Resin Bed Biostratum Segmentation for RO Membrane Protection
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Solution Overview
Problem
Existing water purification methods using reverse osmosis membranes face challenges with biofouling, where bacteria growth creates a biofilm that reduces membrane permeability and increases pressure drop, ultimately shortening the membrane's lifespan.
Innovation Solution
A method involving a resin bed with a biostratum and a bead stratum, where feed water passes through the biostratum to establish a biomass, and then through the bead stratum before undergoing reverse osmosis. This method includes chemical treatment of a partial section of the resin bed using an aqueous chemical conveyed through intermediate conduits, allowing for selective and efficient treatment without affecting the biostratum's viability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If backwashing is performed to remove microorganisms and EPS from the resin beads, then the biostratum is cleaned and membrane biofouling is reduced, but the entire resin bed is disturbed and treatment efficiency temporarily decreases
Solution Approach 1:
The resin bed is divided into two functional zones: a biostratum zone (top 10-20 cm) where microorganisms grow to prevent membrane biofouling, and a bead stratum zone (bottom 80-90 cm) without biostratum for continuous treatment. This segmentation allows selective backwashing of only the bead stratum zone, maintaining the biostratum's integrity and continuous treatment efficiency while still removing EPS accumulation from the lower zone.
Solution Approach 2:
Different regions of the resin bed are given different functional properties: the upper biostratum zone is designed to support microbial growth for biofouling prevention, while the lower bead stratum zone is designed for physical filtration and EPS removal. An intermediate distributor is positioned at the boundary to enable localized backwashing of the bead stratum without disturbing the biostratum, thus maintaining local treatment quality while managing harmful factors.
2Quantity of substance
If chemical treatment is applied to the entire resin bed to regenerate phosphate capacity, then phosphate removal is improved, but the biostratum biomass is damaged and treatment continuity is disrupted
Solution Approach 1:
The resin bed is segmented into a biostratum zone containing living biomass and a bead stratum zone without biomass. Chemical treatment (acid or base) is applied selectively to the bead stratum zone through the intermediate distributor, regenerating phosphate capacity on the resin beads without exposing the biostratum biomass to harmful chemicals, thus maintaining both phosphate removal capability and treatment reliability.
Solution Approach 2:
The intermediate distributor acts as a mediator that enables selective chemical treatment delivery to the bead stratum zone while protecting the biostratum zone. It distributes chemical solutions (acid or base) to the lower resin bed region and collects treated effluent, allowing phosphate capacity regeneration without compromising biostratum viability and ensuring continuous reliable treatment.
3Object-affected harmful factors
If the biostratum is allowed to grow large to effectively trap bacteria, then membrane biofouling is reduced, but pressure drop across the bed increases and water flow is restricted
Solution Approach 1:
The resin bed is segmented into a biostratum zone (10-20 cm height) where bacterial trapping occurs and a bead stratum zone (80-90 cm height) for flow distribution and support. The intermediate distributor is positioned at the boundary to enable periodic backwashing of the bead stratum to remove accumulated EPS, maintaining water flow and pressure characteristics while preserving the biostratum's bacterial trapping function.
Solution Approach 2:
Periodic backwashing is applied to the bead stratum zone through the intermediate distributor to remove accumulated EPS and restore water flow capacity. This periodic cleaning action prevents excessive pressure drop while maintaining the biostratum's bacterial trapping function, balancing biofouling prevention with acceptable pressure characteristics.
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 method effectively reduces biofouling on reverse osmosis membranes by utilizing the biostratum to trap bacteria, while the chemical treatment of the bead stratum regenerates its phosphate capacity and removes contaminants, thereby extending the membrane's lifespan and improving water treatment efficiency.
Implementation Method 1
passing the feed water through a vessel comprising a bed of resin beads. The bed of resin beads comprises a biostratum, which is a layer of resin beads on which a biomass comprising living microorganisms grows
Implementation Method 2
the bead-treated water is preferably conveyed to an apparatus that performs an RO process on the bead-treated water
Implementation Method 3
chemically treating a partial section of the resin bead bed with an aqueous chemical
Data Source
Figure 1
AI summary
Provided is a method of chemically treating resin beads in a vessel (2), wherein the vessel is adapted to treat feed water, and comprises (a) a bed of resin beads comprising a biostratum (1) upstream of a bead stratum (6) in the net direction of feed water flow, wherein the biostratum comprises resin beads and a biomass comprising living microorganisms; (b) a first port (3) at a first end of the vessel, through which feed water enters the vessel; (c) a second port (5) at a second end of the vessel, through which bead-treated water leaves the vessel; (d) the first and second ends are situated at opposing ends of the vessel; (e) at least one intermediate conduit (11) located within the bed, for conveying an aqueous chemical into the bed and/or from the bed; and wherein the bead-treated water is passed through an apparatus that performs a reverse osmosis process on the bead-treated water; and wherein the method of chemically treating the resin beads comprises chemically treating a partial section of the resin bead bed with an aqueous chemical, the partial section having a volume which is less than 100% of the volume of the resin bead bed and being located upstream or downstream of an intermediate conduit in the net direction of feed water flow, and wherein the aqueous chemical is conveyed to the partial section of the bed and/or is conveyed from the partial section of the bed through the intermediate conduit.