Chlorine Dioxide Precursor Dosing for Cooling Water Bacteria Control
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Solution Overview
Problem
Bacteria in cooling water systems, particularly sulfur and nitrogen metabolizing bacteria, consume oxidizing biocides, leading to reduced efficacy and increased formation of corrosive by-products, which can lower pH and require excessive caustic consumption.
Innovation Solution
Dosing a composition comprising alkali metal salts of chlorite and/or chlorate with hydrogen peroxide at high concentrations over a short period to inhibit bacterial metabolism, followed by monitoring and controlling sulfate and nitrate concentrations using a system with sensors and a controller to optimize chemical addition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidizing biocides are used to control bacterial populations, then microbial proliferation is suppressed, but reducing species formed by bacteria consume the biocide and reduce its efficacy
Solution Approach 1:
The patent changes the chemical parameter of the biocide from traditional oxidizing agents to chlorine dioxide precursor compounds (chlorite and chlorate salts). This parameter change allows the biocide to remain effective against reducing species because chlorine dioxide has different redox chemistry that is not as readily consumed by sulfite and nitrite ions, thereby maintaining biocide efficacy while reducing unnecessary consumption
Solution Approach 2:
The patent employs chlorine dioxide precursor compounds that generate active chlorine dioxide in situ. These precursors are more cost-effective than traditional oxidizing biocides and provide sustained protection without being rapidly depleted by bacterial metabolic byproducts, offering an economical solution that maintains reliable microbial control
2Reliability
If adequate amounts of biocide are maintained to control microbial populations, then bacterial proliferation is prevented, but caustic consumption increases to maintain pH levels
Solution Approach 1:
The patent changes the chemical nature of the biocide to chlorine dioxide precursors, which have different interactions with bacterial metabolism. This parameter change reduces the formation of reducing species that would otherwise require additional caustic to neutralize, thereby maintaining reliable microbial control while reducing caustic consumption for pH maintenance
Solution Approach 2:
The patent converts the potentially harmful interaction between traditional oxidizing biocides and bacterial metabolites into a beneficial outcome. By using chlorine dioxide precursors, the system minimizes the formation of problematic reducing species, thereby reducing the need for caustic addition to maintain pH, effectively turning a harmful cycle into a beneficial reduction in chemical consumption
3Productivity
If sulfur and nitrogen metabolizing bacteria are present, then bacterial proliferation provides metabolic activity, but corrosive by-products like sulfuric acid are formed
Solution Approach 1:
The patent changes the chemical environment by introducing chlorine dioxide precursors, which alter the metabolic parameters of sulfur and nitrogen bacteria. This parameter change suppresses the metabolic pathways that produce corrosive by-products like sulfuric acid, while still allowing controlled bacterial activity that does not lead to harmful accumulations
Solution Approach 2:
The patent applies preliminary anti-action by introducing chlorine dioxide precursors that prevent the formation of corrosive by-products before they can cause damage. The chlorine dioxide oxidizes and neutralizes reducing species like sulfite and nitrite before they can be further metabolized into harmful acids, thereby preventing corrosion proactively
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
Significantly reduces bacterial activity, lowers caustic consumption, and maintains pH stability, thereby improving cooling tower performance and operational efficiency.
Implementation Method 1
sulfate reducing bacteria utilize sulfate and reduce it to form sulfite, which is further metabolized by different microorganisms to form sulfide (H2S)... The formed sulfite ions consume any oxidizing biocide and are oxidized to form sulfate ions
Implementation Method 2
adding a composition comprising an alkali metal salt of chlorite and/or an alkali metal salt of chlorate and hydrogen peroxide
Data Source
AI summary
A method of reducing activity of sulfur and/or nitrogen metabolizing bacteria is provided. The method includes adding a composition of an alkali metal salt of chlorite and/or an alkali metal salt of chlorate and hydrogen peroxide to process water of a cooling tower and increasing a concentration of the composition from about 0 ppm to about 300 ppm in about 1 to about 100 minutes.