Reduce your power bill with covered anaerobic lagoons

According to Wiley Process Engineer Heath Barker, “Organisations that are not extracting maximum value from their wastewater are losing out.”

For example, biological wastewater treatment lagoons can be converted into CALs (covered anaerobic lagoons). These CAL systems are not only capable of capturing biogas as a renewable energy source, they can also reduce emissions.

Basic systems can be a simple cover over an existing lagoon that captures biogas which is then flared off. While this may reduce emissions, it misses out on capturing energy.

How CAL systems harness energy?

By covering an existing anaerobic lagoon, the biogas released from that lagoon can be captured and converted into energy.

“It can be tricky dealing with all the rules and regulations for handling biogas, and it can vary from state to state,” said Barker. “But if you have the right people and the right approach, it can be easy.”

Optimising CAL systems

Anaerobic systems are ‘living’ biological systems and must be nurtured. A well-balanced approach to anaerobic treatment will not only increase the biogas yield, it will also reduce the organics left in the system.

“It is not uncommon to achieve a 90% chemical oxygen demand reduction with these anaerobic digestion systems,” stated Barker. This comes from an understanding of the waste stream and surrounding environmental factors. It is important to not overload the system, ensuring peak loads are identified and managed.

“Installing a secondary anaerobic digestion (with a different type of methanogenic bug) downstream can also improve biogas yield and wastewater treatment,” said Barker

Future gazing

The energy a CAL system produces can be enormous. For example, one of Barker’s recent projects at a rendering plant generates half a megawatt of power each day.

In the future, Barker said, this technology could be used for wider applications, so “we need to fine-tune the systems to operate on a smaller footprint”.

Barker concluded by stating, “If there are organics in your wastewater, you need to turn this waste stream into a value stream.”