De. Edwards et al., LABORATORY-SCALE EVALUATION OF AEROBIC FLUIDIZED-BED REACTORS FOR THEBIOTREATMENT OF A SYNTHETIC, HIGH-STRENGTH CHEMICAL-INDUSTRY WASTE STREAM, Water environment research, 66(1), 1994, pp. 70-83
Laboratory-scale fluidized bed reactors (FBRs) containing either sand
or granular activated carbon (GAC) as biocarriers for immobilized bact
eria were evaluated for biotreatment of chemical industry wastes. The
FBRs were fed high levels of a synthetic waste stream containing anili
ne (ANL), methyl ethyl ketone (MEK), p-nitrophenol (PNP) and sodium fo
rmate (FRM) at concentrations increasing from approximately 3 600 mg/L
total chemical oxygen demand (COD) up to 17 000 mg/L COD. Microbial b
iomass attached to the GAC increased from 15 000 mg/L at a COD loading
of 3.2 Kg COD m-3 d-1 to over 40 000 mg/ L at a maximum COD loading o
f 16.0 Kg COD m-3 d-1. The sand was colonized slower during start-up b
ut supported biomass levels of 2600 to 20 000 mg/L at COD loadings up
to 9.6 COD m-3 d-1. Scanning electron microscopy confirmed biomass mea
surements and showed that high levels of bacteria were retained on GAC
after a toxic surge in COD loading, but were significantly reduced in
the sand reactor resulting in diminished performance. Specific chemic
al analyses showed over 99% removal of organic feed components by both
reactors throughout the study. The sand reactor study was terminated
early due to its inability to handle an accidental surge in COD loadin
g. Biological solids production from the GAC reactor ranged from 0.056
to 0.184 g solids/g COD removed. The GAC reactor demonstrated a great
er ability to handle rapid increases in COD loading (for adsorbable ch
emicals) than the sand reactor. This study has increased fundamental u
nderstanding of the operation and performance of FBRs treating a repre
sentative chemical industry waste stream and has demonstrated some adv
antages of GAC over sand as a biocarrier.