A science and technology professor has shown that improving wastewater treatment and saving energy are not only essential, but they’re also compatible.
Dr. Jianmin Wang, professor of civil, architectural and environmental engineering at Missouri Science and Technology, has developed multiple wastewater treatment technologies that produce freshwater that is not only cleaner than wastewater treated using traditional methods, but also requires less maintenance and energy.
Additionally, his inventions can be used to retrofit existing wastewater treatment plants.
Wang says 0.8 percent of America’s energy use is spent on wastewater treatment. Much of that energy is used to aerate the tanks where wastewater is treated.
The energy is used to feed oxygen to the microorganisms that consume the waste, and traditionally wastewater treatment plants maintain an oxygen concentration of 2 milligrams per litre to feed the bugs in the tanks, “which makes them happy,” Wang says.
The prevailing thought has been that providing less than 2 milligrams per litre of oxygen would make the microorganisms “unhappy.”
But Wang does not believe that is an issue, saying that if you feed them at a lower concentration, such as 0.5 milligram per litre, it makes them a little less happy, but the microorganisms will live longer and enrich more – plus you use 30 percent less energy during oxygen infusion to produce the same results.
Achieving superior effluent quality
He has also developed another treatment system called an Alternating Anaerobic-Anoxic-Oxic (A3O) process that “can achieve superior effluent quality since it can remove organic pollutants plus nitrogen and phosphorous nutrients,” Wang says.
It does this without chemicals, and its effluent contains only 5 milligrams per litre of total nitrogen and 0.5 milligram per litre of total phosphorous. It also saves more than 10 percent of energy compared to the conventional pre-anoxic process, which has significantly less total nitrogen and total phosphorus removal.
“Advances such as these demonstrated by Professor Wang represent the next wave of wastewater management,” says Dr. Glen Daigger, past president of the International Water Association, a recognised authority in wastewater technology and a member of the National Academy of Engineering.
“Given growing water and resource constraints on the planet, we must turn to sources such as used water – to both supplement our water supply and to do this with a reduced environment footprint.”