Environmental Engineering Reference
In-Depth Information
species contained in the luid, including natural species such as formation hydrocarbons
and added chemicals such as surfactants, foam inhibitors, and scale reducers.
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The compo-
nents of produced water can be grouped into the following categories:
• Dispersed oil
• Salts
• Dissolved volatile and semivolatile organics
• Barium
• Organic acids
• Naturally occurring radionuclides
• Oilield treatment chemicals
• Phenols
A number of treatment techniques to separate dispersed oil are currently available in
oilield management systems (lotation, skimmers, hydrocyclones, coalescers). These meth-
ods take advantage of the density difference between oil and water in a two-phase system.
However, a signiicant amount of dissolved hydrocarbons, organic acids, and metal ions
are not separated in these processes. Beyond water treatment, it may be conceivable to
harvest hydrocarbons contained in produced water through the development of processes
that can separate dissolved organics and metals from produced water in an economical
and sustainable manner.
Development of new technology to help manage produced water streams is of great
concern with petroleum operations expanding around the world in increasingly stringent
regulatory environments. Toward the goal of improved treatment methods, an organosilica-
based, swellable sorbent (trade name: Osorb
®
) has been developed that can reversibly
extract dissolved organics from water and thus shows good eficacy for produced water
management. The sorbent instantaneously swells up to eight times its dry mass in the
presence of organic liquids, yielding substantial force during expansion. Osorb is synthe-
sized using the process of molecular self-assembly, generating a porous material that is
nanoengineered to mechanically expand when selectively absorbing organics. The pore
size and hydrophobicity of Osorb is controlled in such a manner that organic solutes are
selectively captured without any absorbance of water. Absorption of dissolved BTEX
(benzene, toluene, ethylbenzene, and xylene), aliphatic hydrocarbons, organic acids, and
various production chemicals have been measured across a range of conditions. The per-
formance of two pilot-scale Osorb-based produced water treatment systems were charac-
terized. The irst system was a skid-mounted system that handles inputs of up to 4 gal/min
(gpm). The second system was a trailer-mounted system that handles inputs of up to 60 gpm,
and includes a processing unit for Osorb regeneration. The economics of using a regenera-
tive sorbent media to treat produced water was investigated using performance metrics
from bench-scale and pilot-scale tests.
8.2 Description of Swellable Organosilica Materials
Sol-gel chemical processing
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involves the generation of inorganic networks through the
formation of colloidal suspension (sol) and gelation of the sol to form a network in a con-
tinuous liquid phase (gel) (Figure 8.1). Precursors for this process are metal or metalloid
elements bonded by various reactive ligands. Sol-gels are typically synthesized from
alkoxysilanes, which react readily with water in the presence of an acid or base cata-
lyst. Polymerization follows the process of hydrolysis, alcohol condensation, and water
