This document provides an overview of biofilters for air pollution control. It discusses key concepts like air contaminants, microbes, and biofiltration. It describes the components of a biofilter system and gives an example case study of using a biofilter to remove benzene. The case study describes the benzene generation system, biofiltration process, results and discussion of parameters like inlet concentration, loading rate, residence time, temperature, and pressure drop. It also outlines advantages like low costs and drawbacks like large land requirements. The conclusion states that biofilters are cost-effective but require an understanding of site conditions and system design.

1. BioFilters for air
pollution
control
Given by
B. Manoj Kumar
166211
B.Tech 4th year
Department of Chemical Engineering
NIT Warangal

2. Introduction
Air Contaminants, Microbes, Biofiltration
Biofilter Components
Components
Case Study (Benzene Removal)
Benzene Generation system, Process,
Results and Discussion, Parameters
Conclusion
01
02
03
05
Contents
04 Advantages and Drawbacks
Advantages, Drawbacks

3. KEY WORDS
Air Pollution
Control(APC)
Techniques employed to reduce or eliminate
the emission into the atmosphere of
substances that can harm the environment
or human health.
Biofilter
Microbes
Contaminant
Presence of a constituent, impurity, or some
other undesirable element that spoils,
corrupts, infects, makes unfit, or makes inferior
a material, physical body, natural environment,
workplace, etc.

4. INTroduction
01
Air Contaminants
Microbes
Biofiltration

5. Major surrounding air contaminations
Poisonous metals
Arsenic, lead, cadmium, nickel
chromium, cobalt, zinc and
selenium are highly toxic
VOCs
Benzene, ethylene glycol,
formaldehyde, methylene chloride,
tetrachloroethylene, toluene,
xylene, and 1,3-butadiene
Oxides
Nitrogen oxides, sulfur
oxide, carbon monoxide,
and ozone.

6. Microbes
For life to survive, it must
have a source of energy
(food) and water
(moisture)
How these needs are
used to remove pollutants
from contaminated air
streams?
Almost any substance,
with the help of microbes,
will decompose (decay)
given the proper
environment
This is especially true for
organic compounds
But certain microbes also
can consume inorganic
compounds such as
hydrogen sulfide and
nitrogen oxides.

7. Biofiltration
Definition
An APC technique which involves degradation of contaminants under the action of microorganisms
diffused in a thin layer of moisture known as “BIOFILM”, mainly used for elimination of
malodorous(foul-smelling) and low concentration of VOCs.
Reaction
Organic Pollutant + O2 CO2+ H2O + Heat + Biomass

8. Substances treated
Odorous
substances
Ammonia
Hydrogen Sulfide
Xenobiotics
Organic substances
synthesized in chemical
industry
including chlorinated
hydrocarbons.

9. Biofilter components
02
Components

10. Components
A large vessel made of concrete, metal, or durable
plastic, which holds a filter medium.
Filter medium: Peat, heather, bark, chips, etc.
Provides good water holding
and support for microbial growth
Filter needs to be watered sufficiently to maintain
optimum internal conditions
Biofilm is formed by a community of different
microorganisms (bacteria, fungi, yeast, etc.),
macro-organisms (protozoa, worms, insect's
larvae, etc.) and extracellular polymeric substances
(EPS).

11. Benzene removal
03
Benzene Generation system
Process
Results and Discussion
Parameters

12. Benzene generation system
Benzene, a confirmed carcinogen,
is a representative of VOC’s
It is used as a solvent in many
industries, beside its role in
photochemical reactions
As a VOC, air-borne benzene can
react with other air pollution to form
ground levels ozone which can
damage crops and materials
0.05 g/m3

13. Benzene generation system
The desired benzene
concentration is prepared
by manipulation of the two
valves in system.

14. Process
perspex glass
perforated plate
column diameter is 15 cm
height of 70 cm

15. Process
The biofilter was operated 7 to 9 hours daily for
about 9 months. Shutdowns
of the biofilter included nights, weekends, holidays,
and maintenance periods.
The biofilter medium was animal-waste based
compost.
Fresh animal waste (mainly cow and horse
manure) was exposed to air with periodical stirring
for about two weeks. Composting was completed
inside the biofilter.

16. Process

17. Results and discussion
Effect of Benzene inlet concentration
More
time
• EBCT (Residence time)
• Given residence time
concentration efficency

18. Results and discussion
Effect of Benzene Loading Rate
• Loading rate (g/m3.h) : Mass of pollutant
introduced to the biofilter per cubic
meter of the filter bed per hour.
• Elimination capacity (g/m3.h) : Amount of
pollutant that a cubic meter of the bed
can remove per hour.
• Given residence time
Elimination Capcity Loading rate
More
elimination
Accumulation
Biofilm
toxic

19. Results and discussion
Effect of Residence Time
Removal Efficiency Residence time

20. Results and discussion
Effect of Residence Time
1. Mass transfer
2. Biodegradation
• Effective diffusivity of benzene in the biofilm is very low
• Biological reactions are slow in nature
• Require a long time for complete conversion.

21. Results and discussion
Effect of Temperature
• Heating the inlet air stream
• Elimination capacity of each bed
section was determined as related to
the average temperature.
• mesophilic type (37°C-max activity)

22. Results and discussion
Pressure Drop across the Bed
• P Power consumption
• At a specific gas velocity (or EBCT),
pressure drop across the bed increased
after four months rather than at the start
by a factor of 1.8 as revealed by the
slopes of the two lines
1.8

23. Parameters
• Main challenges ----moisture
• Air---Humidified
• Properly maintained, a natural, organic packing media like peat,
vegetable mulch, bark or wood chips may last for several years ..10
years.

24. ● Moisture (inlet air R.H>98%)
● Temperature (30-40°C)
● pH of support material (6-8)
● Oxygen level (Aerobic)
● Nutrient Supply (O:N:P-100:5:1)
Parameters

25. Advantages and
drawbacks
04
Advantages
Drawbacks

26. Advantages
● Compétitive Capital costs
● Low operating costs
● Low maintenance costs
• Avoids high temperature
requirement or explosion risk
• No CO production
• Low noise
• Safe process with high green profile

27. Drawbacks
● Large land requirement for
traditional design.
● A large biofilter (>200,000 acfm)
may occupy as much or more
land than a football field.
● Less suitable for high
concentrations.
• Requires large acclimation
time for microbial population
growth.
• Bed media needs to be
replaced for every 2 to 5 years
which can take 2 to 6 weeks
depending on bed size.
• Moisture and pH
difficult to control.

28. Conclusion
05

29. Conclusion
• The fundamental points of interest are Low expense, effectively work, and produce biomass.
• The design of biofilter system requires a detailed understanding of site, conditions, site
limitations, system components and cost.
• Bio filtration will assume a noteworthy job in the treatment of natural and inorganic emanations
from an assortment of mechanical and waste air treatment forms.

30. THANKS!
Do you have any questions?