Phytoremediation of Polluted Foundry Sand
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Solution Overview
Problem
Current methods for depolluting foundry sands are only partially effective in removing a wide range of pollutants, including organic and mineral contaminants, and there is a need for a more comprehensive treatment approach that aligns with ecological transition goals.
Innovation Solution
A method involving the use of a porous carbonaceous material to capture mineral pollutants, combined with phytoremediation using selected plants to degrade organic pollutants, followed by separation and aerobic composting to achieve complete degradation, ensuring the effective removal of both types of contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If micro-organisms are used to treat phenolic pollutants in foundry sands, then phenol degradation is improved, but other mineral pollutants like fluorides remain untreated
Solution Approach 1:
The treatment process is divided into two distinct stages: first, micro-organisms degrade organic phenolic pollutants; second, plant roots absorb mineral pollutants like fluorides and sulphates. This segmentation allows each component to target specific pollutant types effectively.
Solution Approach 2:
The system combines multiple depollution mechanisms into a single integrated process that handles both organic and mineral pollutants. The phytoremediation plants serve dual functions: their roots absorb mineral contaminants while their associated micro-organisms degrade organic compounds, creating a universal treatment solution.
2Object-affected harmful factors
If foundry sands are reprocessed using conventional methods, then some pollutants are removed, but the process is not ecologically sustainable
Solution Approach 1:
The system uses naturally occurring processes to achieve depollution: micro-organisms naturally present in the sand degrade phenolic compounds, and plant roots naturally absorb mineral pollutants. This self-service approach eliminates the need for energy-intensive conventional treatment methods and chemical additives, making the process ecologically sustainable.
Solution Approach 2:
The method transforms the polluted foundry sand into a beneficial resource by using the pollutants as substrates for microbial degradation and plant nutrient absorption. The harmful contaminants become food sources for micro-organisms and nutrients for plants, converting waste into valuable biomass.
3Device complexity
If a single treatment method is used for all pollutants, then the process is simple, but it cannot effectively remove both organic and mineral contaminants
Solution Approach 1:
The invention merges biological degradation and phytoremediation into a single integrated treatment system. Micro-organisms and plants work synergistically in the same substrate, combining their different depollution capabilities to remove both organic and mineral contaminants through one unified process rather than separate treatment steps.
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 method significantly reduces mineral and organic pollutant levels in foundry sands, promoting plant growth and fertility while allowing for the reprocessing of the carbonaceous material, resulting in treated sands that can be reused safely.
Implementation Method 1
a step of preparing a substrate by adding to the contaminated sands a porous carbonaceous material chosen to fix mineral pollutants, in particular fluorides
Implementation Method 2
a phytoremediation step consisting in growing on the substrate plants selected to degrade at least some of the organic pollutants
Implementation Method 3
a stage of aerobic composting of the treated sands
Data Source
Figure 1
AI summary
The invention relates to a process for the decontamination of contaminated sands (S1), in particular foundry sands, comprising mineral and organic pollutants, comprising: - a step of preparation (4) of a substrate (S2) by adding to the contaminated sands (S1) a porous carbon material (CA) chosen to fix mineral pollutants, in particular fluorides; - a phytoremediation step (5) consisting of growing on the substrate (S2) plants selected to degrade at least part of the organic pollutants, the phytoremediation step (5) producing intermediate sands (S3) from the substrate (S2); - a step of separation (6) of the porous carbon material (CA) from the intermediate sands (S3), the separation step (6) producing treated sands (S4).