LA Sanitation Districts to convert food waste into RNG for transport

Dinner scraps, spoiled fruit, and vegetables from supermarkets and restaurants are being processed into renewable vehicle fuel by the Los Angeles County Sanitation Districts.

The Sanitation Districts have been converting food waste into electricity for over six years, but have now launched a biogas purification system to recycle the waste into renewable vehicle fuel.

“With this new biogas purification system, we now also produce renewable natural gas (RNG) that is used to fuel vehicles like cars, buses, and trucks,” said Robert C Ferrante, chief engineer and general manager for the Sanitation Districts.

“We know that many cities are grappling with how to meet state requirements for recycling food waste and are pleased to offer a complete and cost-effective solution.”

Under the recycling programme, waste hauliers collect food waste that has been placed in separate bins by their customers. The food waste is delivered to the Sanitation Districts’ Puente Hills Materials Recovery Facility in Whittier. At the facility, the food waste is loaded into specialised equipment that removes contaminants like plastic bags and forks and blends the food waste into slurry.

The Sanitation Districts then transport the slurry to their wastewater treatment plant in Carson. Waste hauliers who have their own processing equipment also deliver slurry to this plant. The slurry is then added to the plant’s digesters.

The biogas is used in two ways: some is sent to the Sanitation Districts’ power plant at the Carson facility, where it converted to electricity that runs the treatment plant. The remaining biogas is sent to the new purification system to make fuel-grade RNG.

The purification system can produce the RNG equivalent of 2,000 gallons of petrol per day.

Bob Asgian, head of the Sanitation Districts’ Solid Waste Management Department, said: Because the Sanitation Districts manage both solid and wastewater, we already had most of the infrastructure needed for food waste recycling.

“We also received a grant from the California Energy Commission that helped fund the new biogas purification facility. As a result, we were able to complete our system relatively inexpensively and pass those savings on to our customers.

“Use of our system has been steadily growing and we have additional available capacity to help more cities.”

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