Multi-Stage Activated Carbon Recycling for Wastewater Treatment
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Solution Overview
Problem
Multi-stage powdered activated carbon treatment (PACT) systems face challenges with increased footprint, material, and operational costs, necessitating more efficient processes and systems for wastewater treatment.
Innovation Solution
A method and apparatus that treat wastewater in a multi-stage PACT system, regenerate spent carbon in a wet air regeneration system, and separate the effluent into cleaned carbon solids and waste liquor, where the cleaned solids are recycled to the second stage and the waste liquor is returned to the first stage, enhancing contaminant removal efficiency and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-stage PACT system is implemented to increase pollutant removal efficiency, then contaminant removal efficiency is improved, but footprint and operational costs increase
Solution Approach 1:
The patent recovers and recycles spent carbon from the second stage back to the first stage after regeneration, transforming a waste stream into a valuable resource. This reduces the need for continuous fresh carbon addition and minimizes ash accumulation, thereby improving contaminant removal efficiency without proportionally increasing system footprint or operational costs.
Solution Approach 2:
The system implements a feedback loop where spent carbon from the second stage is regenerated and returned to the first stage. This closed-loop approach optimizes carbon utilization, maintains high contaminant removal efficiency across both stages, and reduces the overall system footprint by eliminating the need for additional carbon storage and handling infrastructure.
2Reliability
If a multi-stage PACT system is implemented to increase pollutant removal efficiency, then contaminant removal efficiency is improved, but material and operational costs increase
Solution Approach 1:
The patent recovers and recycles spent carbon from the second stage back to the first stage after regeneration, transforming a waste stream into a valuable resource. This reduces the need for continuous fresh carbon addition and minimizes ash accumulation, thereby improving contaminant removal efficiency without proportionally increasing system footprint or operational costs.
Solution Approach 2:
The system changes the operational parameters by regenerating spent carbon and recycling it to a different stage. This parameter change optimizes carbon utilization efficiency, allowing the same carbon material to serve multiple treatment cycles and stages, thereby reducing material costs while maintaining high contaminant removal efficiency.
3Loss of substance
If spent carbon is regenerated in a WAR system, then carbon is recovered for reuse, but ash accumulates in the system
Solution Approach 1:
The patent extracts and removes ash from the regenerated carbon through a separation process before recycling the carbon to the first stage. This extraction of the harmful byproduct (ash) prevents its accumulation in the system while maintaining the valuable carbon material for continued reuse, thereby resolving the contradiction between carbon recovery and ash accumulation.
Solution Approach 2:
The system converts the harmful effect of ash accumulation into a benefit by separating and removing ash during the carbon recycling process. The ash removal step transforms what would be a problematic accumulation into a controlled separation process, enabling continuous carbon recovery and reuse without system degradation.
4Reliability
If cleaned carbon solids are recycled to the second stage, then polishing efficiency is enhanced, but system complexity increases
Solution Approach 1:
The patent makes the regenerated carbon serve multiple functions by recycling it to the first stage where it can perform both bulk contaminant removal and polishing. This multi-functional use of the same carbon material enhances polishing efficiency in the second stage while avoiding the need for separate carbon streams or additional processing equipment, thereby not increasing system complexity.
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 reduces costs and increases contaminant removal efficiency by utilizing recycled, contaminant-free carbon in the second stage as a polishing agent and directing waste liquor back to the first stage to enhance pollutant removal, thereby minimizing the need for additional carbon and ash accumulation.
Implementation Method 1
which utilizes high temperature and pressure conditions for regenerating spent carbon from the PACT system
Implementation Method 2
simultaneously oxidizing biological solids (when present) accompanying the spent carbon
Implementation Method 3
The PACT system is typically coupled with a wet air regeneration (WAR) system, which utilizes high temperature and pressure conditions for regenerating spent carbon from the PACT system
Data Source
AI summary
There are provided herein methods and systems for increasing efficiency in a multi-stage activated carbon system. The methods and systems provide a cleaned carbon solids fraction and a waste liquor from wet air regeneration, and direct the same to a second stage and a first stage, respectively, of the multi-stage activated carbon system to enhance removal efficiency therein.