Design of a new rotating drum bioreactor operated at atmospheric pressure on the bioremediation of a polluted soil

Bioprocess Biosyst Eng (2010) 33:573582 DOI 10.1007/s00449-009-0383-0

ORIGINAL PAPER

Design of a new rotating drum bioreactor operated at atmospheric pressure on the bioremediation of a polluted soil

Miguel A. Rodrguez-Meza Benjamn Chvez-Gmez

Hctor M. Poggi-Varaldo Elvira Ros-Leal

Josena Barrera-Corts

Received: 13 May 2009 / Accepted: 17 September 2009 / Published online: 22 October 2009 Springer-Verlag 2009

Abstract This paper reports the effect of the operation and design characteristics of rotating drum bioreactors (RDBs) aerated by natural convection and applied to the treatment of a soil highly polluted with weathered total petroleum hydrocarbons (TPH) (55,000 2,600 mg/kg). The parameters studied were length to diameter ratio (L/D), rotating speed (N) and lifter type. The highest TPH removal (59.6 0.7%) was obtained with the RDB of the lowest L/D ratio (1.5). Removals diminished by 27, 36 and 56%, with a ratio increment of 2.1, 3.1 and 5.1, respectively. Increment of the N, at an optimal value and lifter change from straight to helicoidal showed an improvement on the TPH removal of 20 and 30%, respectively. According to these results, slurry surface renewal through the variation of the N and the change of slurry ow was able to improve TPH removal in RDBs operated by natural convection.

Keywords Length to diameter ratio Natural aeration

Remediation Rotating drums Slurries

List of symbolsA Gas-slurry interfacial area (m2)

AT Transversal lifter area (m2)dh Diameter of the aeration holedi Slurry chord in the drum of L/D = i (m)

GET Gas exchange time (s)

GETi Exchange time of gases in the RDB of L/D = i (s)

Gair Natural convective air mass ow (kg/s)

ID Internal diameter of the rotating drums (m) L Rotating drum length (m)

Li Length of the drum of L/D = i (m)

L/D Length to diameter ratio of the rotating drums, dimensionless

mair,i Mass of air in front of the four lifters (kg) _

mair;i Air mass ux in the RDB of L/D = i[kg/(m2 s)] _

mO2;i Oxygen mass ux in the RDB of L/D = i[kg/(m2 s)]

N Rotational speed (1/s)

R Radius of the rotating drum bioreactors (m) RDB Rotating drum bioreactorsSSF Solid substrate fermentationSTR Stirred tank reactorsTPH Total petroleum hydrocarbons (mg/kg) TPHinitial Total petroleum hydrocarbons in the polluted

slurry before the slurry biotreatment (mg/kg)...