CO2 is created at many wastewater treatment plants when sludge is incinerated or processed
in an anaerobic digester to produce biogas (a mixture of methane and CO2). Sunrise Ridge
takes CO2 from the plant’s flue stacks and bubbles it through the plastic greenhouses. The
enclosed greenhouses maintain desired CO2 concentrations by preventing the gas from
bubbling out into the atmosphere. In initial testing, algae reduced nitrate levels in the
wastewater to as low as two part per million