Waste Water Treatment

Skimovex are the leading, worldwide, producers of waste water treatment systems, designing, engineering and supplying bespoke individual systems through to complete plants for both onshore and offshore operations.

Fields of Application

Oily Water Treatment - Removal of oil from water, such as refinery effluent, tankfarm drainwater, ballast water, desalter effluent, condensate, cooling water, produced water (both on- and offshore), tank draw-off and injection water.

Industrial Effluent Treatment - Chemical, petrochemical, galvanic, steel and car industries.

Ground Water Treatment - Contamination of ground water can occur over large areas under industrial premises due to low-rate, but steady spillages over a large number of years. Examples include galvanising factories, waste disposal areas, tankfarms and chemical factories. Skimovex equipment can be installed to treat the contaminated groundwater in situ, usually by pumping it up and treating it in an above grade treatment package.

The range of Skimovex waste water treatment systems includes:

Plate Pack Separator (Inclined plate oil-water separators):

For operation at atmospheric or under pressure.

Options include:

• Downflow and crossflow plate pack.
• Steel tank for atmospheric operation.
• For below grade installation in concrete basin.

Flotation

For operation at atmospheric or under pressure.

Induced air/gas flotation

The air/gas above the liquid is used to aerate the liquid in order to facilitate decontamination. If a blanketing gas is used above the liquid (in cases where the unit is blanketed for safety or process reasons), the principle is the same.

There are two methods of operation for this type of system:

1) Impellor Type: An impellor creates a vortex, drawing air in and forcing the air-rich liquid into a cell in a controlled pattern so that it is evenly distributed. Once the two-phase liquid enters the cell, the air (or gas) is released as finely disseminated bubbles. The contaminating oil and/or solids adhere to the bubbles, which rise to the surface, where they are skimmed off.

2) Recycle Type: The wastewater enters the first cell, where clean effluent is injected under pressure. Inside the cell, a venturi creates a locally low-pressure area. Air/gasis sucked in from above the water level in the cell and injected along with the clean effluent below the liquid level. Bubbles are thus created, to which the impurities attach themselves and float to the surface, forming a froth which is skimmed off.

Dissolved air flotation.

In the Dissolved Air Flotation (DAF) process, very fine bubbles are generated by saturating a partial stream of treated water with air at a higher pressure and subsequently releasing this stream to atmospheric pressure at the inlet of the DAF unit. Peerless normally use a rectangular tank of a predetermined length/depth/width ratio where the flocculated water is mixed with the tiny airbubbles. These airbubbles attach themselves to the flocs, thereby reducing the density of the impurities. The flocs then float rapidly to the free liquid surface in the flotation basin, together with the entrained airbubbles A floating froth layer is formed and is removed on a continuous basis by the chain and flight scraper. The airbubbles are generated by dissolving air into a partial stream of the treated water. For this purpose, part of the DAF unit effluent water is pumped into a pressurisation vessel. During its residence time in this vessel, the air, supplied by the compressor, will dissolve into the water. Fron the pressurisation vessel, the water flows towards the inlet compartment of the flotation tank. Immediately prior to entering the raw water inlet pipe, the pressure is released to atmospheric conditions. At that moment the air until then in solution in the water, will come out of solution and form very tiny air bubbles ( in the range of 40-60 micron). These then attach themselves to the flocs, which rise to the water surface to form a froth layer. The De Oiler is used primarily to remove small concentrations of oil (100 - 2,000 ppm) from water. The underflow is very clean water, with nominally less than 20 ppm of oil content. The overflow is an oil rich stream, approximately 1-10% oil in water (depending upon feed concentration).

Hydrocyclones

Static & Dynamic.

The feed enters the De Oiler through a tangential inlet. Its velocity is converted into tangential velocity in the inlet area, imparting a centrifugal force on the fluids. As the feed moves down the conical section, tangential velocity increases, as does centrifugal force. The heavier water phase, which is subjected to higher centrifugal forces, moves to the outer wall of the cyclone. The lighter particles, primarily oil droplets, are displaced towards the inner core of the cyclone. The water phase exits the tailpipe as the De Oiler underflow. The oil core moves axially up the cyclone, due to backpressure on the underflow, and exits out the reject orifice as overflow. By maintaining a certain backpressure on the underflow, the oil core is forced out through the overflow outlet which has a reject orifice sized to achieve a flow of approximately 2-3% of, the total inlet flow.

Dual Media Filters

• Downflow pressure filters.

• Upflow pressure filters.

• Dual flow filters.

• Gravity filters.

Plate Coalescers/Dehydrators

• High velocity flow regimes.

• Entrained solids and large droplets.

Skimming Systems

• Fixed or floating type skimmers.