The estimated values were highly unusual due to CODinflow and COD removal efficiency, defined as the maximum capacity of the system. However, when using only data of year 2011, methane emission was less than values from the oxidation pond. Methane emission from degradable organic carbon in treated wastewater discharged into natural water sources are shown in Table 3. Obtained are in contrast with the calculated methane emissions from wastewater treatment. In 2011, the maximum amount of the methane was released, followed by 2010, 2009, and 2012. The variable that most affected calculations was the COD of treated wastewater discharged.