New research shows that a simple, organic system using woodchip bioreactors can be helpful for cleaning aquaculture wastewater effectively and inexpensively.
Fish farming creates waste that can be difficult and costly to clean up, an issue that impedes the growth of the industry in the United States.
The researchers participating in the study built bioreactors filled with wood chips to treat wastewater from a fully operational recirculating aquaculture system in West Virginia.
These scientists explain that 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.
To carry out the research, the team set up four identical bioreactors, varying only in retention time, or the amount of time it takes for water to travel from end to end.
Laura Christianson, assistant professor of water quality at the University of Illinois and lead author of the study pointed out that the bioreactors worked as a filter for the solids and took nitrates out and clarified that for systems that need to move a lot of water in a short amount of time, her recommendation is an additional microscreen filter to settle some of the solids out before they enter and clog up the bioreactor.
In her opinion, 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 US, we import more than 80 per cent 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. But to do that in an environmentally responsible way, dealing with the wastewater from fish farms will be really important,” Christianson stressed.
The study was supported by the USDA’s Agricultural Research Service and Tides Canada.