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Oil & Grease Removal
OWEA Collection System CommitteeHANDS-ON WORKSHOPS
9/13/07 – 10/11/07Tom Horn
Industrial Fluid Management, Inc.
FOG, where does it come from?
• Usually enters wastewater from washing of cookware and dinnerware
• Hot water between 140 – 190F• Emulsifying agents are added• Direct pouring of fry oils and grease down
drains• All result in high levels of FOG
downstream
FOG, Where does it come from?
• Residential households• Residents often have less care about what
goes down the drain…until the drain is clogged
• Many pump stations serving only residential neighborhoods still have severe grease issues
FOG, Where Does It Come From?
• Food Processors, Manufacturers• From Previous Definitions, any facility that
processes animals or vegetables• Oil seed plants – produce oils from
soybeans, canola plants, sunflowers, etc.• Any place that uses products from the
above for frying, cooking, etc.• Pretreatment Plants and Industrial
Sources
FOG, When Does It Become Problem?
• Downstream sewer systems, FATS of animal origin are solid @ room temperature
• Often water temperatures are very high that keep FATS liquified
• Downstream that water cools down and solidifies.. Often in the first pump station
• Negatively impacts collection systems causing blockages or worse overflows!
Oil & Grease, Who Deals w/ It?
• Grease collectively known as Oil and Grease or Fats, Oils and Greases (FOG)
• Big Impact and probably has affected most,• Operators• Collection System and those who maintain those• Pumpers and Cleaners• Commercial Establishments• Health Dep’t Personnel / Regulators
FOG, Operations
• Usually issues with• Plant Headworks• Pumps and Check Valves• Clarifiers, skimmers• Biological Parts of Plants• Digesters• Collect it and remove from
treatment…What do you do with it
FOG, Collection Systems
• Mess with sewers (gravity and force mains)
• Mess in wet wells… level controls, check valves, pump performance
• Often a potential source of odors where FOG accumulates
• Low pH and organic acids
FOG, Collection Systems
• WE&T Reports• Nearly 50% of SSO’s are from pipe
blockages in Municipal Sewer Systems• 47% of those blockages are due to
excessive grease buildup in lines• Approximately 25% of all SSO’s are FOG
related
FOG, Commercial Establishments
• Usually not concerned until if affects the business
• Drain blockages, odors• Grease Trap Maintenance• @ this point the facility faces health issues
and shut down
FOG, Regulators
• Potential Health Issues w/ Commercial Establishments (Restaurants) Health Dep’t can shut them down
• Pretreatment Personnel deal with it with enforcement of grease trap maintenance
• Likely to become another Federal Priority
FOG, Pumpers
• Contractors that help industry maintain grease trap, skimmer tanks
• Go between originator and final disposal point
• Important to have a manifest system to document loads and origins of loads (even mixed loads)…This is a regulatory type situation. Who handles it?
FOG, Fats, Oils and Greases, Fast Facts
• Many descriptions / definitions are interchanged among all 3
• For our purpose today, we are focusing on FOG from plant / animal origin
• FOG is tested by the Hexane Extraction Method of Method 1664
• Petroleum based compounds are analyzed by the silica gel treated method to separate Total Petroleum Hydrocarbons of Method 1664
FOG Fast Facts• FAT – consists of a wide group of compounds that are
generally soluble in organic solvents and largely insoluble in water
• Can be either liquid or solid, • Typically saturated (animal) are solid @ room
temperature• Typically unsaturated (vegetable) are liquid @ room
temperature – these are often called oils• Collectively all fats are considered lipids• Lipids is the term for fatty acids, oleic, cholesterol. Also,
major compounds of cell membranes
FOG Fast Facts• Oil – in a general sense, is a chemical
compound not miscible with water and is liquid @ ambient temperatures
• Hydrophobic – water hating• Lipophilic – fat loving• Oil refers to triglycerides• Triglycerides from animals are saturated and
solid @ room temperature• Triglycerides from plants are unsaturated• Sources (all seed oils and other oils extracted
from plants and animal fat)
FOG Fast Facts
• Grease – (yellow grease) refers to used frying oils from deep fryers and grease traps
• Lower quality grade of tallow from rendering plants (first candles made from tallow)
• Now becoming a source for yellow biodiesel
FOG, Grease Chemical Formula
• Grease is the term used collectively for all the previous items and their definitions
• Long chain fatty acids connected to a glycerol backbone
• Very high concentrations of BOD5, but very hard to break down due to the long chain fatty acids bond to glycerol. Very strong chemical bond.
FOG, Typical Values
• Wastewater from individual residences ranges 45-100 mg/l (typically around 70 mg/l)
• Domestic WW Ranges• 50-100 weak to medium strength• 150 high strength wastewater
FOG, Chemical Breakdown
• Triglycerides, consists of glycerol and long chain fatty acids
• Glycerol portion easily degraded and only 10% of theoretical value of FOG BOD5
• Stearic Acid• Palmitic Acid• Oleic Acids• Long chain fatty acids that are the most difficult
to break down… but contain the most energy values due to chemical structure
FOG, Chemical Makeup
• Very High Concentrations of BOD5 in FOG, but not highly degradable
• Another disadvantage of its physical characteristics
• Fatty Acids make it tough to break down• COD values are easily in the range of
10,000-30,000 mg/l (5,000-15,000 mg/l BOD5)
FOG Problems
• Next stop that solidified FOG in lift station breaks off a little every now and then
• Congeals in downstream processes reducing pump efficiency, check valve operation
• Eventually gets to treatment process
FOG Problems
• Another Operational Issue• Constant Skimming, Collection and
Disposal• Labor intensive and added costs• Substrate to operational problems,
foaming, scum and filaments that inhibit settling
FOG, Where does it come from?
• Restaurants and Fast Food• Don’t buy into the we only use pre-
prepared food• No matter what food is used• Most FOG is from cleaning dishes,
utensils, countertops and floors and hoods• Where grease trap maintenance is not
routinely performed
FOG Removal Grease Trap / Interceptor
• Rely on time and cooling• FOG typically requires more than 30
minutes to naturally separate and float• Cooling also helps for solidification, which
aids in the floating of FOG• Often flow from commercial institutions is
instantaneous and 30 minutes is not met
Restaurant Grease Trap (kitchen style)
Kitchen Grease Traps• Where you see these type run away as fast as possible• Many tell you these never fill up, which may be true• Too small, never get good separation of FOG from water• Extremely warm due to proximity to sink and dishwasher
and inside kitchens which are naturally warm. Liquefies much of what would separate
• Gas Station pizza outfits – growing number of pizza @ gas stations…what are the regulations on them?
Grease Tank ( in ground ) typical outside interceptor
Problems w/ Grease Trap
• Removal of free oil and grease• Catches other stuff• Cleaners and chemicals emulsify what
would typically separate• Simply not serviced frequently enough• Need infrastructure to accept the amounts
of grease that are “floating” around out there
FOG, Residential
• Based on 100 mg/l of FOG in domestic wastewater
• Neighborhood producing about 20,000 GPD of flow (about 200 people)
• 0.020 x 8.34 x 100 = 17 lbs of FOG / day• 119 lbs / week, 500 lbs / month, >6,000 lbs
/ year• 30 lbs of FOG / person / year
FOG, Where does it come from?
• Food manufacturing• Dairies, largely fats• Bakeries, large and small use large
amounts of oils and lard• Seed oil plants, especially if little or no
pretreatment• Restaurants
FOG, How do we deal with it?
• Got an idea of what FOG is, its orgin(s) and what it can affect through sewer and wwtp’s
• How do we manage and minimize its affects?
• Or how do we utilize or reuse its energy value?
FOG, How do we deal w/ it?• Enforcement, more and more municipalities are writing strict
ordinances on management of grease removal devices. This is already in place. Some municipalities are writing ordinances that deal with this.
• Outlining additives that are allowed for improving grease trap operation.
• Make sure emulsifiers, solvents or large concentration of surfactants are not allowed
• Biological Additives are successful… but warn your customers about those that promise pumping is not necessary. No matter how much treatment you can achieve, solids and grease simply do not go away!
• Grease Trap achieves some biological degradation, but it’s simply not large enough for consistent biological treatment
Municipal Regulations
• City of Lancaster, OH developed a Best Management Practices (BMP) handout for Food Service Industry– Outlines cleaning practices – dry vs. wet cleaning– Maintenance of strainers, hoods and absorbents– Regulated maintenance schedule on grease trap
maintenance• Daily / weekly for in kitchen units• 90 day pumping cleanout of larger outdoor units.• www.ci.lancaster.oh.us
FOG, How do we deal w/ it?
• Best option, get rid of it• Pump grease traps, etc. often• Issue w/ pumping, Where does it go?• Watch out for the all to often blending if
you already accept septage• Regulations catch up w/ grease trap
maintenance, manifesting will be necessary or the municipality enforces it
FOG, How do we deal w/ it?Richmond, IN Grease Reactor
Richmond, IN Grease Reactor
• Located about ½ way between Dayton, OH and Indianapolis, IN on I-70
• Large amount of food and pet food processors in that area
• Issues with grease• Superintendent Larry Baker noticed
several years ago the need for proper grease disposal
Richmond, IN Grease Reactor
• Started from retrofitting old primary clarifiers w/ coarse bubble aeration
• Isolated high grease loads to this tank• Found w/ aeration, detention time and
bioaugmentation, the grease could be degraded• Pretreatment prior to introduction into plant• Basically, could treat it as sidestream to a point
where plant was not negatively impacted
Richmond, IN Grease Reactor
• From that several year trial and the increasing demand for proper grease removal
• Came up w/ new idea• Handles approximately 10,000 gallons / day.
Septage still received @ plant headworks• 2 tank covered aerated reactor w/ biofilters for
odor control• By end of detention time flow goes right into raw
influent without detriment to the system
Richmond, IN Grease Reactor
Richmond, IN Grease Reactor
Example of grease collection
FOG, How do we deal w/ it?
• If pretreated it has great potential to increase anaerobic digestion operation
• Already has VFA’s and high COD values to increase gas production
• Has to also be blended properly to avoid grease cap in digester
• Need to make sure digester is not organically overloaded prior to increased grease addition
• Typically 80 lbs VS / 1000 cf. Some as high as 150 lbs VS / 1000 cf for anaerobic digestion.
FOG, Theoretical Energy Production
• Previously estimated 30 lbs of grease are generated per year per capita
• 30 lb x 85% volatile content = 26 lb VS from grease / year
• With 50% VS destruction = 13 lbs of VS destroyed / year
• 15 cf of biogas per lb of VS destroyed equals 195 cf gas / person / year from FOG
• 2000 people = 390,000 cf / year x 621 btu / cf biogas = 242,190,000 btu / year
FOG, How do we deal w/ it?
• Who wants it?• If free oil could be cooked or spun out of it,
biodiesel blenders could potentially use it• Anaerobic Digestion systems for increased
gas production• Huge renewable energy source
FOG in Lift Station
FOG, Conclusion
• Handling of FOG and related issues is only going to grow
• Regulations catch up w/ major generators, Government (local, state and federal regulators)
• Energy Issues, more and more people are going to innovate ways to collect energy from grease trap wastes, not just used fry oils
• Public Education – Offer publications / flyers on management of grease from household to commercial to industrial customers
FOG, Conclusion
• Questions and Comments
• Thank You!
