Membrane Separation Chlorine Control for Biofouling Suppression
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Solution Overview
Problem
Existing membrane separation methods using combined-chlorine-based oxidizing agents fail to consistently suppress biofouling due to unpredictable chemical effects, leading to reduced operation time in membrane separation systems, as indicated by inconsistent bactericidal power and biofouling potential, despite maintaining similar total chlorine concentrations.
Innovation Solution
The method involves using a Free 300-second chlorine concentration value as an indicator to ensure the water contains a minimum of 0.036 mg/L-Cl2 or more, and a [Free 300-second value/Log10 (biofouling potential) of 0.008 or more, to effectively suppress biofouling and extend the operation time of membrane separation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If combined-chlorine-based oxidizing agents are used to suppress biofouling, then bactericidal effect is improved, but operation time is reduced due to inconsistent chemical effects
Solution Approach 1:
The patent changes the parameter for measuring chlorine concentration from total chlorine to Free 300-second value, which reflects the actual bactericidal effectiveness of combined-chlorine-based oxidizing agents more accurately. This parameter change enables consistent suppression of biofouling and extends operation time by maintaining chlorine concentration within the optimal range of 0.036 mg/L-Cl2 or more.
2Ease of operation
If total chlorine concentration is used as the indicator for water treatment conditions, then operation management is simplified, but biofouling suppression becomes inconsistent
Solution Approach 1:
The patent replaces the total chlorine concentration parameter with the Free 300-second value parameter, which can be measured using the same DPD method but provides more accurate reflection of combined-chlorine-based oxidizing agent effectiveness. This maintains operational simplicity while significantly improving biofouling suppression consistency.
3Reliability
If chemical agents are added constantly to prevent microbial contamination, then bactericidal effect is maintained, but chemical substance consumption increases
Solution Approach 1:
The patent implements a feedback control system where the Free 300-second value is continuously monitored and used to adjust chemical agent dosing. By maintaining chlorine concentration within the optimal range (0.036 mg/L-Cl2 or more) rather than using fixed dosing, the system achieves consistent microbial contamination prevention while optimizing chemical agent consumption.
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 approach allows for prolonged operation of membrane separation systems by ensuring consistent chemical effects, effectively suppressing biofouling and maintaining membrane performance.
Implementation Method 1
combined-chlorine-based oxidizing agents such as sodium chlorosulfamate have been widely used because it is possible to suppress biofouling
Implementation Method 2
chemical effects such as the bactericidal power of combined-chlorine-based oxidizing agents
Implementation Method 3
reverse osmosis membranes (RO membranes), nanofiltration membranes (NF membranes), ultrafiltration membranes (UF membranes), and microfiltration membranes (MF membranes)
Implementation Method 4
separate out suspended matter or dissolved substances and ions in the water of interest using permeable membranes
Data Source
AI summary
The purpose of the present invention is to provide a technique whereby it becomes possible to operate for a longer period of time in an aqueous system equipped with a membrane separation apparatus. The present invention can provide a membrane separation method, the method comprising containing a combined-chlorine-based oxidizing agent to water of interest, and allowing the water of interest which contains the combined-chlorine-based oxidizing agent to pass through a membrane separation apparatus, in which the water of interest which contains the combined-chlorine-based oxidizing agent has a Free 300-second value of 0.036 mg/L-Cl2 or more wherein the Free 300-second value is a result of the measurement of a chlorine concentration after 300 seconds using a free chlorine measurement reagent.