IntroductionInvasive carps, including silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis), have migrated throughout the Mississippi River Basin since the 1970s and are now expanding into other large rivers basins in the United States. Recent expansion toward the Great Lakes Basin has raised conservation and economic concerns related to how invasive carps could adversely affect the $7-billion Great Lakes fishing industry (Conover et al. 2007). Lock and dam structures positioned throughout these interconnected waterways have been identified as key management locations to limit or block the upstream migration of invasive carps toward the Great Lakes. Permanent lock closure was one possible solution to block fish passage, but this approach was not considered a viable option to many stakeholders due to the negative economic consequences of limiting waterway access (Schwieterman 2010, 2015). Therefore, researchers and resource managers have focused on the development of other fish deterrents that could be implemented at lock structures to reduce upstream migration of invasive carps while maintaining a fully operational waterway.Several technologies have been explored to prevent fish passage through locks (Noatch and Suski 2012; Zolper et al. 2019). For example, invasive carp deterrent systems such as underwater acoustics and electric barriers have shown promise under various scenarios (Cooper et al. 2021; Jones et al. 2021; Noatch and Suski 2012). Underwater speakers can be used to broadcast acoustics in certain areas to elicit strong behavioural responses from invasive carps (Bzonek et al. 2021; Vetter et al. 2015, 2017). Similarly, electric barriers create an electrified field that deters and immobilizes fish as they attempt to move upstream (Egly et al. 2021). Each deterrent method has benefits and challenges related to target species responsiveness, acclimation to the deterrent stimulus, variable efficacy with fish size, human safety concerns, and operational costs. Consequently, supplementing existing control methods and further developing additional methods would be beneficial in deterring upstream movements of invasive carps.Chemosensory stimuli, such as carbon dioxide (CO2) infused into water, offer an alternative approach to deter carp movements. The concept is to infuse CO2 into water at specific areas (e.g., lock structures) to repel or immobilize invasive carps. Research has already demonstrated that invasive carps respond strongly to localized CO2 plumes (Cupp et al. 2017a, 2021; Donaldson et al. 2016; Tix et al. 2018), and infusion into water could be accomplished at lock structures with minimal expected effects to navigation or lock operation (Zolper et al. 2019). Aspects of CO2 deterrents may also address limitations with other deterrent technologies due to its nonselectivity across species and taxa, efficacy across most life stages, limited evidence of acclimation to the chemical stimulus, low cost, wide availability, and low risk to human health (Suski 2020). Pesticide registration with the US Environmental Protection Agency in 2019 has further facilitated continued development and created a legal pathway to apply CO2 as an approved pesticide for invasive carp control in the United States (USEPA 2019). However, much of the previous research has been limited to relatively small scales and controlled environments where CO2 applications were accomplished using crude gas injection methods. The next important step is to determine the feasibility of CO2 applications at a management scale in navigation lock structures using more purposefully engineered gas injection systems.The transition of CO2 testing from controlled settings (e.g., laboratory tanks, outdoor ponds) into full-scale environments (e.g., navigation lock structures) requires additional engineering considerations that were not addressed during previous biological research. Several gas-to-liquid infusion methods, including mechanical and fluid dynamic mixers, have been developed for chemical, mechanical, and environmental engineering applications that could potentially be adapted for this new application (Bumrungthaichaichan et al. 2016; Chen et al. 2017; Fossett 1951; Fossett and Prosser 1949; Fox and Gex 1956; Lane and Rice 1982). Jet mixing stands out as a highly effective nonphysical method of mixing. It generally uses a pump to draw liquid from a chamber, pressurizes it, and reinjects it through a nozzle as a high velocity jet. The momentum of a fluid jet entrains surrounding fluid and induces efficient mixing within the chamber. Jet driven liquid-gas mixing also produces multiphase flow that can alter fluid properties, resulting in cavitation, efficiency losses, and other phenomena (Freudigmann et al. 2017; Liu et al. 2017; Loeb 2017; Tian and Van de Ven 2017).The performance of machinery used in mixing applications is often gauged by the uniformity, concentration, and efficiency of the processes. Mixing performance can be quantified in two ways: (1) “mixing homogeneity” describes the uniformity of CO2 concentrations within the lock using the variance in measured CO2 at all monitoring points; and (2) “injection efficiency” is the ratio of dissolved CO2 to injected CO2, an indicator of gas-to-liquid infusion ability. Both mixing homogeneity and injection efficiency are affected by many factors, including the chamber volume, injection velocity, fluids being mixed, jet injection angles, nozzle geometry, manifold configurations, operating pressure, and Reynolds number (Bumrungthaichaichan et al. 2016; Dinsmore et al. 2017; Fox and Gex 1956; Grenville and Tilton 2011; Lane and Rice 1982; Maruyama 1986; Patwardhan and Gaikwad 2003).Nozzle geometry also directly affects mixing time, operating pressure, and flow rate, and a variety of nozzle designs have been evaluated with circular apertures (Cui et al. 2015; Yang et al. 2013), noncircular apertures (Majamaki et al. 2003; Nikitopoulos et al. 2003; Quinn 2005; Smith et al. 1997; Yu et al. 2004; Zaman et al. 1994; Zhdanov and Hassel 2012), and vortex-inducing nozzle covers (Bradbury and Khadem 1975; Foss and Zaman 1999; Reeder and Samimy 1996; Samimy et al. 1993; Zaman et al. 1994; Zhdanov and Hassel 2012). Fox and Gex (1956) demonstrated that good mixing performance can be attained by maximizing a nozzle’s “momentum flux,” the product of velocity and mass flow rate through an aperture (Bumrungthaichaichan et al. 2016; Fox and Gex 1956). Manifolds are used to divide a single fluid stream into multiple outflow streams, and detailed studies of diverse manifold designs, including customized designs, are available in the scientific literature (Bajura and Jones 1976; Bajura 1971; Gandhi et al. 2012; Hassan et al. 2014; Majumdar 1980; Pathapati et al. 2016; Subaschandar and Sakthivel 2016; Tong et al. 2009).The goal of this research is to evaluate the performance of a CO2 injection system at a navigation lock structure on the Fox River near Kaukauna, Wisconsin, USA. System performance was evaluated based on several metrics that characterized the efficiency and timing of this engineered system to reach target concentrations. A target concentration range of 100–150 mg/LCO2 was established based on previous fish behavior testing and discharge allowances on state and federal permits (USEPA 2019). Two manifold distribution types were tested that were designed as possible options to treat the lock without obstructing lock operation. Previous testing in outdoor ponds detailed the mixing performance of singular floor-based and wall-based CO2-to-water injection manifolds in a closed simulated lock chamber (Zolper et al. 2019). The present research uses a system of manifolds, activated in different combinations, to generate a uniform vertical and lateral CO2 field with the intent to prevent fish from entering the lock chamber or force resident fish downstream. This research introduces several new factors to previous research, including full-scale commercial injection equipment, multiple combinations of manifolds, and operation in a management applicable setting in a lock structure.Experimental Setup and MethodsThe CO2 infusion experiments were designed to simulate, as closely as possible but without vessels, the treatment of a lock chamber with CO2 during an upstream lock operation. In a typical upstream passage of a vessel through a navigational lock, the lock must be at tailwater level (downstream water level) with the downstream miter gates open to allow the vessel to enter. Once the vessel is moored in the lock, the downstream gates are closed and the chamber is filled to the head-water level. Upon attaining the head-water level, the upstream miter gates are opened and the vessel can continue upstream. To prevent upstream migration of aquatic invasive species during this process, the lock water can be infused with CO2 before the vessel enters the lock to (1) drive fish out of the chamber and into the downstream pool; and (2) to deter any fish from entering the lock with the vessel. In these experiments, we simulate the pretreatment of the lock chamber with CO2 without the complication of vessel passage.The objective of these experiments was to evaluate the ability of the CO2-to-water infusion system to attain a uniform target concentration of 100 mg/L throughout a lock chamber. Multiple combinations of operating parameters using wall-based and floor-based distribution manifolds were tested to generate diverse flow fields. This resulted in a greater number of operating parameters in comparison to the earlier research (Zolper et al. 2019) and substantially increased overall complexity. Certain parameters were constrained by the greater scope of activities and regulations of the participating agencies, including the US Army Corps of Engineers (USACE), US Geological Survey (USGS), and Wisconsin Department of Natural Resources (WDNR). The maximum allowable CO2 concentration of 150 mg/L in a lock chamber was established by the WDNR under an approved National Pollutant Discharge Elimination System (NPDES) permit based on state requirements in compliance with Federal Clean Water Act standards.A temporary CO2-infusion system with water distribution manifolds was constructed and tested at Kaukauna Lock #2 on the Fox River located in Kaukauna, Wisconsin, as shown in Fig. 1. The test site was entirely on property that was owned and operated by the Fox River Navigational System Authority (FRNSA). Site access approval was gained from FRNSA, and all necessary local, state, federal and historical permits were obtained prior to construction and testing. Construction was completed by a private firm that specialized in water distribution systems. Experiments were performed from August 5, 2019, through September 6, 2019.The lock chamber was approximately 51.82 m (170 ft) long and 11.12 m (36.5 ft) wide at the top, tapering down to 10.72 m (35.2 ft) wide at the bottom (Fig. 2). The upstream (west) miter gates were closed during the experiments, and each gate was 5.7 m (18.7 ft) long and met in the middle. The downstream (east) miter gates were open during the experiments: the line between their hinges divided the lock chamber from the downstream reservoir. The Kaukauna Lock #2 measurements (Fig. 2) were accurate to ± 50.8 millimeters (mm) (±2 in.). Thus, the volume enclosed by the chamber and upstream miter gate was about 2,920,000±47,000 L (771,000±12,400 gal.) at head-water level (5.08 m or 16.7 ft) and 1,548,000±37,000 L (409,000±9,700 gal.) at tail-water level (2.64 m or 8.7 ft). For reference, a typical 183-m (600-ft)-long commercial navigation lock has a tailwater volume of approximately 20 times that of Kaukauna Lock #2.An open-loop CO2 injection system was designed for these experiments (Fig. 2). A diesel-powered pump drew near-bottom water from the northwest corner of the chamber at the upstream end of the lock, lifted it approximately 6.1 m (20 ft), passed it through a filter and into parallel mixing chambers where CO2 was added to carrier water under a prescribed pressure differential, and then distributed the CO2-enriched carrier water in the lock chamber using a series of manifolds that were adjusted for each experiment. The pump intake was positioned approximately 203.2 mm (8 in.) above the floor of the lock, the same height as the discharge of the wall and floor manifolds, resulting in a net pumping height of 0 mm. The piping networks, pressurized solution feed (PSF), manifolds, and nozzles were the primary causes of the system head losses. All treatments occurred with the chamber at tail-water level and downstream (east) miter gates open. After each experiment, the downstream miter gates were closed and the lock was filled to dilute excessive CO2 concentrations before discharging the treated water downstream in preparation for the next experiment.The pump produced water flow rates (V˙H2O) from 6,810 to 12,110 L/min (1,800 to 3,200 gal./min) in accordance with the requirements for the experiment. A TOMCO2 Systems (Loganville, Georgia) PSF was used to infuse CO2 into the carrier water from the pump at mass flow rates of m˙CO2=1,134 to 1,588 kg/h (2,500 to 3,500 lb/h). The CO2-infused-water was mixed into the lock chamber using either a series of wall-based or floor-based manifolds, shown in Fig. 2.High-density polyethylene (HDPE) was used for all piping except for the floor manifold, which used polyvinyl chloride (PVC). The pump intake and outflow pipes were made of 304.8-mm (12-in.) HDPE. Downstream from the PSF, 406.2-mm (16-in.) HDPE pipe was used to divide the flow into two streams (Fig. 2). The downstream (east) pipes provided flow to four wall manifolds. The upstream (west) pipes provided flow to four wall manifolds and included a valve to provide flow to the floor manifold. The floor manifold was made of 203.2-mm (8-in) schedule 40 PVC and was affixed to the bottom using distributed weights. The wall manifold branches used 406.4-mm to 203.2-mm (16-in. to 8-in.) T-fittings and elbows to connect to the eight wall manifold dropdowns (Figs. 2 and 3). Several gate valves were used to control the water flow to the full floor manifold or a maximum of four wall manifolds at a time. The pump intake and discharge pipes were placed on one side of the chamber to minimize obstructions to lock personnel.The wall manifolds were designed to use the kinetic energy and turbulence of a series of jets to induce mixing and diffusion of CO2 into the water. The design is also adaptable to flush-mounted scenarios that would not physically interfere with lock operation or vessel passage. Each wall manifold was constructed from 203.2-mm (8-in.) HDPE and designed to produce six equal-discharge jets from TOMCO2 Systems (Loganville, Georgia) using cast 304 stainless steel nozzles spaced 762 mm apart, as shown in Figs. 3 and 4.Converging nozzles were selected to maximize momentum flux, which has been shown to enhance long-range mixing (Fox and Gex 1956). The nozzles had 76.2-mm (3-in.) inlets and 23.4-mm (59/64-in.) outlets to allow the necessary back-pressure for proper CO2 dissolution and water flow rate. All nozzles discharged horizontally toward the south wall and were located approximately 203.2 mm (8 in.) above the bottom of the lock chamber. In total, eight wall manifolds (designated A–G) were evenly spaced at 5.33 m (17.5 ft) on center along the north wall of the lock chamber (Fig. 5). Combinations of two, three, and four manifolds were variously activated for individual experiments during the test period.The floor manifold was composed of a 406.4-mm (16-in.) HDPE main branch that equally distributed the CO2-infused water into four 203.2-mm (8-in.) PVC side branches with center-to-center spacing of 2.67 m (105 in.), as shown in Fig. 5. Each 48.77-m (160-ft)-long side branch ran parallel to the length of the lock, and branches were connected to one another at the downstream end of the lock by a 203.2-mm (8-in.) PVC pipe. Seventy-two 6.35-mm (1/4-in.) holes (dH2O) were drilled into the tops of the four side branches at a spacing of 508 mm (20 in.) each (288 total). The main branch also had twelve 6.35-mm (1/4-in.) holes spaced at 609.6 mm (24 in.) over its 8-m (26.25-ft) length. Thus, a total of 300 orifices in the floor manifold distributed CO2-enriched water throughout the lock chamber approximately 203.2 mm above the floor of the lock.Flow meters, pressure gauges, and control valves allowed the system to be configured and operated for a variety of experimental conditions. The pump was fitted with a vacuum pressure gauge at the intake port and an operating pressure gauge at the outlet port (Fig. 2), both with accuracies of ±6.9 kPa (±1 psi). The pressure gauge readings at the pump intake port Pin and pump outlet port Pout were used to determine the operating pressure of the system Poper [Eq. (1)] (1) A Fluid Components International (San Marcos, California) CO2 mass flowmeter (accuracy ±1% of reading [lb/h]) was used to measure CO2 flow rate into the PSF every minute during experiments (Fig. 2). A Hach sc200 (Loveland, Colorado) pH and temperature sensor measured the acidity and temperature, respectively, of the incoming and outgoing water of the PSF to ±0.1% of full scale at 25°C. Two Bourdon pressure gauges measured the PSF of incoming and outgoing water pressure with an accuracy of ±6.9 kPa (±1 psi). The volume flow rate of water was measured at three points in the system (Fig. 2) using Greyline Instruments (Largo, Florida) Doppler Flow Meters (DFM 6.1) with an accuracy of ±75.7 L/min (±20 gal./min). The primary flowmeter, located on the 406.4-mm (16-in.) HDPE pipe between the pump and the PSF, measured the total flow through the piping system. Two additional flowmeters were also placed on the 406.4-mm (16-in.) lines feeding each bank of manifolds (Fig. 2). A portable Greyline Doppler Flow Meter (DFM 6.1) calibrated to 203.2-mm (8-in.) pipes was used to assess the flow rate of the dropdowns to individual manifolds. Flow rates were logged every 10 s on all meters.The distribution of dissolved CO2 in the lock chamber was measured during each experiment using an array of pH sensors on multiparameter sondes with real-time telemetry. Ten YSI (Yellow Springs, Ohio) multiparameter sondes (eight YSI Model 600XLM and two YSI/Xylem EXO2) were divided between five Ocean Science (North Falmouth, Massachusetts) tethered boats positioned on taglines throughout the lock chamber (Fig. 6). Each tethered boat was equipped with two sondes positioned at depths of 0.914 m (3 ft) and 1.828 m (6 ft) below the free surface, a Campbell Scientific (Logan, Utah) CR6 data logger, a RF407 high-speed 900-MHz spread-spectrum radio, a 12-volt battery, and a 10-W solar panel and regulator. The radios allowed wireless transmission of real-time data at 5-s intervals from all instruments to a single laptop computer with custom display for real-time feedback during the experiments. A pulley driven hand line attached to each boat allowed the boat to be positioned at any point along the static tagline by a single person. During testing, the boats were simultaneously repositioned from south (S), center (C), and north (N) stations at carefully timed intervals to assess the variation of the CO2 field and other basic water-quality properties (temperature, specific conductance, and dissolved oxygen). Tethered boat #3, located near the center of the lock chamber (Fig. 6), was equipped with the EXO2 sondes, which included additional sensors not found on the 600XLM sondes (optical dissolved oxygen, turbidity, total algae, and phycocyanin sensors).Dissolved CO2 concentration (mg/L) was computed from pH measurements using a CO2-pH regression equation [Eq. (2)] and water samples collected from the Fox River Lock #2 in Kaukauna, Wisconsin, at the beginning and end of the experiments (July 26, 2019, and September 5, 2019, respectively). Details of the development of Eq. (2) are given in the appendix (2) CCO2=3.361·108·e−2.323·pHThe multiparameter sondes were three-point calibrated using pH 4, 7, and 10 standards at the beginning of every week, and all sensors (except temperature) were calibrated. The thermistors on the sondes do not require calibration but are checked annually in a thermal bath. During calibration, sonde clocks were synchronized with the master clock for the experiments.Design of Experiments—Test PlanPrevious research showed that water flow rate V˙H2O and CO2 mass flow rate m˙CO2 have the greatest influence on the performance of the floor and wall manifolds (Zolper et al. 2019). A design of experiments (DOE) full-factorial approach was used to extricate their respective influences on the performance of the manifold systems (Box et al. 2005). Sixteen experiments were identified using four manifold configurations at four flow rates each, as shown in Table 1. The pump provided stable water flow rates at pump speeds of ω=1,200 and 1,800 RPM, which corresponded to different water flow rates whether using floor manifolds or combinations of two, three, or four wall manifolds. The PSF was set to steady CO2 mass flow rates of m˙CO2=18.9 and 26.5 kg/min (2,500 to 3,500 lb/h) with negligible effects on water flow rates. It was found that operating four wall manifolds at low pump speed produced insufficient operating pressure to allow the PSF to efficiently infuse CO2; therefore, those experiments were not pursued.Table 1. Design of experiments factorial design settings showing water volume flow rates (V˙H2O) and CO2 mass flow rates (m˙CO2) of the floor manifold and three configurations of wall manifoldsTable 1. Design of experiments factorial design settings showing water volume flow rates (V˙H2O) and CO2 mass flow rates (m˙CO2) of the floor manifold and three configurations of wall manifoldsManifoldOperating parametersUnits1234FloorVolume flow rate V˙H2O(L/min)8,3308,33011,36011,360(gal./min)2,2002,2003,0003,000Mass flow rate m˙CO2(kg/min)18.926.518.926.5(lb/h)2,5003,5002,5003,500Wall 2 manifoldsVolume flow rate V˙H2O(L/min)6,8106,81010,60010,600(gal./min)1,8001,8002,8002,800Mass flow rate m˙CO2(kg/min)18.926.518.926.5(lb/h)2,5003,5002,5003,500Wall 3 manifoldsVolume flow rate V˙H2O(L/min)8,3308,33011,36011,360(gal./min)2,2002,2003,0003,000Mass flow rate m˙CO2(kg/min)18.926.518.926.5(lb/h)2,5003,5002,5003,500Wall 4 manifoldsVolume flow rate V˙H2O(L/min)9,080a9,080a12,11012,110(gal./min)2,400a2,400a3,2003,200Mass flow rate m˙CO2(kg/min)18.9a26.5a18.926.5(lb/h)2,500a3,500a2,5003,500Test configurations are identified by the following nomenclature: manifold type [floor (F) or wall (W)], wall–manifold combinations (e.g., A-B-C-D; for W manifold type only), water volumetric flow rate (V˙H2O), and CO2 mass flow rate (m˙CO2) in US customary units. Therefore, a test configuration using wall manifolds A, C, E, and G at V˙H2O=3,200 gal./min, and m˙CO2=2,500 lb/h is designated “W A-C-E-G 3200-2500”. Meanwhile, a test configuration of the floor manifold at V˙H2O=3,000 gal./min, and m˙CO2=2,500 lb/h is designated “F 3000-2500”.General Experimental ProceduresThe full scope of the research also includes fish behavioral studies, which largely dictated the duration for each trial. Therefore, nearly 2 h were allocated for each experiment to perform baseline pH measurements and track tagged fish using acoustic fish telemetry. Baseline measurements of CO2 concentration were collected prior to injection (t<0 min). At about t=−10 min, the pump was set to the nominal water flow rate to allow enough time to develop a stable flow field. At the beginning of CO2 injection (t=t0=0 min), the PSF was set to the nominal CO2 mass flow rate. The CO2 injection was stopped when the measured CO2 reached a threshold concentration of 150 mg/L at any sensor on the tethered boats. This was a requirement to comply with issued permits from WDNR for conducting this research project. In practical administration, injection would continue until all locations within the lock reached the desired concentrations and not just at any one sensor. Measurements continued for up to 90 min after the CO2 injection began (t>0 min). The five tethered boats with pH sensors simultaneously measured for 3 min at each station in the lock (north, center, south) throughout the trial period. The following sequence of activities were undertaken to simulate upstream lock changes: 1.At t=−40 min: Baseline testing: Tethered boats start at center stations of lock, then move to north stations (t=−37 min), back to center stations (t=−34 min), to south stations (t=−31 min), and return to center stations (t=−28 min).2.At t=−10 min: Pump starts and attains desired flow rate.3.At t=−1 min: Lower miter gates open.4.At t=t0=0 min: CO2 injection begins.5.Over the course of the test, the tethered boats are moved to the following positions: •(0
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Performance of a Carbon Dioxide Injection System at a Navigation Lock to Control the Spread of Aquatic Invasive Species | Journal of Environmental Engineering | Vol 148, No 4
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Feb 10, 2022