Wastewater treatment plants are one of the most significant users of energy in the urban water supply. Recognizing water-energy nexus pressures, a number of leading wastewater treatment plants are utilizing food waste to become green energy producers.
Severn Trent’s dedicated food waste recycling center
In 2015, Severn Trent in the United Kingdom opened its first network of dedicated food waste recycling anaerobic digestion centers at its Coleshill sewage works. The center receives food waste from both local waste producers, local authorities, and waste service providers and converts it into clean, renewable energy and biofertilizer. With the ability to recycle over 48,500 tonnes of packaged, loose, and liquid food waste per annum, the center produces 2.4MWh of electricity per hour. That is enough to power both the center and the adjoining sewage works, with the excess renewable energy sold back to the national grid. In total, 18,000MWh of green energy is produced each year, enough to power 4,500 homes. In addition, the high-quality biofertilizer produced during the digestion process is used on local farmland.
Yarra Valley’s Waste to Energy Initiative
With climate change and Melbourne’s growing population placing a strain on finite resources including water and energy, Yarra Valley Water has built a Waste to Energy facility to mitigate future resource scarcity risks. Operational since 2017, the facility processes commercial food waste into renewable energy. Waste producers, for example, markets or food manufacturers, deliver the equivalent of 33,000 tons of commercial food waste to the facility each year. The facility is located next to Yarra Valley Water’s Aurora sewage treatment plant and generates enough electricity to power the facility and the sewage treatment plant. Any surplus electricity is exported to the electricity grid. The facility provides a range of benefits including reduced landfill, lower energy costs and greenhouse gas emissions, and lower water bills for customers.
Sanitation Districts of Los Angeles County turning food waste into a resource
The Sanitation Districts of Los Angeles County (Sanitation Districts) has begun a program to increase organics recycling in Los Angeles County by diverting food waste from landfills and converting this waste into a resource. The program involves collecting food waste separated from other wastes at the home or business, processing this waste into slurry at the Puente Hills Materials Recovery Facility, and delivering it to Sanitation Districts’ largest wastewater treatment plant, the Joint Water Pollution Control Plant (JWPCP). Through anaerobic digestion, biogas and mineral-rich soil amendments are produced. JWPCP uses the biogas produced to fuel an on-site power plant that meets all of the treatment plant’s needs.
By utilizing food waste, wastewater treatment plants not only become energy-independent but also generate a range of secondary benefits including surplus electricity for the grid, reduced greenhouse gas emissions, lower landfill volumes, and reduced customer bills.