Biological Aeration Filter (BAF) process was used in an on-the-spot test of the biological treatment of the slightly-polluted water in a refinery.

Aiming at the poor effect of amino nitrogen degradation in conventional refinery oil sewage treatment, the secondary biochemical test was carried with biological aeration filter pool.

The test for SBR indicated that, the emission of gaseous sulfide happens in the anaerobic stage and initial stage of aeration.