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LA County Sanitation Districts overview: wastewater treatment, recycling and food-waste-to-energy operations
Summary
A Los Angeles County Sanitation Districts engineer gave the Redondo Beach Public Works and Sustainability Commission an overview of wastewater and solid-waste operations, describing wastewater treatment steps, recycled-water reuse, food-waste processing and energy recovery from digesters and landfills.
Danny (Danielle) Maurizio, supervising engineer with the Los Angeles County Sanitation Districts, told the Redondo Beach Public Works and Sustainability Commission the districts’ mission is to “protect public health and the environment through innovative and cost effective wastewater and solid waste management.”
Maurizio explained the districts operate 11 water-reclamation plants that together treat roughly 400 million gallons of wastewater a day and produce tertiary-treated recycled water used for irrigation, groundwater recharge and environmental purposes. She described the treatment train—primary sedimentation, biological (secondary) treatment using aeration basins and microorganisms, and tertiary filtration and disinfection—and noted the Warren facility in Carson (formerly the Joint Plant) currently lacks tertiary treatment and discharges to the ocean.
The presentation emphasized resource recovery. Maurizio said biosolids and food-waste slurry are routed to the Warren plant’s digesters, where anaerobic digestion produces biogas that can be converted to electricity or vehicle fuel; remaining biosolids are composted or applied to farmland. She described the Puente Hills Materials Recovery Facility and South Gate transfer stations, the Shoal Canyon and Calabasas landfills, and closed landfills the districts continue to maintain. The districts operate a food-waste preprocessing system (referred to as the DOTA) that converts collected food waste into a slurry for digestion.
On organic-waste policy the presenter cited state-driven programs as a driver of food-waste recycling programs (she referenced SB 1383 as the regulatory impetus). Maurizio said the districts divert over 90% of acceptable food-waste material that arrives at their facilities and described partnerships to transfer slurry and biosolids to composting facilities in the Central Valley.
Commissioners and members of the public asked about diversion rates, facility capacity, truck traffic and where compost and biosolids are applied. Maurizio said the districts own a composting facility in Kettleman City and use a mix of district-owned and contracted composters; she said about 10% of inbound organic material remains as residuals and that energy recovered from wastewater and landfill gas currently supplies the equivalent power for about 43,000 homes.
The commission voted to receive and file the presentation.
