Point of Use Water Recovery for High Technology Application
Exergy’s EthorCEL® is our first patented platform for point of use recovery and reuse of high purity water, in high technology applications. EthorCEL® recovers 90% of the incoming feed rinse water, removing 99% of the incoming impurities at 1/3 of the cost of conventional water purification technologies.
Advanced Advanced Electrodeionization (AEDI) devices remove ionizable constituents from water using ion exchange membranes, ion exchange resins, and a DC electrical potential. AEDI provides two technologies in one module: electrodialysis and ion exchange. Ion exchange membranes separate an ion exchange mixed bed from electrodes. The ion exchange resins remove ionic matter from process water, the electrodes provide electro-regeneration of the resin when energized by a DC rectifier.
Exergy’s AEDI system provides superior separation of ionic process solutions from wastewater and process water.
The AEDI modules are designed and built to ensure the purification of low TDS process water instead of using a mixed-bed filter. A TDS reduction to more than 99% can be accomplished with a standard AEDI skid. For the continuous rinsing of the AEDI module, conductive process water can be used and recirculated, so that no additional wastewater is generated. The resulting effluent from the AEDI rinsing is a low TDS liquid/gas mixture and the gas coming from the electrodes must be bled into the atmosphere. The described process provides a yield of 100% for the AEDI. The energy requirement for the different AEDI modules is 0.8 to 1.6 kWh/1,000 gallons of high-purity water. This depends on various process parameters such as process water quality, AEDI rinse feed quality and temperature. The applied DC voltage is normally between 100 and 300V depending on the type of the modules. The modules are connected electrically in parallel mode in order to keep the voltage as low as possible, independent from the system capacity (gpm). The quality of the water produced by AEDI depends on the process water quality. The specific resistivity of the purified water from process water with 12 ppm TDS quality or less than 20 S/cm at nominal capacity is almost 18.2 megaohm-cm. The diluate quality is only influenced at higher permeate conductivity.
There are two distinct operating areas for AEDI devices: enhanced transfer and electro-regeneration. In the enhanced transfer area, the resins within the device remain in the salt forms. In this area, the transport mechanism is ion exchange on the resin surfaces. The second operating area for AEDI devices is known as the electro-regeneration area. This area is characterized by the continuous regeneration of resins by electrically induced water-splitting reactions. The resins are “regenerated” to their hydrogen and hydroxide forms and this allows AEDI devices to transport compounds that ionize at pH values different from that of the water to be purified.
The AEDI devices operating in the electro-regeneration area can remove weakly ionized compounds by internally creating conditions favorable to ionization reactions. For AEDI mixed-bed devices, the primary objective of operating in the electro-regeneration area is to remove weakly ionized compounds, such as carbonic and silicic acids, and to remove weakly ionized organic compounds. In the electro-regeneration area, the resins in the ion depleting compartments remain conductive either because they are in the regenerated ionic forms, or because the solutes entering them that are relatively nonconductive in the water become conductive under the pH conditions within the resin beads.
Diffusion Dialysis For Acid Recycling (DD)
Exergy’s Diffusion Dialysis (DD) is a state-of-the-art technology that uses ion exchange membranes to recycle used or spent industrial acids. The membranes are installed in single or multiple stacks that is supported in a plate and frame structure. Exergy’s patent pending “one-piece” membrane spacers creates compartments with appropriate cell distances for optimum diffusion. Counter-current streams of spent acid and deionized water alternate through the cells. Free acid is transported from the spent acid stream into the deionized water stream. This stream (diffusate) is recovered acid for reuse in the process. The metals in the feed spent acid are rejected, and are carried as the dialysate, creating a waste stream for metal recovery or treatment.
Diffusion dialysis technology is used in the following industrial applications:
Typical applications include:
The technology is not suitable to handle acids in concentrations higher than 40%. In some instances, due to formation of metal complexes (such as zinc chloride), the separation of acid and metal ions are not possible. In addition, the technology is not designed to handle feed acid temperatures above 130ºF (40ºC).
The membranes require occasional replacement every three to five years, depending on the applications, and process requirements.
Exergy’s Diffusion Dialysis (DD) is a state-of-the-art technology that uses ion exchange membranes to recycle used or spent industrial acids. The membranes are installed in single or multiple stacks that is supported in a plate and frame structure. Exergy’s patent pending “one-piece” membrane spacers creates compartments with appropriate cell distances for optimum diffusion. Counter-current streams of spent acid and deionized water alternate through the cells. Free acid is transported from the spent acid stream into the deionized water stream. This stream (diffusate) is recovered acid for reuse in the process. The metals in the feed spent acid are rejected, and are carried as the dialysate, creating a waste stream for metal recovery or treatment.
Exergy’s DD systems are modular; skid- mounted, and may be fully automated. The system includes high-quality, heavy-duty components:
Exergy’s DD skids can be customized with optional components, and custom DD systems can be provided to meet special plant requirements.
Simple System configuration illustrates passage of acid through ion selective membrane material and rejection of metal salts. Diffusate is the recovered acid product that is recycled. Dialysate is the water carrying metals salts to wastewater treatment or recycling.
Exergy’s Advanced Reverse Osmosis (ARO) achieves superior performance when compared to conventional Reversed Osmosis. ARO operates at 1,000 psi to produce higher concentrations in concentrates and better quality permeates. The ARO features recycle pump operation for the membrane housing, thus reducing the size of the pressure pump and the consumption of energy. ARO uses a proven membrane - including a patented membrane treatment process that allows the process to operate efficiently in a pH range from 0.5 to 13.
Exergy’s ARO technology can reduce operating costs significantly by enhancing recovery and reuse of valuable waste by-products.