Start-up: An UASB reactor requires a long time for start-up, e.g. from 2 – 3 weeks in good conditions (t > 20oC) and sometimes the start-up can take up to 3 – 4 months. In start-up process, hydraulic loading must be Ј 50% of the design hydraulic loading.
The start-up of the UASB reactor can be considered to be complete once a satisfactory performance of the system has been reached at its design load.