U.S. farmers wanting to capitalize on the momentum in aquaculture, or fish farming, face regulatory hurdles when dealing with fish waste.
But new research shows that a simple, organic system can clean aquaculture wastewater effectively and inexpensively.
Researchers built bioreactors -- long containers filled with wood chips -- to treat wastewater from a fully operational recirculating aquaculture system in West Virginia. The idea is simple: water from the fish tank enters the bioreactor at one end, flows through the wood chips and exits through a pipe at the other end. Along the way, solids settle out, and bacteria housed in the wood chips remove nitrogen, a regulated pollutant.
Research by Laura Christianson, assistant professor of water quality at the University of Illinois and lead author of the study, already had shown just how effective bioreactors were at removing excess nitrogen from tile-drained agricultural fields across the Midwest. But "wastewater from a fish farm is a lot gunkier. It looks brown and can be smelly," she said. "We wanted to see if we could get a bioreactor to take the nitrogen out of that kind of water without the bioreactor clogging up with solids."
The team set up four identical bioreactors, varying only in retention time, or the amount of time it takes for water to travel end to end, and found they worked great.
At face value a study about clogging potential of aquaculture bioreactors might not seem revolutionary, but the results could play a part in the evolution of the agriculture industry.
"In the U.S., we import more than 80 percent of our seafood -- mostly from Southeast Asia and China -- so it's an important industry. If we want to increase our food security, especially around this great source of protein, we should raise more fish domestically," Christianson said. "But to do that in an environmentally responsible way, dealing with the wastewater from fish farms will be really important, We were trying to find a balance between moving water through quickly and making sure it's staying in there long enough to get treated properly."
Manure mobile app
Pork producers focus on environmental sustainability by using manure as a natural fertilizer to offset the use of commercial fertilizers, and a new app will help efficiently calculate manure usage.
"The Illinois Manure Calculator is built for the Illinois-specific manure plan rules, enabling a livestock producer to quickly balance manure applications with field crop nutrient needs," said Ted Funk, agricultural engineering consultant for the Illinois Pork Producers Association.
The free app is available for iPhone and Android users.
The app calculates a manure application rate, based on the choice of nitrogen or phosphorus limits, and the N, P and K (potassium) that will be applied to the field. It also allows the user to enter a trial application rate, to see the effect on the nutrient balance. Completed calculations can be emailed directly to the user for entry into the farm's main manure nutrient management plan.
"Calculating the right manure application rate has always been a time-consuming exercise for producers, because they have to gather data from several places before they can compute the answer," said Richard Gates with University of Illinois Extension. "This mobile app puts everything right at their fingertips."
Project funding was provided by the Illinois Soybean Association checkoff and IPPA.