Produced water treatment flotation

Induced Gas Flotation. Mechanically induced gas dotation (IGF) is employed extensively to remove suspended solids, oil, and other organic matter from oil-field and refinery wastewaters. Consequently, these IGF units are particularly suited to the treatment of oil-in-water or reverse emulsions. Such units generally follow gravity oil-water separation units such as FWKOs, gun barrels, and skim tanks in oil-field-produced water-treatment schemes, and also handle the oily water streams generated from all treaters in a specific produced-fiuid treatment plant. 

The volume of wastewater produced from a potable water treatment plant (either a conventional sedimentation filtration plant or an innovative flotation filtration plant) amounts to about 15% of a plant s total flow. Total wastewater recycle for production of potable water may save water and cost, and solve wastewater discharge problems [15,35-38]. 

Environmental regulations prohibit disposal of produced water without primary and. in some instances, secondary treatment. Corrugated-plate interceptors, cross-flow separators, flotation units and other specialized equipment is required to reduce hydrocarbon content to acceptable levels. Authors discuss various equipment used in water treating. Next month, equations and empirical rules to help the engineer select appropriate treating equipment wilt be provided. 

Gas flotation imits require a customized chemical treatment program to achieve adequate results. If produced water originates from several somces in variable quantities, the development of a chemical treatment program may be difficult. 

Fig. 16. Two-hquid flotation flow sheet (39). The original ROM is kaolin (white clay) that contains 11% impurity in the form of mica, anatase, and siUca. Treatment produces high purity kaolin and a Ti02-rich fraction. A, Kaolin stockpile D, dispersant (sodium siUcate plus alkah) W, water K, kerosene C, collector (sodium oleate) RK, recycled kerosene S, screen M, inline mixer SPR, separator CFG, centrifuge P, product and T, to waste.

This facility produces 110 m2/h of enameled steel and operates 4000 h/yr. It uses 0.0042 m3 water/m2 of product in coating operations. Average process water flow is 1.69 m3/h for coating operations and 0.466 m3/h for metal preparation. The primary in-place treatment is chemical coagulation and clarification. Clarification can be either settling or dissolved air flotation. 

Plant 000005 produces approximately 3.2 X 10" kkg/year (7.0 x 10 Ib/year) of isobutene-isopropene rubber. Wastewater generally consists of direct processes and MEC water. Contact wastewater flow rate is approximately 1040m /day (2.75 x 10 gpd), and noncontact water flows at about 327 m /day (8.64 x 10" gpd). Treatment consists of coagulation, flocculation, and dissolved air flotation, and the treated effluent becomes part of the noncontact cooling stream of the onsite refinery. 

Hydrotalcite is often too fine grained to produce treatment columns with suitable permeability. As an alternative, the sorbent may be mixed with contaminated water in a tank (Lazaridis et al, 2002). The spent sorbent is then separated from the treated water by flocculation, flotation, or other separation methods (see Section 7.2.4). Lazaridis et al. (2002) investigated the use of surfactants with dispersed-air flotation to separate spent hydrotalcites from treated water. At ionic strengths of 0.1 M using KNO3, effective flotation and separation could be obtained by using a mixture of dodecylpyridinium chloride, sodium dodecylhydrogen sulfate, and a cetyltrimethyl ammonium bromide frother (Lazaridis et al., 2002,322,323). 

The raw minerals mined from natural deposits comprise mixtures of different specific minerals. An early step in mineral processing is to use crushing and grinding to free these various minerals from each other. In addition, these same processes may be used to reduce the mineral particle sizes to make them suitable for a subsequent separation process. Non-ferrous metals such as copper, lead, zinc, nickel, cobalt, molybdenum, mercury, and antimony are typically produced from mineral ores containing these metals as sulfides (and sometimes as oxides, carbonates, or sulfates) [91,619,620], The respective metal sulfides are usually separated from the raw ores by flotation. Flotation processes are also used to concentrate non-metallic minerals used in other industries, such as calcium fluoride, barium sulfate, sodium and potassium chlorides, sulfur, coal, phosphates, alumina, silicates, and clays [91,619,621], Other examples are listed in Table 10.2, including the recovery of ink in paper recycling (which is discussed in Section 12.5.2), the recovery of bitumen from oil sands (which is discussed further in Section 11.3.2), and the removal of particulates and bacteria in water and wastewater treatment (which is discussed further in Section 9.4). 

Free oil is readily removed by mechanical gravity separation devices. Unstable oil-water emulsions can be broken mechanically or chemically. It is the stable oil-water emulsions which are most difficult and at the same time most. amenable to treatment by UF. Chemical coagulation/flotation or contract hauling are usually more expensive alternatives. Further, all chemical treatment methods produce a sludge in which the dirt, floe and trapped water remain in the oil phase. 

A special kind of nonaqueous foam known as bituminous froth is produced during the application of the hot-water flotation process to Athabasca oil sands, a large-scale commercial application of mined oil sands technology. These froths are multiphase, composed of oil, water gas, and solids, and form an interesting kind of petroleum industry foam. This chapter presents a review of the occurrence, nature, properties, and treatment of bituminous froths. 

Pressure flotation is used especially for the treatment of industrial wastewaters from petrochemistry, pulp and paper mills, production plants of flbreboards, canning factories and other plants producing wastewaters with a high amount of substances whose density approaches the density of water. It is also used for sludge concentration [46]. 

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