Nature's way, Our way

Grease Traps

Fats, Oil and Grease (FOG) upsets the wastewater treatment facility. When it reaches the aeration basin, it produces a very bad and terrible odor. It has to be separated at once or else the population will suffer from its consequence. It is therefore necessary that FOG be separated. Through the years separating FOG using grease trap have been a very tedious albeit challenging operation. In countries that do not enforce well its regulation on wastewater treatment, FOG are inadvertently thrown into the drainage.

This makes FOG one of the hardest wastes to treat. It clogs pipes and emits very unpleasant odor when it finds its way into the treatment plant. Worst still, FOG creates havoc in many known treatment technologies available. In a partially regulated sewage stream, wastewater treatment plant should have a formidable blocking mechanism to deter FOGs from entering treatment proper. For this particular difficulty we have found the appropriate solution in the Cyclonic Grease Stripping Column that we have integrated in our current designs.

THE CYCLONIC GREASE STRIPPING COLUMN

By: Jesselito V . Baring

INTRODUCTION

In the late 1800’s Nathaniel Whiting of California patented the passive gravity separator, a device known as a grease trap. That device remains relatively unchanged today as a means of separating fats, oils and grease from wastewater. Despite the fact that the said technology works well with a little modification from the original design, grease has remained a problem practically almost everywhere.

When grease enters the waste stream it creates a variety of problems and once fats, oils and greases have entered the waste stream they are rarely suitable for recycling because contamination form metals, chemicals and pathogens. The acronym “ FOG” is utilized in most contemporary references to fats oils and greases. This has something to do with the increased use of vegetable oils and fat substitute, in which case the present make up of greases is more than the various configurations of fats.

The first problem is not one which affects the wastewater system. Rather it is the loss of a potentially valuable resource. When recycled before being drained, FOG can be used in a variety of products such as soaps and cosmetics, fertilizer, lamp oil, animal feeds and munitions. Aside from the loss of a valuable potential commodity, when FOG enters the wastewater stream there is also a large and unnecessary economic loss due to other additional problems. Grease can block pipes, form aggregates which in turn can also cause blockages. Grease encapsulated solids can increase the time and cost of treating the wastes at wastewater treatment plant. It also can generate highly objectionable odor that is almost unbearable to human beings.

The problems are not specific to a particular size of wastewater collection system or treatment facility. Grease in a warm liquid may not appear harmful. But, as the liquid cools, the grease or fat congeals and causes mats on the surface of settling tanks, digesters, and the interior of pipes and other surfaces which may cause a shutdown of wastewater treatment units.

WHAT IS A GREASE TRAP AND HOW DOES IT WORK?

A trap is a small reservoir built into the wastewater piping some short distance away from the grease producing area. Baffles in the reservoir retain the wastewater long enough for the grease to congeal and arise to the surface. The grease can then be removed and disposed of properly.

WHAT IS A GREASE INTERCEPTOR?

An interceptor is a vault with a minimum capacity of 1000 gallons that is located on the exterior of the building. The vault includes a minimum of two compartments, and flow between each compartment is through a 90° fitting designed for grease retention. The capacity of the interceptor provides adequate residence time so that the wastewater has time to cool, allowing any remaining grease not collected by the traps time to congeal and rise to the surface where it accumulates until the interceptor is cleaned.

DO I NEED A GREASE TRAP?

A grease trap or grease interceptor will be required to receive the drainage from fixtures and equipment with grease-laden waste located in food preparation areas (e.g.,such as in restaurants, hotel kitchens, hospitals, school kitchens, bars, factory cafeterias, or restaurants, and clubs).

CYCLONIC GREASE STRIPPING COLUMN

Bad odor coming from grease invades the wastewater treatment facility. It is also been responsible for the flooding of waterways. The only available on-site grease stripping technology is the lowly grease trap. The maintenance of these grease traps is usually poor. Nobody wants to do it due to smell and stink of the floating mass on the traps. This problem has prompted us to deliver another kind of grease stripper that improve the grease collection efficiency and on the odor generated.

Grease coming from the kitchen is one of the most problematic areas in wastewater management. It clogs up the drainage line and disrupts treatment operation. It is highly odorous and there is no known treatment of this kind of waste as of this time. Even its disposal poses an even bigger problem and the only way it can be disposed is through some unconventional means which could be violating environmental laws.

Problems encountered in Oil and Grease Management is as follows:
a) Manual excavation of septic tanks for floating solidifying grease
b) Actual regular septic haulers for the septic tanks having this oil and grease.
c) Three shifts manual scrapping of the floating oil and grease from the present STP.
d) Actual throwing of the collected grease from other places

OBSERVATIONS GATHERED FROM THE OPERATION OF THE GREASE STRIPPING COLUMN

  1. The cyclonic grease (FOG) stripping column has been installed for more than a month as a pre-treatment for the mobile wastewater treatment facility.
  2. The influent pump is activated by level control and it shall be pumping every 10 to 15 minutes depending on the quantity of the wastewater received at the underground tank.
  3. Once the pump is operational, it can be observed that the liquid will be moving along the side of the column. A flowing liquid sound can be heard inside the column.
  4. The recirculating pump is also continuously operating such that when the two pumps are operating, there was an observed increase in turbulence of the wastewater in the column. Some droplets were observed to be spilling out of the column’s upper lids.
  5. When, for two days the recirculating pump was turned off, it was observed that bad odor developed within the area and caused unkind reactions from the people nearby.
  6. A liquid was drained at the bottom of the column. It was observed that the liquid taken out from the bottom of the column is totally different in terms of characteristics with the influent wastewater. The withdrawn liquid developed fluid motion in a minute while being held. The solids easily settled giving way for the clear portion to be seen readily.
  7. The odor of the withdrawn liquid together with the solid is not quite objectionable. It can be handled as compared to solids directly taken out of the grease traps.

FINDINGS

The Cyclonic Grease Stripping Column has performed its function as envisioned. It has removed and separated the grease coming with the raw wastewater of a big food catering facility. We have also found out that the regular draining of the columns should be done to unload solid accumulation of the column’s bottom. Excessive solid build-up will make the column inefficient in its grease removal function. Settling characteristics of the bottom’s solid make it ideal for the cloth filtration system. The filtration system should be an integral part of the cyclonic grease stripping column. The filtered solid can be easily dried out in the sun and be used for fertilizing plants.

An electrical or electronic switch will be installed to make sure that only one pump will be in operation at any given time.

CONCLUSION

After 200 years when the first invention of grease trap was patented, the cyclonic grease stripping column have revolutionized the handling and treatment of problematic grease that have been haunting our drainage system and wastewater treatment facility. We have found an appropriate solution to solve one of the recurring problems in wastewater treatment involving the handling and treatment of Fat, Oil and Grease (FOG).

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  • (032) 345 0890
  • (032) 920 905 1906
  • JV Baring building, Gov. Cuenco Ave., Banilad, Cebu City, Philippines
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