STW, an independent solutions provider, works with a number of equipment manufacturers that offer the best technologies for our customers' needs. These technologies include thermal evaporation, membrane technology and reverse osmosis and are available as fixed or mobile units with varying capacities. Various pre and post-treatment options are available as necessary including crystallizers that process very high TDS (>150,000 mg/l).
Thermal Evaporation
This process is capable of handling waters that contain up to 150,000 mg/l TDS, with fresh water recovery rates from 50 to 90% or greater depending on inlet water quality. The recovered fresh water, or "distillate", is highly purified water from the evaporative process and has multiple re-use applications. It is particularly applicable in the gas shale and oil production facilities for reclaiming frac and produced waters. The technology is scalable and can be deployed as mobile units that can process 72,000 gallons per day ("gpd"), or as portable units that can process 216,000 gpd, or as fixed central units capable of processing up to 2,880,000 gpd. Residual brine concentrate can, depending on local conditions and producer's priorities, either be disposed of in deep injection wells or be treated further through a Crystallizer that reduces it into distillate and commercially valuable salt residuals.
Reverse Osmosis
Waters that are below 34,000 mg/l of total dissolved solids and contain low levels of barium, strontium, bromine, and sulfate can be reclaimed through a reverse osmosis unit (RO). Reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a semi-permeable membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. The membranes used for reverse osmosis are generally designed to allow only water to pass through while preventing the passage of solutes (such as salt ions). This process is best known for its use in desalination (removing the salt from sea water to get fresh water), but it has also been used to purify fresh water for medical, industrial and domestic applications. Recovery rates for seawater to drinking water are about 50%. A stream of concentrated brine or higher TDS is the by-product. This brine can be properly disposed of or utilized as a feed solution to a brine concentrator or crystallizer. The latter ensures higher quality water with lower TDS levels for industrial uses. Most oilfield waters cannot be processed through an RO membrane since they contain barium, strontium, or bromine. The barium and strontium are very large molecules and they plug the membrane and create damage or permanent fouling of the membrane. Bromine and other such halogens react with the membrane and destroy its integrity. There are few oil field waters that could be processed through this technology but a thorough study is required to ensure success. STW Resources will utilize this technology where the water chemistry can be processed through RO membranes.
Membrane Bioreator
A Membrane BioReactor ("MBR") is a combination of biological and ultrafiltration technologies for use in municipal wastewater applications. The biological area provides the same process utilized in all sewage treatment facilities. Bacteria are maintained in an aerobic condition which cause decay in all of the organic materials contained in the water, and oxidizing these organic materials into low molecular weight acids, usually acetic acid. Maintaining the bacteria in an oxygen rich environment prevents mutation or growth of any anaerobic bacteria, which would produce inorganic acids such as hydrogen sulfide. A filter membrane removes the water fraction from the unit. The membrane provides filtration in the 0.01 microns or lower range, which is sufficient enough to remove viruses, bacteria, and other colloidal materials. The water exiting the units is potable water and safe for human consumption.
Services
• Analysis: STW's expertise in water management and water chemistries allows us to achieve the desired outcome with the most cost effective solution.
• Regulatory: STW's provides broad experience working with federal and state regulatory agencies on best practices, permitting, and the development of new technologies.
• Technology: Working with a wide range of suppliers allows us to offer the most efficient treatment processes regardless of inlet water qualities.
• Implementation: STW works with manufacturers and EPC companies through the entire process of design, construction, and start up of operations.
• Operations: STW provides continuous operations of treatment processes along with analytical reporting to assure the desired outcome STW has relationships with all major equipment manufacturers, enabling it to get competitive pricing, delivery and financing on equipment purchases.