HomeMy WebLinkAboutNSR Summary of OperationsNorth State Rendering Summary of Operations
North State Rendering Co Inc (NSR) operates a two-stage, mesophilic anaerobic digestion (AD) system.
This system of reactors employs naturally occurring communities of bacteria and archaea to degrade a wide
variety of organic waste under anoxic conditions. The organic compounds are broken down in a series of
biologically mediated reactions. These reactions result in the production of biogas comprised primarily of
methane and carbon dioxide. During the startup of the NSR reactors, seed organisms required to commence
the breakdown of this organic matter were obtained from the Chico Water Pollution Control Plant's anaerobic
digester (~250,000 gallons) as well as and from cow manure.
The receiving of the organic waste at the NSR facility can be divided into two categories: solid and liquid
waste. Solid waste such as food waste is delivered into a hopper where the particle size of the solids are
reduced and the material is transferred into the first reactor. Liquid wastes including grease trap, cheese whey
and septic waste is unloaded into a concrete reception pit. The liquids are then mixed into a slurry before
transfer into the reactor system. Liquid waste that contain inorganic solids are screened by a separation
machine for removal as part of the process of unloading into the reception pit.
In response to disposal price increases for septic waste due to the closure of the Neal Road Landfill
septage ponds, NSR proposed a pilot study to Butte County and the Central Valley Regional Water Quality
Control Board to determine if septage could be integrated as a fraction of the organic waste received by the
facility. The septage waste NSR receives as a feedstock does not to exceed 50% of the total volume of organic
waste received. NSR receives septage as per its other types of liquid organic waste, with the solids fractions
screened and removed prior to unloading into the reception pit. Once the septage is unloaded into the
reception pit, it is mixed into a slurry with the other types of liquid organic waste. It is then pumped into the
reactor system with no additional operational changes required for receiving or processing of this waste.
Over the course of the 100 day pilot trial, operational data for the facility showed no reduction in
reactor capacity or biofuel production due to the addition of septage. In addition, multiple samples collected
over the course of the study and analyzed by a third party, CA-ELAP certified lab showed no increases in
contaminants of concern in the digester effluent which is discharged into the on-site evaporation ponds.
Therefore NSR believes only administrative changes to its use permit should be required.