- While use of treated effluents and industrial wastewater in agriculture could conserve water, it can also pose the risk of harming soil quality and human health.
- The Central Pollution Control Board (CPCB) has hence come out with guidelines for the safe use of effluents in irrigation.
- The agriculture sector consumes a majority share of available groundwater, estimates government data.
Using treated wastewater for irrigation, while a practical way to conserve water, could negatively impact soil quality and further, human health. Given the risks, the Central Pollution Control Board (CPCB) has issued guidelines for the safe usage of treated sewage and effluents from industries in agriculture.
Risks of using industrial wastewater for agricultural irrigation involve changes to physicochemical and microbiological properties of soils that impact crop growth and water retention capacity of the soil, which in turn could be harmful to health.
The CPCB guidelines are a result of directions of the National Green Tribunal (NGT) which in May 2019, while hearing a case, held that “no industry can be permitted to dispose treated effluents on land for irrigation, plantation or horticulture/gardening by prescribing standards applicable without assessment of adequate availability of land and impacts of such disposal on agricultural/crops /plants and the recipient groundwater.”
The NGT order elaborated that while granting approvals for using industrial waste water in irrigation, the impact of precipitation levels needs consideration and Zero Liquid Discharge (where an industry entirely recycles effluent instead of discharging it) needs to be considered with respect to use of effluents in the industrial processes, not in terms of its disposal on land or farm. “Therefore, the CPCB needs to look into this aspect with the help of experts and issue appropriate guidelines in this regard,” NGT had noted.
Following that, the CPCB, which is India’s top pollution watchdog, constituted an expert group that included members from the Indian Institute of Technology (IIT), Delhi, National Environmental Engineering Research Institute (NEERI), Delhi and CPCB to formulate such guidelines.
So far, there have been no national-level guidelines for safe usage of wastewater from industries for irrigation.
The use of treated effluents and sewage for irrigation can be significant in the light of overexploitation of groundwater and shortage of water across the country. According to the official data, of the total available 253 billion cubic meters (BCM) of groundwater in India, domestic and industrial uses account for 24.76 BCM (9.8 percent) while water for agriculture (irrigation) alone consumes 228.3 BCM (about 90 percent).
The data also reveals that of the total of 6,584 units (blocks/mandals/talukas) across India assessed for groundwater levels, 1,968 – around 30 percent – are overexploited, critical and semi-critical.
Engage scientists to ensure the safe use of effluents in agriculture
The pollution watchdog’s guidelines also stressed that the industry should engage an agricultural scientist or tie-up with an agricultural university or institute for advice on the utilisation or the rate of application of the effluent for irrigation, considering the agroclimatic conditions.
While the guidelines advocated the use of treated waste water from the industry for irrigation as a way to conserve water resources, given the irregular availability of water, it highlighted the risk of untreated or inadequately treated water. “It is necessary to ensure the beneficial aspects of this practice before application of treated wastewater in irrigation,” the guidelines cautioned.
Environmentalist Bharat Jhunjhunwala however, said he is not in favour of effluents from the industry being used for irrigation as one cannot monitor what industries will finally dispose off.
“This solution should only be restricted to municipal sewage and not extended to the industry as industrial effluents have heavy metals and harmful pollutants. Secondly, no matter what is proposed there is always the problem of ensuring proper implementation,” Jhunjhunwala told Mongabay-India.
He recounted an instance of Uttarakhand where the industry was giving treated effluents to farmers for irrigation. “It was working fine but after some time the industry stopped treating the effluents properly, resulting in farmers refusing to take them,” said Jhunjhunwala.
The guidelines also cautioned that the physicochemical characteristics of the soil under irrigation with treated effluent as well as the groundwater quality should be monitored twice a year, in summer and post-monsoon seasons. Thereafter, if the deterioration in the soil and groundwater quality is observed, the application of effluent should be stopped immediately and the industry should inform the state pollution control boards, warned the CPCB guidelines adding that
“The industry shall be solely responsible for reclaiming the soil and water quality at their cost in the affected area,” the guidelines said.
The guidelines also said that the industry should construct an impervious lined storage tank of minimum 15 days capacity for storage of treated effluent during low/no demand and that the treated effluent should be analysed regularly, say after every 15 days.
Use of treated wastewater for irrigation recommended by environment ministry too
It is not the first time that the suggestion for using treated industrial wastewater for irrigation purposes has been made.
Recently, an expert committee of the central government’s Ministry of Environment, Forest and Climate Change (MoEFCC) had suggested measures to curb the exploitation of groundwater including a tight regulation on the overuse of water in the agriculture sector.
One of the recommendations of the expert committee was that “use of treated sewage after secondary treatment shall be made mandatory for those areas near to urban centres and have close proximity to sewage treatment plants.”
The recent guidelines by CPCB stating that “as seasons and the sowing periods of the crops put restrictions on the utilisation of effluent for irrigation”, the industry should prepare a comprehensive Irrigation Management Plan (IMP), which should include details like areas to be covered under irrigation, written agreement with the farmers to bring their land under the scheme, the quantity of effluent to be used in different periods of the year and crop-wise, arrangement for low/no demand period and agronomic plan for effective utilisation of land.
The guidelines also held that the treated effluent should meet all the norms prescribed for irrigation under the Environment (Protection) Rules, 1986 but cleared that meeting the prescribed norms shall not be the only criteria for use of treated wastewater in irrigation.
It explained that the requirement of water for irrigation will also be a limiting condition and this depends upon various factors like crop, climate, irrigation type, soil condition, soil permeability and total salt concentration.
Banner image: (Representative image) Treated wastewater can fulfil the water requirement of the agriculture sector which uses 90 percent of India’s groundwater. Photo by Ghazi Al Jabri/Wikimedia Commons.