Wastewater irrigation: past, present, and future

Abstract

With population growth and social and economic development, water shortage is becoming a serious issue worldwide. As a key alternative water resource, wastewater can be used in agriculture to compensate for water shortages. Wastewater irrigation has a long development history and has undergone different phases in developing and developed countries. Untreated wastewater irrigation can come with numerous environmental problems. Strong management practices, such as the application of suitable treated and irrigated technologies, can be used to reap substantial benefits while minimizing risks. We discussed the major challenges associated with wastewater irrigation and its future use to help improve wastewater irrigation practices around the world. PROLOGUEW astewater can partly make up for shortages in water supplies and demand caused by the growing global population. The urban population accounted for 54% of the global population in 2014, and annual water use for the domestic sector is estimated to represent 11% globally. 1 More than 100 countries are facing water shortage of varying severity. 2 Roughly two thirds of the global population is projected to be suffering from moderate to high water stress by 2025. 3 Furthermore, roughly 40% of the global population is situated in heavily water stressed basins 4 that are experiencing agricultural failure due to a lack of water for irrigation. At the same time, a large volume of domestic and industrial wastewater is disposed of and has placed great pressures on the environment. Global wastewater discharge reaches 400 billion m 3 /year, polluting~5500 billion m 3 of water of per year. Due to its high quantities and nutritional properties (nitrogen and phosphorous), wastewater is used as a key water resource for irrigation and especially in arid and semiarid regions. 5 Wastewater can range from raw to diluted, can have various qualities, and is disposed of through various urban outlets (e.g., urban wastewater, treated wastewater, and reclaimed or recycled water) 6 ( Figure 1). Treated or untreated wastewater can be used directly for irrigation and treated urban wastewater can be used indirectly. 7 Wastewater is a reliable and stable source of water that can save fertilizer costs. Unlike clean water, wastewater flows do not vary with seasons, climatic conditions, or precipitation levels, thus allowing farmers to grow crops throughout the year. Moreover, wastewater contains nutrients that can boost crop growth and reduce chemical fertilizer use. Compared with clean water irrigation, wastewater use can save up to 45% of fertilizer applied for wheat while the ratio can reach 94% for alfalfa. 11 Meanwhile, wastewater irrigation poses risks to human health and the environment. The presence of parasitic worms and enriched heavy metals in food can likely spread diseases. 12 Wastewater irrigation can also lead to soil hardening, heavy metals enrichment, and shallow groundwater pollution 13,14 if used directly without pretreatment.While wastewater irrigation is essential, associated r...

A Review of Environmental Contamination and Health Risk Assessment of Wastewater Use for Crop Irrigation with a Focus on Low and High-Income Countries

“…In the areas where fresh water is in short supply, wastewater is frequently used for crop irrigation. Although not legally permitted in most countries, the use of untreated wastewater for crop irrigation has been practiced in many countries worldwide due to the shortage of good quality water [ 2 , 3 , 4 ].…”

“…Wastewater usage for crop irrigation has certain advantages such as providing the essential nutrients and organic matter, saving water and nutrients, and reducing water contamination [ 2 , 10 ]. It has been reported that quite sufficient quantities of macronutrients (N, P, and K) are supplied to soil and plants via wastewater application [ 10 ].…”

Advances in Utilization of Wastewater in Agricultural Practice: A Technical Note

“…The reuse of recycled water in water systems of agrarian fields is greatly encouraged in China, because of its immense population and the developing requirement for water for human needs. Thus, the administration introduced an upgraded coordinated arrangement through the integrated services of construction, agriculture and health ministries for wastewater water system design, and started to build up wastewater water system regions (Zhen et al, 2017). Rice is being grown with use of treated wastewater in Vietnam (Do et al, 2007).…”

Melatonin: Role in Increasing Plant Tolerance in Abiotic Stress Conditions

“…Water scarcity has been becoming a major problem worldwide due to population growth and social and economic development. A number of countries faced to water shortage is more than 100, and approximately two thirds of the world population will be exposed to be suffering from moderate to high water stress by 2025 [53]. Increasing domestic and industrial water demand and pollution of water threatens the water used in agriculture.…”