Ks. Singh et T. Viraraghavan, START-UP AND OPERATION OF UASB REACTORS AT 20-DEGREES-C FOR MUNICIPALWASTE-WATER TREATMENT, Journal of fermentation and bioengineering, 85(6), 1998, pp. 609-614
Two upflow anaerobic sludge blanket (UASB) reactors (total volume=8 l)
were started-up at 48 h hydraulic retention time (HRT) and 20 degrees
C temperature to examine the application of this technology for the t
reatment of dilute municipal wastewater under low temperature environm
ents. HRT was reduced gradually to 10 h during 280 d of operation. The
total and soluble chemical oxygen demand (COD) of municipal wastewate
r varied in the range of 350 to 500 mg/l and 150 to 300 mg/l respectiv
ely during this period. Under steady-state conditions, the removal of
total COD and soluble COD ranged from 60 to 75% and 70 to 85% respecti
vely at each HRT. Sulfate concentration in the influent varied from 50
to 100 mg/l as sulfur (S). About 70 to 80% of sulfate in the influent
was reduced, resulting in a low recovery of methane because 30 to 40%
of the total COD was consumed in sulfate reduction. Image analysis of
sludge samples revealed an aggregation of about 50% of sludge particl
es in small granular forms with a mean size of about 1.5 mm.