Methods for removing odors from process airstreams
AssigneeWashington Suburban Sanitary Commission
InventorsCharles M. Murray, Joel L. Thompson, Lawrence H. Hentz, Jr.
Life of this patent
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Abstract
After aerating sewage sludge in a composting process, a stream of process air is treated to remove odors therefrom by injecting into the airstream an atomized mixture of dilute sulfuric acid and dilute surfactant to remove ammonia and odorous organic compounds therefrom. The airstream is then oxidized with bleach to remove sulfides and treated with a hydrogen peroxide solution to remove chlorine introduced by the bleach while maintaining the oxidation reaction. A dilution fan is used to further dilute the scrubbed airstream as the airstream is exhausted to the atmosphere.
Claims17
A method of scrubbing a stream of exhaust air, wherein the stream includes undesirable odor-causing compounds including ammonia, sulfides, and malodorous organic compounds, the method comprising the steps of:
- (a) treating the airstream with a surfactant-containing acid solution in order to neutralize ammonia in the airstream while removing malodorous organic compounds therefrom;
- (b) treating the neutralized airstream with a liquid bleach to remove sulfides therefrom;
- and
- (c) treating the airstream with hydrogen peroxide to remove chlorine introduced therein by the bleach solution and to maintain the oxidation reaction so as to substantially remove any remaining odor-causing constituents from the airstream.
A method of scrubbing a stream of process air from a sludge composting facility, wherein the process air has been used to aerate compost for passage therethrough, the process air including ammonia, sulfides, and malodorous organic compounds, the process comprising the steps of:
- (a) treating the process air with an atomized mixture of sulfuric acid and surfactant mixed with water and dispensed as atomizing droplets of a selected size at a first atomizing station as the air rises in a first tower;
- (b) removing the sulfuric acid and surfactant mixture from the rising airstream by collecting the mixture at the bottom of the first tower;
- recirculating the collected mixture, and spraying the collected mixture into the airstream upstream of the first atomizing station, the mixture being sprayed having droplets of a size substantially larger than the droplets dispensed at the first atomizing station;
- (c) oxidizing the organic sulfides in the airstream subsequent to removing ammonia and organic compounds therefrom by treating the airstream with an atomized solution of sodium hypochlorite prior to descent of the airstream in a second tower;
- (d) treating the airstream with an atomized hydrogen peroxide solution having atomized droplets of a selected size dispensed at an atomizing station in a third tower as the airstream rises in the third tower to maintain the oxidation reaction while removing chlorine from the airstream;
- (e) collecting the hydrogen peroxide solution at the bottom of the third tower, recirculating the hydrogen peroxide solution, and spraying the hydrogen peroxide solution into the airstream in a droplet size substantially larger than the atomized droplet size at a location downstream of the atomizing station in the third tower;
- and
- (f) exhausting the airstream to the atmosphere through a dilution fan which mixes the air stream with fresh air.
A method of scrubbing a stream of exhaust air, wherein the stream includes undesirable odor-causing compounds including sulfides and malodorous organic compounds, the method comprising the steps of:
- (a) treating the airstream with an atomized surfactant solution in order to remove malodorous organic compounds therefrom;
- (b) treating the airstream treated in step (a) with liquid bleach to remove sulfides therefrom;
- and
- (c) treating the airstream treated in step (b) with hydrogen peroxide to remove chlorine introduced therein by the bleach solution and to maintain the oxidation reaction so as to substantially remove any remaining odor-causing constituents from the airstream.
Dependencies are inferred from the claim text.