Before revision: The attached bacteria in the first reactor, known as a SMART unit, are exposed to a constant high COD, triggering the expression of high concentrations of hydrolytic enzymes in the EPS layer around the bacteria (citation needed) .
After revision: The attached bacteria in the first reactor, known as a SMART unit, are exposed to a constant high COD, triggering the expression of high concentrations of hydrolytic enzymes in the EPS layer around the bacteria .