By Nicole Gaetjens, Sustainability Coordinator at Mills College and Ellen Hopkins, Zero Waste and Composting Consultant
NCRA members Ellen Hopkins and Nina Salvador and Tri-CED Recycling employee Raquel Archuleta led eight other NCRA members on a tour of an on-site composting system in July. Located on 250 acres in the hills of Union City, Masonic Homes is one of the largest assisted living facilities in Northern California. Masonic Homes and the neighboring facility – Acacia Creek Retirement Community, have partnered with Tri-CED Community Recycling for over three years to compost all food discards generated by 600 full-time residents and staff in an on-going effort to increase sustainability at the site. The compost produced is being used for an innovative habitat restoration project led by Math Science Nucleus (MSN) to restore native California flora to the hillside of this Mission Hills property.
The Earth Flow is made by Green Mountain Technologies. Ellen Hopkins, composting consultant, and Raquel Archuleta explained the collection flow, in-vessel compost process and operations. Raquel collects prep (pre-consumer) and dining (post-consumer) food waste daily in four to five 64-gallon containers and brings it to the compost station. The compost system has a tote-tipper that tips each container into the loading end of the machine and an electric auger mixes the material into the existing compost in the system. Food scraps (nitrogen source) are mixed with equal parts of bulking agent (carbon source) in the system to produce a C:N ratio that makes the composting process effective. Daily input of food waste is about one ton or two yards, and bulking agent is about ½ ton or 2 yards. The bulking agent(s) used in this case is horse bedding from a neighboring horse stable and chipped wood waste from landscape maintenance on the property. The NCRA group checked out the compost in the vessel and were surprised there was no noticeable odors.
The Earth Flow is a fully automated, fully contained, in-vessel composting system that provides optimum conditions for thermophilic composting. The auger, aeration and moisture addition systems are programmable for process and product objectives. The traveling auger mixes in the new feedstock at the load end. The new material is quickly inoculated with active composting microbes as it is blended in. Process air above the compost in the vessel is pulled through a biofilter next to the Earth Flow. The biofilter is composed of moistened woodchips. Microbes that normally inhabit woodchips (no inoculants needed) scrub odors and volatile organic compounds (VOCs) with 95% efficiency. The “plug flow” matrix migrates to the discharge end over the course of 2-3 weeks. In-vessel time depends upon the amount of material loaded and system size. After processing within the vessel, the compost is unloaded and cured to completion outside of the vessel within 6-8 weeks.
Nina Salvador, who is familiar with the reforestation project, described it in more detail: Masonic Homes and partners aim to restore the native oak woodland that once inhabited this region prior to the over grazing of cattle. The woodland will provide ecosystem services and enjoyment to the community. Nearby California State University-East Bay faculty and students are also involved in the restoration effort led by Joyce Blueford of MSN. This closed-loop system demonstrates a win-win-win project and was a great tour for the NCRA group.
WHOIS… MATH SCIENCE NUCLEUS is a 33 year old national and international educational and research non-profit composed of scientists, educators and community members. Locally it is associated the Children’s Natural History Museum in Fremont. It serves as an online science resource center to assist school districts, teachers, and administrators around the world. The major goal is to develop problem solving capacity through science for the world’s children. Read more… MSN: http://msnucleus.org/