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Turning ton of daily school food waste into biogas fuel
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A typical Manteca Unified School District student generates roughly 1.75 ounces of food waste a day when they are done with lunch.
Multiply that by 24,000 students, and it comes to 1.06 tons on any given school day.
While that sounds like a staggering amount it translates into just 70 pounds per campus per school day.
“One and three quarter ounces per student struck me as an awful lot of waste,” noted Patti Page who serves as the Manteca Unified director of nutritional services.
But after further investigating it didn’t seem that bad.
Page soon found out an apple core tossed into the orange carts set aside for food waste came to three quarters of an ounce. A typical banana peel weighs an ounce.
“That figure (1.75 ounces) includes all students, even those who bring their own lunch,” Page said.
Interest in food waste has picked up since the City of Manteca started rolling out its food waste collection program as the first step toward converting what food Manteca residents toss out into biogas to fuel municipal refuse collection trucks.
Manteca Unified has embraced the city effort whole heartedly to the point they want all of the district’s schools — including those in Lathrop, French Camp, Weston Ranch, and French Camp as well as Nile Garden and New Haven — to participate. The city is working with Allied Waste Management, the private contractor that serves those areas, to either collect the orange food waste carts or have Manteca trucks do it.
“We want all of our students to participate regardless of where they are at,” Page said.
Currently all elementary school campuses within the city limits of Manteca are participating. Page said her staff is still trying to determine how to roll the food waste collection program out at Manteca, East Union and Sierra high schools. It is more problematic as each campus has multiple places serving food.
The city started implementing its food waste programs at Manteca schools back in August given their volume plus the track record they have of embracing recycling. Manteca, as well as other municipalities, is working to meet a state mandate to divert food waste from being buried at landfills.
Student volunteers in school lunch rooms help monitor carts to make sure garbage and food waste are separated by fellow students as they clear their plates or dump leftovers from home lunches. The carts used are filled only a third of the way due to the dense weight of food waste. That allows easier and safer handling by the school custodial staff.
Rexie LeStrange, the City of Manteca’s solid waste division manager, has lauded the schools for collecting food waste that “is exceptionally clean” meaning it is not contaminated with other garbage.
Food waste currently collected from schools as well as restaurants and grocery stores where the city has assigned orange carts is being taken to a Lathrop site where it is combined with green waste from yards to make compost.
In roughly two years it will be taken to a conversion facility at the municipal wastewater treatment plant and converted into biogas.
The Manteca biogas production facility will also use fats, oils, and grease — known as FOG — generated from cooking that is now being shipped to the Bay Area for recycling.
Manteca Unified won’t be a big contributor to FOG recycling.
“We (Manteca Unified) changed the way we cook years ago so it is done in a healthier manner,” Page said.
Manteca’s wastewater treatment plant-biogas facility could become a regional hub for other cities that need to recycle food waste.
If that happens and Manteca Unified moves toward buses that are fueled by compressed natural gasses to keep up with ever tightening San Joaquin Valley air pollution standards, it’s not out of the possibility that someday the food waste Manteca Unified students recycle will power the school buses they ride.
“That would be interesting,” Page said of the possibility.
 For now the city expects food waste collection once it is implemented citywide at commercial ventures, schools, and hospitals will produce enough fuel for 20 plus refuse collection trucks and have enough left over for some sales to the public to fuel their CNG powered vehicles.
Eventually food waste recycling will get down to the residential level.
An audit of brown carts two years ago shows 40 percent of what Manteca residents throw out is food waste.
Page said the school districts is still working on finding a recycler that will take the Styrofoam cubes created every day when used food plates are collected and compressed. Several school sites crush the plates so they don’t take up volume in garbage bins which in turn would result in higher charges at the school district for refuse collection.

To contact Dennis Wyatt, email