Membrane Bioreactor Cleaning Method for Sludge Management
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Solution Overview
Problem
Out-of-basin type separation membranes in biological treatment tanks face rapid plugging due to high MLSS levels, requiring frequent chemical cleaning that damages microorganisms and impairs biological treatment ability by returning chemical-laden backwash water to the tank.
Innovation Solution
The method involves pre-peeling sludge from the membrane surface using water backwash, reducing chemical usage and avoiding the return of chemical-laden backwash water to the tank by discharging it to a separate sedimentation basin, where it can be treated, thereby minimizing microorganism damage and maintaining biological activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical cleaning is performed frequently to remove sludge from the membrane surface, then filtration efficiency is improved, but microorganisms in the biological treatment tank are damaged and biological treatment ability is impaired
Solution Approach 1:
The patent applies preliminary action by performing water backwash before chemical cleaning to remove loose sludge deposits from the membrane surface. This pre-cleaning step reduces the amount of sludge that requires chemical treatment, thereby minimizing chemical exposure to microorganisms in the biological treatment tank while still maintaining effective membrane cleaning
Solution Approach 2:
The patent extracts harmful chemicals from the biological treatment tank by collecting backwash water containing detached sludge and chemicals in a separate sedimentation basin. This separation prevents chemicals from contacting and damaging microorganisms in the main biological treatment tank, resolving the contradiction between effective chemical cleaning and microorganism protection
2Productivity
If backwash water containing chemicals and sludge is returned to the biological treatment tank, then sludge removal is effective, but biological treatment ability is impaired due to chemical contamination
Solution Approach 1:
The patent extracts chemicals and sludge from the system by directing backwash water to a separate sedimentation basin instead of returning it to the biological treatment tank. This separation removes harmful chemicals from the biological treatment environment while still achieving effective sludge removal from the membrane surface
Solution Approach 2:
The patent introduces a sedimentation basin as an intermediary between the membrane cleaning system and the biological treatment tank. This intermediary component allows for the separation and settling of sludge and chemicals before any potential discharge, preventing direct contamination of the biological treatment tank while maintaining sludge removal effectiveness
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 reduces chemical consumption and protects microorganisms, maintaining the biological treatment tank's performance and filtration efficiency by preventing chemical contamination, allowing for effective sludge removal without impairing the tank's biological activity.
Implementation Method 1
The out-of-basin type membrane filters tank water from a biological treatment tank by connecting the membrane to the biological treatment tank through a circulation passageway and sending the permeate to a treated water tank
Implementation Method 2
the sludge caused by allowing deposits to be peeled to the raw water side by applying a backwash pressure from a filtrate side
Implementation Method 3
tank water in the biological treatment tank has been usually guided to a final sedimentation basin for solid-liquid separation by gravitational sedimentation
Data Source
Figure 1
AI summary
When an out-of-basin type separation membrane, which is connected to a biological treatment tank through a circulation passageway for filtering tank water, is cleaned, a part or all of the backwash drainage containing the sludge peeled from the membrane surface is returned to the biological treatment tank through a backwash drain passageway or circulation passageway to maintain the suspended solid concentration MLSS of the biological treatment tank constant. In the case of chemical cleaning, the sludge is peeled from the membrane surface by backwash with water, and the sludge is discharged out of the membrane module through a sludge line and then followed by chemical cleaning. Thus the need for using a large amount of a chemical solution is eliminated and the peeled sludge containing the chemical solution can be discharged out of the system as well, thereby preventing the microorganism from being damaged by the chemical solution.