Power Plant Water Management
Environmentally-Safe Control of Zebra Mussel Fouling -
New York State Education Department
Coal-fired power plants within North America need an effective, economical, and non-polluting technique for managing infestations of zebra mussels within their facilities, particularly in cooling water intake systems. Unfortunately, due to a lack of options, many facilities have relied on the use of broad-spectrum, chemical biocides for control of these freshwater, macro-fouling mussels. Biocide treatments, such as continuous chlorination for three weeks, are widely regarded as environmentally unacceptable.
Chlorine, for example, can combine with organic compounds in water resulting in the formation of trihalomethanes, dioxins, and other potentially carcinogenic substances. Because of this, there is growing concern within the power generation industry that such broad-spectrum biocides will be banned by individual states and/or the U.S. Environmental Protection Agency. This would result in a crisis situation for the electric utility industry. Even if such an outright ban does not occur, the reduction in the use of such biocides is generally viewed by coal-fired and other power generating industries as environmentally prudent and desirable.
Funded by a consortium of state, federal (including US DOE), and private industry (including coal-fired electric utilities), major breakthroughs have been achieved at the Principal Investigator's laboratory in the development of a bacterium, Pseudomonas fluorescens strain CL0145A, as the first biological control agent for zebra mussels. This naturally-occurring bacterium shows realistic promise for commercial development as an effective, yet environmentally-benign, control agent for zebra mussels – precisely the kind of control agent desired by coal-fired power plants for the replacement of chlorine and other biocides for treatment of their intake systems. Laboratory and small scale facility trials have demonstrated that, due to a highly selective biotoxin, dead cells of this bacterial strain are lethal to zebra mussels, but not to any non-targets tested (i.e., no mortality to ciliates, blue mussels, unionid mussels, fathead minnows, young-of-the-year brown trout, and young-of-the-year sunfish).
To facilitate evaluation of this innovative control method, Rochester Gas & Electric Corporation (RG&E), has offered one of its coal-fired power plants as a test site for a pilot demonstration project. The overall research goal of this proposed three-year project is to conduct experiments at the RG&E coal-fired power plant with bacterial strain CL0145A to evaluate its technical and economic feasibility to control zebra mussel fouling. Current funding from the Power Systems Advanced Research unit of the National Energy Technology Laboratory has primarily supported small-scale laboratory trials defining the abiotic, biotic, and treatment factors that will maximize zebra mussel kill. The proposed research will extend this research project to the pilot demonstration level by evaluating the feasibility of control within the entire service water system of the RG&E coal-fired power plant.
The overall objective of the proposed work is the development of an innovative solution to address an environmental challenge associated with coal-burning power plants whose cooling water intake systems are infested with zebra mussels, Dreissena spp. It is proposed that an environmentally-safe, biological control technology for zebra mussel management be developed which incorporates selective toxins from a naturally-occurring bacterium, Pseudomonas fluorescens strain CL0145A. This new technology will allow coal-burning plants to reduce or eliminate the use of chlorination as a zebra mussel control method thereby reducing the risk of chlorine’s potentially harmful affects on aquatic ecosystems.
Project activities are designed to lead to the demonstration of the feasibility of zebra mussel control by treating the entire service water system of the RG&E Russell Station power plant during the third year of the project. To accomplish this goal, the following work is planned.
Activities within the RG&E Research Trailer
This is the facility on the Russell Station property where RG&E has done all their research to date on determining effective chlorination protocols. Work during Year 1 and Year 2 will focus primarily on doing treatments in pipes within the research trailer. Tests will be run under once-through conditions using service water and at incrementally larger scales to mimic the conditions present in pipes within the power plant. Trials will be conducted to evaluate non-target impact of treatment protocols. Bluegill sunfish, rainbow trout, and Daphnia magna are candidate nontarget organisms. These tests, although they are not within the power plant per se, are extremely valuable because they permit multiple treated and control (untreated) replicates to be concurrently run within each test, thereby providing a more comprehensive data set from which to draw conclusions. Results will be used to predict the best protocols to use during the annual test within the power plant itself. The bacteria used in these trials will be produced throughout the year by project staff through rental of 10-L and 75-L fermentation units at Cornell University.
Activities at the New York State Museum’s Field Research Laboratory
This is the facility where all bench-level research on this bacterial strain has been conducted to date. In addition to having small-scale fermentation capabilities for producing small quantities of bacteria for experiments, the facility also has once-through stream water testing capabilities useful for small-scale pipe trials and realistic non-target exposures. Pipe testing systems and protocols developed at this facility for once-through stream water trials will be used as starting models for constructing of the once-through stream water testing units within the Rochester trailer. Bacterial fermentation runs produced both at Cornell University and obtained from commercial contractors throughout the three-year study will be bioassayed for quality control purposes. Tests will be conducted on an ad-hoc basis with either zebra mussels or non-targets to supplement the testing activities within the Rochester trailer.
Activities within the RG&E Russell Station Power Plant
A single test will be run in the service water system within the power plant at the end of Years 1, 2, and 3 to confirm the efficacy of the latest treatment protocol design that has been developed from pipe trials within the research trailer. The impact of treatments on caged non-targets held downstream of the service water system will be assessed in all three years. In Years 1 and 2, only a limited subsection of the service water system will be treated. The bacteria used in these two annual trials will be obtained from purchase of cells derived from a 1,250-L run from a commercial fermentation company. Side-stream bioboxes and videoscope inspection (where possible both pre- and post-treatment) will be used to assess mussel mortality along the length of the treated pipe. An upstream section of pipe in the same service water line will serve as an (untreated) control. In Year 3, the project will culminate in a single test treatment of the entire service water system. The bacterial cells used in this trial will be obtained from the purchase of eight 1,250-L fermentation runs from a commercial fermentation company. Mussels upstream of the service water system at the power plant will serve as the (untreated) control. As in past years, side-stream bioboxes and videoscope inspection (where possible both pre- and post-treatment) will be used to assess mussel mortality.