Water conservation in farming could be new engineering frontier
Former brewery is converted into an aquaponics facility that breeds both fish and plants
The nature of agriculture could dramatically change as water becomes scarce, making this a new frontier of innovation for consulting engineers.
Several radically new farming approaches are already bearing fruit in the U.S. involving new building types and water re-use systems.
At the 20th annual WateReuse Research Conference in Denver, Colorado on May 24, Dr. Phil Rolchigo, vice president of technology at Pentair, pointed out: “Seventy per cent of the world’s water is used for agriculture. As the world’s population continues to grow, the increased demand for food will put tremendous stress on the world’s supply of water for agriculture. Water reuse technologies can help accelerate Mother Nature’s process — rather than disposing wastewater back to the environment, we can safely capture and purify it so that it can be used over and over again in agriculture, as well as other industries.”
The organizers of the conference launched a new video that profiles two examples of water saving.
First, in St. Paul, Minnesota a former brewery has been converted into an aquaponics facility that houses fish and plants in a symbiotic relationship. The facility run by Urban Organics and Pentair has a closed-loop, recirculating aquaculture system where fish provide the nutrients for the plants, and the plants help to clean the water for the fish. The waste-filled water from the fish tanks is released through gravity and seeps into a filtration system. Once the sludge is removed the cleaned water filled with nitrates is pumped into rows of vegetables growing hydroponically. The plants remove the organic buildup and metabolic byproducts and the water is then returned to the fish tanks and reused. This controlled environment uses less than 2 per cent of the water conventional farming uses, and the produce grows year around and nearly twice as fast as it does in the field.
The second example in the video is in Monterey, California which has the largest agricultural reuse irrigation project in the U.S.. Artichokes, lettuce and strawberries are among the edible crops produced on some 12,000 acres of farmland which is irrigated by recycled water delivered by the Monterey Regional Water Pollution Control Agency (MRWPCA). Since the 1940s, heavy agriculture and municipal groundwater demands in Monterey’s Salinas Valley have led to the development of severe groundwater over-pumping, resulting in saltwater intrusion. By using recycled water, growers no longer have to pump groundwater from their wells for irrigation purposes.
Other companies are building indoor farms. AeroFarms of Newark, New Jersey, opened a 6,400-square metre warehouse this month. The largest indoor farm in the world, the facility can produce nearly 1 million kilograms per year of leafy greens and herbs.
The advantage of indoor farming is that the crops require no soil or pesticides, and they use 75 per cent less water than traditional farms. AeroFarms’ indoor facilities use LED lamps instead of sunlight and sensors to monitor the conditions such as humidity, oxygen levels and temperature. The company has nine indoor farms so far, and plans to open them on four continents in the next five years.