Sintered Soil Bed PFAS Removal via Thermal Desorption
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Solution Overview
Problem
Current soil remediation technologies are inadequate for effectively treating high molecular weight compounds in saturated fine grain soils and lack a method for non-destructive removal of per- and polyfluoroalkyl substances (PFAS), leading to inefficiencies and environmental concerns such as groundwater contamination.
Innovation Solution
A static thermal desorption process using a sintering vessel with sequential treatment of heated air and ambient air waves to mobilize and condense PFAS and hydrocarbons, avoiding combustion and utilizing capillary flow through densified soil beds with hexagonal holes or slots for precise energy application and contaminant removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extreme high temperatures are used to destroy PFAS, then PFAS removal is achieved, but hazardous Hydrofluoric Acid gas is produced and energy consumption increases
Solution Approach 1:
The patent changes the temperature parameter from extreme high temperatures (required for destruction) to moderate temperatures (200-400°F) that enable desorption without decomposition. This parameter change allows PFAS to be removed from soil through phase change rather than chemical destruction, avoiding HF gas production while maintaining removal effectiveness
Solution Approach 2:
The patent utilizes phase transitions of PFAS compounds. By heating soil to 200-400°F, PFAS are desorbed from soil particles and transition from adsorbed state to vapor phase, then condensed and collected. This phase transition approach removes PFAS without requiring temperatures that would decompose them into hazardous by-products
2Productivity
If mechanical agitation is used during thermal desorption, then treatment efficiency is improved, but device complexity and energy consumption increase
Solution Approach 1:
The patent employs natural convection currents created by localized heating to drive gas flow through the soil bed. The heated gas naturally rises and circulates through the porous media without requiring mechanical agitation devices. This self-service approach maintains treatment efficiency while eliminating complex mechanical systems
Solution Approach 2:
The patent uses gas flow through the soil bed to achieve treatment. Heated gas is introduced and flows through the porous soil matrix, carrying desorbed contaminants to collection points. This pneumatic approach replaces mechanical agitation with fluid flow dynamics, reducing device complexity while maintaining productivity
3Productivity
If continuous process is used for thermal desorption, then productivity is improved, but energy consumption and operational complexity increase
Solution Approach 1:
The patent employs periodic batch processing where soil is loaded, treated with sequential heating cycles, and then unloaded. The process uses periodic heating phases followed by cooling and unloading phases. This periodic action allows for efficient energy use through thermal mass retention while achieving continuous overall productivity through sequential batch operations
Solution Approach 2:
The patent maintains continuous useful action by immediately loading new soil into the treatment chamber as treated soil is removed. The thermal energy is retained in the chamber and soil bed, continuously available for the next batch. This continuity eliminates energy-wasting heating cycles and maintains high productivity with reduced energy consumption
4Use of energy by moving object
If combustion is used for heating, then energy efficiency is improved, but harmful by-products such as oxides of nitrogen and sulfur are formed
Solution Approach 1:
The patent uses air heating systems or electric heaters that operate in controlled atmospheres to generate heat without combustion. By eliminating combustion, the system maintains heating efficiency through direct energy transfer while avoiding the formation of oxides of nitrogen, sulfur, and other harmful by-products associated with fossil fuel combustion
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 enables efficient, non-destructive removal of PFAS and hydrocarbons, reducing energy consumption and environmental impact by using capillary flow and sequential treatment, while avoiding the formation of harmful by-products associated with combustion.
Implementation Method 1
the ability to take Cristobalite in the soil through its sudden inversion volumetric change to remove residual contaminants at extremely low concentrations, the sequential treatment (treat small sections at a time) approach and the ability to remove both hydrocarbons and PFAS (nondestructive removal) puts this invention in its own unique field of art in soil remediation.
Implementation Method 2
The present invention may be categorized as a thermal desorption technology although cold air treatment gases and aqueous solutions or a combination could be used for organic compound contaminant removal (including PFAS), metal stabilization or oxidation processes to reduce anaerobic noxious odors.
Implementation Method 3
cooling the sintered soil bed by passing cooling air at ambient temperature through the formed vertical channels of each of the plurality of lateral sections of the sintered soil bed in sequence and collecting the cooling air at the lower surface of the media bed by drawing the cooling air into one or more lateral extraction lines in a floor of the sealable sintering vessel using a vacuum blower; and condensing PFAS contaminants from the collected cooling air
Data Source
AI summary
Methods of treating porous media, including methods of nondestructive removal of PFAS contaminants from soil, and apparatus for carrying out thermal decontamination of porous substrates. The thermal decontamination apparatus sinters and shapes the media to be remediated, and then provides sequential sectionalized treatment using treatment gases that are drawn through the sintered media, extracted, and then treated to remove contaminants extracted from the treated media.