Ammonium Removal Membrane Stack for Wastewater
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Solution Overview
Problem
Current methods for removing ammonium from ammonia-containing wastewater, such as biological processes, air stripping, resin-based ion exchange, and breakpoint chlorination, face challenges including low processing efficiencies, high costs, and inefficiencies with varying ammonia loads and saline waters.
Innovation Solution
A membrane-based system utilizing alternating product and concentrate chambers with cation exchange membranes and proton permselective cation exchange membranes, coupled with an electrolyzer and chlorine-based oxidizing agents, to efficiently remove and convert ammonium into nitrogen gas, while maintaining efficiency across varying ammonia concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If biological processes are used to remove ammonium, then ammonia removal efficiency is improved, but the system lacks flexibility for changing ammonia loadings and environmental temperature sensitivity increases
Solution Approach 1:
The patent replaces biological processes with a membrane-based electrodialysis system that uses electrical fields and ion-exchange membranes to remove ammonium. This mechanical/electrical system eliminates sensitivity to environmental temperature and provides operational flexibility for varying ammonia loads, as the process is driven by electrical potential rather than biological activity.
2Productivity
If air stripping processes are used, then ammonia can be removed from water, but air pollution is created and base solution consumption increases
Solution Approach 1:
The patent extracts ammonium ions from wastewater using ion-exchange membranes that selectively transport ammonium across the membrane into a concentrate stream. This separates the ammonium removal function from atmospheric release, eliminating air pollution while maintaining effective ammonia removal capability.
3Productivity
If resin-based ion exchange processes are used, then ammonium can be removed from water, but regeneration costs and resin disposal costs increase for large-scale continuous treatment
Solution Approach 1:
The patent implements continuous ammonium removal using an electrodialysis stack where multiple chambers operate simultaneously. The system continuously processes wastewater through electro-driven ion transport across membranes, eliminating the intermittent regeneration cycles required by batch resin-based ion exchange systems and reducing operational costs for large-scale continuous treatment.
4Productivity
If breakpoint chlorination processes are used, then ammonium can be removed from water, but the process is only economical when ammonia content is less than 10 ppm and large quantities of chlorine are required
Solution Approach 1:
The patent replaces chemical chlorination with a membrane-based electrodialysis system that uses electrical fields and ion-exchange membranes to physically separate and concentrate ammonium ions. This mechanical separation method eliminates the need for large quantities of chlorine, making the process economical for treating wastewater with ammonium concentrations above 10 ppm.
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 tolerates high total dissolved solids, maintains ammonia-removing efficiency, and reduces costs by converting ammonium into nitrogen gas, addressing inefficiencies and cost issues of existing methods.
Implementation Method 1
alternating cation exchange membranes ("CEMs") and proton permselective cation exchange membranes ("pCEMs") located between and bounding the product and concentrate chambers
Implementation Method 2
the pCEMs have a proton permeability of more than ten times that of other cations, and the ammonium moves from the product chambers to the concentrate chambers across the CEMs and protons move from the concentrate chambers to the product chambers across the pCEMs
Implementation Method 3
The first and second electrodes may be coupled to a direct current power supply operable in a first polarity in which the first electrode is at a higher potential than the second electrode and at a second polarity in which the second electrode is at a higher potential than the first electrode
Implementation Method 4
a chlorine-based oxidizing agent addition subsystem fluidly coupled to the concentrate chambers of the stack and configured to remove the ammonium from the concentrate chambers as nitrogen gas
Data Source
AI summary
Methods, systems, and techniques for removing ammonium from ammonia-containing water involve using a stack that has alternating product chambers and concentrate chambers for receiving ammonia-containing water and an acidic solution, respectively, with the chambers being bounded by alternating cation exchange membranes and proton permselective cation exchange membranes. Ammonium moves from the product chambers to the concentrate chambers across the CEMs and protons move from the concentrate chambers to the product chambers across the pCEMs when the stack is in use. An electrolyzer may also be used to convert the ammonium in the concentrate chambers into nitrogen.