BIO-OXIDATION - A TECHNOLOGY FOR SUSTAINABLE AIR POLLUTION CONTROL

Air pollution

Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment into the atmosphere

• Silica, silicon dioxide• Metal oxides• Inorganic salts• Heavy metals(mercury, chromium)• Ammonium salt particles• Condensable hydrocarbons• Byproducts of combustion• Soluble VOC formaldehyde• Acid gases such as HCl,HF, H2SO4, HNO3• Sulfur dioxide (SO2)• Chlorine gas (Cl2)• Hydrogen sulfide (H2S)• Ammonia

Air pollutants

What is bio-oxidation ?

Bio-oxidation is a biological air pollutioncontrol technology that utilizes bacteria & fungi to biologically absorb and digest vapor phase VOCs and odorous compounds commonly found in industrial and municipal applications.

Techniques

• Bio-filtration• bio scrubber• Bioremediation

Bio-filtration

• Use moist solid media• Driving force is solubility in water and biodegradability• High treatment performance is associated with low

molecular weight and high water solubility

Filter media is for providing:-• large surface area• Energy source and nutrients to the microorganism.• Stable structural matrix to allow the gas stream to pass through

• Utilization of Natural Materials and Microorganisms Growing in a Media Bed to Destroy Organic Compounds and Remove Air Toxics from an Air Stream

• Addition of Biomass Support Media (Wood or other packing) improves bio-filter performance through reduced pressure drop and improved air flow and contaminant distribution

Bio filter Advantages:

• Very moderate initial capital costs

• Low operating costs • Large energy savings over RTO

technology• Generates non-hazardous by-

products • Treatment to handle wide range

of VOCs • Consortium of microorganisms,

once well developed can handle moderate fluctuations in input gas content

Bio-filter Disadvantages

• Large land requirement for traditional design.• No continuous internal liquid flow in which to adjust bed pH or to add nutrients.• Traditional design does not have a covered top• Bed replacement can take 2 to 6 weeks, depending on bed size.

BIOTRICKLING FILTER

• similar to a biofilter.• pollutants are also transferred from

the gas phase to a biofilm that grows on a packing material.

• packing materials are made of chemically inert materials, such as plastic rings.

• nutrients are not available in these materials.

• consists of two reactors:-• The first part is an absorption tower, where

pollutants are absorbed by a liquid phase.• second reactor, which is a kind of activated sludge

unit, where microorganisms growing in suspended flocks in the water degrade the pollutants.

• The effluent of this unit is re-circulated

Bio scrubber

Bioscrubber Advantages:• save the cost of installing a humidification process.•smaller footprint than other bioreactors• Because pH control and nutrient feed can be automated, it requires less attention than other bioreactors.• Process is ideal for emissions that produce acids upon treatment.• Bioscrubber can treat emissions containing particulate matter.

Bioscrubber Disadvantages:• more expensive • Over feeding can cause excessive biomass growth, which can plug the bioscrubber.• Operating cost can be higher• Needs expensive and complex feeding and neutralizing systems.• To control biomass growth, toxic and dangerous compounds must be inventoried and handled.

Bioremediation can be defined as any process that uses microorganisms to return the natural environment altered by contaminants to its original condition. Bioremediation may be employed to attack specific contaminants, such as degradation of chlorine hydrocarbon by bacteria.

bioremediation

Effectiveness of bioreactor .

• Moisture • Temperature • pH

Challenges for Biological Systems

• Large Footprint • Media heterogeneity and

compaction • Unsteady inputs of VOCs • Regulatory uncertainty for proof

of reliability• Operator training

Thank

you