Dual Reactor Electrolytic Struvite Recovery System
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Solution Overview
Problem
Current methods for removing orthophosphate and ammonium from wastewater are inefficient and costly, with existing electrolytic processes lacking optimization and requiring complex reactor designs and high energy consumption.
Innovation Solution
An electrolytic system comprising two reactors, one for electrocoagulation and the other for electroflotation, using magnesium anodes to produce Mg2+ ions that react with orthophosphates and ammonium to form struvite precipitates, allowing simultaneous elimination of orthophosphate and ammonium while optimizing struvite production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical coagulation is used to remove orthophosphate and ammonium, then removal effectiveness is improved, but operational complexity and cost increase due to chemical handling and sludge treatment
Solution Approach 1:
The patent replaces chemical coagulation with electrocoagulation, substituting chemical reactions with electrical current-driven processes. Magnesium anodes undergo electrochemical dissolution to release Mg2+ ions that react with orthophosphate and ammonium to form struvite precipitates, eliminating the need for chemical dosing and complex sludge handling while maintaining removal effectiveness
Solution Approach 2:
The electrocoagulation system uses the electrical current itself to generate the coagulating agents (Mg2+ ions) in situ through anode dissolution. The process is self-regulating where the applied current directly controls the rate of ion release and precipitate formation, simplifying operational control compared to chemical dosing systems
2Reliability
If existing electrolytic processes are used, then orthophosphate and ammonium removal is achieved, but energy consumption is high and treatment time is prolonged
Solution Approach 1:
The patent optimizes several parameters to reduce energy consumption: using magnesium anodes instead of traditional aluminum or iron, operating at controlled current densities (1-10 mA/cm²), maintaining optimal pH ranges (8-10) for struvite formation, and controlling temperature (20-40°C). These parameter optimizations significantly reduce the electrical energy required while maintaining high removal effectiveness
Solution Approach 2:
The system performs preliminary conditioning of the wastewater to optimize conditions for electrocoagulation before the main treatment process. This includes adjusting pH to the optimal range and ensuring proper mixing, which prepares the solution for more efficient ion release and precipitate formation during electrolysis, thereby reducing the overall treatment time and energy requirement
3Quantity of substance
If complex reactor designs are used to optimize struvite production, then struvite yield is improved, but device complexity and installation difficulty increase
Solution Approach 1:
The reactor is divided into distinct functional zones: an anode compartment with magnesium electrodes, a cathode compartment, and a decantation zone for struvite separation. This segmentation allows each zone to perform its specific function efficiently while keeping the overall design modular and manageable, reducing installation complexity compared to integrated complex systems
Solution Approach 2:
The patent introduces a decantation zone as an intermediary step between the electrocoagulation chamber and the effluent discharge. This intermediate zone allows struvite precipitates to settle and separate from the treated water without requiring complex filtration or separation equipment, simplifying the overall reactor design while maximizing struvite recovery
4Reliability
If traditional coagulation methods are used, then colloidal particles are neutralized, but bound water content in flocs increases and filterability decreases
Solution Approach 1:
The patent replaces chemical coagulation with electrocoagulation, where electrical current drives the release of Mg2+ ions that form struvite precipitates. These electrocoagulated flocs contain less bound water and have more open structures compared to chemically coagulated flocs, making them more resistant to shearing and easier to filter, thus improving ease of operation
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 system effectively reduces organic matter and calcium, achieving efficient struvite production with improved pH and temperature control, reducing treatment time and energy consumption, and enabling easy installation and operation.
Implementation Method 1
using magnesium anodes to produce Mg2+ ions that react with orthophosphates and ammonium to form struvite precipitates
Implementation Method 2
form struvite precipitates
Implementation Method 3
Flocs are created during the electrocoagulation water treatment with oxydo-reduction reactions
Implementation Method 4
Flocs are created during the electrocoagulation water treatment with oxydo-reduction reactions
Implementation Method 5
The electrolytic reactions that take place at the electrodes are accompanied by production of micro bubbles of hydrogen (at the cathode) and oxygen (at the anode)
Implementation Method 6
These micro bubbles heading up will result in an upward movement of the flocs formed thereof that are recovered at the surface (this mechanism is named flotation)
Data Source
AI summary
An electrolytic system for treating wastewater by electrocoagulation, electroflotation or a combination of both is disclosed. The electrolytic system comprises a first electrolytic reactor adapted for receiving the wastewater to be treated, the first electrolytic reactor comprising at least one cathode and at least one anode to perform a first electrolytic treatment for eliminating organic matter and calcium present in the wastewater that impact on nucleation of struvite; and a second electrolytic reactor downwardly connected to the first electrolytic reactor, the second electrolytic reactor comprising at least one cathode and at least one magnesium anode to perform a second electrolytic treatment for producing Mg2+ ions which react with NH4+ and orthophosphates from said wastewater to form a struvite precipitate. The electrolytic system allows eliminating simultaneously orthophosphate and ammonium from the wastewater while enabling the production of struvite.