County commissioners awarded the contract for the project to the global engineering firm Black and Veatch in December 2016. The plan calls for construction of an energy saving anaerobic digester at the county’s biggest sewage plant.

Though costly, the new equipment being installed at the facility is expected to reduce energy bills at the plant by $1.5 million a year. Plant Superintendent Phil Cummings said the savings in operating costs should enable the county to pay off the construction costs in 15 years and to do so without any increase in rates to customers.

The current Zimpro process employed at the wastewater treatment plant requires a lot of gas and electricity to pressurize and heat sludge to levels that kill the pathogens and harmful bacteria it contains.

An anaerobic digester, by contrast, is an environmentally-friendly way of processing sludge which requires a heavy tank in which organics are digested by bacteria in the absence of oxygen. The byproduct of the process is a biogas, which can be captured and used to power generators to operate the facility.

The new construction at the Liverpool plant is not expected to be completed for another year but a key phase of the project began in August and should continue through September. That is the construction of the two 800,000-gallon stainless steel tanks that will house the digester.

Those tanks are the first of their kind in the United States, according to Cummings. They are being constructed of high-grade stainless steel in a process unique to the German company Lipp, which is supervising construction of the tanks through its patented spiral formation. The process involves the rotation of the tank around successive strips of metal which are crimped together and sealed with a corrosive resistant compound.

Another part of the new processing operation planned at the plant will be the introduction of thermal hydrolysis reactors which also sterilize sludge and make it more biodegradable. The process increases the loading rate to the anaerobic digesters and results in sludge that can be sold as a class A biosolid fertilizer.

Cummings said thermal hydrolysis reactors like the ones being ordered for the Liverpool plant have been installed in just one other location in the United States, the Blue Plains water treatment plant outside Washington, D.C.

Blake Childress, a managing director for Black and Veatch, said his company has built many similar facilities around the world, but no other comparable projects in Ohio.

“The design is quite popular in Europe and becoming more common in the United States,” Childress said when his company was awarded the contract. “We’re incorporating newer technology to increase gas production in the Liverpool design and the goal is to make the plant energy neutral when we’re done.”

The Liverpool Treatment Plant serves most of Brunswick and Medina and is the biggest of three main wastewater treatment plants operated by the county. The county sanitary engineer’s office also operates treatment plants in Hinckley and Westfield townships. The entire sewer system treats about 12.5 million gallons of water a day and has the capacity to treat 19.5 million gallons.