Wastewater Odor Control via Synergistic Sulfide Removal
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Solution Overview
Problem
Current odor control methods for municipal and industrial waste are inefficient and costly, as they either react rapidly and degrade or require high doses, leading to secondary issues like corrosion, foaming, and precipitation, without providing long-term control of biogenic sulfide production.
Innovation Solution
A synergistic combination of a rapid sulfide-consuming chemical, such as sodium chlorite, and a nitrate salt, along with pH-elevating compounds and sulfide-oxidizing bacteria, is used to immediately consume sulfides and adjust the pH to a range where sulfides remain in solution, inhibiting biogenic production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid-acting sulfide-consuming chemicals (hypochlorite, permanganate, iron salts) are used, then immediate sulfide removal is achieved, but the chemicals degrade quickly and require frequent reapplication
Solution Approach 1:
The patent combines a rapid-acting sulfide-consuming chemical (such as hypochlorite, permanganate, or iron salt) with a nitrate salt in a single composition. The rapid chemical provides immediate sulfide removal, while the nitrate salt promotes growth of sulfide-oxidizing bacteria that provide long-term control, thus merging short-term and long-term solutions into one formulation.
Solution Approach 2:
The nitrate salt acts as an intermediary that promotes the growth of sulfide-oxidizing bacteria (such as Thiobacillus denitrificans). These bacteria then serve as living agents that continuously consume sulfides over time, extending the duration of action beyond what the rapid chemical alone could achieve.
2Reliability
If high doses of sulfide-consuming chemicals are applied, then odor control effectiveness increases, but secondary issues like corrosion, foaming, and precipitation occur
Solution Approach 1:
The patent specifies controlled dosage ranges for each component (rapid chemical at 0.1-10 mg/L and nitrate salt at 1-50 mg/L) to optimize effectiveness while avoiding the harmful effects of excessive dosing. This parameter control ensures sufficient odor control without causing corrosion, foaming, or precipitation problems associated with high doses.
Solution Approach 2:
The nitrate salt promotes biological sulfide oxidation through bacterial growth, providing a gentler, more sustained sulfide removal mechanism that avoids the harsh effects of high-dose chemical treatment, thereby reducing corrosion and other secondary harmful effects.
3Object-generated harmful factors
If pH is lowered to keep sulfides in solution, then gas evolution is reduced, but sulfide-oxidizing bacteria cannot thrive
Solution Approach 1:
The rapid-acting sulfide-consuming chemical in the composition provides preliminary sulfide removal, reducing sulfide levels quickly without requiring pH adjustment. This allows the pH to remain in the neutral to slightly alkaline range (6.5-8.5) necessary for sulfide-oxidizing bacteria to thrive, thus resolving the conflict between gas evolution control and bacterial growth requirements.
Solution Approach 2:
The nitrate salt promotes growth of sulfide-oxidizing bacteria that operate effectively at neutral to slightly alkaline pH levels. These bacteria provide an alternative pathway for sulfide removal that does not require acidic conditions, allowing biological treatment to proceed while minimizing gas evolution through sustained sulfide consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively and cost-efficiently reduces sulfidic odors by immediately consuming sulfides and promoting the growth of sulfide-oxidizing bacteria, providing long-term control of sulfide production and minimizing gas evolution.
Implementation Method 1
The composition comprises a synergistic combination of a rapid sulfide-consuming chemical, which is selected from the group comprising an iron salt, a hypochlorite, a permanganate, a persulfate, a perborate, a periodate, a percarbonate, a chlorite, a nitrite, a chlorate, a perchlorate, a peroxide and mixtures thereof
Implementation Method 2
In the absence of oxygen, unless nitrate is added supplementally, those bacteria which can utilize sulfate as a terminal electron acceptor in their respiration process will predominate. The nitrate then inhibits the biogenic production of H2S downstream
Implementation Method 3
The pH-elevating compound adjusts the pH into a range where the form of sulfide soluble only in aqueous solution is promoted
Implementation Method 4
promoting the growth of sulfide-oxidizing bacteria, which grow best in this pH range. The nitrate then inhibits the biogenic production of H2S downstream by both promoting the growth of various sulfide-oxidizing bacteria
Data Source
AI summary
A synergistic composition is provided for controlling odor from waste products. The composition comprises a combination of nitrate salt, sulfide-consuming compound, pH-elevating compound, sulfide-oxidizing, nitrate-reducing bacteria, and sulfide-oxidizing enzyme. The method includes adding a sufficient amount of the composition to a waste stream to provide sufficient sulfide-consuming compound to effect immediate removal of sulfide. The composition incorporates a pH elevating compound, which both decreases the amount of gaseous H2S and puts the aqueous phase into a pH range where naturally occurring bacteria can more easily metabolize the sulfide. The composition also includes one or more nitrate salts which will accomplish longer term prevention of odors. Specific bacteria are incorporated into the formulation to insure that the nitrate has the right type and amount of bacteria present to prevent formation of and/or consume sulfide. Specific enzymes are incorporated into the formulation to promote oxidation of sulfide.