Challenges and opportunities for using wastewater in agriculture: a review

Use of wastewater for irrigating the agricultural land is becoming a common and a widespread practice throughout the world, particularly in arid and semiarid regions where freshwater resources are insufficient to meet water demand. According to estimates, 20 million hectares area on global scale is being irrigated with treated, partially treated and untreated wastewater, contributing to food security. Increasing water scarcity, industrialization, urbanization, increasing urban wastewater flows due to expanded water supply and sewerage services, nutrient value, consistency and reliability in supply are the key drivers for the widespread use of wastewater for irrigation. These drivers are expected to become even more powerful in the near future, making wastewater use in agriculture an emerging priority. Wastewater consists of mainly municipal wastewater, industrial effluents and storm water runoff. Wastewater is a potential resource for overcoming water shortage, and has both opportunities and challenges associated with its use. Wastewater can have multifaceted uses including urban and industrial uses, artificial groundwater recharge, crop land and landscape irrigation, aquaculture, and recreational and environmental uses. However, use of wastewater can involve potential risks such as harmful influences on plant growth, soil health and environment. It is also supposed to be the carrier of certain toxic substances including salts, heavy metals, pesticide residues, poisonous gases and a wide spectrum of enteric pathogens which have deleterious effects on crops, soil, air, groundwater, and eventually on human beings. Social concerns about using the produce of crops grown with wastewaters and subsequent influence on market value of these crops are also the main areas of thorough investigation. The present paper reviews the current literature on wastewater with focuses being made on its potential benefits and hazards on plant growth and soil health.