29 research outputs found
Biotrickling filtration of isopropanol under intermittent loading conditions
This paper investigates the removal of isopropanol by gas phase biotrickling filtration. Two plastic packing materials, one structured and one random, have been evaluated in terms of oxygen mass transfer and isopropanol removal efficiency (RE). Oxygen mass transfer experiments were performed at gas velocities of 104 and 312 m h-1
and liquid velocities between 3 and 33 m h-1. Both materials showed
similar mass transfer coefficients up to liquid velocities of 15 m h-1. At greater liquid velocities, the structured packing exhibited greater oxygen mass transfer coefficients. Biotrickling filtration experiments
were carried out at inlet loads (IL) from 20 to 65 g C m-3
h -1
and empty bed residence times (EBRT) from
15 14 to 160 s. To simulate typical industrial emissions, intermittent isopropanol loading (16 h/day, 5
16 day/week) and intermittent spraying frequency (15 min/1.5 hours) were applied. Maximum elimination
capacity (EC) of 51 g C m-3
h
-1
has been obtained for the random packing (IL of 65 g C m-3
h
-1
17 , EBRT of
18 50 s). The decrease in irrigation frequency to 15 min every 3 hours caused a decrease in the outlet
emissions from 86 to 59 mg C Nm-3
(inlet of 500 mg C Nm-3). The expansion of spraying to night and
weekend periods promoted the degradation of the isopropanol accumulated in the water tank during the
day, reaching effluent concentrations as low as 44 mg C Nm-3. After a 7 week starvation period, theperformance was recovered in less than 10 days, proving the robustness of the proces
Kinetic and stoichiometric characterization of anoxic sulfideoxidation by SO-NR mixed cultures from anoxic biotrickling filters.
Monitoring the biological activity in biotrickling
filters is difficult since it implies estimating biomass concentration
and its growth yield, which can hardly be measured in
immobilized biomass systems. In this study, the characterization
of a sulfide-oxidizing nitrate-reducing biomass obtained
from an anoxic biotrickling filter was performed through the
application of respirometric and titrimetric techniques. Previously,
the biomass was maintained in a continuous stirred tank
reactor under steady-state conditions resulting in a growth
yield of 0.328±0.045 g VSS/g S. To properly assess biological
activity in respirometric tests, abiotic assays were conducted
to characterize the stripping of CO2 and sulfide. The
global mass transfer coefficient for both processes was estimated.
Subsequently, different respirometric tests were performed:
(1) to solve the stoichiometry related to the autotrophic
denitrification of sulfide using either nitrate or nitrite as
electron acceptors, (2) to evaluate the inhibition caused by
nitrite and sulfide on sulfide oxidation, and (3) to propose,
calibrate, and validate a kinetic model considering both
electron acceptors in the overall anoxic biodesulfurization
process. The kinetic model considered a Haldane-type equation
to describe sulfide and nitrite inhibitions, a non-competitive
inhibition to reflect the effect of sulfide on the elemental
sulfur oxidation besides single-step denitrification since no
nitrite was produced during the biological assays
Biofiltration of wastewater lift station emissions: evaluation of VOC removal in the presence of H2S
Biodegradation of gaseous styrene by Brevibacillus sp using a novel agitating biotrickling filter
A novel biofilter with an agitator to control excessive biomass accumulation, the agitating biotrickling filter (ABTF) system, was developed for treatment of gaseous styrene using Brevibacillus sp. as the sole microorganism the ABTF exhibited an elimination capacity of 3 kg styrene m(-3) day(-1). After 110 days, the biodegradation efficiency decreased because of the clogging. The excess biomass was effectively removed by agitation. After the first agitation step, 42.4 g biomass was eliminated, and the removal efficiency increased from 60% to 95%. Stable operation of the ABTF was achieved by controlling the biomass accumulation via the agitation of the filter bed