Carbon dioxide infusion reduces invasive mussel biofouling (quagga mussel; Dreissena rostriformis bugensis) in raw water systems.

The efficacy of carbon dioxide (CO2) to reduce biofouling by quagga mussels (Dreissena rostriformis bugensis) in raw water systems was investigated. Experiments were conducted in a mobile laboratory located at Bureau of Reclamation Davis Dam Hydropower Facility and supplied with raw water from Lake Mohave, a reservoir of the Colorado River, USA. Incoming water was split between five chambers, each infused with CO2 at a different rate. Raw reservoir water containing quagga larvae (veligers) was mixed with CO2 chamber outflows and delivered to tanks containing settlement plates. Two experiments were conducted. Experiment 1 tested continuous infusion at target concentrations of 30, 45, 60, 75, and 100 mg L-1 dCO2 (dissolved CO2). Experiment 2 evaluated intermittent infusion schedules: 24 h on/off with 50, 75, and 100 mg L-1 dCO2 and 24 h once/week with 100 mg L-1 dCO2. In Experiment 1, the percent settlement decreased with mean CO2 concentration, ranging from 5.0% to < 0.1% in 28.7 and 92.2 mg L-1 dCO2, respectively. In Experiment 2, the efficacy of 24 h on/off at dCO2 > 72.2 mg L-1 was similar to continuous treatment. The least effective treatment was 24 h once weekly at 95 mg L-1 dCO2. These results demonstrate that CO2 treatment may reduce mussel biofouling in raw water systems.