Slime Control in Reverse Osmosis Membranes via Chemical Merging
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Solution Overview
Problem
Current methods for controlling slime (biofilm) in reverse osmosis membrane apparatuses are inefficient, requiring multiple steps and disrupting continuous operation, especially when using slime controlling agents like 2,2-dibromo-3-nitrilopropionamide (DBNPA), which necessitate additional treatments such as ultraviolet irradiation and ion exchange.
Innovation Solution
A method involving the combination of 2,2-dibromo-3-nitrilopropionamide (DBNPA) with other slime controlling agents such as 5-chloro-2-methyl-4-isothiazolin-3-one, chloramine compounds, stabilized bromides, and glutaraldehyde, added to the water supply at specific pH levels and concentrations, to effectively control and remove slime from reverse osmosis membranes without stopping the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slime controlling agent (DBNPA) is used alone to control slime in reverse osmosis membrane apparatus, then slime control effect is achieved, but additional treatment steps (ultraviolet irradiation and ion exchange) are required, increasing process complexity and time
Solution Approach 1:
The patent combines DBNPA with other slime controlling agents (such as isothiazolinones, chloramines, stabilized bromides, or glutaraldehyde) into a single water-supplying step. This merging of multiple agents eliminates the need for separate ultraviolet irradiation and ion exchange treatment steps, reducing process complexity while maintaining effective slime control.
2Reliability
If chemical washing with caustic soda is performed to remove slime from reverse osmosis membrane, then slime removal is achieved, but continuous running of the apparatus is hindered and running costs increase
Solution Approach 1:
The patent applies slime controlling agents to water to be treated before it enters the reverse osmosis membrane. This preliminary action prevents slime formation and accumulation on the membrane surface during continuous operation, eliminating the need to stop the apparatus for chemical washing and maintaining continuous productivity.
3Reliability
If multiple treatment steps are used to control slime effectively, then slime control reliability is improved, but time required for treatment increases
Solution Approach 1:
The patent merges multiple slime controlling agents into a single water-supplying step that occurs during normal operation. This combination approach achieves reliable slime control without requiring separate sequential treatment steps, thereby minimizing treatment time and avoiding operational interruptions.
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 combination allows for rapid and effective control and removal of slime, maintaining continuous operation and reducing operational costs by minimizing the number of treatment steps and enhancing membrane performance.
Implementation Method 1
a slime controlling agent X which contains 2,2-dibromo-3-nitrilopropionamide (DBNPA) and a slime controlling agent Y which contains at least one type selected from a group consisting of the following components (A) to (D) are added to water to be treated
Implementation Method 2
a water-supplying step of supplying water to be treated to a reverse osmosis membrane
Data Source
AI summary
A method for controlling slime is used in a reverse osmosis membrane apparatus and has a water-supplying step of supplying water to be treated to the reverse osmosis membrane. The water-supplying step includes a first water-supplying step in which a slime controlling agent X which contains 2,2-dibromo-3-nitrilopropionamide (DBNPA) and a slime controlling agent Y which contains at least one type selected from a group consisting of components (A) to (D) are added to the water to be treated which has a pH of 10 or less, and the water to be treated which contains the slime controlling agent X and the slime controlling agent Y is supplied to the reverse osmosis membrane. The component (A) is mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) and 2-methyl-4-isothiazolin-3-one (MIT), the component (B) is chloramine compound, the component (C) is stabilized bromide, and the component (D) is glutaraldehyde.