The coalescing media creates a uniform cross-sectional resistance and the back pressure helps to evenly distribute the flow through the media. The bulk liquid flows through the coalescing media promoting intimate contact with the oil droplets and the media surface. The coalesced oil takes the least restricted path to exit and rises or floats through the media to the top of the bulk liquid surface. The separated oil accumulates on the bulk liquid surface and displaces the water. The oil layer continues to grow until it spills over an adjustable rotary pipe skimmer and into an integral oil reservoir from which it can either flow by gravity or be pumped to disposal or storage.
Solids entering the coalescing media encounter a 60° angle of inclination which is the optimum to promote the agglomeration of the fine particles and settling. The agglomerated solids slide down the inclined surface of the coalescing media and collect in the Sludge Thickening And Storage Chamber. The walls of the Sludge Thickening And Storage Chamber are sloped at 45° to ensure easy complete removal of the sludge.
The “oil free” effluent flows under a baffle over the effluent weir and into the effluent chamber. The treated effluent can either flow by gravity or be pumped to disposal or post treatment.
Gravity Separation of non emulsified oil water mixtures is a common practice. To separate emulsified oils chemical pretreatment for emulsion breaking must precede the separator. The oil, solids and water phases have different specific gravities and will rise and settle at different rates. Applying Stokes Law we can predict the separation characteristics and required retention times. To increase the efficiency of separation and to allow the removal of fine oil droplets smaller than 150 micron a Coalescing Media is recommended.
By placing an oleophilic (oil attracting) material in the waste stream the efficiency of separation can be dramatically improved. The fine oil droplets are attracted to and impinge on the media surface. The fine droplets on the media surface coalesce or agglomerate to form larger droplets. The droplets continue to grow in size until they are large enough and buoyant enough to break free and rise to the liquid surface where they are skimmed or decanted. The coalescing process enables the removal of smaller oil droplets than it is possible to remove with a conventional gravity separator.
The effectiveness of the coalescing media is dependent upon the media shape, media surface area, liquid and oil density, bulk liquid velocity and direction of flow. The media must also be designed to facilitate the removal of suspended solids and sludges.
The feed stream enters the Inlet Chamber and is evenly dispersed by a non clogging inlet distributor. Large or Heavy suspended solids fall out of suspension in the Inlet Chamber and collect in the Sludge Thickening And Storage Chamber. The bulk liquid flows across the Sludge Thickening And Storage Chamber through the coalescing media in the separation chamber.