PollutionEngineering November 2012 : Page 34
Advertorial GREYLINE INSTRUMENTS INC. HOWTO: Choose the Right Technology for Flow Measurement from Outside A Pipe • (315) 788-9500 email@example.com • www.greyline.com/twotechnologies.htm D Doppler and Transit Time are two very popular types of flow meter for non-invasive mea-surement of flow in full pipes. We tend to confuse these technologies because they are both ultrasonic and both measure flow by using sensors clamped onto the outside of a pipe. In the real world, they actually work best in opposite applications. Success in your installation depends on under-standing the differences and making the right choice. Ultrasonics are a mature technol-ogy and widely used in medical and industrial applications. The clamp-on transducer design is popular because the flowmeters can be installed with-out cutting the pipe or shutting down flow. There is no pressure drop and the non-contacting transducers immune to chemicals, abrasives and pressure. They work on non-conductive fluids including oils and are not affected by electromagnetic fields or radiation. They have a wide temperature operat-ing range plus excellent properties of repeatability and reliable operation. WITH YOUR PAST, PRESENT AND FUTURE CUSTOMERS Our Expertise | Engaging Media Tools | Your Message Delivered IT’S ALL ABOUT CONNECTING BNP CUSTOM MEDIA GROUP Founded in 1926, BNP Media has over 80 years of experience in the publishing industry! Personalized Media Solutions for Your Organization Is your organization thinking about launching its own magazine, website, or e-Newsletter? How about creating g a video, coffee table book or webinar? Let our media a , staff experts do all the work for you, from start to nish, s producing a powerful media package that showcases your message in the marketplace. In today today’s highly competitive market, more retailers, manufacturers and agencies are taking control of their manufa most valued assets --customer relationships --through v custom custo media and creative integrated marketing. By tailoring messages in a controlled and targeted medium, you engage your market and strengthen me customer relationships. In fact, spending on custom c media has risen by more than 25 percent annually m over the past several years. Why? Because it works. o http://custommedia.bnpmedia.com 34 Pollution Engineering NOVEMBER 2012 For More Information, contact: SETH FISHER, 248-244-6248 firstname.lastname@example.org
How To Selections
Choose the Right Technology for Flow Measurement from Outside A Pipe<br /> <br /> Doppler and Transit Time are two very popular types of flow meter for non-invasive measurement of flow in full pipes. We tend to confuse these technologies because they are both ultrasonic and both measure flow by using sensors clamped onto the outside of a pipe. In the real world, they actually work best in opposite applications. Success in your installation depends on understanding the differences and making the right choice.<br /> <br /> Ultrasonics are a mature technology and widely used in medical and industrial applications. The clamp-on transducer design is popular because the flowmeters can be installed without cutting the pipe or shutting down flow. There is no pressure drop and the non-contacting transducers immune to chemicals, abrasives and pressure. They work on non-conductive fluids including oils and are not affected by electromagnetic fields or radiation. They have a wide temperature operating range plus excellent properties of repeatability and reliable operation.<br /> <br /> measure sulfur content in crude and fuel oils on-line<br /> <br /> Sulfur content plays a significant role in the economy, performance, and environmental impact of processing crude oil, hydrocarbon fuels, and other hydrocarbons.<br /> <br /> The combustion of sulfur-containing fuel oils produces sulfur oxides that are further oxidized in the presence of oxygen and moisture to create sulfurous and sulfuric acids that are detrimental to equipment and the environment. For this reason, the sulfur content of fuels is regulated, and recent Marpol Annex VI regulations lower the permissible sulfur content in marine fuels as well.<br /> <br /> On-line analysis of sulfur content has become the norm, primarily using X-ray spectrographic analyzers that offer cost-effective, nondestructive direct measurement of sulfur content. Two main X-ray technologies are useful for sulfur content determinations: X-ray Transmission (XRT) and X-ray Fluorescence (XRF). Each offers particular advantages and limitations. Analyzing these pros and cons, and comparing them to the requirements of various applications can help in deciding which is the right technology for each.<br /> <br /> In many cases, the analyzer must be able to operate at the pressures and temperatures typical of process pipelines, and that means the analyzer should require little or no sample conditioning. At the same time, tested samples should be returnable to the process to eliminate the need for effluent sumps or storage systems. And operating conditions typically involve high pressure and temperature. <br /> <br /> These conditions generally favor XRT systems. <br /> <br /> How X-Ray Transmission/ Absorption (XRT) Sulfur Analyzers Work <br /> <br /> X-ray Transmission/Absorption (XRT) systems consist of an X-ray source, a sample flow cell and an X-ray detector or counter. In on-line XRT analyzers, like the AMETEK 682T-HP, X-rays emitted from the X-ray source have high enough energy to pass through the flow cell’s beryllium entrance window, through the volume of oil inside the flow cell, through the beryllium exit window, and into the detector on the opposite side.<br /> <br /> As they pass through the sample, some of the emitted X-rays will be absorbed by molecules in their path. Sulfur absorbs X-rays at approximately ten times the rate of the primary components of crude and fuel oils (hydrogen, carbon and oxygen). Therefore, the number of X-rays emitted from the source that are counted at the detector is inversely proportional to sulfur content; i.e., the higher the sulfur content, the more X-rays are absorbed travelling through the sample and the fewer are counted at the detector. The analyzer can be calibrated in such a way that it can translate counts and display results directly in % sulfur.<br /> <br /> XRT analyzers, like the 682T-HP, offer several distinct advantages for on-line sulfur measurement. They require little, if any, sample conditioning, and no recovery system. They use a noncontact, nondestructive measuring technique that generates no waste products and requires no consumables. The technology is well suited for high-temperature and highpressure processes, and the relatively long X-ray path eliminates the effect of window fouling on results (fouling thickness is very small compared to the overall path length). No routine maintenance is required other than calibration.<br /> <br /> Among the limitations of XRT online analyzers is that only one element is detectable and the minimum detectable concentration is 200 ppm.<br /> <br /> For at-line and laboratory detection of very low sulfur content oils like lowsulfur diesel, energy-dispersive X-ray Fluorescence (EDXRF) systems offer a suitable alternative.<br /> <br /> Www.ametekpi.com<br /> <br /> Factors that Infl uence the Nozzle Material Selection Process<br /> <br /> Sometimes, selecting the right nozzle material can be simple. Other times, it can be very complex and confusing. Depending on how harsh (or mild) the environment is in any given process, determining the right material for a nozzle may be as easy as matching an installed material that has proven to weather the conditions just fine. Other times, there are factors that can lead to confusion about which material is best.<br /> <br /> Temperature. Melting or softening of material establishes maximum temperature limits. However, these temperature limits must be reduced when corrosion, oxidation, or chemical attack are also present.<br /> <br /> Corrosion. Material performance and reliability varies with exposure to different chemical types and concentrations. It is important to consider the properties of the environment where the nozzle is installed and the properties of the fluid spraying through the nozzle. Plastics offer superior corrosion resistance at relatively low cost, but can only be used in lowtemperature applications. In general, metals can be ranked in the following order of corrosion resistance (from lowest to highest): carbon steel, brass, stainless steels, nickel-based alloys, refractory metals and precious metals. Ceramics have excellent corrosion resistance except in very high pH environments. Corrosion and erosion are material related. Chemical attack causes corrosion while suspended solid particles abrading the surface lead to erosion. There is a very wide range of materials from which a nozzle can be made; proper selection of the nozzle material will minimize corrosion and erosion problems.<br /> <br /> Erosion. Abrasive wear, or erosion, can cause the nozzle to wear out prematurely, leading to increased flow and degraded spray formation. This leads to increased process fluid costs and unacceptable process quality. Hardened stainless steel, Cobalt Alloy 6, tungsten carbide, and ceramics are commonly used in applications where abrasive fluids are sprayed.<br /> <br /> Weight. There are times when minimizing structural weight is an important consideration. A nozzle made from a strong yet lightweight material such as titanium can be the perfect answer.<br /> <br /> Initial Cost vs. Total Cost. There are exceptions, but materials can generally be ranked in the following order in terms of cost (from lowest to highest): brass, carbon steel, plastics, stainless steels, cobalt-base alloys, nickel-base alloys, ceramics, refractory metals and precious metals. Beyond the initial cost of a nozzle, it is extremely important to consider the long-term costs of having a nozzle in a material not suited for the application. How much do the operating costs increase due to frequent shutdowns for nozzle replacement? What is the cost impact to a poor quality product or process due to a spray nozzle that wears out too quickly and performs poorly?<br /> <br /> Once the right material is determined, BETE can supply your nozzle no matter how exotic or routine that material may be.<br /> <br /> BETE uses three basic manufacturing processes: injection molding, CNC machining and investment casting. Injection molding is used for large quantities of nozzles made from plastics such as PVC, ABS and PVDF. CNC machining is often used for metal alloy and plastic nozzles that have relatively small quantities.<br /> <br /> Investment casting at our in-house foundry offers the flexibility to produce complex shapes in common or specialty alloys that provide a unique performance advantage to our customers. Having a foundry on our premises in Greenfield, Massachusetts means that we have total control of production quality and schedule at every step.<br /> <br /> BETE Fog Nozzle <br /> T (413) 772-0846 <br /> email@example.com <br /> www.bete.com<br /> <br /> Rapid Remediation of Large Plumes Using Horizontal Remediation Wells<br /> <br /> Large Plumes present many technical challenges because their aerial extents usually encompass surface features such howas roads, buildings, airports and wetlands, which can be difficult or impossible to access via vertical wells. Horizontal Remediation Wells (HRW) have been found to be extremely effective in delivering chemical treatments such as ISCO reagents, reductants, nanoparticles (ZVI), bioremediation reagents, ozone, oxygen, and air to zones of contamination. This article discusses the hows and whys of HRW and describes two typical successful HRW in-situ remediation projects.<br /> <br /> The advantages of HRW over stationary vertical wells are often dramatic. For example, HRW delivering ISCO reagents (HRW-ISCO) enhances remediation by : 1) reaching inaccessible locations; 2) concentrating the oxidant on hot spots; and 3) increasing contact area using long horizontal screens compared to vertical well screens. It is often said that “ISCO is a contact sport;” HRW increases the contact time for oxidants such as peroxide, permanganate and persulfate, which results in an increase in the rate of degradation of contaminants. A good example of the effectiveness of HRWISCO was demonstrated on a dry cleaner site in Maryland. The PCE plume extended laterally for over 1,000 feet beneath busy streets, utility corridors and occupied buildings and required rapid remediation due to redevelopment of the site. Directional Technologies designed and installed 10 HRWs for injection of permanganate during the site construction program without interrupting the project schedule. The results were impressive: PCE pre-HRW-ISCO concentrations were as high as 13,000 parts per billion and shortly after two HRW-ISCO injections, PCE concentrations averaged from nondetect to 400 ppb.<br /> <br /> HRW also can improve air-sparge efficiency. For example, HRWs rapidly remediated a large gasoline plume from a subsurface pipeline release in the Northeast. Directional Technologies installed a network of parallel HRWs, four air sparge and three soil vapor extraction, approximately 600 feet long to remediate the release. The horizontal well performance was extraordinary as the pilot test data for one of the wells demonstrates. Daily volatile organic compound recovery rates (in pounds per day) for SVE well HSVE-2 for the first six months of 2012 are presented in Exhibit 1.<br /> <br /> The VOC recovery rates ranged from 174 to 320 lbs. Per day, with a cumulative VOC recovery of 26,687 lbs. Over six months. These performance results were achieved by a single well, indicating that the full-scale horizontal well system will, and did, achieve site closure much more rapidly than any equivalent vertical well system. Why is HRW performance so impressive? Horizontal well screens deliver fluids (or induce a vacuum) into an impacted soil horizon evenly, as a line source, which is much more effective than the point sources provided by a series of vertical wells in the same formation (see Exhibit 2).<br /> <br /> HRWs can be used to rapidly remediated large plumes by providing significantly greater contact area with impacted media than vertical wells . Coupling horizontal directional drilling with long engineered well screens results in a unique, proven technology that consistently delivers superior results for ISCO, air sparging and other remedial treatments, which leads to less time onsite and significant cost savings.<br /> <br /> Contact Directional Technologies at 1-877-788-4HRW or email them at firstname.lastname@example.org to utilize their 20 years of experience in designing and installing horizontal remediation systems for your next in-situ project.<br /> <br /> Rapidly mitigate Vapor Intrusion Exposure Using Horizontal Remediation Wells<br /> <br /> Vapor intrusion (VI) in buildings of toxic contaminants, such as chlorinated solvents and petroleum hydrocarbons, is a critical exposure pathway that can threaten the health of children, workers and other human receptors at many contaminated sites. Mitigation of the VI exposure pathway is often confounded by the presence of the building itself, which limits the types of remedies that can be put in place. This article shows how horizontal remediation wells (HRW) can be used in a smart, fast and cost-effective way to extract (or treat) harmful gases from the subsurface and mitigate risk to occupants without affecting the integrity of the building.<br /> <br /> Two typical HRW projects rapidly mitigated VI issues in commercial structures using single, long horizontal sub-slab wells with impressive results. In the first project, the owner of a high-end office building leased the structure to an international corporation that used the building as its US headquarters. The structure is located in a highly urbanized area that was at one time used for industrial manufacturing and then later redeveloped into an office park. The structure measures approximately 320-feet by 100- feet, slab on grade construction. The owner became aware that VI may be an issue in the building and the owner’s environmental consultant recommended that an active VI mitigation system be installed. The building owner agreed but was adamant that the tenant’s operations could not be interrupted or disturbed in any way and that the VI mitigation system could not be installed inside the building.<br /> <br /> Directional Technologies mobilized its medium-size horizontal directional drilling rig to the building’s parking lot and advanced a single 320-foot long horizontal boring beneath the building’s centerline. The horizontal boring terminated at the opposite end of the building approximately three feet below the floor slab, as illustrated in Exhibit 1. Directional Technologies next withdrew the drill string and installed the three-inch diameter polyvinylchloride horizontal well screen and riser by pushing it into place with the drill rig.<br /> <br /> Exhibit 1 Horizontal VI Mitigation Well Orientation <br /> <br /> The owner’s consultant installed and began operating the surface-located vapor extraction blower system. Tests subsequently confirmed that the single horizontal well’s zone of influence was sufficiently extensive to depressurize the entire slab. DTI successfully completed this assignment in three days. <br /> <br /> In a second project at a multi-hundred thousand square foot former manufacturing facility (now a warehouse), chlorinated solvents were found beneath the floor slab, creating a VI issue. Directional Technologies installed a single 800-foot long horizontal well beneath the building’s centerline. Test results indicated that the horizontal well’s zone of influence was sufficient to depressurize the entire floor slab. In other words, the ZOI extended approximately 400-feet on either side of the horizontal well screen – an extraordinary result that mitigated the risk of exposure to workers (see Exhibit 2).<br /> <br /> Exhibit 2. Radius of Influence of HRW Vapor Intrusion Mitigation System.<br /> <br /> Directional Technology’s horizontal directional drilling experience, engineered well-screen design expertise and horizontal well installation methodology has a decades-long successful track record. Horizontal remediation wells are finding new applications such as Vapor Intrusion Mitigation because of their unique capabilities related to site/structure access, business-disruption avoidance, accelerated site closure and enhanced site safety. In addition, horizontal remediation wells consistently out-perform vertical wells because they provide an effective delivery mechanism to reach previously inaccessible contaminants such as those contaminants found beneath buildings. Cost-effective and expedited mitigation of the VI exposure pathway using HRW is a true advance in remediation technology.<br /> <br /> Contact Directional Technologies at 1-877-788-4HRW or email them at email@example.com to utilize their 20 years of experience in designing and installing horizontal remediation systems for your next in-situ project.<br /> <br /> Manage Back Diffusion from Low Permeability Zones using EOS XR<br /> <br /> Problem <br /> <br /> Chlorinated solvents and other persistent contaminants present in high permeability (K) zones (sands or gravels) will slowly diffuse into lower K zones (commonly silts or clays) over decades of exposure (loading phase in Fig. 1a), then gradually diffuse back out (back diffusion phase in Fig. 1b) through a process called matrix diffusion.<br /> <br /> Low levels of contaminants can be released to groundwater from the lowpermeability matrix over decades or even centuries after source removal, dramatically increasing site management costs. Figure 2 shows a common pattern in contaminant concentrations following source removal.<br /> <br /> Solution <br /> <br /> Injection of an emulsified vegetable oil (EVO) like EOS PRO is an excellent approach for rapidly reducing contaminant concentrations, and only needs to be injected once every 3 to 5 years. However, if contaminants slowly diffuse out of low K zones for decades, multiple reinjections could be required. If the reinjection frequency could be reduced to once every 10 or 20 years, this could dramatically reduce site management costs.<br /> <br /> EOS XR <br /> <br /> EOS XR is a premium, food-grade oil/ water emulsion developed by EOS Remediation, LLC to overcome the challenges of matrix diffusion. EOS XR is the only extended time-released substrate for cost effective management of matrix diffusion. EOS XR is a mixture of regular EOS® (fast release soluble substrate and medium release vegetable oil) and a proprietary slow release substrate that slowly ferments to hydrogen and acetate for decades, to treat chlorinated solvents and other persistent contaminants slowly released from low K zones, resulting in fewer substrate reinjections and lower costs.<br /> <br /> The analysis presented in Figure 3 shows the cumulative costs of using a soluble substrate, a traditional EVO and EOS XR when back diffusion from low K zones extends cleanup times. Increasing the time between reinjections to 10-20 yr can reduce costs by 65% to 95%.<br /> <br /> Using EOS XR can save a lot of money <br /> <br /> Control NOX, SOX, and PM – Industry’s 3 Major Pollutants – with a Single System<br /> <br /> UltraCat Catalyst filters systems by Tri-Mer Corporation remove NOX, ac i d ga s e s (including SO2 and Hcl) and particulate (PM), in one efficient system. They are also highly effective for the control of mercury and dioxins. The heart of the system is the latest generation of lightweight ceramic filters. Standard application of the ceramic filters is specified where gas stream temperatures are above 300°F.<br /> <br /> NOX: UltraCat catalyst filters are composed of advanced, low-density fibrous ceramic materials. Filter walls are embedded with nanobits of highly-efficient SCR catalyst. Injection of aqueous ammonia is integrated into the system. NOX and ammonia react at the catalyst surface and the NOX is converted into harmless nitrogen gas and water vapor. Unlike traditional SCR that requires temperatures over 600°F, the UltraCat nano-catalyst SCR allows effective NOX destruction at temperatures as low as 350°F. Destruction efficiencies above 90% are common.<br /> <br /> SOX: Acid gases are removed in the same system with integrated dry sorbent injection of sodium bicarbonate, trona, or lime. Injected upstream of the filter modules, the powdered sorbent reacts with the acid gas to form a solid particulate that is easily captured on the filter downstream. SO2 removal is typically over 90%, Hcl removal is typically above 95%.<br /> <br /> PM: The level of particulate at the outlet of the UltraCat is typically less than 2.0 mg/ Nm3 (about 0.001 grains/dscf) – even with inlet loadings over 10,000 mg/Nm3. The loading only affects how often the filters are cleaned with a reverse pulse jet of air. Particulate is captured on the filter face and does not penetrate, allowing complete, repetitive cleaning. This highly engineered filter does not blind like other filters; only after 5 to 10 years in service will the pressure drop gradually increase to the point where change-out is needed. Filters are effective on PM10, PM2.5 and submicron particulate.<br /> <br /> The UltraCat catalyst system is replacing the traditional ESP + Block SCR combination, and similar pollution control trains that might also include a semi-dry spray dryer or sorbent injection for acid gases. The filter systems deliver much better performance on PM and NOX, while offering both lower capital cost and lower operating cost.<br /> <br /> The ceramic filters are a choice far superior to ESPs wherever PM levels include a significant fraction of PM2.5 and submicron particulate. They handle much higher inlet loadings (which might include powdered sorbent loads that would overwhelm an ESP), are not subject to the selective removal constraints of ESPs, have lower maintenance requirements and fewer corrosion issues, and are energy efficient.<br /> <br /> If sorbents are used for acid gases, the formation of a sorbent cake on the filter surface greatly enhances exposure to the sorbent, resulting in significantly less sorbent consumption for an equivalent removal level compared to ESP.<br /> <br /> Tri-Mer Corporation is at forefront of air pollution control technology, providing turnkey engineering, manufacturing, installation and service from its Michigan headquarters.<br /> <br /> www.tri-mer.com<br /> <br /> Pump Wastewater/Chemicals Corrosion-Free<br /> <br /> With the increasing need to contain and treat wastewater comes a growing requirement to pump unknown pollutants from collection pits and transfer corrosive chemicals to wastewater treatment areas.<br /> <br /> Caustic and acidic wastewater treatment chemicals commonly attack pumps constructed of stainless steel or high alloys – all of which have annual corrosion rates – and can cause plastic lined pumps to delaminate, and fiberglass pumps to wick the fluid. In many cases, wastewater containing abrasives, cause metal, lined-metal and fiberglass pumps to wear, compromising efficiency and longevity.<br /> <br /> Corrosion-related pump problems can be eliminated, says Vanton Pump, by isolating the fluids being pumped, from any metal or fiberglass component.<br /> <br /> The company injection molds all wet end components of PVC (polyvinyl chloride), PP (polypropylene) and PVDF (polyvinylidene fluoride) which are abrasion resistant, and 100% inert relative to the fluid(s) being handled. The parts are molded thick-sectioned, stand-alone, replaceable components, and have smooth, tight-tolerance surfaces. In addition, they are virtually unaffected by wear, and are not subject to delamination.<br /> <br /> All wetted components of Vanton's SUMP-GARD® Vertical Centrifugal Pumps are of solid thermoplastics to resist the broad range of chemicals that can enter a sump pit during its life, significantly reducing the possibility of pump failure.<br /> <br /> CHEM-GARD® horizontal centrifugal pumps feature thermoplastic wet ends encased by structural metal armor, enabling them to handle the same nozzle loadings as metal pumps.<br /> <br /> Also offered are FLEX-I-LINER® Rotary Peristaltic Pumps for dosing/feeding of liquids and viscous fluids to 6000 SSU.<br /> <br /> All are offered individually or pre-configured with non-metallic tanks from 60 to 5,000 gal (227 to 1827 liter) complete with automatic level controls and remote control panels.<br /> <br /> Caustic Soda Pumps for Acidic Groundwater<br /> <br /> Acidic Groundwater Presents Corrosion Problems <br /> <br /> Over time, acidic groundwater adversely affects piping, valves and other components in residential water distribution systems. For many water districts, which have acidic groundwater, the solution is to inject caustic soda, (49 % sodium hydroxide solution), at the well site to raise the pH to approximately 7.8 to 8.4. <br /> <br /> For years, many water districts have been using diaphragm pumps to meter the caustic soda on order to raise the pH. The struggle has been with issues of varying accuracy and ongoing pump maintenance. Diaphragm pumps have check valves, which need to be routinely serviced. Also, the pump’s flexible diaphragm wears and deforms over time, causing accuracy drift between maintenance periods, and requires recalibration.<br /> <br /> Fluid Metering Inc. offered a solution by replacing the diaphragm pumps with Fluid Metering’s Model CTS Valveless Piston Pump system. FMI’s patented CeramPump® pumping principle uses one moving part, a rotating and reciprocation ceramic piston, for all fluid control functions in the pump. Eliminating check valves eliminates all of the associated rebuilding maintenance and downtime. The sapphirehard, ceramic internals are dimensionally stable, eliminating accuracy drift and the need for recalibration.<br /> <br /> The Results Have Been Dramatic <br /> <br /> Downtime, resulting from check-valve maintenance, was virtually eliminated. The dimensionally stable internal components provide drift free accuracy of better than 1 % for millions of cycles without recalibration. The CTS also uses considerably less power, has a smaller footprint, and comes housed in a protective enclosure suitable for wall mounting.<br /> <br /> Fluid Metering is a major manufacturer of Dispensers and Metering Pumps for Water, Wastewater, Laboratory, Industrial and OEM applications. These unique piston-type positive- displacement units feature no valves, lowdead volume, 1 % accuracy and a ceramic/ fluorocarbon fluid path. Flows from 2.5 ìl/ dispense to flows of 4,600 ml/min with pressures to 200 psig.<br /> <br /> For complete information on the FMI Model CTS system and additional solutions to Water/Wastewater treatment, go to: <br /> <br /> www.chloritrol.com or <br /> www.fmipump.com<br /> <br /> Produce Chemical Oxidants and Reductants Utilizing a ‘Combined Oxidant’<br /> <br /> In-Situ Remediation Approach for Comingled Plumes <br /> <br /> A former chemical plant was demolished and the property has laid dormant for two decades in an economically depressed area in central New Jersey. Soil and groundwater in part of the site were impacted with VOCs (primarily chlorobenzene, carbon tetrachloride (CT) and its breakdown products, including a DNAPL phase) and pesticides. An initial remedial design for the DNAPLimpacted areas called for sheet pilling, dewatering, and soil excavation. However, this type of a design would consist of high remedial costs, large sustainability implications, and transport of thousands of truckloads of heavily contaminated soil through urban and residential areas. <br /> <br /> Based upon previous academic research, Geo-Cleanse developed an approach utilizing a combined oxidant in-situ remediation plan to treat the heavily impacted comingled plumes at this large 100-acre site. This combined oxidant concept is capable of oxidizing and reducing the contaminants present in situ without excavating the hazardous material. This novel in-situ treatment approach utilizes permanganate to precipitate manganese dioxide (MnO2), which contains Mn(IV), to catalyze hydrogen peroxide at circum-neutral pH producing superoxide radicals. The permanganate reduced by the reaction with organics precipitates the MnO2 catalyst preferentially in zones with the highest organic concentrations, such as DNAPL interfaces; thus the catalyst is precipitated directly with the targeted contaminants. A phosphate buffer solution stabilizes the reaction of the peroxide with MnO2 to produce superoxide radicals and results in destruction of CT and other compounds that cannot be oxidized. Hydrogen peroxide also reacts with naturally occurring transitions metals (e.g., iron) to produce hydroxyl radicals, enabling treatment of mixed plumes of CT with compounds that can only be oxidized.<br /> <br /> Geo-Cleanse has conducted bench-scale treatability studies and a pilot-scale application to further enhance the effectiveness and efficiency of this remedial approach. Full-scale application of this technology is currently underway at the former chemical plant, and is expected to be complete by 2013. For additional information regarding this novel and sustainable “combined oxidant” in-situ remedial approach, please feel free to contact our office.
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