Air Pollutants Associated With Wastewater Treatment
DENNIS A. TROUT, Staff Meteorologist
ROBERT S. REIMERS. Research Scientist
Atmospheric Sciences Section
Battelle Columbus Laboratories
Columbus, Ohio 43201
INTRODUCTION
In an attempt to recycle wastewater, a wide variety of options are available. These
options in turn can be combined to form various approaches of wastewater treatment,
including primary, secondary, and tertiary systems. The most complex form of treatment is
often referred to as Advanced Wastewater Treatment (AWT) which utilizes tertiary treatment (beyond conventional means). In general. AWT plants can usually be subdivided
into four successive components: pretreatment, primary treatment, secondary treatment,
and tertiary treatment.
The purposes of this paper will be to identify potential air pollutants, their sources of
emissions, approximate magnitudes generated, and estimates of the influence of such
emissions on ambient air quality due to wastewater treatment. In order to consider the
overall impact of wastewater treatment on air quality, it is necessary to consider not only the
wastewater plant but also the collection system, and the sludge disposal system.
WASTEWATER COLLECTION SYSTEM
Collection systems associated with a wastewater plant may be classified as sanitary or
combined. In a sanitary sewer, the wastewater is the only input to the sewer or closed
conduit (controlled vents to the atmosphere) going to the sewage treatment facility. When
wastes enter through storm drains or open conduits (uncontrolled vents to the atmosphere),
the wastewater collection system is referred to as an open or combined sewer system.
When wastewater is pumped in a force main to a treatment facility, it is necessary that
the collection system be a sanitary or closed collection system. If the wastewater treatment
facility uses gravity flow, the collection system may be sanitary or combined.
Typical air pollutants generated within a collection system may include H2S, S02,
NH„ CH4, H2, CO, CO,, and pathogens, all resulting from biological activity. As the
quantity of waste carried by the collection system and or the residence time in the collection
system increases the probability and magnitude of air pollutants generated within this
system also increases.
The air pollutants generated within the collection system may be emitted to the atmosphere at any point where the system is vented to the atmosphere. In open or combined
systems, such points of emissions (uncontrolled) would include vented manhole covers,
storm drain openings, and other points of access. Points of air pollutant emissions (con-
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