SCHOTT solutions no. 1/2016 > Water recycling

Water recycling
Photo: Thinkstock

As Clear as Water

The US company Clearas has developed a biological, algae-based method by which water can be purified for reuse and, at the same time, valuable biomass as a byproduct can be obtained. Photobioreactors that contain glass tubes demonstrate their ability to perform in a test facility.

Christine Fuhr

The view from space clearly shows why our earth is also called the ”blue planet.” 29 percent of the earth’s surface is occupied by land, the greater share (71  %) by the oceans which contain more than 97 percent of the earth’s total water. More than 70 percent of the 2.5 percent fresh water is in frozen form. All living beings on earth, except for marine life, thus share the remaining 0.75 percent of the total water. With the world’s population increasing to currently nearly 7.3 billion and an estimated nine billion in 2050, the world’s water has to be shared among more people. At the same time, in recent decades the proportion of water used for agriculture and for growing food has tripled to 70 percent of the world’s water supply. And industry requires water, amounting to about 22 percent. The remaining eight percent of the world’s water is used by households.
Photo: Clearas

Global need for clean water

According to the UN’s 2015 World Water Report, water efficiency needs to be increased and contamination of water reduced by adopting stricter regulations. “Vision for 2050: Water for a Sustainable World,” also points out that “waste water should be viewed as a resource that provides energy, nutrients and fresh water for reuse.”

Clearas Water Recovery in Missoula, Montana, is a company that pursues this very goal with great commitment. With its patented ”Advanced Biological Nutrient Recovery” (ABNR™) solution, the Clearas team has been offering innovative biological wastewater treatment technology for industrial, municipal and agricultural customers since 2011. Substances such as nitrogen and phosphorus in wastewater pose a particular challenge for these consumers. Other advantages for the user include the fact that the system is modular and if necessary can be connected to an existing water treatment infrastructure as a retrofit system.
Water recycling
Photo: Clearas
”Our approach is to achieve sustainable, future-oriented resource recovery. Here, algae are not a pure product, but rather viewed as a process,” says Rick Johnson, Vice President of Clearas and responsible for market development. The principle is that ABNR™ technology reliably gains back excess nutrients and other pollutants from industrial, municipal and agricultural wastewaters by using a special flow process involving algae and other existing biological organisms. During the first phase, to initiate the recovery of nutrients, contaminated waste water and carbon dioxide (CO2) are mixed with a composition of algae and other existing biological organisms in a mixing vessel. In a second phase, the biodiverse mixture is forwarded for cleaning in a closed photobioreactor, which consists of horizontally arranged glass tubes that lie on top of each other. The greenhouse structure and light sources provide for optimal biological activity and photosynthesis. ”Around the clock, 24/7,” says Johnson.
Photo: Clearas

”Our approach is to achieve sustainable, future-oriented resource recovery.
Here, algae are not a pure product, but rather viewed as a process.”

Rick Johnson, Vice President of Clearas

The algae inside continuously break nitrogen down biodegradably in symbiosis with bacteria phosphates, carbon dioxide and unwanted pollutants. In this process, pollutants are absorbed by the algae and converted into biomass without generating any new pollutants. In a third separation phase, modern micro-filtration separates the mixture into two streams: purified clear water which can be easily introduced into rivers, lakes and streams, or be reused in plant operations; and a recirculation or recycle stream.
The latter leads algae and other microorganisms back into the mixing vessel, from where they undergo the same process again. Another advantage: excess algae can now be removed and used as valuable biomass. Johnson states, ”Clearas is actively looking for applications for the biomass produced. One idea is to use it to produce special algae plastics, for example.”
Kevin McGraw
Kevin McGraw, Operations Manager & Co-Founder, explains the patented Advanced Biological Nutrient Recovery (ABNR™) solution. Glass tubes from SCHOTT are also used successfully in this innovative algae-based wastewater treatment technology. Photo: Clearas

Glass tubes in test mode

SCHOTT is an important partner to the algae industry with its products and comprehensive expertise with photobioreactors (see solutions 1/14: The Algae Turbo). ”Our glass tubes are also perfect for use in algae-based sewage treatment,” explains Dr. Niko Schultz, Product Manager for Photobioreactors at SCHOTT. This was demonstrated at a Clearas test facility inside a paper mill in Spokane, Washington. SCHOTT delivered 531 tubes and 381 bends made of high-quality DURAN® borosilicate glass and 675 couplings . ”We are very pleased with the performance,” says Vice President Rick Johnson. ”Glass is a material that ideally meets the high demands on our closed photobioreactors,” he notes. ”Compared to plastic, glass offers many advantages,” expert Dr. Schultz explains. ”Our special glass tubing is highly chemically resistant and durable, mechanically very strong, and also very resistant to pressure in combination with glass arcs and pipe connections.”

The balance sheet is rather impressive. By using the new method, phosphorus can be reduced by a factor of 10 and nitrogen by a factor of 3 compared with conventional technologies. The purified water is below the detection limits for harmful substances and can be safely discharged or used as recycled water. 45 million liters (12 million gallons) of wastewater were actually treated with the ABNR™ System in 2015. Clearas also has high goals for the future. ”We challenge the current status, face up to new challenges and strive to exceed expectations,” explains CEO Jordan Lind. And perhaps this also includes developing the wastewater treatment technology via algae to such an extent that drinking water quality can be achieved. <