EFFECT OF TEMPERATURE ON BIO-KINETIC COEFFICIENTS INUASB TREATMENT OF MUNICIPAL WASTEWATER

KRIPA SHANKAR SINGH1 and T. VIRARAGHAVAN2

1 Department of Civil Engineering, University of New Brunswick, Fredericton, New Brunswick,Canada E3B 5A3; 2 Faculty of Engineering, University of Regina, Regina Saskatchewan, Canada

S4S 0A2

(Received 22 October 1999; accepted 3 May 2001)

Abstract. Upflow anaerobic sludge blanket (UASB) reactors were used to treat municipal wastewa-ter at temperatures of 6, 11, 15, 20 and 32 ◦C and at hydraulic retention times (HRTs) rangingfrom 48 to 3 h over an operational period of approximately 860 days. The Monod model was used toevaluate substrate utilization. The Arrhenius model was used to calculate the activation energies fromwhich temperature coefficients were determined. It was found that the maximum specific substrateutilization rate constant (k) decreased from 0.387 d−1 (at 32 ◦C) to 0.041 d−1 (at 6 ◦C). The decayrate constant (kd), yield coefficient (Yg), half velocity constant (Ks) and maximum specific growthrate (µm ) were also impacted by temperature in the UASB treatment of municipal wastewater.

Keywords: UASB treatment, municipal wastewater, bio-kinetic parameters, temperature

1. Introduction

High-rate upflow anaerobic sludge blanket (UASB) reactors have been generallyconsidered successful in treating wastewaters at mesophilic temperatures (around35 ◦C) or thermophilic temperatures (around 55 ◦C). Recently, however, it has beenrecognized that reasonably effective treatment can be accomplished through high-rate anaerobic reactors such as anaerobic sequencing batch reactor (ASBR), UASBreactor, and expanded granular sludge bed (EGSB) reactors at lower temperatures(Banik et al., 1998; Singh and Viraraghavan, 1998; Collins et al., 1998; Seghezzoet al., 1998 and Agrawal et al., 1997). Since the temperature of most wastewa-ters other than a few industrial wastewaters is well below 35 ◦C, a considerableeconomic advantage is possible if the external heating requirement can be elim-inated or reduced by treating these wastewaters at lower temperatures. In mostcold climate regions, the municipal wastewater temperature varies between 7 and15 ◦C; it would be of great advantage to develop information on the application ofa UASB reactor system for wastewater treatment under low-temperature operatingconditions.

A rational basis for process analysis and design including a knowledge of pro-cess kinetics is essential to a realization of the full potential of high-rate UASBreactors. At present, the UASB system is facing a challenge in the developmentof a successful application of low-strength dilute municipal wastewater treatment,

Water, Air, and Soil Pollution 136: 243–254, 2002.© 2002 Kluwer Academic Publishers. Printed in the Netherlands.