Oil separators / Oil collectors are prefabricated systems for the wastewater treatment. They are installed in tank stations, car wash stations and car stations. They separate and collect silt and mineral oil products from the waste water in accordance with European Standard EN858. These systems are classified in 2 main categories:
• EN 858 class I with a coalescence filter
• EN858 class II gravity driven
Both types can be fitted with an Oil Stop Valve, which will stop flow at the system’s output, once oil concentration in the system’s exceeds the foreseen limits. Maximum concentration in HC at the output of a silt/oil separator Class I is 5mgr/lt and for Class II 100mgr/lt.
Nominal size of a separator is amount of maximal flow of wastewater it can be processed. It is calculated from several parameters accounting for geographical position, surface to be covered and the type of equipment.
1. Silt and Dirt Separator
Retains sand, silt and dirt as well as granular waster which can cause wear on mechanical parts or can be
accumulated in the next stages of the installation.
They are separated by gravity utilising the difference in specific weight of different materials within the waste. This principle is effective when the fluid to be separated is moving at low speeds to allow for adequate time for the heavy parts to settle out. After the separation, sedimentation is removed periodically.
2. Oil separator / Oil collector / Mineral Oil collector
Oil and other petrochemical products are separated from water, due to the different density. They are concentrated in the surface of the liquid. The slower the flow, the more effective the separation. The separator performance is tremendously improved using a coalescence filter. Small droplets of oil are absorbed over the coalescence material as the flow passes through the filter, forming bigger drops which can separate from the filter surface and buoyancy driven can float in the surface. The oil layer must to be removed periodically. Separator systems can be enhanced by installing sensor (alarm controllers) which detect the sediment level, the quantity of oil separated as well as the maximum height of wastewater in case of outflow blockage.