Iron Anode Electrolysis for Raw Water Pretreatment
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Solution Overview
Problem
Existing water treatment technologies are inadequate for effectively handling waters with high loads of sludges, salts, nitrites, organic compounds, and heavy metals, failing to meet modern standards for drinking water quality and requiring improvements to treat waters of degraded quality.
Innovation Solution
A novel electrolysis process producing a dense suspension of ferric ions and fine particles as a coagulant by electrolyzing an aqueous solution with high sodium hypochlorite concentration in the presence of iron, which is used in a plant incorporating aerobic and anaerobic biological filtration steps, along with additional electrolysis for further treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional water treatment technologies are used, then the treatment process is simple, but they are inadequate for effectively handling waters with high loads of sludges, salts, nitrites, organic compounds, and heavy metals
Solution Approach 1:
The treatment process is divided into distinct functional modules: electrolysis cell for coagulant generation, aerobic filtration stage, anaerobic filtration stage, and UV disinfection stage. Each module performs a specific function, allowing the complex treatment process to be managed through standardized, interchangeable components that can be independently optimized and maintained.
Solution Approach 2:
The electrolysis cell generates coagulants (ferric chloride and ferric hydroxide) in advance before the water enters the filtration stages. This preliminary generation of treatment chemicals eliminates the need for separate chemical dosing systems and ensures coagulants are readily available when contaminated water enters the aerobic filtration stage, improving overall process reliability.
2Manufacturing precision
If high concentration sodium hypochlorite electrolysis is used to produce coagulant, then the coagulant activity is enhanced, but the energy consumption increases
Solution Approach 1:
The electrolysis cell uses the contaminated water itself as the electrolyte medium, eliminating the need for separate chemical reagents. The high concentration of dissolved salts, nitrites, and other ions in the contaminated water provides excellent electrical conductivity, enabling efficient coagulant generation at lower energy consumption compared to using pure water or dilute electrolytes.
Solution Approach 2:
The system operates the electrolysis cell at controlled potential ranges (0.2-2.0V) and current densities (0.1-1.0 A/m²) to optimize coagulant generation efficiency. By adjusting these electrical parameters and maintaining high sodium hypochlorite concentration (at least 1 g/l), the system achieves enhanced coagulant activity while managing energy consumption through efficient current utilization.
3Reliability
If multiple treatment stages are implemented, then the water quality output is improved, but the device complexity increases
Solution Approach 1:
The aerobic and anaerobic filtration stages are combined into a single integrated plant structure with sequential flow paths. The electrolysis cell, aerobic filter, anaerobic filter, and UV disinfection unit are merged into one compact system that treats water through multiple mechanisms (coagulation, oxidation, biological filtration, and disinfection) in a continuous flow process, achieving high water quality without requiring separate distributed treatment facilities.
Solution Approach 2:
The electrolysis cell serves multiple functions simultaneously: it generates ferric chloride coagulant, produces ferric hydroxide coagulant, and acts as a pre-oxidation stage. The aerated filter bed performs both aerobic biological degradation and physical filtration. This multi-functionality reduces the number of separate devices needed while maintaining comprehensive treatment capability.
4Quantity of substance
If iron particles are used as anode in electrolysis, then ferric ions are generated for coagulation, but the electrode material consumption increases
Solution Approach 1:
The iron anode particles are designed to be consumed and replaced periodically rather than preserved. As the iron particles dissolve and generate ferric ions, they are replenished to maintain optimal coagulant generation. This approach converts the electrode from a permanent component to a consumable reagent, simplifying the system design and eliminating the need for complex electrode protection or regeneration systems.
Solution Approach 2:
The iron anode uses inexpensive iron particles (such as iron turnings, iron powder, or iron shot) that are readily available and low-cost. These particles are intentionally designed to be consumed during operation, replaced periodically in a simple manual or automated replenishment process, rather than using expensive durable materials that would require complex protection systems.
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
The process effectively treats raw water with high contaminant loads, achieving a 'technical' water quality suitable for non-potable uses and requiring only readily available raw materials, with the potential for further purification to drinking water standards.
Implementation Method 1
A novel electrolysis process producing a dense suspension of ferric ions and fine particles as a coagulant by electrolyzing an aqueous solution with high sodium hypochlorite concentration in the presence of iron
Implementation Method 2
an aqueous solution containing sodium hypochlorite is introduced into said tank so that it at least partially covers the iron particles and is in contact with the electrode
Data Source
AI summary
The invention relates to an electrolysis method that uses iron particles and an aqueous solution containing sodium hypochlorite. The method is characterized in that said method uses direct current, the iron particles form the anode (46) and the sodium hypochlorite concentration of the aqueous solution is at least 1 g/L. The invention further relates to a method and to a plant for the pretreatment of raw water for producing water that can then be easily treated in order to produce drinkable water or a so-called technical water that cannot be consumed but that can be used for household, agricultural or industrial applications such as cleaning, washing, laundry, flushing, garden watering or irrigation.