A fatberg is a congealed mass in a sewer system formed by the combination of flushed non-biodegradable solid matter, such as wet wipes, and congealed grease or cooking fat. Fatbergs became a problem in the 2010s in Britain, because of ageing Victorian sewers and the rise in usage of disposable (so-called “flushable”) cloths.
Fatbergs form at the rough surfaces of sewers where the fluid flow becomes turbulent. In pipes and tubes with smooth inner linings, fluid near the containing wall flows only slightly slower than fluid in the central channel of the pipe; thus, the whole volume of fluid flows smoothly and freely. When fluid encounters an obstruction, a resulting swirl of water starts trapping debris.
In some areas, such as London, fat blocked in a sewer can react with the lining of the pipe and undergo saponification, converting the oil into a solid, soap-like substance.
Grease and fat blockages can cause sanitary sewer overflows, in which sewage is discharged into the environment without treatment. In the United States, almost half of all sewer blockages are caused by grease. By using a grease trap, the amount of FOG (fat, oil and grease) reaching the sewer from commercial hot food premises, such as restaurants is greatly reduced.
Fatbergs have been considered as a source of fuel, specifically biogas. Most of the fatberg discovered in Whitechapel in London in 2017, weighing 130 tonnes (130,000 kg) and stretching more than 250 metres (820 ft), was converted into biodiesel.
Curated with thanks from Wikipedia.
Junge, Peter Heinz
Dishwashing or dish washing, also known as washing up, is the process of cleaning cooking utensils, dishes, cutlery and other items to prevent foodborne illness. This is either achieved by hand in a sink using dishwashing detergent or by using a dishwasher and may take place in a kitchen, utility room, scullery or elsewhere.
Most institutions have a dish-washing machine which sanitizes dishes by a final rinse in either very hot water or a chemical sanitizing solution such as dilute bleach solution (50-100 parts per million chlorine; about 2 ml of 5% bleach per litre of water, approximately one capful of bleach per gallon water). Dishes are placed on large trays and fed onto rollers through the machine. Dishwashers typically exceed 145 °F (63 °C) and kill all germs, while hand-washing reaches temperatures of at most 104 °F (40 °C).
Bleach is less effective in the presence of organic debris, so a small amount of food residue can be enough to permit survival of, e.g., Salmonella bacteria. Scrubbing followed by soaking in bleach is effective at reducing Salmonella contamination, but even this method does not completely eliminate Salmonella bacteria.
In hand-washing, plastic brushes with nylon bristles are preferred to washcloths or sponges, which can spread microorganisms. Use of soap or sanitizer is mandatory in washing by hand in public food facilities.
Use of hot water and or bleach may sanitize the dishes, however, it does not get rid of FOG (fat, oil and grease). In commercial food preparation units, a grease trap is necessary to trap the FOG items, so they cannot enter the sewage system to contribute to the development of a fatberg.