please give me the seminar report of biofiltration ,its argent

Abstract
Air streams can be purified by passing them through a biologically active filter medium to destroy organic and inorganic contaminants. It is especially effective for low concentrations of VOCs and inorganic chemicals (e.g., sulfur compounds). It has proven effective for mixed waste air streams and especially applicable for odor abatement. Heavily halogenated compounds present problems

Overview
Biofiltration is generally effective for aqueous wastes where concentrations are less than 1%. As with all biological treatment, it requires stable, consistent operating conditions.

Biofiltration is not suitable for highly chlorinated organics, aliphatics, amines, and aromatic compounds. Heavy metals and organic chemicals may kill the microorganisms. Heavy metals and non-biodegradable organics may also concentrate in the sludge. Hydrogen sulfide gas may also be released. Biofiltration swales and strips are vegetated areas that remove pollutants from storm water runoff as it flows through the vegetation.

Removal mechanisms include filtration and infiltration. In this study, one biofiltration strip and six swales treat highway runoff, while two strips treat runoff from maintenance yards (for pretreatment for infiltration trenches). Runoff is captured in drain inlets and routed to the swales, while strips receive sheet flow directly from the pavement. Swales are conveyance channels where storm water flow passes through the grass. Strips are broad surfaces with a grass cover that allows storm water to flow in relatively thin sheets.

Biofiltration swales and strips are providing useful information about vegetation that can filter storm water pollutants effectively in dry areas with little rainfall. These biofiltration devices can also be used for pretreating storm water going to infiltration BMPs (i.e., trenches and basins). This "treatment train" approach can increase the overall effectiveness of storm water treatment.

Biofiltration is a relatively new pollution control technology. It is an attractive technique for the elimination of malodorous gas emissions and of low concentrations of volatile organic compounds (VOCs). The most common style biofilter is just a big box. Some can be as big as a basketball court or as small as one cubic yard. A biofilter's main function is to bring microorganisms into contact with pollutants contained in an air stream. The box that makes up this biofilter contains a filter material, which is the breeding ground for the microorganisms. The microorganisms live in a thin layer of moisture, the "biofilm", which surrounds the particles that make up the filter media. During the biofiltration process, the polluted air stream is slowly pumped through the biofilter and the pollutants are absorbed into the filter media. The contaminated gas is diffused in the biofilter and adsorbed onto the biofilm. This gives microorganisms the opportunity to degrade the pollutants and to produce energy and metabolic byproducts in the form of CO2 and H2O.(Anit.,Artez, Biofiltration of Air) This biological degradation process occurs by oxidation, and can be written as follows:
Organic Pollutant + O2 à CO2 + H2O + Heat + Biomass

This site contains links that will explain how the process of biofiltration began being used, the actual methodology of the biofiltration process, a list of commercial applications, advantages and disadvantages of biofiltration, and a discussion/conclusion about the above topics.

Background and Introduction
Methods
Commercial Applications
Advantages
Disadvantages
Discussion/Conclusion
References


Background and Introduction

Biological treatment or biofiltration is now the mainstay of wastewater management systems. Patent applications for odor control using biofiltration have been filed since the 1950s for soil filters and large biological trickling filter plants.

Biofilters have been designed primarily for odor control at wastewater treatment plants, rendering plants, and composting operations. They are becoming more popular in the treatment of VOCs (volatile organic compounds), as an innovative method to treat toxic air emissions from commercial processes.

What Does a Biofilter Do?
Biofilters perfom the removal and oxidation of compounds from contaminated air using microorganisms. Smelly air emissions generally contain low concentrations of hydrogen sulfide, mercaptons, and other reduced sulfur compounds.

During the 1990s, biofilters were also used to remove airborne contaminants, including aliphatic and aromatic hydrocarbons, alcohols, aldehydes, organic acids, acrylate, carbolic acids, amines and ammonia. These substances are not just smelly, they are dangerous as well.

Timeline - Biofilters

1923: The first proposition to use biological methods to treat odorous compounds was as early as 1923. Bach thought of using a biologically active biofilter to control emissions of H2S from a waste water treatment plant.
1955: Biological methods were first applied to treat odorous emissions in low concentrations in Germany.
1959: A soil bed was installed at a sewage treatment plant in Nuremberg for the control of odors from an incoming sewer main.
1960's: Biofiltration was first used for the treatment of gaseous pollutants both in Germany and US; research was intensified.
1970's: Biofiltration becomes widespread in Germany.
1980's: Biofiltration is used for the treatment of toxic emissions and volatile organic compounds (VOCs) from industry.
1990's: There are more than 500 biofilters operating both in Germany and Netherlands, and it is spreading in the US.