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

Abstract

Population densities and freshwater resources are not evenly distributed worldwide. This has forced farmers to use wastewater for the irrigation of food crops. This practice presents both positive and negative effects with respect to agricultural use, as well as in the context of environmental contamination and toxicology. Although wastewater is an important source of essential nutrients for plants, many environmental, sanitary, and health risks are also associated with the use of wastewater for crop irrigation due to the presence of toxic contaminants and microbes. This review highlights the harmful and beneficial impacts of wastewater irrigation on the physical, biological, and chemical properties of soil (pH, cations and anions, organic matter, microbial activity). We delineate the potentially toxic element (PTEs) build up in the soil and, as such, their transfer into plants and humans. The possible human health risks associated with the use of untreated wastewater for crop irrigation are also predicted and discussed. We compare the current condition of wastewater reuse in agriculture and the associated environmental and health issues between developing and developed countries. In addition, some integrated sustainable solutions and future perspectives are also proposed, keeping in view the regional and global context, as well as the grounded reality of wastewater use for crop production, sanitary and planning issues, remedial techniques, awareness among civil society, and the role of the government and the relevant stakeholders.

Treatment of Post-Hydrothermal Liquefaction Wastewater (PHWW) for Heavy Metals, Nutrients, and Indicator Pathogens

“…Therefore, previous studies have examined the use and treatment of wastewater for crop irrigation [2,3]. However, the health and safety of such practices have garnered concern; metals, pathogens, and medical drugs have been reported in using conventionally treated wastewater [4,5]. This study examines a wastewater treatment that has potential to supply nutrients for crop growth under hydroponic conditions: post-hydrothermal liquefaction wastewater (PHWW).…”

Spatiotemporal Variation and Pollution Assessment of Pb/Zn from Smelting Activities in China

“…The method was proposed by Hakanson in 1980 [31], and the results can reflect the potential ecological risk degree of heavy metals in the soil to the environment. The calculation formula is Equation (5).…”

“…The rapid development of industrialization resulted in many environmental problems; soil heavy metal pollution has especially caused worldwide concern due to their persistence, toxicity, and harmful effects on plants and human health [1][2][3][4][5][6]. Nonferrous metal smelting is an important source of heavy metals in soil [7][8][9][10].…”

Salmonella grows massively and aerobically in fecal matter

“…Environmental transmission of intestinal pathogens is extremely important especially in Lowand Middle-Income Countries (LMICs) due to deficient sanitary infrastructure, unplanned urban growth, lack of wastewater treatment, etc. One of the main concerns in LMICs is the large proportion of untreated wastewater used for irrigation (Khalid et al, 2018) and the increasing use of animal manure as fertilizer without suitable treatment (Mandrell, 2009); these are problems that remain neglected in LMICs (Khalid et al, 2018). Reports of grave enteric infections caused by environmental contamination of produce are also commonplace nowadays in industrialized countries (Callejón et al, 2015).…”

“…The use of animal waste as fertilizer constitutes a serious risk which can be controlled by appropriate composting technology (Tiquia et al, 1998;Szogi et al, 2015). Human waste contamination, however, is much more difficult to monitor or control in LMICs where wastewater treatment or toilets are not available (Khalid et al, 2018); the fate of Salmonella in these conditions is not understood completely, although some researchers indicate that Salmonella enters into a viable-non culturable state outside the host (Winfield and Groisman, 2003). The reduction of the risk of this type of transmission requires the understanding of every aspect of Salmonella physiology in the environment outside the host (Mandrell, 2009).…”