A skimmer is a device that collects and removes pollutants from the surface of the water. Skimmers are one of the basic pieces of equipment for an oil spill response plan and are most often used in conjunction with containment booms. The two most common skimmers on the market today are oleophilic and weir skimmers.
Oleophilic skimmers use materials that attract oil and repel water. This oil attracting feature allows the skimmers to be very efficient in not picking up any appreciable amounts of water even when oil is not present. Less water results in less disposal cost by not having to pay for water mixed with the collected oil. Oleophilic skimmers use a rotating element such as a drum, disc, or brush to collect oil off the surface of the water. The oil is then scrapped off the drum, disc, or brush by scrappers and the oil is deposited into a container for removal. These units are either powered by an air source or hydraulic power pack. The air or pneumatic systems tend to be cheaper to operate and more maneuverable. A small self contained air compressor or even the air supply from a vacuum truck is all that is required to operate them. The main drawback with pneumatic systems is they are difficult to operate in extremely cold environments that cause the moisture in the air line to freeze. Although hydraulic power packs work well in all weather environments they tend to be much more expensive to operate and not as easy to transport due to the size and weight of the power pack.
Weir skimmers float on the surface of the water where the highest concentration of contaminates are located. Weir skimmers collect oil while allowing water to flow through them. The weir is adjusted to skim the oil off the surface of the water and removed by a pump or vacuum system. The intake weir can be adjusted to allow the skimmer to remove thin or thick layers of oil. Some weir skimmers have self adjusting weirs and are a great advancement over the systems that relied on mechanical means to adjust the depth of the skim. Weir skimmers can be used for permanent insulation or emergency response systems. They are light weight, easy to transport, and can be operated by one person. They are however not as selective as the oleophilic skimmers and will collect water with the recovered oil.