Cold (9-15° C) deammonification biofilm achievment by gradual temperateure decrease

Abstract

For N-rich wastewater treatment the anaerobic ammonium oxidation (anammox) and nitritationanammox (deammonification) processes are often used. Temperature gradual lowering by 0.5° C per week achieved a similar maximum total nitrogen removal (TNRR) of 1.5 g N m-2 at 15° C as at 20° C in a deammonification moving bed biofilm reactor (MBBR). Our experiments show that a biofilm of a deammonification reactor adapted to 15° C successfully tolerates short-term cold shocks down to 9° C retaining a high TNRR.

To study the short-term effect of temperature on the TNRR, a series of batch-scale experiments were performed which showed remarkable TNRRs even at 9-15° C (4.3-5.4 mg N L-1 h-1, respectively). Anammox temperature constants (Q10) ranged 1.3-1.6. After biomass was adapted to 15° C, the decrease in TNRR in batch tests at 9° C was lower (15-20%) than for biomass adapted to 17-18° C showing efficient biomass adaption to low temperature. qPCR analysis showed an increase in Candidatus Brocadia quantities from 5×103 to 1×107 anammox gene copies g-1 TSS despite temperature lowered to 15° C.