The use of urban wastewater in agriculture is receiving renewed attention, with the increasing scarcity of fresh water resources in many arid and semi-arid regions of the world. Wastewater is a low-cost alternative to conventional irrigation water, although it may carry health and environmental risks. This book critically reviews experience worldwide of these issues. Emphasis is placed on untreated wastewater use by means of field-based case studies from Asia, Africa, the Middle East and Latin America. It brings together a range of perspectives including economic, health, agronomic, environmental, institutional, and policy dimensions.

This book offers a broad and global level description of the current status of wastewater use in agriculture and then brings the readers to various places in the MENA Region and Europe to explain how some countries and regions have addressed the challenges during implementation. On a global scale, over 20 million hectares of agricultural land are irrigated using wastewater. This is one good, and perhaps the most prominent, example of the safe use potential of wastewater. Water scarcity and the cost of energy and fertilisers are among the main factors driving millions of farmers and other entrepreneurs to make use of wastewater. In order to address the technical, institutional, and policy challenges of safe water reuse, developing countries and countries in transition need clear institutional arrangements and more skilled human resources, with a sound understanding of the opportunities and potential risks of wastewater use. Stakeholders in wastewater irrigation who need to implement from scratch or improve current conditions, find it difficult to gather the necessary information on practical implementation aspects. The main objective of this book is to bridge that gap.

As the world's population increases and the demand for water increases apace there is a rising demand for information concerning the reuse of wastewater, particularly for the irrigation of key food crops worldwide. This important new book addresses in detail the use of treated wastewater in agricultural situations, its impact on crops and the soil environment. Coverage includes the composition and treatment of wastewater, health considerations, regulations and economic aspects. Major sections of the book also concentrate on crop management and the soil environment. This book is an essential purchase for all those working in irrigation, water management and crop production worldwide. Use of Treated Wastewater (TWW) for irrigation is increasingly important as the world's population increases Chapters prepared by leading scientists in the field Comprehensive coverage of current knowledge and advances in the area of TWW Focus on possible environmental impacts (positive and negative)

This book provides a unique synthesis of concepts and tools to examine natural resource, socio-economic, legal, policy and institutional issues that are important for managing urban growth into the future. The book will particularly help the reader to understand the current issues and challenges and develop strategies and practices to cope with future pressures of urbanisation and peri-urban land, water and energy use challenges. In particular, the book will help the reader to discover underlying principles for the planning of future cities and peri-urban regions in relation to: (i) Balanced urban development policies and institutions for future cities; (ii) Understanding the effects of land use change, population increase, and water demand on the liveability of cities; (iii) Long-term planning needs and transdisciplinary approaches to ensure the secured future for generations ahead; and (iv) Strategies to adapt the cities and land, water and energy uses for viable and liveable cities. There are growing concerns about water, food security and sustainability with increased urbanisation worldwide. For cities to be liveable and sustainable into the future there is a need to maintain the natural resource base and the ecosystem services in the peri-urban areas surrounding cities. This need is increasing under the looming spectre of global warming and climate change. This book will be of interest to policy makers, urban planners, researchers, post-graduate students in urban planning, environmental and water resources management, and managers in municipal councils.

The objective of this paper is to provide a review of the characteristics of wastewater used for irrigation, and the reasoning behind the international guidelines presently used in regulating wastewater reuse for agriculture. This paper presents various systems of wastewater treatment available and discusses their benefits and shortcomings. A selective review of recent empirical studies identifies major impacts both positive and negative impacts of wastewater irrigation. Finally, the paper provides the review of environmental valuation techniques for analyzing impacts of wastewater uses in agriculture, and suggest a framework for application of some of these techniques. This framework will be applied to a developing country case study (Faisalabad area in Pakistan), in the ongoing IWMI research program.

The reuse of wastewater in irrigation is being practiced only recently to solve water scarcity problems in agriculture. Management of water, soil, crop, and operational procedures, including precautions to protect farm workers, play an important role in the successful use of sewage effluent for irrigation. Appropriate water management practices mus

Safe, equitable water reuse is a fundamental component of resilient water systems both in the western United States and around the world. As the dominant water user, agricultural water use is central to this discussion. Urban water infrastructure sits at the interface between health risk mitigation and the quantity and quality of water received by downstream agricultural water users. For the vast majority of the world, wastewater receives little to no treatment before being discharged to surface waters, often resulting in irrigation water quality that is far lower than the standards set for direct reuse schemes. Even when wastewater is treated, urban wastewater return flows can constitute a significant portion of the water available in a given region. In both instances, there is a great need for improved knowledge on both the extent of these practices and the efficacy of different risk mitigation strategies. The first portion of this dissertation addresses this knowledge gap through the development of a spatially explicit, global assessment of the extent and characteristics of wastewater use in irrigated agriculture. GIS-based models incorporating global data on irrigated croplands, hydrography, urban extents and populations, water and sanitation coverage, water availability, and terrain were used to develop these estimates. The first component of this analysis quantified the global extent of urban and peri-urban croplands, finding that 130 Mha or 60 percent of all irrigated croplands are located within 20 km of urban extents. Thirty-five percent of these croplands are irrigated compared to 17.7 percent of non-urban croplands. Cropping intensity in these urban croplands was also 32 percent higher than non-urban croplands, alluding to the potential economic significance of these croplands. The degree of health risks posed via the indirect or de facto reuse of wastewater depends on concentrations of pathogens in the irrigation water. However, global water quality monitoring data is scant and current water quality models are both coarse and uncertain. Given these considerations, this analysis instead opted to use wastewater return flows and levels of wastewater treatment as proxies for wastewater dependence and irrigation water quality. This analysis found that nearly 26 percent (35.9 Mha) of irrigated croplands are located in a catchment where wastewater return flows constitute more than twenty percent of available water. Of these wastewater dependent irrigated croplands, 29.3 Mha are located in countries where less than 75 percent of wastewater receives some form of treatment. These same catchments are home to some 1.37 billion urban residents. These figures provide some of the first global-scale estimates of the magnitude of the role wastewater reuse plays in meeting the water and food needs of people around the world and will hopefully contribute to the on-going discussion on resource recovery and reuse and the scale-up of wastewater treatment in rapidly urbanizing cities. While understanding the scale of agricultural water reuse is important in the guidance of planning decisions, the health risks associated with this practice are realized on farms and in markets and households. The second component of this dissertation focuses on a case study in Dharwad, India to better understand the relationship between irrigation water quality, food and farmer safety. This study interviewed 29 vegetable growers and collected 330 water, soil, and produce samples from their farms and local markets. These samples were analyzed for both culturable E. coli and five diarrheagenic E. coli pathotype gene targets. Selected farms were divided roughly evenly amongst those using wastewater versus those using borewell water. Culturable E. coli were detected in all sample types except borewell water. This suggests the presence of additional sources of contamination beyond irrigation water source on farms. At least one pathotype gene target was detected in all sample types from farms irrigating with wastewater, but only on produce samples from farms using borewell water for irrigation. Greens were the most contaminated class of crops on both types of farms. Enterotoxigenic and enteropathogenic E. coli were the two most common strains of diarrheagenic E. coli detected. Concentrations of culturable E. coli showed a strong positive association with the detection of ETEC and the count of pathotype gene targets detected in water, soil, and greens samples, suggesting that, in this context, E. coli was a good indicator of the presence of at least some pathotypes of diarrheagenic E. coli. These findings provide new insights into how exposure to diarrheagenic E. coli varies on farms and forms the basis of future risk assessment modeling work. These findings also allude to a need for further characterization of concentrations of actual pathogens, particularly on different types of produce, and the role of non-irrigation related sources of contamination on farms such as inadequate sanitation facilities, livestock, and wildlife. Access to wastewater for irrigation makes important contributions to global crop production, but can introduce exposure to health risks when levels of treatment are low. This dissertation provides initial insights into the scale of agricultural water reuse and explores the heterogeneity of exposure that occurs on farms and in markets. As the Sustainable Development Goals emphasize, safe disposal, treatment, and reuse are all important components of complete access to sanitation. This dissertation examines the scale and diversity of ways in which agricultural water reuse is practiced. Planning practices incorporating the vast existing indirect reuse of wastewater are an important component of safe, equitable management of scarce water resources and complete sanitation.