Ozonation as pre-treatment step for the biological batch degradation of industrial wastewater containing 3-methyl-pyridine

A combined chemical-biological treatment of industrial wastewater using ozo nation as the first step of a Sequencing Batch Biofilm Reactor (SBBR) proce ss, in which 3-methylpyridine (3MEP) was degraded as a model industrial pol lutant, has been developed. The steps of the entire process were ozonation, heterotrophic degradation, denitrification and nitrification. An ozonation bubble-column reactor was used to produce biodegradable molecules, such as formate, acetate, ammonium or nitrate. These were then biologically degrad ed downstream in the biofilm reactors. The gas-liquid mass transfer coeffic ient (K(L)a=2.3*10(-3) (1/s)), the rate constant for the reaction of 3MEP w ith ozone (k(B)=6.63 (1/Ms)) and the surface tension were determined indepe ndently. The latter stayed almost constant through the whole batch ozonatio n (approximately sigma =72E-3 (N/m)). The process was limited by mass trans fer during the first 80 minutes, when about 75 % of the initial pollutant w as degraded. Only a small amount of the total consumed ozone reacted direct ly with 3MEP, while the rest reacted with the non-stable byproducts or was decomposed.