Page 134 - WaterSense at Work

WaterSense at Work: Best Management Practices for Commercial and Institutional Facilities
Scraping dishes and disposing of food waste prior to dishwash-
ing can be a very water- and energy-intensive process, depending
upon the food disposal method used. Typically, commercial kitchens
dispose of food scraps using a garbage disposal with a grinder that
processes food waste into pieces small enough to pass through the
plumbing system.
Garbage disposals in and of themselves do not use water; however,
kitchen staff often run water at high flow rates through the garbage
disposal to prevent damage to the grinder blades and keep food waste
from building up and clogging the plumbing system. Some facilities
have a sluice trough, which feeds the garbage disposal and is usually
built into a stainless steel table system. Water is applied continuously at
the top of the trough, often at a rate of 2.0 to 15.0 gallons per minute
depending upon howmany nozzles are installed. Food waste is
scraped into the trough and rinsed down into the garbage disposal. Alternatively, some
facilities rinse food from dishes into a garbage disposal using a pre-rinse spray valve.
As an alternative to a traditional garbage disposal with a grinder, some facilities use food
pulpers to collect and dispose of food scraps. Food pulpers are located where the grinder
would otherwise be located. Unlike a traditional garbage disposal with a grinder, how-
ever, food pulpers crush food waste into a pulp (i.e., slurry), extract excess water from the
pulp, then send the pulp waste to a bin for later disposal or composting. Inmany food
pulper systems, the extracted water can be recycled within the food pulping process or
reused to pre-rinse dishes or act as a sluice trough where food wastes are dumped. When
a recirculation system is used, pulpers can recirculate 5.0 to 15.0 gpm through the system,
needing only 2.0 gpm for make-up water.
Figure 4-6 illustrates the food pulping process.
Food Disposals
Garbage disposal with grinder
Sluice trough
Koeller and Company and H.W. (Bill) Hoffman & Associates, LLC. June 2010.
A Report on Potential Best Management Practices—Commercial Dishwashers.
for the California Urban Water Conservation Council. Pages 5-7.