New federal regulations for fossil fuel-fired power plants are giving owners more than updated standards — they’re also providing opportunities to evaluate water treatment systems for potential boosts in efficiency and resiliency.
The new regulations include updated standards for reducing greenhouse gas emissions, modified mercury and air toxics standards (MATS), revised effluent limitation guidelines (ELGs) for water pollutants, and an extension of coal combustion residuals (CCR) regulations. In addition, the EPA recently finalized a national primary drinking water standard for per- and polyfluoroalkyl substances (PFAS). While the standard only covers drinking water, additional investigation of PFAS in industrial wastewater discharge streams is expected to eventually occur.
Currently, power plants are focused on federal regulations covering ELGs and CCR. In the future, new regulations for PFAS and other pollutants could be instituted by federal, local and state regulatory agencies during National Pollution Discharge Elimination System (NPDES) permit renewals, further impacting power plant operators and their water/wastewater systems. Following are six strategies that demonstrate how regulatory compliance can dovetail with optimization opportunities at power plants. By embracing these strategies, power plant owner-operators can better navigate an ever-evolving regulatory landscape.
1. Review power plant operations holistically. Operators can utilize regulation compliance activities as a chance to evaluate their plant operations comprehensively, aiming to optimize efficiency and sustainability while complying with updated standards. By giving all components of an operation a close look — including detailed studies and sampling of incoming water and outgoing wastewater for pollutants and contaminants — operators will gain a deeper understanding of the composition of water streams, allowing them to see to it that effective treatment processes are in place and pinpoint areas in need of enhancements.
2. Analyze plant water balance and determine opportunities for improvement. A water balance assessment should analyze water intake, usage within plant processes, and wastewater discharge. It should identify all water consumers and wastewater producers within the facility and map out flow rates. This assessment should cover average daily, instantaneous peak, and minimum usage rates. It’s important to take into account reduced load operations, seasonal impacts, off-design transient scenarios and multiple flow rate and sampling locations. A thorough analysis of the water balance enables owner-operators to make informed decisions about conserving resources, minimizing waste, lowering costs, adhering to compliance, advancing sustainability and improving overall processes.
3. Optimize water and wastewater treatment management and update long-term plans. Older plants may have treatment systems that have been updated in a piecemeal fashion over time, warranting a holistic review to optimize existing equipment and integrate new technologies that address ELGs and PFAS. This could involve evaluating ion exchange resin changes to potentially remove PFAS from incoming water or outgoing wastewater. Additionally, reviewing clarifiers for optimum coagulant and flocculant types and usage and the resulting sludge management improvements could help significantly improve water use and treatment processes.
4. Increase resilience through sustainable practices. Putting in place additional system capacity measures like additional water or wastewater storage tanks and optimizing existing automated controls are two examples of adapting to changing regulations and future plant needs. Exploring ways to reduce wastewater discharge by utilizing spray dryer evaporation systems, mixing wastewater with fly ash for off-site disposal, or incorporating water reuse and recycling measures for lower-purity plant processes can help achieve sustainability goals by reducing the flow rate of wastewater requiring discharge. Implementing creative short-term solutions — especially if a plant has a set closure date in the future — is an important strategy to add to the overall mix.
5. Investigate water treatment membrane system efficiency. Evaluating the frequency of clean-in-place (CIP) procedures on reverse osmosis (RO) and ultrafiltration (UF) equipment used in demineralized water systems is an important consideration for the development of a highly efficient plant water system. Assessing different membrane types used in UF and RO systems, and optimizing performance by exploring new available options, can lead to improved treatment efficiency and reduced operation and maintenance costs. Redundant equipment trains can be utilized to compare the performance of two or more membrane types on a trial basis, while limiting the risk of trying all new materials. Examining the efficiency of UF and RO systems by comparing permeate produced relative to reject rate for possible improvement and reducing UF system backwash frequency by achieving more effective backwashes can play an important role in better efficiency.
6. Pilot new processes. Explore innovative solutions for PFAS and the removal of other pollutants by pilot testing new technologies offered by water and wastewater treatment vendors. This proactive approach enables operators to lead the way in evaluating the effectiveness and feasibility of incorporating new advancements throughout their operations.
Dovetail Regulatory Compliance with Existing System Optimization
Although regulations pose challenges for power plant owner-operators and their water and wastewater treatment systems, incorporating improvements into existing systems can lead to more efficient and effective water and wastewater management practices in the long run. A holistic evaluation of a power plant’s operation allows for the identification of enhancements that can reduce water usage, minimize wastewater production and ultimately lead to life cycle cost savings.
Many critical considerations must be made when navigating the changing regulatory landscape of water treatment operations.