Methods and systems for enhanced dissolved gas floatation

A separation system (10) comprising:

• a pump (22) in fluid communication with a gas source and a fluid source, the gas source and the fluid source configured to deliver a gas (26) and a fluid (24), respectively, to the pump (22), the pump (22) comprising:
• a housing that defines a first chamber (54);
• an impeller (56) disposed within the first chamber (54) and defining a front section (58) in front of the impeller (56) and a back section (60) behind the impeller (56);
• and
• a first gas inlet (68) associated with the front section (58) in front of the impeller (56) and a second gas inlet (70) associated with the back section (60) behind the impeller (56), the first inlet and the second inlet formed in the housing;
• the pump configured to introduce the gas (26) into the fluid (24) to form a fluid/gas mixture (20), the fluid/gas mixture (20) comprising a plurality of dissolved bubbles (28) having an average bubble size of 100 micron or less;
• and
• a floatation unit (12) comprising an amount of a waste stream having oil droplets (33) of an average oil droplet size, the floatation unit (12) comprising an inlet in fluid communication with the pump (22) for receiving an amount of the fluid/gas mixture (24) therein, wherein the average bubble size is dependent on a ratio of the gas (26) introduced into the first gas inlet (68) and the second gas inlet (70);
• and
• wherein the controller (46) is configured to regulate the ratio of gas (22) introduced to the first gas inlet (68) and the second gas inlet (70).

A separation process comprising:

• dissolving an amount of a gas (26) in a fluid (24) within a pump (22) to form a fluid/gas mixture (20) comprising a plurality of dissolved bubbles (28), dissolving including introducing a first amount of gas into the pump from a floatation unit via a first gas inlet and introducing a second amount of gas from a discrete gas source into the pump via a second gas inlet;
• modifying a ratio of the first amount of gas to the second amount of gas to change an average bubble size;
• during the dissolving, increasing an electrical frequency of the pump (22) to increase a motor speed of the pump (22) and increase an amount of the gas (26) drawn into the pump (22), wherein the increased electrical is effective to provide an air bubble density in the fluid (24) of at least about 9% by volume;
• delivering the fluid/gas mixture (20) from the pump to the floatation unit (12) comprising a waste stream (18) comprising an amount of oil droplets (33) therein;
• releasing the dissolved bubbles (28) from the fluid/gas mixture (20);
• and
• separating the oil droplets (33) from the waste stream (24) in the floatation unit (20) via attachment of the released bubbles (28) to the oil droplets and rising of the oil droplets (33) toward a fluid surface in the floatation unit (12).