Refractory organics are the main composition of residual COD in the effluent of s petrochemical biological wastewater treatment plant.It is the bottleneck in improving water quality with biological methods.The effect of pre-ozonation on a typical petrochemical biological effluent was studied.Molecular weight distribution(MWD)
3-D fluorescence scan
gas chromatography-mass spectrometry(GC-MS)were used to analyze water quality before and after pre-ozonation.The removal rates of COD and UV254 were 11.4% and 23.9% respectively with an ozone dosage of 10 mg·L-1 and a duration of 4 min.Pre-ozonation could remove the refractory organics
such as soluble microbial products(SMP)and humic acids
including some unsaturated bond organics.Pre-ozonation changed the MWD of the wastewater
increasing the percentage of small-molecular-weight organics(<1×103)from 53% to 67%.And it greatly improved the ability of bio-treatment performance of wastewater.Compared with the original biological effluent
COD removal rate of pre-oxidation wastewater treated by the biological aerated filter(BAF)increased by 14.9%.