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Decentralized Water Reuse Can Help Preserve Sources of Fresh Water

Crop growers can reduce the water footprint of their operations by implementing many water-saving measures, including better irrigation techniques and decentralized water reuse.

As the world population grows, so does the demand for food and the need to grow more crops. In many regions of the world, water has become a scarce resource, with supplies affected by climatic changes. Not only does water scarcity limit farmers’ ability to irrigate their crops, but overdrawing groundwater supplies for irrigation contributes to water scarcity.

Improving Crop Irrigation Techniques

By improving their irrigation strategies and techniques, crop growers can reduce their water footprint with limited additional cost. In a study published in July 2017 by Hydrology and Earth System Sciences, researchers shared the results of the methods they developed to reduce agricultural water footprint by using a combination of irrigation strategies, irrigation techniques, and mulching practices. The article was called “Marginal Cost Curves for Water Footprint Reduction in Irrigated Agriculture: Guiding a Cost-Effective Reduction of Crop Water Consumption to a Permit or Benchmark Level.” Among the researchers’ conclusions were that:

  • Moving from a full to deficit irrigation strategy reduces water consumption (and therefore the water footprint) while having negligible effects on yield production.
  • The use of organic mulching can significantly reduce the water footprint at a relatively low cost.
  • Switching from sprinkler or furrow irrigation to drip or subsurface drip irrigation will reduce the water footprint, but at a significant cost.

Water Reuse and Other Alternative Sources

In regions where freshwater resources are scarce or limited, such as in urban and suburban areas, improvement in irrigation techniques may not be able to provide the water needed to grow enough to feed the local population.

One way to decrease freshwater acquisition is to seek alternative sources of water, such as recycled water, brackish water, or saline water. The Food and Agriculture Organization of the United Nations (FAO) believes that, instead of treating it like garbage, communities should consider wastewater a valuable resource for crop production.

Because the agriculture industry already uses 70% of global sources of fresh water — and its water use will increase with population growth — communities must develop sustainable solutions for their crop irrigation needs. Since many regions grow different crops and use different systems, no one solution will be the answer for all, but every solution should include the reuse of water. Water reuse and other solutions such as desalination can all reduce the agriculture industry’s dependence on fresh water.

The reuse of wastewater has the greatest potential for success near cities, where the supply is high. Activated sludge treatment has long been used in aerobic wastewater treatment, but its aeration stage is particularly energy-intensive, which makes it less cost-efficient as a step in decentralized water reuse.

Fluence’s innovative membrane aerated biofilm reactor (MABR) integrates a natural nitrification-denitrification process and passive aeration, which uses up to 90% less power than conventional aeration technologies. MABR can treat sewage and other wastewater for crop irrigation, reducing pressure on freshwater resources.

Because of its low energy requirements, MABR is particularly suited for decentralized treatment, that is, away from municipal infrastructure networks. For example, MABR has been successfully employed in a small farming community in Israel’s Jezreel Valley. With MABR on-site, high-nutrient effluent is converted to water suitable for irrigation.

For remote areas located near a source of either brackish water or seawater, desalination with Fluence’s NIROBOX™ is a cost-effective and low-footprint solution. Nirobox units are easy to configure for small or large-scale water treatment projects, providing desalination of seawater or brackish water for irrigation purposes.

Because industrial agriculture heavily relies on finite water resources, it has the responsibility to seek alternative methods of irrigation to reduce its water footprint. While irrigation strategies and techniques can help reduce water footprints without much added cost, water reuse will be the most responsible and effective solution to sustain farming needs in the long-term.