Modeling of a Combined Ultraviolet-Biofilter System to Treat Gaseous Chlorobenzene I: Model Development and Parametric Sensitivity

Figures & data

Figure 1. Relationship simulations between Φ and c _A0.

Table 1. A list of symbols and parameters and their values for UV submodel

Symbol	Parameter	Numerical Value	Methods and Source
b	Optical path	0.04 m	Measured in this study
c A0	UV inlet chlorobenzene concentration	100–4000 mg m^−3	GC analyzed in this study
c A1	UV outlet chlorobenzene concentration	100–3000 mg m^−3	GC analyzed in this study
E 1	Energy of one photon	7.8 10^−19 J	Reference 16
H	Reactor height	0.45 m	Measured in this study
H	Planck's constant	6.62 × 10^−34 m^2 hr^−1	Reference 16
I ave	Average light intensity	38 W m^−3	Equation 15
L	Lamp length	0.44 m	Measured in this study
N A	Number of chlorobenzene molecule
N	Avogadro constant	6.023 × 10^23 m^2 hr^−1	Reference 16
P i	Emission energy fraction at wavelength i	0.75	Lamp parameter
Q	Gas flow rate	0.1–0.5 m^3 hr^−1	Measured in this study
R	Reactor internal radius	0.04 m	Measured in this study
r 1	Lamp radius	0.001 m	Measured in this study
R	Radial coordinate
S L	Light source strength per unit length	52.3 W m^−1	Calculation in this study
V UV	UV reactor volume	2.2 × 10^−3 m^3	Measured in this study
X	Number of absorbed photons
Z	Rectangular coordinate
τUV	Gas empty-bed residence time in the UV reactor	0–81 sec	Calculation in this study
Φ	Quantum yield		Calculation in this study
μi	Absorbency per unit optical thickness	0.0894 m^−1	Reference 11
ϵA	Mole extinction coefficients	7.4 × 10^3 L mol^−1 cm^−1	Reference 17

Table 2. A list of symbols and parameters and their values for biofilter submodel

Symbol	Parameter	Numerical Value	Methods and Source
A BF	Cross-sectional area of biofilter	1.13 × 10^−2 m^2	Measured in this study
a	Specific area of the filter bed	860 m^2 m^−3 (UV-BF) 820 m^2 m^−3 (BF)	Calculation in this study
c A1	Biofilter inlet chlorobenzene concentration	100–3000 mg m^−3	Measured in this study
c A2	Biofilter outlet chlorobenzene concentration	100–3000 mg m^−3	Measured in this study
c S	Chlorobenzene concentrations at the biofilm/liquid interface
c f	Chlorobenzene concentrations in the biofilm
D	Diffusion coefficient of chlorobenzene in water	2.44 × 10^−6 m^2 hr^−1	Reference 18
D f	Diffusion coefficient of chlorobenzene in biofilm	1.97 × 10^−7 m^2 hr^−1	Reference 18
H′	Distribution coefficient of chlorobenzene	0.15	Reference 19
K s	Half-saturation constant	1.5 × 10^3 mg m^−3	Reference 20
L′	Thickness of the water layer over the biofilm
L f	Thickness of biofilm	0.15 mm (UV-BF) 0.2 mm (BF)	Measured in this study
L	Height of biofilter	0.3 m	Measured in this study
Q	Gas flow rate	0.1–0.5 m^3 hr^−1	Measured in this study
V BF	Biofilter volume	3.4 × 10^−3 m^3	Measured in this study
νm	Maximum substrate utilization rate	0.85 hr^−1	Reference 20
X f	Microorganism concentration	6.7 × 10^4 g m^−3 (UV-BF) 7.2 × 10^4 g m^−3 (BF)	Measured in this study
τBF	Gas empty-bed residence time in the biofilter	0–122 sec	Calculation in this study
∈o	Initial void fraction of the filter bed	0.59 (UV-BF) 0.53 (BF)	Calculation in this study
Notes: BF = biofilter.

Figure 2. Setup of the experiment system.

Table 3. Operating conditions of the UV-biofilter system

		Operating Conditions
Run Number	Running Days	UV Lamp (on/off)	τuv (sec)	τBF (sec)	Inlet Concentration (mg m^−3)
Run 1	0–30	Off	0	122, 41, 24	250 ± 150
Run 2	31–47	On	81	122	1000 ± 500
Run 3	48–59	On	40	61	1000 ± 500
Run 4	60–80	On	27	41	1000 ± 500
Run 5	81–95	On	20	30	1000 ± 500
Run 6	96–108	On	16	24	1000 ± 500
Run 7	109–120	On	27	41	250 ± 150
Run 8	121–146	On	27	41	800 ± 200
Run 9	147–180	On	27	41	1500 ± 500
Run 10	181–194	On	27	41	400 ± 150
Run 11	195–207	On	27	41	2500 ± 300
Run 12	208–228	On	40	122	800 ± 300
Run 13	229–238	On	27	122	800 ± 300
Run 14	239–280	On	20	122	800 ± 300

Figure 3. Model simulations (lines) and experimental data (symbols) of chlorobenzene removal efficiencies for (a) c _A0 changes and (b) gas flow rate variations.

Figure 4. Model simulations (lines) and experimental data (symbols) of chlorobenzene removal efficiencies of the control biofilter (no UV treatment).

Figure 5. Relationship between ozone concentration and ψ.

Figure 6. Modified model simulations (solid lines), combined model simulation (dashed line), and experimental data (symbols) of the combined UV-biofilter system performance at various operating conditions: (a) outlet concentration, (b) removal efficiency, and (c) removal rate.