A closed tank for wastewater treatment, in which bacterial action is induced to break down organic matter. Wastewater treatment plants utilize anaerobic digestion in order to generate wastewater digester gas which is a methane-rich byproduct which can be used as an energy source. Digesters exploit the decomposition of sewage sludge to generate digester gas from major and minor clarifiers. Wastewater digester gas is rich in methane byproducts and provides a terrific energy source, with digester meters routinely utilized to keep track of digester gas applications.