"Best-in-Class" Fluidized Bed Reactor Technology Offers Dramatically Lower Costs for Initial Construction, Improved Operations and Reliable Treatment to <5 mcg/L
KINGWOOD, Texas, Aug. 3, 2011 — Envirogen Technologies, Inc. (Envirogen) announced today that it has entered the market for treatment of selenium-containing coal mining wastewaters with a portfolio of treatment solutions, highlighted by the company's fluidized bed reactor (FBR) biological treatment systems and augmented, where appropriate, with its High Efficiency Ion Exchange technology. Envirogen FBR technology has features that make it ideally suited for selenium and nitrate treatment in the coal mining industry, and combined with the decades of FBR experience held by the Envirogen team, allows the design and installation of systems with capital, operating and lifecycle costs that are significantly lower than competitive fixed-film biological systems – such as packed bed bioreactors.
The noteworthy features of Envirogen FBR technology include its ability to consistently reduce selenium levels to less than 5 mcg/L, shorter required residence times for treatment and a smaller overall footprint. Its flexibility in the choice of electron donor chemicals can translate into capital and operating cost savings with reduced solids generation. It also responds well to changes in feed flow and composition, consistently achieving discharge limit conditions. In addition, these systems can be modular, with all-weather protection where desired. The company has recently completed several long-term operational studies with FBR systems in coal mining operations, demonstrating the effectiveness of the technology in the field.
According to Michael M. Stark, CEO of Envirogen, the coal mining industry is in need of proven, effective technology immediately, as new pressures are brought to bear by environmental groups and regulatory agencies on selenium discharges. "With new regulations either in place or being developed, it appears that the ability to deal with selenium wastes will increasingly become a limiting factor on the ability of the coal mining industry to grow," he said. "Envirogen has technology that can be designed and deployed immediately to handle a broad range of selenium-containing wastewaters – with varying flow rates, concentrations and water qualities. Both our own and independent studies show that our FBR systems' small-footprint and steady-state operation allows us to meet very stringent clean-up guidelines, consistently, at dramatically lower costs than competitive alternatives," he added. Selenium is commonly found in mining wastewaters in concentrations ranging from 3 to >12,000 mcg/L. The U.S. National Primary Drinking Water Standard MCL is 50 mcg/L for selenium. The National Fresh Water Quality Standard is 5 mcg/L. The U.S. Fish and Wildlife Service has recommended that the National Fresh Water Quality Standard be lowered to 2 mcg/L to protect fish, waterfowl and endangered aquatic species. Several states have followed with enforcement actions at these low levels. In Canada, permits may require stakeholders to monitor levels in water or biota, or to address the Canadian Water Quality Guidelines of 1 mcg/L in surface waters.
The Fluidized Bed Reactor – "Best-in-Class" Technology
Envirogen's FBR is an active, fixed-film bioreactor that fosters the growth of microorganisms on a hydraulically fluidized bed of fine media. In this type of reactor, a fluid is passed through a granular solid medium at velocities sufficient to expand or fluidize the media. Envirogen FBR installations typically feature one or more vessels, depending on influent water characteristics and discharge limits. Pre-fabricated FBR vessels range from 2 to 14 feet in diameter and up to 30 feet in height. This vertical orientation is one of the factors that contribute to the FBR's higher treatment bed volume and smaller footprint than other biological treatment systems.
FBRs have been shown to have some significant advantages over packed bed reactors in coal mining environments. First, they operate in a steady-state "plug flow" manner that avoids channeling and gas binding. This ensures that the microorganisms in the system are optimally utilized. They do not require periodic backwash, as do packed bed reactors. These features allow for significantly higher treatment efficiency, resulting in much lower hydraulic residence times (1/5 to 1/10 as long as packed bed). This efficiency results in smaller overall systems and a smaller system footprint – both of which contribute to the dramatically lower costs of construction of the FBR compared to the packed bed reactor.
From an operational standpoint, Envirogen FBR systems function effectively over a wide range of feed flow rates and influent composition. Compared to other fixed-film bioreactor systems, Envirogen's FBRs are far more tolerant of high feed water nitrate, suspended solids (TSS) and metals concentrations. They also have the ability to treat water with high total dissolved solids (TDS), and recover very quickly from upsets such as power outages and loss of chemical feeds.
In many cases, Envirogen FBR systems can be pre-fabricated for delivery to mining sites – compared with packed bed reactor systems which, because of their large size, are often built-in-place. Envirogen FBR systems are essentially modular and containerized – which allows for ease of transportation and rapid installation – even in bad weather conditions. Generally, it is expected that biological treatment systems suffer loss of efficiency in cold weather environments (<15 degrees C). Recent tests on selenium-containing wastewater showed that the Envirogen FBR system performed effectively at influent water temperatures as low as 4 degrees C.
According to Stark, Envirogen's offering for treating selenium-containing coal wastewaters has been designed to meet the real-world operating environments of coal mining operations and is ready today to start meeting those needs. "Recently, the coal mining industry has been examining a broad range of technologies for treating selenium. While many of these show promise, most are either cost prohibitive or untested – meaning they aren't yet ready for the field," he said. "With our FBR technology, we have the operating background and the understanding of the needs of this market to be able to offer our systems with performance guarantees – and we're ready to do this today," he added.
For the full news release, visit:
http://www.envirogen.com/news/envirogen-news/envirogen-enters-selenium-treatment-market-for-coal-mining-wastewaters
For further information, contact:
Julie Mamaux
Voice: 877.312.8950
Fax: 281.358.2443
http://www.envirogen.com
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