Underground brine waste containing high concentrations of
ammonium and with a salinity of 3% is usually generated during the production of
methane gas and
iodine in the
gas field of Chiba Prefecture, Japan. In this study, one swim-bed reactor, packed with a novel
acrylic fiber biomass carrier (Biofringe), was applied to the partial nitritation treatment of this kind of underground brine waste. A stable
nitrite production rate of 1.6 kg NO(2)-N m(-3) d(-1) was obtained under a
nitrogen loading rate of 3.0 kg-N m(-3) d(-1), at a pH of 7.5 and a temperature of 25 degrees C.
Nitrate production was negligible and the effluent NO(2)-N/NO(x)-N ratio was above 98% due to the successful inhibition of nitrite-oxidizing
bacterial activity. Free
ammonia was considered to be the main factor for inhibiting the activity of nitrite-oxidizing
bacteria. A
microbial community shift was demonstrated by
16S rRNA analysis, and it was shown that the ammonium-oxidizing
bacteria became the predominant species after successful
nitrite accumulation was observed.
