Hydrogen Sulfide and Methyl Mercaptan
Removals with Soil Columns
DALE A. CARLSON, Associate Professor
ROBERT C. GUMERMAN,  Graduate Student
Civil Engineering Department
University of Washington
Seattle, Washington
INTRODUCTION
Industrial operations are under ever increasing public pressure to eliminate
waste discharges. Responsible industries themselves agree that this is necessary,
but often lack a suitable method for treatment of their waste streams, both liquid
and gaseous.
In the past the atmosphere was considered a vast reservoir which would dilute
acceptably all wastes delivered to it. Today we recognize the limited capacity
of the atmosphere to receive these pollutants. Rapid growth of our population and
economy is tending to make this limited capacity an even more critical factor
than in the past, especially in developing regions which tend to have seasonal restrictions on atmospheric air movements. In such cases removal of noxious or
odorous emissions to the atmosphere becomes an important aspect of waste treatment.
Many methods have been considered and applied, successfully and unsuccessfully, in odor elimination schemes. Adsorption offers promise, but requires
periodic surface reactivation. Wet and dry scrubbing operations require large
amounts of equipment and material, yet must be tailor made for the operation
considered. Burning of odor requires a furnace of proper design, but often involves
destroying one odor with consequent production of another. Masking and neutralization require careful selection and proportioning of chemicals. Chemical reactions are useful, but require purchase of chemicals, unless by chance they are
present in the industrial waste stream. All of these deodorization schemes (1) face
some drawback, either technically or economically.
Recently, the soil filtration principle has been introduced and successfully applied to odors emanating from sewage. This principle was patented by Pomeroy
in 1957(2). Pomeroy suggested passing sewage odors through two to four ft of soil,
allowing soil microorganisms to biologically degrade the various malodors present.
Figure 1 illustrates Pomeroy's idea.
A successful application of the principle was used on Mercer Island, Washington, in 1961. Here, "soil filters were employed experimentally to deodorize
gases emanating from anaerobic sewage in sewage lift stations. The initial installations proved so successful that all 13 lift stations on the island now utilize
the "soil filter" principle.
The sewer trench installations on Mercer Island are similar to Figure 1. Design specifications for an installation of this type are based on the amount of sewage flow through the lift station, as shown by the data (3) in Table I.
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