Electrolysis Wastewater Treatment Preventing Cathode Scaling
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Solution Overview
Problem
Industrial wastewater from fertilizer plants, particularly nitrophosphate processes, contains high levels of chloride, which can destabilize ammonium nitrate and pose safety concerns when recirculated, and existing treatments are inadequate for reducing chloride levels to environmentally safe concentrations.
Innovation Solution
The method involves using electrolysis in a batchwise mode within an electrochemical cell to treat wastewater, maintaining an acidic pH in both the anode and cathode chambers to prevent scaling and efficiently reduce chloride concentrations to below 250 ppm, with optional steps for pH control and gas removal to ensure safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrolysis is used to treat wastewater to reduce chloride levels, then chloride concentration is reduced to below 250 ppm, but scaling occurs on the cathode due to pH increase
Solution Approach 1:
The patent applies preliminary action by acidifying the catholyte before electrolysis begins and maintaining acidic pH throughout the process. This preventive measure stops scaling from forming in the first place, rather than treating it after it occurs. The acidification is done by adding acid to the catholyte or by having the catholyte flow through an acidifying unit, ensuring the pH remains below 7.0 during the entire electrolysis operation.
Solution Approach 2:
The patent changes the pH parameter of the catholyte from neutral/alkaline to acidic conditions. By maintaining pH below 7.0 through acid addition or acidifying units, the chemical environment is fundamentally altered to prevent calcium phosphate precipitation on the cathode surface, thereby eliminating scaling while maintaining effective chloride removal through electrolysis.
2Reliability
If pH is controlled to prevent cathode scaling, then scaling is minimized, but additional acid addition and monitoring are required
Solution Approach 1:
The patent applies self-service by using the anolyte (anode chamber effluent) which naturally contains acid from the electrolysis process to acidify the catholyte. The system essentially uses its own byproducts to maintain the required acidic conditions, reducing the need for external acid addition and simplifying the pH control mechanism while still preventing cathode scaling effectively.
3Object-affected harmful factors
If wastewater is recirculated to reduce discharge, then environmental pollution is reduced, but chloride levels can destabilize ammonium nitrate
Solution Approach 1:
The patent applies parameter changes by using electrolysis to fundamentally alter the chloride concentration parameter in the wastewater, reducing it from typical levels (which can destabilize ammonium nitrate) to below 250 ppm. This parameter transformation enables safe recirculation of the wastewater back to the fertilizer plant without compromising the stability of ammonium nitrate, thus resolving the conflict between environmental protection and chemical safety.
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 reduces chloride levels in fertilizer plant wastewater, enhancing safety by preventing ammonium nitrate instability and allowing safe recirculation, while minimizing costs associated with pH control and water balance management.
Implementation Method 1
The method involves using electrolysis in a batchwise mode within an electrochemical cell to treat wastewater, maintaining an acidic pH in both the anode and cathode chambers to prevent scaling and efficiently reduce chloride concentrations to below 250 ppm
Data Source
Figure 1~1D
Figure 2~2D
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AI summary
The present invention relates to treatment of industrial wastewater, and more particularly wastewater from a fertilizer plant such as a nitrophosphate, organic or organo-mineral fertilizer plant. Chloride ions and other impurities can be removed by electrolysis and to control the pH of the cathode chamber, treated wastewater from the anode chamber is directed to the cathode chamber and new wastewater sent to the anode chamber for the subsequent run of electrolysis. This is an efficient method of controlling the pH of the cathode chamber and preventing white scaling from appearing on the cathode. By efficiently reducing the chloride concentration in the fertilizer wastewater, it is then possible to safely recirculate the wastewater back to the fertilizer plant.