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“Wastewater is a resource in the wrong location,” says Zhen He, professor in the Department of Energy, Environmental & Chemical Engineering at Washington University in St. Louis. How should we interpret his words?

The explanation is simple. Wastewater simply has a bigger potential than previously assumed. Wastewater recycling for irrigation, toilet flushing, or consumption does not necessarily have to be the sole purpose.

Scientists at Washington University discovered that wastewater can be also used to create electricity.

Professor Zhen He (above), together with his team, has developed one system that recovers water while creating electricity. Retrieved from: Source.wustl.edu

The wastewater is full of organic materials which are a great source of food to bacteria. It is the bacteria which allow the conversion of the “waste” to electricity.

The system is set up like a typical microbial fuel cell, a bacterial battery, that uses bacteria attached to the electrode as a catalyst.

When wastewater is pumped into the anode, the bacteria “eat” the organic materials and release electrons, creating electricity.

The permeable anode filters up to 90% of pollutants which leaves water clean enough to be released into nature or further treated for non-potable water uses.

What amount of electricity can be created?

In the U.S., about 3% to 5% of electricity is used for wastewater treatment activity. It might seem insignificant but, when converted into watt hours, it is a considerable amount.

Even though the electricity could be used for lighting or as an energy supply for electronic devices of similar size, the aim of this project is to create electricity for communities. In other words, the treatment plants will not yet be transformed into power plants.

The scientists intend to use the system to lower the energy consumption in the WWTPs.

The estimates suggest that the “bacterial system” produces 20 watts of energy per 1,000 liters of wastewater. “Typically, the process consumes about 0.5 KWH of electricity per cubic meter. We can reduce it by half, or more of that,” says professor He for The Source.

In the best-case scenario the WWTP will achieve energy neutrality and also save money.

City wastewater treatment plant in St. Louis pays $15 million for electricity per year. If they reduced the consumption by half, you can count the savings for yourself.

However, the professor reminds that the purpose is still mainly wastewater treatment and recovery of reusable organic materials, such as phosphorus and nitrogen.

These serve as a great plant fertilizer. He also says that only if these materials were not treated at all, they would become a real waste.

Wastewater transformed into energy is nothing new

Biogas is recovered during the decomposition of biological waste. This renewable source of energy can be used to generate heat or electricity.

Furthermore, biogas is an eco-friendlier alternative to natural gas. The invention of microbial fuel cell by American scientists is not the first method to create energy in the WWTPs. At Hydrotech Group, this has been our focus for quite some time.

Anheuser-Busch, an American brewing company, has found a way to make this source of energy work a long time ago.

Biogas is created in the reactors and the energy is used as a fuel for the boilers, making it a great alternative source of energy

This allows the plant to save both money and energy as well as reduce the consumption of fossil fuels and the amount of emissions.

If you have a similar mindset and are searching for a wastewater treatment solution, feel free to get in touch with our experts.