Membrane Filtration Clogging Control via BOD-TOC Ratio
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Solution Overview
Problem
The membrane separation activated sludge process faces challenges in maintaining stable filtration due to biopolymers and contaminants adhering to the membrane surface, leading to potential clogging, which affects the efficiency of solid-liquid separation in wastewater treatment.
Innovation Solution
The method involves determining a γ value based on the ratio of biochemical oxygen demand (BOD) to total organic carbon (TOC), TOD, or COD Cr, and adjusting the BOD-sludge load to prevent membrane clogging by optimizing the BOD-sludge load according to specific ranges for different γ values, thereby controlling the risk of clogging and enhancing filtration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If membrane filtration is used for solid-liquid separation in activated sludge process, then separation efficiency is improved and final sedimentation tank is eliminated, but membrane clogging occurs due to adhesion of biopolymers and contaminants on membrane surface
Solution Approach 1:
The patent applies preliminary action by controlling the BOD-sludge load before membrane clogging occurs. By determining the appropriate BOD-sludge load based on the γ value (ratio of BOD to TOC/COD Cr/TOD) and adjusting operational parameters accordingly, the system prevents biopolymer accumulation that would lead to membrane clogging, thereby maintaining filtration stability while achieving high separation efficiency
Solution Approach 2:
The patent employs parameter changes by using the γ value (ratio of BOD to total organic content) as a key parameter to determine the appropriate BOD-sludge load. By adjusting the BOD-sludge load based on this ratio and monitoring membrane filtration flux, the system optimizes operational conditions to prevent membrane clogging while maintaining high separation efficiency
2Productivity
If BOD-sludge load is increased to improve treatment efficiency, then organic matter degradation is enhanced, but membrane clogging risk increases due to excessive biopolymer production
Solution Approach 1:
The patent uses parameter changes by establishing the relationship between γ value and optimal BOD-sludge load. By calculating the γ value (BOD/TOC or BOD/COD Cr or BOD/TOD ratio) and adjusting the BOD-sludge load accordingly, the system maximizes treatment efficiency while preventing membrane clogging through controlled biopolymer production
Solution Approach 2:
The patent applies feedback by continuously monitoring the membrane filtration flux and adjusting the BOD-sludge load based on the observed filtration performance. When filtration flux decreases indicating membrane fouling, the system adjusts operational parameters to reduce biopolymer production, thereby maintaining treatment efficiency while preventing membrane clogging
3Reliability
If aeration is applied to membranes to prevent contaminant accumulation, then membrane surface cleaning is improved, but energy consumption increases and vibration effects may damage membrane structure
Solution Approach 1:
The patent applies preliminary action by preventing contaminant accumulation on membrane surfaces through proper BOD-sludge load control before significant fouling occurs. By maintaining optimal biopolymer production levels through γ value-based BOD-sludge load determination, the system reduces the need for intensive aeration cleaning, thereby lowering energy consumption while maintaining membrane surface cleanliness
Solution Approach 2:
The patent converts the potentially harmful effect of biopolymer production into a benefit by optimizing the BOD-sludge load to produce sufficient biopolymers for effective biological treatment while preventing excessive accumulation that would cause membrane clogging. This approach reduces the need for energy-intensive aeration cleaning
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 stable and efficient solid-liquid separation by adjusting the BOD-sludge load based on the γ value, preventing membrane clogging and maintaining treated water quality, even with varying organic wastewater biodegradability.
Implementation Method 1
carrying out solid-liquid separation to separate the activated sludge and treated liquid by filtration
Implementation Method 2
a medium such as filtered water is effused in the opposite direction from the direction of filtration to remove adhered substances on the surface of the membrane
Implementation Method 3
agitation effects produced by the upward movement of air bubbles
Data Source
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AI summary
The present invention provides a method that allows solid-liquid separation of activated sludge and a treated liquid to be carried out stably and efficiently by suitably evaluating the risk of clogging prior to membrane clogging and adopting necessary and adequate countermeasures. The present invention provides a wastewater treatment method employing a membrane separation activated sludge process, by which the upper limit of BOD-sludge load is determined based on an index indicating the total organic content of the organic wastewater and a BOD value, and the BOD-sludge load in the activated sludge tank is adjusted so as not to exceed the upper limit.