Leading-edge water treatment technology for Power Plants
Envirogen offers a range of environmental and process solutions for wastewater management that can help meet environmental goals, such as selenium and nitrate reduction, and reduce costs.
Meeting Compliance Challenges
On August 31, 2020, the U.S. Environmental Protection Agency (USEPA) Administrator signed the final rule revising the 2015 Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category (ELGs). For flue-gas desulfurization (FGD) wastewater, the 2020 ELGs rule establishes revised numeric effluent limitations on mercury, arsenic, selenium, and nitrate/nitrite (as nitrogen) based on the Best Available Technology Economically Achievable (BAT). For those plants who will need to comply with the new 2020 ELGs, Envirogen has leading-edge solutions for treating wastewater to remove metals, selenium, nitrate and other contaminants.
Envirogen Technologies offers the most reliable biological technology for treating FGD wastewater: The Fluidized Bed Reactor (FBR). In addition to delivering the most consistent removal of selenium and nitrate, the FBR offers the benefits of greater system reliability and significantly lower costs than other commercially available technologies. Envirogen has the broadest background and installation base of biological treatment systems for selenium and other oxyanions in the industry. Our long track record of designing, building and operating biological systems offers the engineering community and power utilities a strong partner in developing reliable, least-cost FGD wastewater treatment solutions.
To learn more about Envirogen’s treatment options for Flue Gas Desulfurization wastewater, download our FGD Fact Sheet here.
Denitrification for FGD Wastewater
The USEPA’s BAT for meeting ELG limits for FGD scrubber wastewater is chemical precipitation to remove metals followed by biological treatment to remove nitrate and selenium. However, some biological treatment options may plug or channel at higher nitrate loads, causing reduced selenium treatment efficiency. Envirogen’s FBR can be inserted into existing chemical precipitation processes to reduce the nitrate load on the downstream biological system, thereby improving selenium compliance. Removing nitrate up-front can also reduce the size and cost of downstream biological treatment. Overall FBR system packages include pumps, piping, valves and instruments pre-assembled on skids to minimize installation costs. One possible scenario is depicted in the figure below, showing the Envirogen FBR skid in blue.
The system can be installed after either the primary clarifiers as shown above or after the final clarifiers, as shown in the next illustration, based on the type of chemical precipitation process and the overall vessel layout. Our FBR can reduce high concentrations of nitrate-N – up to 250 mg/l – to below 3 mg/l or any desired level.
A detailed view of the FBR skid is shown here.
Click here for Envirogen’s Brochure on Denitrification for FGD Wastewater
Legacy Wastewater and Coal Combustion Residue Leachate
Envirogen offers a solution for meeting selenium and other metal discharge requirements associated with legacy wastewater and Coal Combustion Residue (CCR) leachate. Our Advanced Metals Removal System (AMRS) utilizing select Zero Valent Iron media is a stand-alone technology for a number of metals. Our AMRS can enhance traditional physical/chemical metals removal systems by adding the capability of polishing especially recalcitrant metal forms, such as selenate, downstream. A recent validation study conducted on legacy wastewater stored in a coal ash pond demonstrated the performance of the AMRS to remove selenate from 200-250 μg/l down to below 1 μg/l.
To learn more about Envirogen’s pilot success in CCR Ash Pond Water, here.
CCR Impacted Groundwater
For sites where the groundwater may be impacted by Coal Combustion Residue leachate, Envirogen offers groundwater extraction and treatment systems for hydraulic control, removal of arsenic and other metals, O&M services and groundwater monitoring. Envirogen has extensive experience treating selenium, arsenic, mercury, chromium, lead, thallium, iron, manganese, aluminum, vanadium, cadmium, copper and other metals.
To learn more about our work in Groundwater Remediation click here
Research, Development and Piloting Capabilities
In addition to designing full scale water treatment systems, we also offer small, bench-scale studies and on-site pilot-testing to validate system design and fully meet the client’s requirements. Using fundamental research, we can identify the optimal and most effective water treatment system for a particular site.
For FGD systems with Selenium water treatment needs, Envirogen is on the forefront of modeling biological system performance.
Read more about our well received presentation at the EPRI Selenium Summit 2019 where Envirogen expert Paul Togna explained all the most recent research and learnings around selenium treatment and our groundbreaking predictive modeling.
At the EPRI Selenium Summit 2020 Envirogen followed up with details on further improvements in Envirogen’s Fluidized Bed Reactor (FBR) design through the use of smaller media, and the expected improvements in performance and/or reduced system size and height.