Ground-breaking technology for advanced biological nutrient recovery
Regional Director of Project Delivery for CLEARAS Autumn Fisher and John Bond, the Robertson Public Works director, have put countless hours into the new advanced biological nutrient recovery system being constructed in the village. Tom Lindfors / RiverTown Multimedia
ROBERTS -- Anticipation is beginning to build globally as the partnership between the village of Roberts and CLEARAS Water Recovery Inc. prepares to unveil the first full-scale Advanced Biological Nutrient Recovery system in the world.
CLEARAS’ ground-breaking ABNR technology harnesses algae's’ appetite for nutrients in a carefully controlled continuous flow environment to remove harmful pollutants from municipal wastewater to deliver effluent that meets the highest water quality standards.
”It’s exciting to be the first one in the world with this. Looking at the possibilities that will be here for the treating process, it’s exciting as an operator. I truly expect to be able to put out drinking water quality effluent,” Roberts Public Works Director John Bond said.
Compelled by the Wisconsin Department of Natural Resources to lower its phosphorus discharge level from 4.0 to 0.04 milligrams by liter by Dec. 31, 2020, the village began researching solutions in 2015. A number of solutions were investigated including, different chemical treatments, pollutant trading, microfiltration and an economic variance.
In the end, the village signed a $3.6 million contract in 2018. The CLEARAS solution proved to be a more sustainable, more comprehensive, more flexible and more cost effective solution, they said. The CLEARAS system not only addresses the immediate phosphorus issue, it removes or reduces other pollutants likely to be regulated in the future and it produces an algae product that will be sold to return a revenue stream to the village.
To sustain optimal conditions for algae growth 24/7, the photobioreactor is supplemented with special light to keep growth consistent regardless of conditions. The lights provide a combination of light in red and blue wavelengths controlled by photoactive radiation sensors. Tom Lindfors / RiverTown Multimedia
“In addition to phosphorus, the ABNR process will also remove nitrogen, total suspended solids, biochemical oxygen demand and pathogens such as E. coli and fecal coliform. There is also the added benefit of the reduction of some metals commonly found in wastewater,” said Autumn Fisher, regional director of project delivery for CLEARAS.
Through a unique application of biomimicry, ABNR injects a biodiverse blend of algae into the influent wastewater, pumps that mixture in a photobioreactor consisting of more than seven miles of glass piping igniting a photosynthetic reaction. In combination with the phosphorus-rich wastewater and sunlight, the algae blooms consuming the phosphorus, nitrogen and other nutrient pollutants.
“We’re balancing what is referred to as the food, which is the phosphorus and the nitrogen, and the organisms, which is the algae. You have to make sure the algae has enough to eat. They will eat the food and then on the backside, we have to remove some of the algae because it’s growing, eating and reproducing. The mixture serpentines through the glass tubing entering at the bottom exiting out at the top of two separate bioreactors stacked on top of one another,” Fisher said.
That mixture passes through a filtration processing tank where a membrane separates the algae from the cleaned water.
In addition to separating out the algae, the membrane filters out particulates the algae doesn’t eat including pathogens like bacteria and some heavy metals.
Part of the algae is recirculated, looped back into the influent mix to continue the recovery process while another portion of the algae is harvested as algae biomaterial. The portion to be harvested is fed into a centrifuge where it is spun into a thick paste enabling the mixture to be dried more easily and less expensively.
“At design conditions, the ABNR system is expected to generate as much as 400 pounds of algae biomaterial each day or 146,000 pounds a year and the algae has a gross value between $0.50 - $1.00 per pound,” Fisher said.
Through a unique application of biomimicry, ABNR injects a biodiverse blend of algae into the influent wastewater, then pumps that mixture in a photobioreactor consisting of more than seve miles of glass piping igniting a photosynthetic reaction. The Roberts facility will be a full-scale first in treating sewage. Tom Lindfors / RiverTown Multimedia
Since the ABNR system addresses the phosphorus issue, it should also eliminate the usage of aluminum sulfate saving the village $25,000-$30,000 annually.
After suffering some setbacks due mostly to the weather this past winter, construction of the ABNR addition to the wastewater treatment plant is back on track and scheduled to be fully functional by August.
”I would say probably the biggest challenge has been, because there isn’t anything like this, educating the contractors on how to put it together. They had nothing to go by, however, CLEARAS has been very involved. There’s been someone here from CLEARAS every day pretty much from the beginning. They’ve been great,” Bond said.
The final components of the glass photobioreactor and filtration system were installed at the end of June, setting up the complete system for commissioning in July 2020.