Effect of Cold‐Temperature Shock on Nitrification

Abstract

Nitrification is known as the most temperature‐sensitive step among the biological processes in wastewater treatment. The purpose of this study was to investigate the effect of temperature on nitrification, in the case of a sharp decrease of temperature, and to compare this effect with that of a gradual temperature decrease. It was found that a sudden temperature decrease affected nitrification much more than predicted. The immediate decrease of temperature by 10°C led to a 20% larger decrease of specific nitrification rate than predicted by the temperature correction factor of 1.072. The change of nitrification rate resulting from a gradual temperature decrease was modeled correctly with the current default temperature correction factor of 1.072. It was concluded that the correction factor actually can be applied to a gradual temperature‐change situation; however, in the case of a sudden temperature decrease, measures need to be taken to avoid nitrifier washout.

Manometric measurements of temperature influence on Anammox activity

“…Considering the fact that the tests were performed without biomass acclimatization, this may suggest that a short-term temperature effect due to a shock caused by sudden temperature change may have contributed to the observed differences [18]. Lotti et al [12] recommended an acclimatization period of 24-48 h to allow biomass to recover from the temperature shock effect.…”

Applicability of the Arrhenius model for ammonia oxidizing bacteria subjected to temperature time gradients

“…More recent works in bench, pilot and full scale reported temperature correction factor in the range 1.05-1.4 [16][17][18][19][20][21]. The variability of these values of the Arrhenius coefficients may reflect the differences in the type of biomass, as well as in the test conditions, that is, at least, on the considered temperature range, on the monitoring technique and, finally, on the temperaturetime gradient: a significant difference between the impact of sudden and gradual temperature changes on nitrification was demonstrated by Hwang and Oleszkiewicz [9].…”

“…Bacterial adaptation to temporal temperature gradients was shown to be dependent on their ability to produce coldshock proteins [6,7] and to adjust cell membrane's viscosity [8]. In some wastewater treatment plants (WWTPs), the spring thaw may decrease the temperature of the incoming sewage by more than 10°C in a matter a few hours [9] and the impact of this sudden change on process kinetics, is still unquantifiable using conventional activated sludge models.…”

“…At the same time, temperature time gradients and temperature difference between the seeding and the seeded reactor [7,[9][10][11] was shown to influence the efficiency of nitrifiers bioaugmentation when operated by seeding concentrated nitrifying biomass selected in a side-stream reactor fed with anaerobic digesters supernatant [11,12], into main-stream biologic reactors.…”

“…Although several models have been developed to describe the temperature dependency of biologic processes (i.e., Arrhenius, Eyring-Polanyi, Ratkovsky, Williams-Landel-Ferry models), the Arrhenius model has been, by far, the most commonly used to provide a simplified estimation of temperature effects on activated sludge reactions, including nitrification [9,13].…”