fats oils and grease

7/22/2019 Fats Oils and Grease

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Fats, Oil and Grease Removal

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I. Course Description

For generations, man has been pouring all kinds of undesirables

down the drains of homes, commercial businesses, and institu-

tional facilities. With the inception of the residential garbage dis-

posal, it has become even more prevalent because, after all, once

kitchen waste is ground up, it will all go down the drain, right?

While the concept is a good one, the reality is that fat, oil and

grease collect on the walls and components of a municipal collec-

tion system (or sanitary sewer system) and wastewater treatment

plant, and that is just the fallout from residential disposal. Add

to the problem, additional disposal of fats, oil and grease from

commercial and institutional facilities and it becomes clear that

this problem can be widespread, costing communities in terms

of maintenance of collection systems and wastewater treatment

plant facilities, potential violations of federal and state disposal

regulations, and in the potential health risks to man and the en-

vironment. This course looks at the reality of the disposal of fats,

oil and grease and the impact on municipal systems, as well as

methods to remove these prior to entry into those systems.

II. What is F. O. G.?

The acronym F. O. G. stands for fats, oil and grease. This

is a term used in the water and wastewater industries for

the combination that is poured down sinks and drains and

accumulates in the sanitary sewer system. For the most

part, fats, oil and grease are a byproduct of cooked foods.

While it is logical to believe that only fried foods are thesource of problems associated with the presence of fats, oil

and grease in the sanitary sewer system and wastewater

treatment plant components, all types of foods and food

preparation processes may contain fats, oil and grease. F.

O. G. includes the following:

Cooking oil

Shortening/lard, butter, and margarine

Fats from meat

Dairy products (milk, cream and cream sauces, ice

cream, cheese, yogurt)

Mayonnaise, gravy, and salad dressings

When residential homeowners, institutional facilities,

and commercial businesses prepare foods, fats, oil and

grease attach to the sides of pans, utensils and work surfac-

es. In the process of cleanup, they are scrubbed and rinsed

from the pots, pans, and utensils, down the sink drains and

into the collection system. While more water than grease

may be poured down, ANY amount of F. O. G. that enters

the collection system eventually causes problems, not only

in the sanitary sewer system, but it may reach the waste-

water treatment facility and impair wastewater treatment

processes.

It may seem unbelievable to the average citizen that the

sewer systems are not designed to handle what they deem

to be insignificant amounts of fats, oil and grease when

they handle much larger, disgusting amounts of residential

matter from each home. Sanitary sewer systems are not

designed to capture or eradicate the fats, oil and grease that

enter them.Grease is a triglyceride. It is made up of three carbon

atoms. These three fatty acids connect to a glycerol mol-

ecule (Figure 1). All of the compounds are hydrophobic


Terminal ObjectiveUpon successful completion of this course, the operator will be able to describe the impact of fats, oil andgrease on a municipal collection system and wastewater treatment plant and methods to improve their removalfrom those systems.

Enabling Objectives1. Describe the term F.O.G.

2. Identify contributors of fats, oil and grease to a

municipal sanitary sewer system.

3. Discuss the impact of fats, oil and grease disposalon municipal systems.

4. Identify the equipment used to prevent fats, oil andgrease from entering the sanitary sewer system.

5. Discuss best management practices for handlingfats, oil, and grease


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(water-fearing). That is why F. O. G. floats on primary and,

sometimes, secondary treatment equipment.

Figure 1: Plate-type mechanical aerator.

The grease floats on top of the water and, therefore, col-

lects on top of the collection lines. It attaches to the walls of

piping systems and accumulates in areas where the piping

system turns. Sooner or later, so much can accumulate that

it causes chokes in the collection system. The F. O. G.

deposits in these areas narrow the path for disposed water

to travel and can eventually stop the flow completely. The

accumulation of F. O. G. can cause a backup in the collec-

tion lines, which in turn can cause a sewer spil l or overflow.

III. Fats, Oil and Grease Contributors

F. O. G. enters the sanitary sewer system from numerous sources.

Each contributor adds an amount in proportion to their use of fats,

oil and grease, size of their contribution, and prevention practices

in place to keep those materials from being washed down the drain.

Residential Contributors

It is common knowledge that homeowners contribute grease to the

municipal collection system through the disposal of grease down

residential sinks and garbage disposals. In daily life, families pre-

pare and cook meals, with clean-up to follow. In the process, bits

of food and remnants of meal preparation are washed down the

kitchen drain. It is not uncommon for many undesirables to be

poured down the drain or flushed down the toilet as a means of

disposal. Residents flush unwanted pill, potions, solvents, paints,

and other chemicals down residential drains. Some believe that ifthose items are flushed down the drain, what can a little grease or

oil harm? In actuality, none of the aforementioned should enter

the sanitary sewer system or storm sewers.

The garbage disposal has become a standard in most

modern American kitchen sinks. As homeowners and fam-

ily members rinse dishes and dispose of food fragments,

the materials pass from the residence and travel through

the collection system and eventually end up in the water

treatment facilities. Prior to the invention of the garbage

disposal, food and other waste was disposed of in kitchen

trash cans, and eventually ended up in sanitary landfills,rather than in the sanitary sewer system. If anything, the

garbage disposal may have increased the likelihood that

fats, oil, grease, and other undesirables will enter municipal

water and wastewater treatment systems.

A simple garbage disposal does not stop the entry of

fats, oil and grease to the collection system. The grinding

process of the garbage disposal simply makes the pieces of

fat or grease smaller. These pieces may pass through the

residential piping systems just fine, but they eventually con-

tribute to an accumulation or clog elsewhere in the collec-

tion system. Adding detergent to break up the grease onlyhelps to transport the grease further down the collection

system lines. The smaller pieces eventually attach to the

pipe walls and structure anyway.

Some may be convinced that running hot water down

the drain while discarding fats, oil or grease effectively

transports the typically hardened matter through the

piping system. It may transport the material out of the

residential pipes. But, how far will hot water actually travel

in a piping system that is miles long? Will it simply move

the fats, oil and grease out of the residential piping system?

Will it move the same through the piping system down the

street? Will the hot water last long enough to push the fats,

oil and grease to the water treatment facility? Not likely.

Once the water cools, the once-liquefied fats, oil and grease

begin to congeal and attach to the inside walls of pipes

and other structures within the residential or commercial

piping system, collection system, or wastewater treatment

piping systems (Figure 2).

Figure 2: Residential disposal of fats, oil and grease.



Multiply the impact that an individual residence make

to the incidence of fats, oil and grease in the collection

system by the number of residents in a community. Then

magnify this amount exponentially when the residents of

apartment complexes, multi-family dwellings, condomini-

ums, and townhomes are included in the residential con-

tributors category. While the individual homeowner may

be more concerned with harming his/her own dwelling orhaving to pay out of his/her own budget for repairs caused

by fats, oil and grease, the residents of multi-family com-

plexes often rent their residences and may not be concerned

with the condition of the piping systems or costs associated

with repairs to the complex that are caused by deposits of

fats, oil and grease.

While it is not typically poured down a kitchen drain,

motor oil that is improperly disposed can also end up in

the sanitary sewer system. This oil is disposed daily by

residential homeowners and commercial businesses. Both

individual residential contributors and residents of multi-family complexes change the oil in their vehicles, recre-

ational vehicles, lawnmowers, and other small engines.

The used oil that is collected is often poured down drains,

into the yard, into the storm sewer or into a trash can.

Improperly discarded motor oil can seep into groundwater

and surface water runoff and end up in streams, lakes, and

rivers. If it is poured down a drain or into a storm sewer, it

ends up in the sanitary sewer system and wastewater treat-

ment plant. It is harmful to people, pets, plants, and pipes.

If the end goal of a wastewater treatment system is to

return water to consumers or recharge local streams, why

should humans dump anything harmful down a house

drain or storm drain? Many believe that education is the

key to preventing this kind of disposal.

Commercial Contributors

In addition to residential contributors of fats, oil and grease, there

are a large number of commercial contributors. Restaurants and

fast food establishments are significant contributors (Figure 3).

Figure 3: Commercial disposal of fats, oil and grease

There are other entities that produce grease that may

not be as well known. Some of these include the following:

Doughnut shops

Supermarkets

Truck stops

Shopping malls

Butchers markets

Meat packaging plants

Flea markets

Caterers

Banquet facilities

Car washes

Amusement and theme parks

Retirement homes

Mobile home and RV parks

Day care centers

Stadiums and professional sports arenas

Vehicle maintenance shops and garages

This list is in no way complete. The list of contributors

of grease to the collection system is lengthy.

At the same time, each of these contributes different

amounts of fats, oil and grease to the system, depending

on the size of the operation and its operational guidelines

concerning the disposal of grease. Many in this particular

list may have no established guidelines for the disposal of

fats, oil or grease to prevent their disposal to the sanitary

sewer system.

Institutional Contributors

In addition to residential and commercial contributors, there are

institutions that contribute fats, oil and grease to the sanitary



sewer system. These may include some of the following:

Public and private schools and colleges

Churches

Nursing homes

Hospitals and medical centers

Airports

Prisons

While industrial contributors can impact municipalsystems and the environment, the focus of this course is

on the impact of residential, commercial and institutional

contributions of fats, oil and grease to municipal systems.

IV. Impact on Municipal Systems

Physical Impact

What happens when a sewer pipe is blocked with fats, oil and

grease? A number of undesirable situations can occur when a pipe

becomes clogged or blocked. These may include one or more of

the following: The sewer system backs up into a residence or

residences.

Sewer overows can occur through manholes at the

street level.

The smelly mess has to be cleaned up, which is

unpleasant and costly.

It is possible to come in contact with disease-causing

matter.

There may be increases in sewer bills due to increased

incidence of repair to the sanitary sewer system due to

deposits of fats, oil and grease.

Spills and overows can lead to environmental con-

tamination and fines.

If a pipe backs up into a residence or a residential clean-

out, it makes a mess that the homeowner must clean up. It

is up to the homeowner to locate the blockage, have repairs

made, and clean up or replace the damaged surroundings,

whether indoors or outdoors.

For multi-family dwellings, several residences may ex-

perience the effects of a backup. While the blockage may be

the result of one family pouring F. O. G. repeatedly down a

kitchen sink, it can affect an entire section or building. The

cost of location, repair and clean-up falls upon the complex

owner and the residents affected.

A sewer overflow can occur at a manhole in the cen-

ter of a busy city street. The city must send out a team of

professionals to assess the situation, locate the problem,

make the repairs, and clean up the mess. Most municipal

budgets are stretched thin already. The process of locating

the problem within the collection system and cleaning out

the accumulation can be very costly. Often, the city has nochoice but to pass this expense to the residents in the form

of an increased sewer use fee.

Some F. O. G. will travel all the way to the wastewater

treatment plant and cause problems with system pipes,

clogging pump volutes, and adding unwanted floating

material to primary and secondary treatment tanks. This

grease or scum can coat and kill the bacteria needed for the

treatment processes.

Most large wastewater treatment plants do not have a

problem with the grease added to their wastewater. Theamount of flow coming in the wastewater treatment plant

will dilute and carry the grease through the preliminary

treatment units and to the primary units. In the process, the

grease will float because it is lighter than water. The grease

is skimmed off the primary clarifiers and, sometimes, the

second or final clarifier.

In the chlorine contact chamber (CCB), F. O. G. can

settle to the bottom if it clings to inorganic solids before it

gets there. The bottom of the CCB can then be cleaned, and

the F. O. G. and inorganic matter can be properly disposed.

Some of the grease however, will go over the efuent weirsand be carried into the wastewater treatment plant effluent

and to the creek, stream, lake or reservoir.

Costs of Maintenance and Repair

Backups and overflows are costly, no doubt. The first, and usu-

ally the highest, price is paid by the public utility system. The city

typically has a collection crew that rods the collection lines and

cleans up the mess caused by a backup in the collection system.

Overows can occur at a manhole (MH) that is located

at the lowest point in the area near the blockage. Once the

overflow occurs, that area becomes contaminated with

grease and small amounts of organic and inorganic solids.

The city invests time and money to clean the area due to

the public health hazards caused by the backup in the line.

The grease and solids have to be raked up. When the

area is free of the greasy mess, it should be cleaned with a

disinfectant such as 5.25% bleach or calcium hypochlorite

(HTH). If the area is not disinfected, imagine children and

domestic animals being exposed to this health risk! The

citys concern does not just involve the risk to public health.

It must take into consideration any monetary wastewater

fines or surcharges imposed by state and federal regulatory

agencies as a result of an accidental overflow or spill.

Health Hazards

Sewage spills and overows pose a health risk for all who may

be exposed to the mess. Humans and domestic animals are at

risk if the exposure is in an area that they may frequent. A pet

might roam and pick up potential contaminants on their paws or

faces and carry it back to their yards and homes. Overflows and

discharges into local streams, lakes and rivers can affect humans,

domestic animals and aquatic life.A municipal sewer use ordinance establishes certain

uniform, minimum standards for controlling the amount of

matter pushed into the sanitary sewer system and to protect



and preserve the public health, safety and general welfare

of a community. The ordinance may include the following:

Requirements for the regulation of pumping out grease traps

Procedures for cleaning and servicing septic tanks, grease

traps, car washes, interstate restroom facilities, grease inter-

ceptors, and package wastewater treatment plants

For health reasons and as a means of cost control, a citymay focus on the instances of frequently clogged lines. This

should be monitored because it is a potential health hazard,

but it can also identify establishments that may not be in

compliance with city ordinances related to the proper dis-

posal of wastes. Any time emulsified grease is passed into

the collection system from an establishment, grease is going

to relocate in the system. Because of

F. O. G. buildup, the wastewater treatment facility may

have trouble meeting required effluent levels.

The Environmental Protection Agency (EPA) intends to

keep waters of the United States shable and swimmable.Discharges that do not meet the appropriate standards ac-

cording to state and federal guidelines are punishable. If

water from the commercial business exits the effluent line

and is not in compliance with the municipal wastewater

ordinance, it may cause non-compliance with the citys

wastewater permit for discharge to a stream, lake or reser-

voir. Fines can be posed by the Environmental Protection

Agency (EPA) and state environmental agency for this Total

Suspended Solid (TSS) output to the environment.

Biochemical Oxygen Demand (BOD) is the amount of

oxygen needed for the stabilization of the water (organics)

by the wastewater plant bacteria. BOD may be regulated by

the state in a wastewater treatment facility, although the city

typically sets the standard for BOD. The efuent is released

to the source, and any grease that gets out to the stream,

lake, creek or reservoir can be unsightly to the public, could

cause stream breakdown, and produce odors and vector

insect problems (such as flies, etc.).

V. Equipment Used to Limit Disposal of Fats, Oil andGrease

Prior to construction of a commercial business that will contribute

fats, oil and grease to the sanitary sewer system, ordinances should

be established that require the installation of pretreatment equip-

ment, such as grease interceptors and/or grease traps, to capture

and contain used F. O. G. The installation of a grease interceptor

or a grease trap is usually a function of the size of the establishment

and the type of food processes used. Grease traps are generally

used as point source control and are used in smaller establishments

that do not produce high volume foods. Generally, fast food res-

taurants, hotels, factories, and school cafeterias require a grease

interceptor. Local plumbing codes typically outline the parametersfor the installation of grease interceptors such as the type and size

of equipment necessary for the size of the establishment. Some

communities regulate placement of oil and grease separators on

the interior of the business, while others mandate the use of exte-

rior oil and grease separators.

Mechanical Grease Separator

A mechanical grease separator is a device that performs oil skim-

ming. The purpose of a mechanical oil skimmer is to remove free-

floating grease and oil. They can be installed in the same area that

a grease interceptor is placed; usually in the kitchen area. It shouldbe noted that this device does not remove emulsified grease and

oil. These separators are usually stationary and non-active. Cool

water is run into the separator first, and then oil is poured into the

separator. The device is turned on and the oil and emulsified grease

flow through the mechanical separator and flow down line to a

collection tank. The water from this process enters the municipal

collection system and moves on to the wastewater treatment plant

for treatment.

Grease Trap

A grease trap is installed under a sink where disposed water flowsfrom the sink drain into the grease trap. Inside the trap, the water

moves through baffles that separate the fats, oil, and grease from

the wastewater

(Figure 4). The grease rises to the surface, where it can be

removed. There are many different designs of grease traps.

Many grease traps are electro-mechanical, with the grease

being removed automatically.

Inlet

Air Intake Vent

Flow Regulatory Device

Removable Baffles

Lock and Lift Ring

Fog Accumulation

Solids Accumulation

Cleanout

Outlet

Sample Point

Air Relief

Figure 4: Grease trap

In order to decide which is best for an establishment,

there are many factors to consider. The size of the area to

be served and the type of food being served are important

considerations for food establishments. Another consider-

ation is the water consumption of the business. The grease

trap must be able to handle the volume of water that flows

through the establishment.

In making a pre-construction decision, it might be wise

to survey similar businesses in the area to see what types

of traps are in use and how effectively they function for the

purpose intended. City ordinances may mandate the size of

grease trap that is required for a particular purpose. It isimportant to plan where the sampling or clean-out port is

to be located. This should be located before and after the

grease trap on the drain line.



It is important to research potential grease trap disposal

problems. Problems can occur at the sanitary T on the ef-

fluent side. It is important that the line goes down 24 inches

off the bottom of the grease trap. If the line goes down too

far and solids are allowed to accumulate, a blockage can

occur in the effluent line, causing an overflow at the effluent

T. Any accumulated grease could overflow into the effluent

line. One manhole access lid is necessary for this particulargrease trap. It is located between the influent and effluent

sides of the grease trap(s).

There are grease traps with two manhole lids (Figure

5). One manhole opens over the grease area and provides

access for pumping out the grease and solids. The second

manhole access opens to allow for visual inspection of the

effluent water area to ensure that the effluent water flow can

exit to the collection lines.1200 Gallon Grease Trap

Cleanout

Manhole Lids

Cleanout

Water Flow

Water Flow

Water Flow

Influent Line

Grease Accumulation

Solids Accumulation

Baffle

Clean Water

Open

Effluent Line

Figure 5: Grease trap with two manhole accesses

Grease Interceptor

A grease interceptor is designed to separate fats, oil, and grease

from wastewater. As wastewater travels from the sink to the inter-

ceptor, it passes through a vented flow control device that prevents

siphonage and back pressure. It then travels over a series of baffles

inside the interceptor that separates the fats, oil and grease depos-

its from the rest of the wastewater (Figure 6). As the wastewater

cools, those deposits float and accumulate at the top of the 1,000

to 1,500 gallon interceptor. The remainder of the wastewater

moves through the interceptor into a discharge pipe and continues

to the sanitary sewer system. The accumulated material must be

removed from the top and bottom of the interceptor.

Inlet

Air Intake Vent

Flow Regulatory Device

1-10' Typ.

Interceptor Cover

Solids Accumulation

Outlet

FOG AccumulationFOGAccumulation

Sample Point

10'

Figure 6: Grease interceptor

In many communities, it is not uncommon for inspec-

tors to verify that interceptors are the correct size, were

installed properly, are being maintained adequately, and

are operating efficiently. There are usually fines associated

with non-compliance. Municipal ordinances often provide

specific guidelines for the minimum and maximum size

limits for grease interceptors, as well as how often they

must be pumped out, maintained, and inspected. It is bestthat building plans for new commercial businesses include

the appropriate installation of grease interceptor(s).

Recycling (De-Watering) Pump Trucks

Recycling pump trucks are useful to remove grease from any con-

tainers or for establishments that want to recycle grease and oil.

These trucks may be owned by the commercial business or hired

to remove grease from establishment. Recycling pump trucks

may not be workable for grease trap separation and collection of

grease and oil. The idea for restaurants and fast food establish-

ments is to remove the layer of grease (cap) at the facility, leavingthe collected solids behind to break down and provide stabiliza-

tion in the tank. Most of the skim grease traps are not allowed to

be pumped out with a recycling pump.

VI. Best Management Practices for Handling Fats, Oiland Grease

What can be done with fats, oils and grease?

Collect (strainers/interceptors/grease traps) and dispose in

the trash

Recycle

There are a number of grass roots programs across the

country aimed at educating the public on the hazards of

disposing fats, oil and grease into the domestic wastewater

systems. While it is possible for local and state government

to exert some control over commercial businesses that dump

excess fats, oil and grease down the drain, it is nearly impos-

sible to control what is disposed in every residence. Cities

can impose ordinances concerning the installation of grease

traps or interceptors in new commercial construction. They

can create ordinances requiring commercial businesses to

empty those traps on a set schedule or face monetary pen-

alty. Rather than impose such on residential homeowners,

communities across the country are choosing to implement

public education campaigns that encourage disposal of fats,

oil and grease safely, without adverse impact on the munici-

pal wastewater systems or the environment.

Excesses within the system can lead to sanitary sewer

overflows, which can lead to code violations, environmen-

tal violations, and pose health hazards to the public. In

order to prevent these smelly, costly occurrences, there are

some widely regarded best management practices for theproper handling and disposal of fats, oil and grease.



Controls for Wastewater Treatment

Municipal collection crews are always looking for ways to control

grease. A common method of control is the use of a surfactant

product that helps to relocate the grease down the collection line.

However, this method does not eliminate the grease. The grease

can still build up in long collection lines or collection lines that

have 45 or 90 angles.

There are several methods used by wastewater collec-tion crews and wastewater plant operators for separating

grease as a means of control. These are skimming off

the primary treatment units, aeration, pre-chlorination,

and primary digesters. In the collection system, methods

of removal can include mechanical (rodding machines),

hydraulic (jet machines), and chemical processes. In the

wastewater treatment plant, grease is removed mechani-

cally on bar screens and primary clarifiers.

F. O. G. affects the pH of the wastewater. The pH in

a wastewater permit indicates a certain acceptable range

for pH values, usually between 69 units in most waste-water treatment plants. If the wastewater flows down the

wastewater line at 25 feet/second, the grease and inorganic

material will stay in suspension. The size of the collection

line makes a difference in how fast the lines flow. The flow

of the wastewater is important part of the grease control

in the pipe. If the grease in the collection system is flowing

slowly, more grease will collect on the walls of the pipe as

the slow movement of the water cools and grease solidifies

and collects on pipe walls. The slower the water, the more

time that grease is able to collect on the pipe walls.

Water temperature is important in controlling the

impact of F. O. G. The average flow of wastewater in the

collection system on its way to the source is 7276F. A

temperature range near 72F is considered normal for

wastewater. Warmer water can come from residential

sources (showers, dishwashers, washing machines, or

other) and commercial sources (grease garbage grinders,

laundromats, power plants, or other).

When the water must turn 45 and 90 angles in the

pipes, the flow of water slows down where there is no dis-

solved oxygen (DO) being added or not added fast enough

to keep grease in suspension until it gets to the next lift sta-

tion or reaches the wastewater plant for removal. Costs are

incurred if and when maintenance crews must go in and

mechanically clean the lines to keep the water flowing to

its destination.

It is important to track and monitor the point originator

or the grease trap waste, transporter and disposal location.

New facilities that are limited by space or other factors and

cannot install a grease trap (as specified) could be required

to install and maintain internal grease interceptors of

twenty gallons in size. If a facility does not meet dischargecompliance levels, the facility may be subject to discharge

fines based on effluent parameters.

In controlling grease, the monitoring rules should be

outlined by the pretreatment program to maintain effluent

discharge limits. An example of these limits could be as

follows:

BOD less than 300 mg/L

TSS less than 300 mg/L; grease and oil less than

75 mg/L

pH less than 9 or greater than 6 Grease trap efuent water temperature in excess

of 111F

All surcharges could be added to a food establishments

monthly water bill. This may be written in the pretreatment

ordinance.

Commercial Business Best Management Practices

Most communities rely on regulation of commercial businesses to

curtail the disposal of excess fats, oil and grease. Generally, there

are a number of suggested best management practices for com-

mercial businesses to control the disposal of fats, oil and grease.Some could be written into municipal ordinances, some relate

to proper construction of the facility to handle proper disposal,

some relate to the proper use of preventive equipment, and others

are general guidelines for proper disposal of fats, oil and grease.

Some that could be written into municipal ordinances

include the following:

Discharges from commercial businesses must comply with

local, state, and federal guidelines.

Applicable commercial businesses must have installed and

fully functioning grease interceptors and/or grease traps.

The design and installation of such devices must comply with

building codes for the applicable state.

Grease interceptors and grease traps must be properly in-

stalled to drain directly from the device according to design.

Disposals, if installed, should pipe through the grease re-

moval device or trap.

Consider the installation of a three sink system: wash, rinse,

and sanitizing basins to utilize water that is 140F or less.

(Commercial dishwashing equipment uses 160F minimum

temperature, which dissolves grease and allows it to pass into

the sanitary sewer system.)

Hot water, greater than 140F, should not be allowed down

drains connected to grease traps or interceptors as the hot

water allows the fat or grease to liquefy and pass through the

system into the collection system.

Some best management practices that could be either

written into municipal ordinances or adopted by commer-

cial businesses that relate to preventive equipment include

the following:

Grease traps and interceptors should be cleaned routinely.

Establish cleaning protocols for the grease interceptor basedupon the type of establishment, interceptor size, and flow vol-

ume of discharge for the establishment. It is common practice

to clean grease interceptors every 60 to 90 days.



Manual grease traps should be cleaned every week unless

historical maintenance logs indicate sufficient performance

for a longer period of time.

Electro-mechanical grease traps should have the following

performed daily: empty oil containers, clean solids strainer.

Wiper blades should be cleaned weekly.

Commercial grease traps and interceptors must be emptied,

and the equipment maintained on a regularly scheduled basisas determined by the commercial business.

Removal of grease and solids from interceptors or traps must

occur when the amount of fats, oil and grease reach a certain

percentage of functional volume of the device.

Mandatory removal of all fats, oil and grease from all inter-

ceptors and traps on a semi-annual or annual basis as man-

dated by local authority.

Mandatory inspection of the interceptor and/or grease trap

on a semi-annual or annual basis, or when the devices are

emptied as mandated by local authority.

Establish protocol for the use of interceptor additives, if use isallowed.

Appropriately schedule and record visits from commercial

haulers for interceptor/trap contents.

Determine improvements to practices based on annual statis-

tics of grease removal for the commercial business.

Perform routine maintenance of food preparation equipment

to prevent breakdown and subsequent disposal of fats, oil and

grease into the facility sinks and drains.

Consider the disposal of food waste into containers for recy-

clers to pick up for animal consumption.

Maintain records for installation, cleaning, emptying, inspec-

tions, and maintenance of all grease interceptors and grease

traps. Pretreatment programs may require routine mainte-

nance logs for grease interceptors.

Perhaps one of the best management practices for a

commercial food establishment to prevent disposal of ex-

cess fats, oil and grease to the collection system is the main-

tenance of equipment that is used to prepare food. If proper

maintenance is performed and recorded, breakdowns are

less frequent. That means equipment functions as intended,

and the facility should perform as designed. Grease inter-

ceptors and traps that malfunction or do not function at all

cannot fulfill their purpose for the facility.

Equipment Maintenance

The following are some suggestions for routine maintenance of

food service equipment:

Exhaust hoods

Routinely inspect and clean small and large exhaust hoods

so they perform efciently and effectively. Small hoods maybe wiped down with spray detergent and a soft cloth. Large

exhaust hoods can be cleaned by professional service compa-

nies.

Frequently spray lters with hot water over a mop sink so that

any greasy residue drains through the grease trap. Oil and

grease can also escape through the ventilation system filters

and coat the roof of the establishment.

Once rinsed, place in a commercial dishwasher for nal

cleaning.

Keep the ventilation systems functioning properly, with an

adequate balance of air intake.

Commercial Fryers

Skim the oil for food particles on a daily basis.

Keep surfaces wiped clean with absorbent paper products.

Routinely test oil for life span and change as indicated by the

test.

Check the bottom of the fryer for carbon buildup and clean to

lengthen the life of the oil and the equipment.

For facilities with multiple fryers, alternate the use of fryers

that process heavy foods (those that produce a large amount

of deposits) with those that do not and/or change out the oilfor the fryer that has heavy deposits more often.

Collect used oil in covered, oil-rendering tanks for transport.

Facility Maintenance

Perform routine cleaning of the entire facility to eliminate the ac-

cumulation of fats, oil and grease on surfaces other than kitchen

surfaces. Other maintenance may include the following:

Grease Trap Maintenance (electro-magnetic or automatic

grease interceptor [or AGI])

Remove contents of solids strainer and outside grease

cup.

Clean wiper blades and grease outlet.

Remove solids from entire trap and clean.

Change wiper blades as necessary to maintain efciency.

Reset auto timer.

Grease Trap Maintenance (passive system)

Remove the accumulated grease and place into a con-

tainer for recycling.

If possible, remove the bafes.

Scrape any remaining greasy residue from the trap walls,

lid, and baffles.

Return the bafes to their position.

Make note of the date, volume of grease removed, and

other maintenance details in a maintenance log.

Grease Interceptor Maintenance

These devices should be maintained by a professional

grease hauler or recycler, however, it is a paid service. It

may be in the best interests of the commercial owner/man-

ager to understand what should be done to maintain the

interceptor so that the service received warrants the cost

of service. Pump the grease content from the grease interceptor.

Remove any excess residue from the walls, lid and bafes

of the interceptor.



Close the lid and wipe the surface clean.

Make note of the date, volume of grease removed, and

other maintenance details in a maintenance log.

BMPs for Employees

In addition to the proper installation and use of devices to control

the amount of fats, oil and grease that enter the collection system,

there should be some best management practices established forthe employees of commercial businesses to eliminate unnecessary

disposal of fats, oil and grease. Some of those best management

practices might include the following:

Establish and post guidelines for proper disposal of fats, oil

and grease for personnel of commercial businesses. Speci-

cally target the following employee practices as part of those

guidelines:

Do not pour any fats, oil or grease from cooking down a

sink or drain.

Wipe fats, oil and grease from pots, pans, utensils and

surfaces with scrapers, paper towels, or other absorbentmaterial and discard in a trash receptacle.

Use water at a temperature of 140F or less in all sinks.

Discard any yellow grease in a container to be rendered

and recycled.

Use absorbent paper products to catch grease beneath

fryer baskets.

Perform initial cleanup of all surface areas with absor-

bent paper products. Cloth materials will collect fats, oil

and grease and can be washed down the sink or drain.

Consider the reduction in use of garbage disposals.

Eliminate the disposal of food particles down sink drains

or other facility drains.

Frequently clean/wipe down exhaust hoods.

Maintain the use and cleanliness of drain screens.

Use a cover when moving the contents of a container with

fats, oil or grease to eliminate spills.

Maintain a spill kit.

Recycle fats, oils and grease whenever possible.

Keep outdoor grease containers and holding tanks tightly

covered and secured.

Never pour fats, oil or grease into a storm sewer.

If grease containers must be near a storm sewer, place absor-

bent pads in the sewer to capture any spill before it enters the

sewer.

Use appropriate absorbing materials for outdoor spills (sug-

gest an alternative to cat litter), remove them upon absorp-

tion, and dispose in a trash receptacle. Cat litter and saw dust,

if left out, can be washed into gutters and storm drains.

Wash mats, trash cans, and grills indoors so that wastewater

and cleaning detergent flow through a grease interceptor or

trap and not into gutters or storm drains.

Residential BMPs

It is up to each community to determine how to effectively regu-

late the disposal of fats, oil and grease into their sanitary sewer

systems. While designing guidelines for commercial businesses, it

is also important to consider the impact of a residential awareness

or education program regarding proper disposal of fats, oil and

grease. Both are contributors to the sanitary sewer system. Hav-

ing guidelines for one without some type of recommendations for

the other would be ineffective if the goal is to limit the amount of

fats, oil and grease entering the community sewer system.

A training program to educate the public on properdisposal of F. O. G. that begins with residential practices is

worth its weight in gold. These educational programs can

benefit the wastewater collection system, wastewater lift

station, wastewater treatment plant, and the community.

The public should be made aware of all collection and recy-

cling efforts available locally and the cost, if any, for these

services.

The public needs to understand the nature of the grease

and how it affects the integrity of their plumbing. They

should also understand the affects that F. O. G. has on city

piping and structures and the cost that can be passed on tothem as a result of costly repairs. The public should know

how the overflows can affect the environment, stream,

lakes, rivers, and reservoirs. They should understand the

state and federal regulations that target discharges to local

water systems and how spills and overflows can be costly

for the community. An effective public education program

must include suggestions for proper disposal of all fats, oil

and grease and any community programs that could make

that disposal easy for them.

Emphasize that proper disposal of F. O. G. helps to

eliminate foul drain odors in their homes. Also, disposing

of fats, oil and grease in a trashcan helps prevent blockages

in residential drains and keeps the homeowner from having

to call a plumber to unblock costly grease backups.

The public should be discouraged from putting kitchen

any form of F. O. G. down the garbage disposal system,

especially with hot water. It is always best to wipe out pots

and pans before hand-washing or placing in a dishwasher.

Plates and utensils should be thoroughly rinsed before be-

ing placed in the dishwasher. Home kitchens should keep

all sink strainers and floor drain covers in place.

A number of communities across the country have es-

tablished fats, oil and grease programs aimed at educating

all members of the communityresidential, institutional,

and commercial contributors to the sanitary sewer sys-

temon the acceptable disposal practices established in

their communities. The web is a wonderful resource for

those who wish to research such programs. Search fats, oil

and grease programs to discover a wealth of information

on the internet.

Many communities offer recycling centers for motor oil.

Used motor oil never belongs in community drains of anykind. Instead, educate residents on the ease and benefits

of recycling. It is as simple as collecting used motor oil in

a sturdy plastic container (milk jugs work perfectly) and



transporting it to a local recycling center or service station

for disposal. The center usually has a log where residents

can indicate the date the oil was recycled and how much

was added to the receptacle. It is simple, usually free, and

beneficial to the environment.

VII. Summary

Fats, oil, and grease wreak havoc on municipal collection systemsand wastewater treatment plans. They hinder and clog piping

systems intended to effectively treat wastewater. The first step to

remedy this problem is public education. If humans can learn to

limit the disposal of these wastes into the wastewater system, it will

greatly benefit municipalities in terms of maintenance and cost.

The next step is to remove as much of these nuisances from the

systems they have inltrated. Current methods of removal, if used,

will improve the wastewater treatment processes, prevent possible

federal and state violations, and help to protect the environment.


12/1412 www.WaterWorldCE.com

Questions

Online CompletionUse this page to review the questions and choose your answers. Return to www.waterworldce.com and sign in. If you have not previously purchased

the program select it from the Online Courses listing and complete the online purchase. Once purchased the exam will be added to your Archives

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and/or printing. Verification Forms can be viewed and/or printed anytime in the future by returning to the site, sign in and return to your Archives Page.

2011. Texas Engineering Extension Service. All Rights Reserved.

1. A grease trap is instal led under asink where disposed water flows from

the ________ into the grease trap.A. fryerB. sink drainC. prep tablesD. HVAC

2. In a grease interceptor, wastewatertravels over a series of ________inside the interceptor that separatesthe fats, oil, and grease depositsfrom the rest of the wastewater.

A. rakesB. tubesC. bafesD. sponges

3. F. O. G. stands for ________,________ and ________.

A. fats, oxygen, gasesB. fuel, oil, gasC. fats, oil, greaseD. fats, oxygen, grease

4. Some commercial contributors of F.O. G. to the sanitary sewer systeminclude which of the following?

A. restaurantsB. fishing vesselsC. schools and collegesD. a and c

5. F. O. G. affects a municipal wastewatertreatment facility in the following ways:

A. It clogs pump volutes.B. It can kill bacteria necessary for

wastewater treatment processes.C. It adds unwanted oating

material to primary andsecondary treatment tanks.

D. All of the above

6. Best management practices forcommercial control of F. O. G.include which of the following:

A. Do not pour any fats, oil or greasefrom cooking down a sink or drain.

B. Discard any yellow greasein a container to berendered and recycled.

C. Keep outdoor grease containersand holding tanks tightlycovered and secured.

D. All of the above.

7. Fats, oil and grease that are poureddown a residential kitchen sink with

hot water are likely to ________.A. collect elsewhere in the

sanitary sewer systemB. disintegrateC. help to digest matter in the

sanitary sewer systemD. congeal

8. Grease is a ________.

A. triglycerideB. cause of blockages in

the collection linesC. contributor to sewage overowsD. all of the above

9. Some best management practicesfor residential homeowners includewhich of the following?

A. Wipe out pots and pans before hand-washing or placing in a dishwasher.

B. Install a grease trap in the kitchen.C. Use hot water when pouring

grease down the sink.D. Only dump motor oil in

the drain at the street.

10. A common method of control isthe use of a(an) ________ productthat helps to relocate the greasedown the collection line.

A. acidB. fertilizerC. surfactantD. oxygen


13/14

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14/14

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