Flocculant Polymer Composition for High Conductivity Dissolved Gas Flotation
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Solution Overview
Problem
Conventional flocculants used in dissolved gas flotation processes for pulp and paper industry face challenges with elevated conductivity and cationic demand, leading to reduced performance in removing suspended solid materials, especially with increased use of recycled fibers and anionic trash.
Innovation Solution
A polymer composition with a cationic synthetic first polymer and a (meth)acrylamide copolymer is used, having a higher charge density than the second polymer, which interacts with anionic substances to form stable and long-lasting flocs, maintaining extended polymer chains and preserving flocculation ability even in high conductivity environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high-molecular weight polyacrylamide flocculants are used to flocculate suspended solid particulate material, then floc formation occurs, but floc stability and flocculation efficiency deteriorate in the presence of elevated conductivity and cationic demand
Solution Approach 1:
The patent changes the charge density parameter of the flocculant polymer from conventional high values (typically >2.0 meq/g) to a specific range of 0.5-1.5 meq/g. This parameter modification allows the polymer to maintain extended chains in high conductivity environments while preserving flocculation ability, resolving the contradiction between floc stability and performance under elevated conductivity and cationic demand conditions
Solution Approach 2:
The patent employs a composite polymer structure combining cationic synthetic polymer segments with (meth)acrylamide segments. This composite material design creates a dual-function flocculant that can interact with anionic substances through cationic groups while maintaining physical entanglement and extended chain structure through the (meth)acrylamide portions, thereby achieving stable floc formation even in challenging water quality conditions
2Adaptability or versatility
If the aqueous feed uses more recycled water to reduce fresh water consumption, then environmental performance improves, but conductivity and total ionic strength increase, interfering with flocculant performance
Solution Approach 1:
The patent modifies the charge density parameter of the flocculant to a lower range (0.5-1.5 meq/g) that is specifically adapted to function in high conductivity environments. This enables the flocculant to maintain effectiveness even when recycled water increases the ionic strength of the aqueous feed, thus supporting water recycling operations without sacrificing treatment performance
3Adaptability or versatility
If the aqueous feed contains more recycled fibre to increase fibre source utilization, then resource efficiency improves, but load of dissolved and colloidal substances (anionic trash) increases, interfering with flocculation
Solution Approach 1:
The patent uses a composite polymer structure with cationic synthetic polymer segments that specifically target and interact with anionic dissolved and colloidal substances (anionic trash). The cationic groups in the composite flocculant neutralize the negative charges on these interfering substances, allowing effective flocculation to proceed even when recycled fibre content and associated anionic contaminants are elevated
4Productivity
If polymer chains are extended to improve flocculation ability, then floc formation efficiency improves, but in high conductivity environments polymer chains compress, reducing flocculation performance
Solution Approach 1:
The patent optimizes the charge density parameter to a lower range (0.5-1.5 meq/g) that reduces electrostatic compression effects in high conductivity environments. This parameter adjustment allows polymer chains to maintain their extended conformation and flocculation ability even when ionic strength is elevated, resolving the contradiction between maintaining chain extension and operating in conductive environments
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 polymer composition enhances floc stability and density, improving the efficiency of suspended solid removal, reducing turbidity, and maintaining effective flocculation in high conductivity and cationic demand conditions, leading to improved clarified water quality and increased feed capacity.
Implementation Method 1
the first polymer has a higher charge density than the second polymer... interactions between the first polymer and anionic substances
Implementation Method 2
The bubbles cause the flocs to float on the surface... clarified water is usually removed from the lower part of the basin
Implementation Method 3
bringing a flocculant in contact with the aqueous feed and flocculating suspended solid particulate material into flocs through interaction of flocculant and suspended solid particulate material
Data Source
AI summary
A method is disclosed for treating aqueous feed by dissolved gas flotation. The aqueous feed originates from industrial processing of fibrous material, where the aqueous feed includes an aqueous phase and solid particulate material suspended in the aqueous phase. The method includes bringing a flocculant in contact with the aqueous feed, flocculating suspended solid particulate material into flocs and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant includes a polymer composition having a charge density of at the most 1.7 meq/g dry and the polymer composition includes a cationic synthetic first polymer having a charge density at least 1.0 meq/g dry at pH 2.8, and at least one second polymer obtained by polymerization of (meth)acrylamide, the second polymer being polymerized in presence of the cationic first polymer, where the first polymer has a higher charge density than the second polymer.