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US 4,304,673 AGranted
Wastewater treatment process
AssigneeInternational Environmental, Inc.
InventorsJames H. Reynolds, V. Dean Adams
Life of this patent
Estimating the term…
Abstract
Wastewater is continuously disinfected by combining the wastewater with sufficient SO.sub.2 that the wastewater has a selected free SO.sub.2 content of at least 5 mg/liter. The combined SO.sub.2 /wastewater is maintained at the selected free SO.sub.2 content for at least about 10 minutes. The wastewater can be treated by dissolving SO.sub.2 into a first portion of the wastewater and combining the first portion with SO.sub.2 dissolved therein with a second portion of the wastewater stream.
Claims27
A continuous process for disinfecting wastewater containing infectious microorganisms comprising the steps of:
- (a) combining the wastewater with sufficient SO.sub.2 that the wastewater has a selected free SO.sub.2 content no less than a selected free SO.sub.2 content of at least about 5 mg/liter and less than about 200 mg/liter;
- (b) maintaining the combined SO.sub.2 /wastewater in a treatment zone at the selected free SO.sub.2 content and at a pH of from about 1 to about 4 to about 10 to about 60 minutes;
- and
- (c) withdrawing wastewater from the treatment zone, the withdrawn wastewater containing substantially no infectious microorganisms.
1 more element
A continuous process for disinfecting wastewater containing coliform bacteria comprising the steps of:
- (a) combining the wastewater with sufficient SO.sub.2 so that the wastewater has a selected free SO.sub.2 content of from about 10 to about 150 mg/liter and a selected pH of from about 2 to about 3;
- (b) maintaining the combined SO.sub.2 /wastewater in a treatment zone at the selected free SO.sub.2 content and the selected pH for about 10 to about 60 minutes;
- (c) withdrawing wastewater from the treatment zone, the withdrawn wastewater containing substantially no coliform bacteria;
- and
- (d) neutralizing the wastewater withdrawn from the treatment zone to a pH of from about 6 to about 8 and dissolving oxygen in the wastewater withdrawn from the treatment zone to raise its oxygen content.
2 more elements
A continuous process for disinfecting wastewater containing infectious microorganisms comprising the steps of:
- (a) combining the wastewater with from about 10 to about 2000 mg of SO.sub.2 per liter of wastewater so that the wastewater has a selected free SO.sub.2 content of from about 10 to about 200 mg/liter and a selected pH of from about 1 to less than about 3;
- (b) maintaining the combined SO.sub.2 wastewater in a treatment zone at the selected free SO.sub.2 content and the selected pH for about 10 to about 60 minutes;
- and
- (c) withdrawing wastewater from the treatment zone, the withdrawn wastewater containing substantially no infectious microorganisms.
1 more element
A continuous process for disinfecting wastewater containing infectious microorganisms comprising the steps of:
- (a) introducing only a first portion of the wastewater and a SO.sub.2 containing gas into a gas-liquid contact zone for dissolving at least a portion of the SO.sub.2 into the first portion of the wastewater, the first portion being introduced directly into the gas-liquid contact zone;
- (b) withdrawing wastewater containing SO.sub.2 from the contact zone;
- (c) combining a second portion of the wastewater with SO.sub.2 by (i) introducing substantially all of the withdrawn wastewater containing SO.sub.2 directly into a mixing zone and (ii) introducing the second portion of the wastewater into the mixing zone;
- (d) maintaining the combined withdrawn wastewater and the second portion of the wastewater in a treatment zone for about 10 to about 60 minutes at a pH of from about 1 to about 4;
- and
- (e) withdrawing treated wastewater from the treatment zone, the withdrawn treated wastewater containing substantially no infectious microorganisms;
- wherein sufficient SO.sub.2 is introduced into the contact zone so the water in the treatment zone has a selected free SO.sub.2 content of at least about 5 mg/liter and less than about 200 mg/liter.
4 more elements
A continuous process for disinfecting wastewater containing coliform bacteria comprising the steps of:
- (a) introducing only a first portion of the wastewater and a SO.sub.2 containing gas into a gas-liquid contact zone for dissolving at least a portion of the SO.sub.2 into the first portion of the wastewater, the first portion being introduced directly into the gas-liquid contact zone;
- (b) withdrawing wastewater containing dissolved SO.sub.2 from the contact zone;
- (c) combining a second portion of the wastewater with SO.sub.2 by (i) introducing substantially all of the withdrawn wastewater containing SO.sub.2 directly into a mixing zone and (ii) introducing the second portion of the wastewater into the mixing zone;
- (d) maintaining the combined withdrawn wastewater and the second portion of the wastewater in a treatment zone for a residence time of about 10 to about 60 minutes at a pH of from about 1 to about 4;
- (e) withdrawing wastewater containing substantially no coliform bacteria from the treatment zone;
- and
- (f) neutralizing the wastewater withdrawn from the treatment zone to a pH of from about 6 to about 8 and dissolving oxygen in the wastewater withdrawn from the treatment zone to raise its oxygen content,
- wherein sufficient SO.sub.2 is introduced into the contact zone in that the wastewater in the treatment zone has a selected free SO.sub.2 content of from about 10 to about 150 mg/liter.
5 more elements
A continuous process for disinfecting wastewater containing coliform bacteria comprising the steps of:
- (a) combining the wastewater with sufficient SO.sub.2 so that the wastewater has (a) a free SO.sub.2 content no less than a selected free SO.sub.2 content of from about 10 to about 150 mg/liter and (b) a pH of from about 1 to about 4;
- (b) maintaining the combined SO.sub.2 /wastewater in a treatment zone at the selected free SO.sub.2 content and the selected pH for about 10 to about 60 minutes;
- (c) withdrawing wastewater containing substantially no coliform bacteria from the treatment zone;
- (d) removing contaminants from the wastewater withdrawn from the treatment zone by increasing its pH to at least about 8, flocculating it, and removing flocculated material from the flocculated wastewater;
- and
- (e) neutralizing the flocculated wastewater and dissolvihng oxygen in the flocculated wastewater.
3 more elements
Dependencies are inferred from the claim text.