A $32 million upgrade to the Hermitage Municipal Authority wastewater treatment plant in Pennsylvania to allow it to co-digest food waste is has dramatically cut its energy bill.
First opened in May 2014, the plant was designed in part by Jason Wert of water technology firm RETTEW, and uses advanced anaerobic digestion to produce biogas.
The plant then uses the biogas to produce electricity and heating for the site. By recycling the waste, more than 15,000 gallons (57,000 litres) of waste per week is no longer sent to landfill.
Since opening the operator said that plant has performed as expected, enabling it to process food waste from commercial sources while meeting some of the the plant’s power requirements.
“The fact that we could significantly reduce the cost of the electricity needed to run the plant was a big deal for us,” said Gary Hinkson, City Manager in a recently published video.
“And then there was the fact that the sludge that we’re producing could be used for land applications, thereby eliminating the fact that we had to pay to landfill it,” he added.
The facility’s operations separate waste from liquid, purifying the liquid and then releasing it to local waterways.
The waste is passed through a thermophilic digester, a heating conductor operating at about 135 degrees (57 Celsius) Fahrenheit.
The waste then moves through a second digester, this one a mesophilic type, heating the waste to about 95 degrees Fahrenheit (35 Celsius). Both of the digesters generate biogas.
The plant also recovers plastic packaging which is it able to sell for recycling.
A short film about the facility can be viewed below.
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