BOILERS, PUMPS & VALVES
PUMP UP
THE VOLUME OF BIOGAS
As California takes affirmative action to address climate challenges, including the
23 million tons of organic waste that it produces annually, the environmental services industry is also taking positive steps to ensure that the unwanted material is put to the best possible use. This includes upgrades of the important
mixing process at anaerobic digestion facilities to boost biogas yields from material that would have otherwise been destined for landfill
I
n May 2023, Republic Services, a leader in the environmental services industry, made a
significant expansion of its organics recycling operations when it acquired North State Bioenergy, a biogas facility at Oroville – its first anaerobic digester. The site was once home to a rendering plant, from whom the AD plant received organic matter, but it now mainly uses commercial food waste from across Northern California as feedstock for its principal, 64’ high, 2200m3
(580,000-gallon) digester.
With Republic Services wanting to optimise the biogas operation at Oroville, a new submersible
Food waste is
homogenized by the new Landia Chopper Pump
The new stainless-steel Landia Chopper Pump continuously reduces the particle size of the food waste feedstock at Republic Service’s biogas plant in California
chopper pump has been introduced for the facility’s 20,000-gallon Receiving Pit. This was provided by the same company whose equipment still works efficiently and effectively on the main digester. The company chose the Landia GasMix system for the main digester. “We made a calculated investment when we chose the Landia GasMix system for the main digester,” explained Dave Meyer, operations manager at Republic Services. “It is a highly dependable system, with external accessibility,
straight into the Receiving Pit. This now blends up all the incoming food waste (25-30% solids; some of it pre-processed at a Republic Services’ facility in Sacramento), ensuring that there is a continuous, consistent, flow of homogenized feedstock going into the digester. Following this, the homogenized food waste is transferred into two tanks (40’ diameter by 24’ high), where the first acid-forming phase of the biogas production process takes place. These heated tanks contain bacteria that break
“In 2022, Republic Services recycled two billion pounds of organic waste. Diverting this organic material from a
landfill provided a climate benefit equivalent to removing the annual emissions from 22,000 passenger vehicles”
which simplifies maintenance and avoids costly downtime associated with internal components. Unlike other systems with moving parts inside, Landia’s design minimises safety risks for our operators and ensures a seamless, efficient, and profitable process without the challenges of shutting down a delicate biological operation.” Ten years on, and the GasMix
Chopper Pumps on the main digester are still going strong.
INSTALLING THE NEW PUMP When Republic Services decided to replace the pump for the Receiving Pit, it chose Landia again for the demanding food-waste application that runs 24/7, 365-days a year. The new Landia Chopper Pump is stainless-steel, 30HP, with an external five-blade knife system that continuously reduces the particle size of the feedstock. By using the original site
drawings, the new submersible could be integrated with the original pump and mix system, dropping the new Chopper Pump
18 ENERGY & SUSTAINABILITY SOLUTIONS - Spring 2024
down the material and prepare it for its onward process. When the feedstock is ready, it is then pumped into the main digester where the biogas-producing bacteria get to work.
ENVIRONMENTAL BENEFITS Ken Jacobs, Landia’s aftermarket manager, commented: “It’s fair to say that we had some fun and games at first with the install of the new Chopper Pump. Sometimes, nothing seems straightforward when upgrading a biogas plant, but Dave and I worked closely to make everything right. We have a fully-stocked inventory in the US, so can always provide back-up, without delay.” In 2022, Republic Services recycled two billion pounds of organic waste. Diverting this organic material from a landfill provided a climate benefit equivalent to removing the annual emissions of 22,000 passenger vehicles. Organics recycling directly supports Republic Services’ sustainability goal to increase the recovery and circularity of key materials from the waste stream by 40% by 2030.
Landia
www.landiainc.com
Republic Services
www.republicservices.com
www.essmag.co.uk
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