Why is FOG a problem in Wastewater Treatment plants

Fats, Oils and Grease, popularly known by its acronym FOG, has been a growing concern worldwide. It affects the performance of wastewater treatment plants and industrial treatment units. According to reports, 47% of sanitary sewer overflows occur due to FOG related issues in the US. Similarly, more than 50% of sewer blockages happen in the UK due to FOG.

Accumulation and solidification of fats, oils and grease on walls of the sewer system lead to blockage of pipes and clogging of the system. It directly impacts the flow of wastewater, resulting in overflow issues. The wastewater consisting of toxic substances may contaminate nearby water sources and cause environmental pollution, putting public health at risk. Therefore, efficient FOG treatment solutions are urgently required to maintain the performance of wastewater treatment plants.

Major Sources of FOG
Fats, Oils and Grease or FOG enters the system from different sources. However, major sources of FOG includes households, commercial establishments and industries. Generally, FOG is the by-product of the cooking process in households. Also, sewer blockages are many times reported due to cooking oil and fats being disposed of in the kitchen sink. In the case of commercial establishments, those areas with food services such as hotels, restaurants and cafes are affected with more FOG concentration. As for industries, food processing and manufacturing processes potentially generate an extensive amount of fats, oils and grease.

Physical Properties of FOG

  • FOG in its pure state is usually colourless and odourless but occurs in a liquid or solid-state with a very greasy texture.
  • It is insoluble in water. However, fats, oils and grease are soluble in organic solvents.
  • Density is less than water, and hence it floats on the surface of the water.

These stubborn physical characteristics of FOG makes it one of the most challenging things to be treated and removed from wastewater.

How FOG Affects Wastewater Treatment Plants
First, it is important to know that the rapidly growing urban population, rising number of food outlets and malfunctioning sewer networks contribute to FOG build up in the system. As mentioned before, FOG deposits on the drain surface and pipes cause clogging and overflow problems. It can also lead to more issues such as bad odour, pest infestation and pollution of soil, water and air. In addition, it can corrode the drain lines leading to expensive repair requirements.

As for wastewater treatment plants, due to the slow degradation process and high BOD requirement, fats, oils and grease cause a wide range of problems. In food processing industries, treatment plants get overloaded resulting in high operational and treatment costs. In raw sewage that flows into municipal treatment plants, FOG may account for about 25-35% of the total chemical oxygen demand. It can further lead to:

  • Clogging of the system, hence reducing and restricting the capacity.
  • Increase in time required for cleaning and maintenance of pipes
  • If the FOG isn’t efficiently removed from the receiving waters, it depletes the surface of oxygen
  • Additional energy and capacity is required for the wastewater plant to handle excess FOG
  • May affect the performance of microorganisms that feed on sludge, reducing effluent quality.

Other industrial problems include:

  • Foaming
  • Problems with Nocardia Filaments
  • High effluent TSS
  • Increased sludge volume


Solutions for FOG in WWTP
For the removal of FOG in wastewater treatment plants, bioremediation has emerged as an effective and efficient biological solution. Special microbial strains that produce lipase can effectively break down the triglyceride molecules of fat. Along with lipase, microorganisms also produce bio-surfactants that are useful in the bio-degradation process of fats, oils and grease by facilitating efficient growth of the microbes. The selected strains of microbes work towards rapidly breaking down FOG as well as the reduction of scum. Moreover, rancidification of FOG is prevented, thereby eliminating odour released through accumulation.

Organica Biotech is a leading company with advanced bioremediation solutions. Cleanmaxx FOG is a microbial treatment solution capable of effectively treating wastewater plant effluent containing fats, oils and grease. The specially designed consortium of enzyme-producing microbes decompose fats, oils and grease aggressively and prevents scum formation. The emanation of odour from treatment systems due to the rancidification of oils is also prevented. Fats, Oils and Grease is a serious concern for wastewater treatment plants across the world. Using Cleanmaxx FOG can help in overcoming this challenge and maintain the efficiency and performance of treatment plants.

Post by Karen Sam