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H2O2 |
Alkalis |
| Description |
Hydrogen peroxide (H2O2) is a liquid product supplied as a 35% or 50% solution. It is available in containers of 50 or 300 gallons, or in bulk shipments of 500 - 20,000 gallons. Solid peroxide products (sodium percarbonate and calcium peroxide) are also available. |
The two most commonly used alkalis (magnesium hydroxide - Mg(OH)2 and sodium hydroxide - NaOH) are supplied as a slurry and solution, respectively - the former in bulk truckloads and the latter in a range of container sizings as well as bulk truckloads.
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| Control Mechanism(s) |
Oxidizes H2S Retards septicity (adds dissolved oxygen) Promotes bio-oxidation of organic odors |
Solubilizes H2S (keeping it from volatilizing)
Inhibits biogrowth (retarding odor generation)
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| Chemical Reaction(s) |
Neutral - Acid pH: H2S + H2O2 --> S + 2 H2O
Alkali: S2- + 2 O2 ----> SO42-
Prevention: 2 H2O2 ----> O2 + 2 H2O
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H2S (volatile) + OH- --> HS- (non-volatile) + H2O |
| Dose Ratios (for typical domestic sewage) |
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Neutral - Acid |
Alkali |
Prevention |
| Theoretical |
1.0 |
4.0 |
4.0 |
| Practical |
1.2 - 1.5 |
4.5 - 5.0 |
2 - 8 |
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H2S Removal |
mg/L OH- |
| pH 8 |
75% |
50 |
| pH 9 |
95% |
150 |
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Applications |
Gravity mains (< 3-4 hours retention)Force mains (< 1-2 hours retention)
Terminus of long retention force mainsTreatment plant headworksSolids processingSeptage and leachate
Odor scrubbersPonds and lagoons |
Collection lines containing high levels of sulfide (> 10 mg/L)
Odor scrubbers
Ponds and lagoons
Solids processing
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Advantages |
High selectivity toward H2SAdds dissolved oxygen to retard downstream septicity
Produces no harmful by-productsExtensive history of useIn-line nitrification and BOD reduction possible
Simple feed systemsRelative low feed rates (small storage tanks) |
Fast reaction
Provides long-duration control
Costs are unaffected by sulfide concentration or oxygen uptake rates
Inhibits downstream sulfide generation
Residual alkalinity may enhance performance of biotreatment processes
Mg(OH)2 is a non-hazardous chemical that buffers the pH (typically to pH 8.5 -9)
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Disadvantages |
High dosages are needed for control > 2 hoursOrganic odors require bio-mediated oxidation
Reaction may take several minutes (without catalysis)Oxidizer classification may restrict dosing sites
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Limited applicability (typically not cost-effective for H2S levels > 10 mg/L)
May change or worsen odors
Removal of H2S to low levels may be cost-prohibitive
Does not destroy sulfide - volatilization will occur once the pH is neutralized
NaOH is a hazardous chemical
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Special Notes |
Hydrogen peroxide is one of the more rapidly growing alternatives due to its cost-effectiveness and environmental compatibility. |
Use of magnesium hydroxide for odor control may be covered under US Patent held by Premier Services Corp.
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