Surface-Treated Calcium Carbonate for Water Purification
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Solution Overview
Problem
Current water treatment processes using flocculants are inadequate in removing inorganic impurities and often result in high energy consumption due to incomplete flocculation, and the use of polymeric flocculation aids leads to environmental concerns and increased costs.
Innovation Solution
A process involving surface-treated calcium carbonate with at least 1% of its accessible surface area coated with a cationic polymer is used for water purification and dewatering of sludges and sediments, reducing the amount of polymeric flocculation aids and improving the quality of the filter cake and purified water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flocculants (aluminium sulphate, polyaluminium chloride, iron(III) chloride) are used for water purification, then the purification process can be performed, but toxic residues remain in the finished water and additional corrosion risks are created
Solution Approach 1:
The patent changes the chemical composition parameter by using calcium carbonate instead of aluminium or iron-based coagulants. This substitution fundamentally alters the chemical properties of the purification process, eliminating toxic residues while maintaining effective purification through calcium-based flocculation mechanisms
Solution Approach 2:
The patent employs calcium carbonate, a naturally occurring, inexpensive material that decomposes into harmless substances (calcium ions and carbonate/bicarbonate). This replaces persistent toxic materials with a benign, easily disposed of substance that leaves no harmful long-term residues in the water
2Quantity of substance
If activated carbon or bentonite with high specific surface area are used for adsorption, then adsorption capacity is improved, but separation becomes very difficult due to finely divided state
Solution Approach 1:
The patent creates a composite material by coating calcium carbonate particles with cationic polymer. This composite structure combines the high surface area benefits of fine particles with the flocculation properties of the polymer, allowing the coated particles to aggregate into larger, easier-to-separate flocs while maintaining adsorption capacity
Solution Approach 2:
The cationic polymer acts as an intermediary substance that bridges the gap between fine adsorbent particles and the separation process. The polymer coating enables fine particles to associate into larger aggregates through electrostatic and steric interactions, facilitating separation while preserving the high surface area of individual particles
3Productivity
If polymeric flocculation aids are used to improve flocculation, then sedimentation and filterability are improved, but environmental concerns arise and costs increase
Solution Approach 1:
The patent changes the polymer characteristics by selecting cationic polymers with specific properties (positive charge, appropriate molecular weight). This parameter optimization enables effective flocculation at lower concentrations, reducing environmental impact while maintaining improved sedimentation and filterability
Solution Approach 2:
The patent applies polymer coating locally on the surface of calcium carbonate particles rather than using bulk polymer. This localized application provides flocculation functionality at the particle surface while minimizing the total amount of polymer required, thereby reducing environmental concerns and costs
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 process effectively decreases the concentration of inorganic impurities and polymeric flocculation aids, resulting in a lower energy consumption for dewatering and reduced environmental impact, with improved water quality and filter cake compactness.
Implementation Method 1
Many flocculants are multivalent cations such as aluminium, iron, calcium or magnesium. These positively charged ions interact with negatively charged particles and molecules to reduce the barriers to aggregation.
Implementation Method 2
Flocculation refers to a process where dissolved compounds and/or colloidal particles are removed from the solution in the form of flocs or 'flakes.' The term is also used to refer to the process by which fine particulates are caused to clump together into floes.
Implementation Method 3
The floes may then float to the top of the liquid, settle to the bottom of the liquid, or can be readily filtered from the liquid.
Data Source
AI summary
The invention relates to a process for the purification of water and/or dewatering of sludges and/or sediments, to the use of a surface-treated calcium carbonate for water purification and/or dewatering of sludges and/or sediments, as well as to the use of a surface-treated calcium carbonate for reducing the amount of polymeric flocculation aids in water and/or sludges and/or sediments and to a composite material comprising a surface-treated calcium carbonate and impurities originated from different sources obtainable by said process.