“Performance of a bioreactor using organic compound and Pall ring media

for the treatment of BTEX vapors Authors: SIQUEIRA, L. C. G, De ASSUNÇÃO, J. V.,

Ligia Siqueira 2013

•High cost

•Waste generation and fuel consum

•Inefficient for:

•High flow of gases

•Low concentrations of pollutants (PÂQUES, 1997)

CONVENTIONAL TECHNOLOGIES

ADVANTAGES AND DISADVANTAGES

Advantages Disadvantages

Both equipment and operation are relatively simple

It is pollutant specific

Usually do not form additional pollutants. It produces only CO2, water, biomass, and minerals

Corrosion potential of the equipment due to moisture from gas stream

Process occurs at room temperature and thus the security is inherent

Sensitivity to temperature, concentration and humidity

Capital and operation costs are lower than classic technologies

Proper control of moisture vapor at high load of organic compounds may be difficult

(HUNTER, OYAMA, 2000)

POTENTIAL APPLICATIONS

• Production of adhesives

• Animal Breeding

• Chemical industry

• Storage of chemicals

• Composting waste

• Crematoria

• Food industry

• Fragrance production

• Iron Foundries

• Landfills

• Petrochemical plants

• Oil Refineries

• Printing industry

• Rendering plants (recovery of animal matter)

• Wood and furniture industry

(DEVINNY et al., 1999)

• Natural Materials – Peat

– Splinter

– Wood bark

– Compost

– Bagasse

• Processed or Synthetic Materials • Activated charcoal • Perlita • Monolithic ceramics • Polyurethane foam • Glass Wool • Diatomaceous earth

(FRITZ, KERN, 1992)

MATERIALS OF FILTERING BED

EXPERIMENTAL SYSTEM

(SIQUEIRA, 2011)

HUMIDIFICATION AND NUTRIENT INJECTION

Use of phosphate solution to provide both nutrient and water

CARACTERISTICS OF THE BIOFILTER

Parameter Conditions

Column height (m) 1.20

Column inner diameter (m) 0.08 Bed height (m) 0.48

Bed volume (m3) 0.0024

Air flow rate (m3/h) 1 Lpm

Pressure drop across media (mmH2O) 1.1-1.4

Inlet BTEX concentration (ppm) 70-250

(SIQUEIRA, 2011)

• Heteropopulation

• Presence of microorganisms that metabolize BTEX

(SIQUEIRA, 2011)

COMPOST PALL RINGS

BIOREACTOR FILTERING BED SELECTION

Mercury bulb thermometer from -10°C to 50°C (division of 1°C)

MONITORING PARAMETERS AND METHOD

Ambient condition

Room temperature, barometric pressure and relative humidity of air throughout the experimental period.

Pressure drop Micro manometer (minimum reading division length of 1mm of water column)

Gas flow rate Rotameter (minimum division length reading of 1 liter/min)

Gas volume Dry gas meter (minimum division length reading of 1 liter)

Temperature

PERFORMANCE PARAMETERS

where: CL = concentration loading (g/ m3xh) EC = elimination capacity (g/ m3xh) EBRT = empty bed residence time (min) ER = eficiency of removal (%) SL= surface loading (m3/m2 x h) Cin and Cout= inlet and outlet concentration of BTEX respectively (g/m3) Qg = air flow rate (m3/h) Al = transversal section área of the filter bed (m2) Vl = volume of filter bed (m3) Vg = volume of gases (m3)

Efficiency of removal

Retention time in the bed void Surface load Mass load in bed

Elimination capacity

PERFORMANCE PARAMETER RESULTS

PERFORMANCE PARAMETER VALUE EBRT (min)

SL (m2/m3.h)

CL (g/m3.h)

EC (g/m3.h)

ER (%)

2.2-2.4

11.9 - 13.1

8 -67 (46 critical)

4 - 29

86.6 - 93.4

•Higher EBRT helps to increase removal efficiency by promoting the dissemination and retention of BTEX in the bed and contact between pollutants and microorganisms, which may have contributed to the high efficiency found around 93% in the stationary phase.

RESULTS AND DISCUSSION

•Being lower the surface load, the retention time should be higher in order to increase the removal efficiency (Swanson and Loher, 1997).

•Agreement with the results due to the operating conditions used, as the lower surface load was found associated with a high retention time (2.2 - 2.4 minutes), thus favoring the removal efficiency of up to 93.6%.

References Retention time in the bed void - EBRT (min)

Biofilter 2.2 - 2.4 min (HIGH)

CONVERTI, ZILLI (1999) e SWANSON, LOHER(1997) 0.25 - 1 min

DELHOMENIE et al. (2005) seconds to several minutes

References Surface load (SL)

Biofilter 11.9 -13.1 m3/m2. h (LOW)

CONVERTI, ZILLI (1999) 50-120 m3/m2. h

RESULTS AND DISCUSSION

- High mass loads favor the clogging of the filter medium (SWANSON and LOHER, 1997). -No clogging of the bed during the tests because of low mass load in the bed.

References Mass load in bed (CL)

Biofilter 8 - 67 g/m3.h (LOW)

CONVERTI, ZILLI (1999) 10-160 g/m3.h

References Efficiency of removal - ER (%)

Biofilter 86,6 – 93,4 for BTEX (HIGH)

ZILLI (1999) 95 to 99% for aromatics (benzene and toluene) from gasoline tanks

75 to 90% (eventual 95%) for BTEX emissions in petroleum refining

RESULTS AND DISCUSSION

• As the elimination capacity is a function of the biodegradability conditions of the medium, lower removal capacities are associated with low mass loads and low concentration of the pollutant in the gas and increased retention time (CONVERTI and ZILLI, 1999).

•Thus, the result is in agreement with the conditions under which the tests were performed: low surface load, low concentrations of BTEX (70 - 250 ppm) and high retention time.

•EC = 29 g/m3.h (critical mass load in bed) (biofilter with compost mixed with Pall rings)

References Elimination capacity (EC)

Biofilter 4-29 g/m3.h (LOW) (BTEX in the bed with compost + Pall rings)

CONVERTI, ZILLI (1999) 10-160 g/m3.h

HUNTER and OYAMA (2000) 20 to 30 g/m3.h (BTEX in the bed with compost )

GRACY et al. (2006) 30g/m3.h (biofilter with compost for toluene)

PRESSURE DROP -Small change -Indicator: no bed clogging (main reason for Pall ring use)

REMOVAL EFFICENCY (%) -Variation pattern in removal efficiency (RE) - Biodegradation curve similar to the curve by Monod.

- KLAPKOVÁ et al. (2006) got same result with a biofilter using compost for the removal of a mixture of toluene and xylene. - It is an indication that the growth of microorganisms in this environment is relevant for the biodegradation process, and to attain and maintain higher removal efficiency.

• Technology feasible to treat low concentrations of BTEX by biodegradation process and to achieve high removal efficiencies.

• Conditions for good level of biodegradation and to maintain high and more constant removal efficiency throughout its useful lifetime are, among others:

– For each type of pollutant a set of design criteria and monitoring parameters should be developed

– To choose microorganisms compatible with the pollutant

– To maintain homogeneous temperature throughout the bed

– Moisture content should be compatible with the microbiota

– pH without need no drastic changes.

• It is an environmental technology simpler, cleaner and cheaper, which uses local inputs and it is appropriate for developing countries.

• Bioreactors can be a viable alternative to meet the requirements of environmental legislation.

CONCLUSIONS

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