19 January 2024

Grease traps: guide to efficient wastewater treatment

Growing concern about the climate and the environment has led to the search for solutions to solve the water crisis. In this context, grease traps emerge as crucial tools for the treatment and purification of waste water, so that these can be reintroduced into the environment, and reused for example for irrigation or in industrial production and washing processes.

These devices, also known as grease traps or biological grease traps, are designed to separate vegetable oils and greases suspended in gray wastewater, preventing blockages in the pipes and water contamination problems following the release of the oils into the environment.

How do grease traps work?

Grease traps are usually positioned upstream of a wastewater treatment plant, for example before an imhoff tank. A grease trap consists of a settling chamber, a stationary environment in which incoming wastewater slows its flow rate.

Due to the effect of gravity, oils and fats, lighter than water, float on the surface until they harden, while heavy sediments, such as solid food residues, settle on the bottom. Thus separated, the pollutants can be collected and removed by the grease trap, leaving only clean water to be safely discharged into the environment, or into the sewer system, or to proceed along the treatment plant to remove other potential pollutants.

How to choose a grease trap?

When choosing the type of grease trap, there are some factors to consider to identify the device best suited to your needs.

• Size and capacity. The size of the grease trap depends on the number of equivalent inhabitants, i.e. it is linked to the waste water to be managed and the waste generated by the activity. Di Camillo Serbatoi makes grease traps from 1 to 1000 inhabitants, therefore with a capacity of 110 up to 35 thousand litres. Di Camillo Serbatoi’s Infinitenk polyethylene grease traps, for example, are designed to meet the needs of company canteens, large communities or hotels with a large number of daily meals.
• Easy maintenance. Regular maintenance is essential to guarantee the functioning of the device over time: it is necessary to periodically check that no coarse bodies are obstructing the inlet and outlet pipes, and once a month make sure that the grease level does not exceed the bottom of the pipe exit. Furthermore, every 6-12 months you should contact a service company for a complete and professional cleaning of the grease trap. To facilitate these operations, Di Camillo Serbatoi grease traps have two upper nozzles for inspection, cleaning and maintenance.
• Regulatory compliance and certifications. The grease trap must comply with a series of national and regional regulations, and therefore possess a series of certifications of compliance with quality and safety standards. All Di Camillo Serbatoi grease traps, for example, are certified according to the UNI- EN 1825-1 standard, which prescribes the design and construction principles.
• Construction materials. The durability of the grease trap depends on the resistance of the materials with which it is built. Di Camillo Serbatoi’s underground grease traps, for example, are made of polyethylene, and with a corrugated shape, equipped with reinforcing ribs, which increases their sturdiness, and allows for easy burial.

Reference legislation

In Italy, the use of grease traps is regulated by specific regulations on environmental and safety standards. Legislative Decree 152/2006, known as the “Environmental Code“, establishes for example the maximum discharge limits for various pollutants, including oils and fats, which companies must comply with by adopting measures such as the installation of grease traps.

There are then two specific standards, which define the design, sizing and use criteria for grease traps.

• UNI EN ISO 1825-1, “Grease separators – Part 1: Principles of design, performance and testing, marking and quality control”
• UNI EN ISO 1825-2, “Grease separators – Choice of nominal dimensions, installation, operation and maintenance”, which includes a list of activities (restaurant, canteen and hotel kitchens, meal and food production plants, meat processing or other vegetable oil and fat refinery plants, soap factories…) which must include a grease trap for the treatment of gray water produced by their activity.

However, there are specific regulations for the regions of Emilia Romagna, Molise and Umbria, which may prescribe the use of specific grease traps for the discharge in tab.3, or grease traps sized on the number of lids for activities such as restaurants and canteens. To make sure that your grease trap is approved and complies with all relevant laws and regulations, contact Di Camillo Serbatoi.With his decades of experience in the field of wastewater treatment plants, Di Camillo Serbatoi and his qualified technicians will be able to help you find the grease trap, and the wastewater treatment solution, best suited to your needs.