancy | January 1st, 2019

The Arroyo Las Posas, a creek in Ventura County, is a good example of a stream supported by flows from a wastewater treatment plant (WWTP). These flows are a s

The Arroyo Las Posas, a creek in Ventura County, is a good example of a stream supported by flows from a wastewater treatment plant (WWTP). These flows are a significant factor in the basin’s water balance and support important GDEs. How this treated water is used in the future may therefore play a significant role in planning for the basin’s groundwater sustainability.

Unintended consequences of water conservation on the use of treated municipal wastewater

Nature Portfolio (Springer Nature) | May 11th, 2020

Municipal water managers are intensifying efforts to reduce urban water use and increase the reliability of local water supplies to combat rising water scarcity and droug

Municipal water managers are intensifying efforts to reduce urban water use and increase the reliability of local water supplies to combat rising water scarcity and drought. Incentivizing increases in water-use efficiency and mandating conservation are two strategies to rein in demand. Concurrently, local water supplies are being augmented through investments in reclaiming and treating municipal wastewater. Although reducing urban water consumption is necessary to deal with population growth and a more variable climate, it does come at a cost. In particular, cutting back on indoor water consumption impacts the generation and quality of wastewater, which can have widespread and underappreciated consequences on human society and the environment. Here, to quantify these impacts, we tracked monthly effluent flow, salinity levels and the properties of 34 wastewater treatment plants throughout Southern California from 2013 to 2017—a period that included extreme drought and abundant precipitation. Our analysis demonstrates that conservation measures significantly reduced effluent flow and increased effluent salinity (P value ≤ 0.05). Our findings further highlight the need for policymakers to recognize the interdependencies and complexities within a water system.

Urban Water Systems—A Conceptual Framework

I.B. Tauris (Bloomsbury) | December 1st, 2014

We will here show how a focus on water/urban relationships can further our knowledge of city developments, and how urban studies can deepen our understanding of the rol

We will here show how a focus on water/urban relationships can further our knowledge of city developments, and how urban studies can deepen our understanding of the role of water in societies. The basic premises for this proposal are two facts of huge importance for understanding the history and development of the city; the universal needs of water and the actual, physical waterscape at a given place. All urban dwellers1—from the first few people who settled around a natural spring in a desert in Jericho and built a wall around it almost 10,000 years ago, to the Incas living in the royal city Machu Picchu on a mountain top in the Andes, to stock traders relaxing in spacious apartments in a skyscraper on Manhattan, and to the party officials assembled for one of their meetings in a grand conference hall in Beijing—share the need for one resource: water. The theoretical and empirical importance of this state of affairs can hardly be overestimated: these people all need water to survive, and as long as they live in cities, it has to be provided in one way or another. Water is the only universal urban resource that in this sense is a must and that can be controlled in this strict understanding of the word.

Wastewater Infrastructure: Overview, Funding, and Legislative Developments

Congressional Research Service (CRS) | September 22nd, 2017

The collection and treatment of wastewater remains among the most important public health interventions in human history and has contributed to a significant decrease in

The collection and treatment of wastewater remains among the most important public health interventions in human history and has contributed to a significant decrease in waterborne diseases during the past century. Nevertheless, waste discharges from municipal sewage treatment plants into rivers and streams, lakes, and estuaries and coastal waters remain a significant source of water quality problems throughout the country. The Clean Water Act (CWA) establishes performance levels to be attained by municipal sewage treatment plants in order to prevent the discharge of harmful wastes into surface waters. The act also provides financial assistance so that communities can construct treatment facilities and related equipment to comply with the law. Although approximately $95 billion in CWA assistance has been provided since 1972, funding needs for wastewater infrastructure remain high. According to the most recent estimate by the Environmental Protection Agency and the states, the nation’s wastewater treatment facilities will need $271 billion over the next 20 years to meet the CWA’s water quality objectives. Meeting the nation’s wastewater infrastructure needs efficiently and effectively is likely to remain an issue of considerable interest to policymakers. The CWA authorizes the principal federal program to support wastewater treatment plant construction and related eligible activities. Congress established the CWA Title II construction grants program in 1972, significantly enhancing what had previously been a modest grant program. Federal funds were provided through annual appropriations under a state-by-state allocation formula contained in the act. States used their allotments to make grants to cities to build or upgrade categories of wastewater treatment projects including treatment plants, related interceptor sewers, correction of infiltration/inflow of sewer lines, and sewer rehabilitation. In 1987, Congress amended the CWA and created the State Water Pollution Control Revolving Fund (SRF) program. This program represented a major shift in how the nation finances wastewater treatment needs. In contrast to the Title II construction grants program, which provided grants directly to localities, SRFs are loan programs. States use their SRFs to provide several types of loan assistance to communities, including project construction loans made at or below market interest rates, refinancing of local debt obligations, providing loan guarantees, and purchasing insurance. In 2014, Congress revised the SRF program by providing additional loan subsidies (including forgiveness of principal and negative interest loans) in certain instances. The law identifies a number of types of projects as eligible for SRF assistance, including wastewater treatment plant construction, stormwater treatment and management, energy-efficiency improvements at treatment works, reuse and recycling of wastewater or stormwater, and security improvements at treatment works. In both FY2016 and FY2017, Congress provided $1.394 billion for the clean water SRF program. President Trump’s FY2018 budget proposal requests the same amount as provided for the previous two fiscal years. Although appropriation levels have remained consistent in recent years (in nominal dollars), policymakers have continued to propose changes to the funding program. Issues debated in connection with these proposals include extending SRF assistance to help states and cities meet the estimated funding needs, modifying the program to assist small and economically disadvantaged communities, and enhancing the SRF program to address a number of water quality priorities beyond traditional treatment plant construction—particularly the management of wet weather pollutant runoff from numerous sources, which is the leading cause of stream and lake impairment nationally.

Wastewater Reuse for Agriculture: Development of a Regional Water Reuse Decision-Support Model (RWRM) for Cost-Effective Irrigation Sources

American Chemical Society (ACS) | August 8th, 2016

Water scarcity has become a critical problem in many semiarid and arid regions. The single largest water use in such regions is for crop irrigation, which typically relie

Water scarcity has become a critical problem in many semiarid and arid regions. The single largest water use in such regions is for crop irrigation, which typically relies on groundwater and surface water sources. With increasing stress on these traditional water sources, it is important to consider alternative irrigation sources for areas with limited freshwater resources. One potential irrigation water resource is treated wastewater for agricultural fields located near urban centers. In addition, treated wastewater can contribute an appreciable amount of necessary nutrients for plants. The suitability of reclaimed water for specific applications depends on water quality and usage requirements. The main factors that determine the suitability of recycled water for agricultural irrigation are salinity, heavy metals, and pathogens, which cause adverse effects on human, plants, and soils. In this paper, we develop a regional water reuse decision-support model (RWRM) using the general algebraic modeling system to analyze the cost-effectiveness of alternative treatment trains to generate irrigation water from reclaimed wastewater, with the irrigation water designed to meet crop requirements as well as California’s wastewater reuse regulations (Title 22). Using a cost-minimization framework, least-cost solutions consisting of treatment processes and their intensities (blending ratios) are identified to produce alternative irrigation sources for citrus and turfgrass. Our analysis illustrates the benefits of employing an optimization framework and flexible treatment design to identify cost-effective blending opportunities that may produce high-quality irrigation water for a wide range of end uses.

Wastewater surveillance for public health

American Association for the Advancement of Science (AAAS) | January 5th, 2023