Thermal Flash Vessel for Waste Sludge Pathogen Lysis
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Solution Overview
Problem
The disposal of waste activated sludge (WAS) from municipal and industrial water treatment facilities is challenging due to its high water content and pathogen presence, leading to increased disposal costs and limited reuse possibilities.
Innovation Solution
A thermal system that uses heat and pressure to lyse pathogens and break down cell walls in biologically contaminated water, allowing for higher dewatering efficiency and pathogen destruction, thereby reducing disposal costs and enhancing reuse possibilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional dewatering technologies are used on WAS, then the dewatering process is simple and low-cost, but the solids-to-water ratio remains low (20% solids, 80% water) and pathogen destruction is insufficient
Solution Approach 1:
The patent applies parameter changes by heating the WAS to elevated temperatures (e.g., 60-100°C or higher) to alter the physical and biological properties of the sludge. This thermal treatment destroys pathogens through heat denaturation while simultaneously modifying cell wall structures to improve dewaterability, thereby achieving both pathogen destruction and enhanced solids separation in a single integrated process
Solution Approach 2:
The patent replaces traditional mechanical dewatering methods with a thermal treatment approach. Instead of relying solely on mechanical forces (centrifugal, pressure, or filtration-based dewatering) that fail to adequately reduce water content or destroy pathogens, the invention uses thermal energy to lyse microbial cells and coagulate organic matter, which then facilitates easier and more effective dewatering through subsequent mechanical means
2Object-affected harmful factors
If digesters are employed to process WAS, then pathogen destruction is achieved and some energy is recovered, but the dewatering efficiency does not improve and disposal volumes remain high
Solution Approach 1:
The patent applies preliminary action by performing thermal treatment and cell lysis on the WAS before it enters the digester or dewatering equipment. This pre-treatment breaks down microbial cell walls and coagulates organic matter in advance, which prepares the sludge for more effective dewatering and reduces the volume requiring disposal, while also ensuring pathogen destruction occurs during the thermal phase
3Ease of operation
If WAS is dewatered to 20% solids content, then the dewatering process is straightforward, but disposal costs increase significantly (above $50/ton at landfill sites)
Solution Approach 1:
The patent changes the thermal parameters (temperature, heating rate, residence time) to optimize both the simplicity of the dewatering operation and the reduction of disposal volume. By controlling these parameters, the system achieves pathogen destruction and enhanced solids separation simultaneously, producing a more concentrated sludge product that reduces landfill volume and costs while maintaining operational simplicity
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 achieves a higher solids-to-water ratio in WAS, reducing disposal volumes and costs, while also destroying pathogens, which increases the potential for safe reuse of the treated sludge.
Implementation Method 1
cycling the circulation stream between a pressurized state and a non-pressurized state which causes a phase change from a liquid state to a vapor state and back to a liquid state
Implementation Method 2
allowing a portion of the circulation stream to flash evaporate
Implementation Method 3
A thermal system that uses heat and pressure to lyse pathogens and break down cell walls in biologically contaminated water
Implementation Method 4
cycling the circulation stream between a pressurized state and a non-pressurized state
Data Source
AI summary
A system for treating a biologically contaminated water stream to lyse pathogens within the biologically contaminated water stream is provided. The system can include a flash vessel configured to receive a biologically contaminated water stream and to separate steam from liquid in the biologically contaminated water stream, a blower configured to receive the separated steam from the flash vessel and compress the separated steam for reintroduction into the biologically contaminated water stream, a circulation pump configured to receive the separated liquid from the flash vessel and to pressurize the separated liquid into a circulation stream, a preheater exchanger configured to receive treated water from the circulation stream and preheat the biologically contaminated water stream, and a pressure drop device configured to lower the pressure of the biologically contaminated water stream prior to receipt by the flash vessel.