FOG - Fat, Oil and Grease are a major challenge in wastewater treatment. FOG often includes emulsions, fatty acids solid components, solids composed of esters of glycerol, triglycerides derived from animal or vegetable sources
FOG - Fat, Oil and Grease are a major challenge in wastewater treatment. FOG often includes emulsions, fatty acids solid components, solids composed of esters of glycerol, triglycerides derived from animal or vegetable sources
FOG floats on water and quickly turns into soap in an alkaline medium. Such characteristics make FOG one of the most challenging substances to remove from wastewater. If discharged untreated, it can lead to serious environmental problems.
Some factories send their wastewater to municipal treatment plants for FOG removal, but it’s expensive. Instead, on-site treatment is becoming an increasingly attractive option for many industries.
FOG accounts for 25-35% of total chemical oxygen demand (COD) in raw wastewater flowing into municipal wastewater treatment plants. Although often discussed together, triglycerides that remain liquid at room temperature are considered “oil,” while “grease” refers to fats, oils, waxes, and soaps that clog pipes. It can coagulate with other materials into massive “fatbergs” that shut down sewer mains, like the 820-foot, 200-metric-ton fatberg discovered beneath the streets of Liverpool.
Each year, FOG is blamed for approximately 50% of the United Kingdom’s 25,000 flooding incidents.
Grease also makes aerobic and anaerobic treatment less effective, and subsequently, the lower-quality effluent can threaten aquatic ecosystems and groundwater. Even a low load can make water unsuitable for drinking.
Insoluble FOG is frequently removed by gravity separation. Because grease is 10-15% less dense than water, fats, oils and grease (FOG) float on top. When kitchen wastewater enters a grease interceptor, the grease rises to the top of the liquid level. This is possible through a system of baffles, plastic walls inside a grease interceptor tank to slow down and often control the flow of water. Captured grease fills the trap from the top down, while grease-free water exits through piping at the bottom of the trap into the following plumbing.
The oil refining industry and the meat, dairy, and food processing industries all need to remove FOG from their wastewater. Operators in many industries have opted to remove FOG on-site to meet environmental discharge standards or lower municipal disposal costs.
While high FOG poses many challenges in wastewater treatment, it does come with an advantage: Its high organic load is ideal for waste-to-energy systems. Wastewater from food production can carry 10 times the organic load of ordinary municipal wastewater, which already contains approximately five times the energy needed to treat it. Adding anaerobic digestion (AD) to wastewater treatment generates biogas that can be sold or used to power operations.
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Inadequate grease management can lead to high costs in commercial kitchens. To avoid fines, maintenance expenses, and operational disruptions, follow these seven strategies:
Local authorities are empowered to inspect premises under the Food Safety Act 1990. Issues caused by fat, oil, and grease in drains, resulting in non-compliance with Food Hygiene regulations, could lead to prosecution or an emergency prohibition order, preventing the premises from trading.
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