Influent and effluent water TSS and VSS
During the startup period the reactor TSS removal was quite sufficient as the up flow velocity was low (0.4 m/h), the gas production rate was low ranging between 4.89 and 12.05 (l/g COD removed/day) and the washout was avoided. When the HRT was decreased the up flow velocity was increased to decrease the TSS and VSS removal efficiency.
During the cold temperature Runs the anaerobic microorganisms and in specific the methanogenic bacteria growth was declined leading to lower reactor performance and the accumulation of the suspended solids in the reactor that leads to the rising of the sludge blanket that exceeded to washout accordingly. The average removal efficiency of TSS & VSS is shown in