I7.1 | Water Optimization – 30% Groundwater Use Reduction
AECOM assisted the Entergy Lewis Creek gas/coal fired electric power plant with water conservation efforts prompted by a goal of 30% groundwater (GW) use reduction by 2016 mandated by the local GW authority. To complete this work, personnel interviews were conducted to investigate the GW losses and this information, along with engineering knowledge, was used to develop a detailed water balance. Water quality requirements for each process were established to identify areas where water was used inefficiently and where reuse opportunities existed. Then, AECOM designed equipment and procedural alterations for each instance of water loss at the plant. A retrofit options table of all of the plant’s water losses and associated costs, along with corresponding proposed solutions and associated capital and operations and maintenance costs was prepared. This data permitted the project team to develop a feasibility strategy for optimizing water use, in addition this information served to facilitate negotiations with the local water authorities. The options identified included a multitude of solenoid valves, liquid level detectors, programming, and equipment conversions to other water sources (as necessary). Through specific system alterations, options to meet the 30% GW reduction were identified along with many options for longer term water optimization.
I7.2 | Environmental and Greenhouse Gas Impacts of Water Conservation
Water use has differing ranges of impacts on environmental resources based on source, use, wastewater discharge location, This presentation examines the environmental impacts resulting from water conservation and protection, including greenhouse gas reduction. It examines the broader environmental value of water conservation beyond water use reduction and how those benefits can be characterized, captured and potentially monetized. This includes identifying more direct and less direct environmental impacts on such parameters as water levels and flows, air quality and greenhouse gases, water quality, recreation, terrestrial habitat, groundwater recharge, wetlands, fisheries, and other aquatic habitat. The presentation, based on the findings of a project funded by the Great Lakes Protection Fund, also examines the potential for carbon and other greenhouse gas credits in a market system related to reduced electrical generation associated with pumping and treating water supplies and treating and discharging wastewater and sold as carbon credits on international greenhouse gas exchanges.
I7.3 | Pilot Project Update – Constructed Wetland Treatment Systems for FGD Blowdown Treatment
Constructed wetland treatment systems use natural biological processes to reduce the concentrations of constituents in the wastewater and have demonstrated promise for the treatment of FGD wastewater. However, limited industry and academic research has been conducted and very few full scale applications have been undertaken. Constructed wetland treatment systems have been used effectively for the treatment of other industrial and municipal wastewaters but widespread use in the power generation sector has not yet developed due to lack of research and project experience. A major power producer has decided to undertake a constructed wetland treatment system pilot project to evaluate the technology. The constructed wetland, scheduled for completion in December 2010, will be approximately 2 acres in size and will treat approximately 10 percent of the plant FGD wastewater stream. The constructed wetland includes the beneficial use of both fly ash and bottom ash. A pilot project of this scale in an area of the country without a round-year growing season has yet to be undertaken in the U.S. This presentation will cover the design and construction of the pilot wetland treatment system.
I7.4 | California OTC Policy and New York BTA Policy Verses EPA Phase II/III BTA
Under Section 316(b) of the Clean Water Act (CWA), EPA is planning to publish the draft combined Phase II and III Rule by February 1, 2011. This regulation will provide national performance standards for existing once through cooling (OTC) water intake structures (CWIS). It is anticipated that the draft EPA Phase II and III Rule will define Best Technology Available (BTA) as closed cycle cooling for sites located in sensitive habitats. The EPA definition for BTA for other habitats and for lower flow rates may be different. The State of New York will issue a new policy on BTA for CWIS with closed cycle cooling as BTA in mid to late October, 2010. The New York State policy is expected to regulate all OTC of 20 MGD or greater. Also, the State of California adopted a Policy on the Use of Coastal and Estuarine Waters for Power Plant Cooling (OTC Policy) and was approved on September 27, 2010. The policy establishes technology-based standards and applies to thermal power plants that withdraw cooling water from navigable waters. This paper compares the EPA, California and New York performance criteria and schedules for implementation.
I7.5 | Utilizing Reclaimed Wastewater at Power Generating Facilities
Reclaimed wastewater can be used by electric generation facilities for cooling and process water in lieu of expensive or scare potable water supplies. When used a source of cooling water, softening or reducing the total dissolved solids (TDS) using reverse osmosis (RO) systems is often required to achieve cycles of concentration comparable to local water supplies. The TDS of wastewater increases 300-700 mg/L above the raw water TDS, and often results in reclaimed wastewater with greater than 1000 mg/L in arid areas. Examples of the use of reclaimed water at power generating facilities (east and west coast) are presented, and issues related to reliability, user agreements, backflow prevention, rates, rules and regulations are summarized including a method of calculating the rate structure for the reclaimed water. The regulatory and permitting implications of using reclaimed water at a generating facility are discussed. Finding acceptable disposal alternatives for the concentrated residual stream from the RO process often determines the cost effectiveness and feasibility of wastewater reclamation. This paper will describe the quality of reclaimed water available as a resource; concentrate management processes, and alternative high recovery systems that can support cooling tower operations with high quality reclaimed water.
I7.6 | Institutional Water Conservation Opportunities: Keys to Energy and Cost Savings
With the world’s fresh water supply in unsustainable decline, the quest for improved water efficiency is gaining momentum across private and public sectors. This presentation was created to serve as a robust water conservation resource for sustainability and facility managers in higher education and beyond. Strategies discussed are low-flow toilets and fixtures, leak detection and reduction, building water metering, waterless urinals, laundry technology, rainwater harvesting, graywater reuse, weather-informed irrigation, and xeriscaping. Topics include analysis of effective water conservation case studies in the US; original survey insights on campus water efficiency implementation plans in the Northeast; the water-energy relationship; and strategic recommendations for water, energy and cost savings. By understanding lessons learned across the states, institutions can begin a flow a positive change towards a sustainable water future.
I8.1 | Oxigen Enrichment in Combustion of Toxic Waste Water
Oxigen enrichment in combustion of toxic, salt-rich waste waters was developed in 2002 and has been commercially applied since then at two plants, heightening the waste water combustion capacity and lowering at the same time the need of high caloric fuel to support the so-called water combustion (mainly endothermal). The paper gives insight in the correlation between thermal NOx-formation and CO-formation, caused by incomplete combustion. Both NOx and CO formation can be suppressed – or at least minimized – by optimal operations temperature control – though direct measurements of the fire-box temperature is not possible.
I8.2 | Stormwater Recovery for Commercial & Industrial Reuse
The recovery of stormwater from commercial and industrial properties represents a largely untapped, low cost, green sustainable resource. Stormwater recovery has broad application for the following facilities: ·HVAC Cooling water and cooling towers ·Industrial process water ·Boiler feedwater ·Powerplant Cooling and process water ·High purity water applications ·Irrigation and landscape water ·Potable water potential This paper presents: ·A methodology for evaluating sites for stormwater recovery ·Computerized modeling projections ·Water quality testing requirements ·Projections of recovered stormwater quality ·Stormwater treatment requirements, technologies, systems ·Collection and pumping techniques ·Estimated costs for construction ·Estimated O&M costs ·Case studies from facilities around the U.S. Evaluation of sites includes: ·Hydrologic watershed simulation modeling ·Collection of watershed data ·Projection of daily, monthly and annual stormwater recovery ·Use of stormwater captured from existing detention ponds ·New pond storage area and volume requirements ·Evaluation of alternative storage systems, chambers, basins ·Critical water quality parameters needed for testing ·Source water quality requirements ·Discharge permit issues Treatment needs and evaluation: ·Particle size and TSS ·Filtration requirements ·Water chemistry ·Chemical treatment ·Organics ·Microbiological parameters Presentation of case studies includes: ·Previous watershed simulation modeling based on the NRCS (Curve Number) methodology ·Illustration of recovery with graphs and charts ·Existing pond modifications needed ·Integration with Existing Stormwater Systems ·Drawings showing pumping and pipe lines ·Drawings showing treatment systems ·Costs of recovered stormwater ($/1000 gal.) lower than alternative sources Environmental/economic benefits of stormwater reuse: ·Reductions in energy use ·Reductions in chemical use ·Reductions in CO2 emissions ·Improvement of facility carbon footprint ·Reductions in water discharges to environment ·Savings in elimination of process chemicals and wastewaters (e.g., cooling tower blowdown)
I8.3 | Selenium in Water Emissions – How To Find Appropriate Treatment Options?
Selenium can be a challenging regulatory compliance issue in wastewater discharges from coal-fired electric utilities. Wastewater selenium concentrations have increased due to improved flue gas scrubbing technology, while concurrently regulatory limits have become more stringent. In this presentation, the key challenges facing coal-fired utilities and state of the practice approaches for addressing these challenges will be reviewed. Selenium management has been a water environment challenge since the mid 1980s, and the technologies for removing selenium are still developing to meet discharge criteria down to 5 parts per billion (ppb), or less. End of pipe treatment technologies are commercially available, but the technologies are not equally effective and must be considered on a case-by-case basis for each application. The available technologies for achieving the low selenium discharge concentrations that regulators are proposing or implementing will be reviewed and considerations in their selection and application will be addressed.
I8.4 | On-line Catalog of Alternative sources of Water for Coal Fired Power Plants
In recent years, rising populations and regional droughts have caused coal-fired power plants to temporarily curtail or cease production due to a lack of available water for cooling. In addition, concerns about the availability of adequate supplies of cooling water have resulted in cancellation of plans to build much-needed new power plants. These issues, coupled with concern over the possible impacts of global climate change, have caused industry and community planners to seek alternate sources of water to supplement or replace existing supplies. The Department of Energy, through the National Energy Technology Laboratory (NETL) is researching ways to reduce the water demands of coal-fired power plants. As part of the NETL Program, ALL Consulting is developing an internet-based Catalog of potential alternative sources of cooling water. The Catalog identifies alternative sources of water, such as mine discharge water, oil and gas produced water, saline aquifers, and publicly owned treatment works (POTWs), which could be used to supplement or replace existing surface water sources. This paper will provide an overview of the Catalog, and examine the benefits and challenges of using these alternative water sources for cooling water.
I8.5 | Field Evaluations of the Toxin TrapTM Technology for Removal of Heavy Metals in FGD Wastewater
Robert Jones, Managing Partner, Energy and Environmental Enterprises
A novel wastewater treatment technology has been developed for the removal of trace metals. The Toxin TrapTM technology utilizes partially-submerged, membrane-covered drums containing highly selective adsorbents. The adsorbents are designed to capture metallic trace elements such as arsenic, mercury, cadmium, and others. The drums are rotated to sustain a bi- directional flow, allowing the sorbents to remain separate from the suspended solids, avoiding plugging or fouling. The constant flow reversal is unique to the device and reduces clogging that has prevented coal power plants from using more common adsorbent filtration methods. The technology has been evaluated in field studies at the Tennessee Valley Authority’s (TVA) Paradise Fossil Plant. Field tests conducted with wastewater from TVA’s flue gas desulfurization (FGD) process showed promising results for reduction of mercury concentrations to less than ten parts per trillion and arsenic reductions to less than ten parts per billion.