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Re: oil and grease training


What you are compiling is needed.   I'm currently troubleshooting a chain
type restaurant with an on site alternative aerobic sewage treatment
system.   A major problem is grease carryover into the treatment unit.
The restaurant has a conventional exterior underground grease trap with 1.5
days retention.   Exiting fats, oil and grease (FOG) from the trap average
200ppm when desired is less than 70.   I am evaluating double tanking,
venting, and change of detergent to reduce FOG.  Reports from other
restaurants suggest two grease tanks in series with flow through venting is
effective at reducing FOG to around 30ppm.   

Detergent is another issue.   I suspect the detergent used chemically
emulsifies the grease, which prevents separation in the grease trap.  I
haven't found another detergent that is compatable with the restaurant dish
machines (they use powder) and releases the grease in the trap.   Any

Under sink grease traps are not particularly effective.   They load up with
grease rapidly and when full the grease bypasses the trap.   More advanced
designs utilize skimmers or other devices to route the separated grease to
an exterior container.   Reports on the use of these systems are equivocal.
  Some report success with the units, others report no improvement in
grease removal.   Manufacturers of these type of units are:

Atlas Systems Inc.
PO Box 747
Rockland, MA 02370

Big Dipper
Thermaco, Inc.
Diversified Sales Co. (Local Rep)
20 Spring Valley Rd.
Woodbridge, CT 06525

Attention to scraping plates and other cookware to remove residual grease,
sauces and gravies before washing helps in reducing the grease load
entering the grease trap.

Please send me any information you develop on this design problem.   Thanks.

Craig Stead
P.O. Box 1000
Putney, Vermont 05346
Tel. 802-387-4748
Fax. 802-387-4511 


At 03:05 PM 4/5/99 -0400, you wrote:
>Hello Everyone
>Our department is in the early planning stages of developing materials to
>assist both POTWs and restaurants with oil and grease management issues.  We
>hope to coordinate assistance from sizing a grease trap to permitting a
>restaurant. If anyone has experience with these issues, has developed
>training / outreach materials, or has any suggestions, your input would be
>greatly appreciated.  Thanks in advance.  Greg 
>Greg Newman
>NC Div. of Pollution Prevention & Environmental Assistance
>PO Box 29569
>Raleigh  NC 27626-9569
>Ph: (919) 715-6515  Fax: (919) 715-6794