On a sunny Saturday in mid March, after months of heavy winter rains, young scientists gathered at CSUMB’s University Center for the 2017 Monterey County Science and Engineering Fair. Once again, plaques, medals, and cash awards were up for grabs, including the beautiful recycled glass trophy (and $100 cash prize) for this year’s winner of the Water For Our Future Award!
Three graduate students from Stanford’s Hopkins Marine Station* and CSUMB’s Watershed Institute* met me early in the morning to assist as judges. We set off into a sea of nearly 400 science posters and found 36 that met our criteria. They ranged from computerized shower alarms to fog collectors to hydroponics with or without recirculating pumps. By the afternoon we had a list of four finalists. After much discussion, we decided on two winners.
Congratulations to RIO LAUER and MIA DOSTAL for their winning projects on Greywater Recycling and Aquaponics!
Reusing Greywater to Reduce Usage and Dependency of the Carmel River
Rio Laur begins her Introduction with a fascinating statement: “Imagine if the Monterey Peninsula could reuse enough water [such] that there would be no need for a seawater desalination plant.”
Rio appreciates the value of greywater recycling. After learning that daily toilet flushing uses up to 40% of a household’s water budget, she decided to focus her project on ways to reduce that impact with greywater. She reasoned that if toilets could be flushed with greywater, not potable drinking water, then residents on the Monterey Peninsula could save significant amounts of water each year. In doing so, they would lessen their impact on the Carmel River watershed and reduce their need for seawater desalination.
Rio learned that greywater generated in homes could be acidic. As we learned from news stories out of Flint, Michigan last year, acidic water corrodes pipes. It also damages o-rings and washers on toilets creating leaks. Rio set out to measure pH of greywater in her home and at two local restaurants. She found that in most cases, greywater was not acidic (pH>7). She concluded that it would be okay for toilets.
Rio next presented a mathematical model to highlight the value of greywater. She assumed all households on the Monterey Peninsula would install a recycling system (for example, AQUS greywater system) and that all toilets would be flushed only with greywater from showers (third largest water use). She discovered that the community could save 1,800 acre feet of water (586 million gallons), which is 12% of the Peninsula’s annual water budget. While this is less than 6,900 acre feet of water needed from a proposed ocean desalination plant, Rio does show how in-home greywater recycling can reduce our water demand. In the future, greywater reuse leaves open the possibility of considering less costly alternatives to augment water supply such as purifying more wastewater and storm water instead of taking even more water to desalinate from the sea.
NOTE: Indoor grey water systems are already in use in parts of California. In fact, all new buildings on Stanford’s campus have greywater plumbing for toilets. However, in Monterey County greywater is approved only for outdoor irrigation, not indoor reuse – for now.
Plant Growth in Aquaponic Systems
Mia Dostal began her study with a futuristic thought: “If we replaced some farms with aquaponic systems, we could save 20 times more water.”
The combination of fish farming and crop production is a very forward-thinking approach to a future with limited water. Instead of choosing between fish and farms, imagine a world where we could have both. For her science fair project, Mia built her own aquaponic system. She wanted to compare growth rates of food crops in soil to growth in aquaponics. Using PVC pipe, she drilled holes to plant lettuce, chives, and broccoli. She attached a pump to recirculate water from an aquarium containing nine fish through the pipe and back. In aquaponics, fish provide the nitrogen for plant growth so the need for fertilizer is eliminated. Because fish use the water too, toxic pesticides cannot be used. To limit pathogens and insects, aquaponic farms are often housed indoors.
Mia wanted to know whether plants grown with aquaponics were bigger than those potted in soil. Her results show both systems produced similar results. However, aquaponics promoted slightly better overall growth. Mia’s work suggests that aquaponic farming could make fertilizers and pesticides a thing of the past. Her vision of a new age of indoor farming saves water, money, and benefits the environment while at the same time, produces food.
Mia recommends that her system be compared to hydroponic systems next. In terms of economics, hydroponics initially costs a lot less. However, fish are food too. Growing both fish and crops with the same water could pay off in big ways for future food production.
NOTE: The judges were inspired by glimpses of future farming ideas proposed for Monterey County that use orders of magnitude less water than traditional methods. It should be noted that entrepreneurs are already investing in hydroponic farms. In fact, Kimbal Musk (brother of Tesla founder) recently unveiled a high-intensity farm system housed in shipping containers in New York City. His company, Square Roots, claims to be creating the next generation of real food entrepreneurs for urban settings. You can check it out by going to: Squareroots.com.