Ozone-Treated Backwash Effluent Reintegration in Membrane Bioreactors
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Solution Overview
Problem
Side stream type membrane bioreactor processes face challenges in maintaining membrane filtration stability and MLSS concentration due to foulant accumulation and the need for additional effluent treatment facilities when handling backwash effluent, especially during low sludge activity in winter.
Innovation Solution
The process involves ozone treatment of backwash effluent to reduce foulants to sizes smaller than the membrane pore size, allowing their reintegration into the bioreactor without disrupting MLSS concentration, using a ceramic monolithic membrane with circular or polygonal cross-section channels, and returning the treated effluent to the bioreactor, thereby maintaining stable filtration performance and avoiding external discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backwash effluent is returned to the bioreactor, then membrane filtration performance stability is improved, but foulant accumulation occurs in the bioreactor during low sludge activity periods
Solution Approach 1:
The patent applies parameter changes by using ozone treatment to alter the physical-chemical properties of foulants in the backwash effluent. The ozone oxidation process changes the molecular structure and aggregation state of foulants, transforming them into smaller particles that can be effectively reincorporated into the bioreactor without causing accumulation problems during low sludge activity periods.
Solution Approach 2:
The patent introduces an intermediary treatment process (ozone treatment) between the membrane separation unit and the bioreactor. This intermediary step processes the backwash effluent to convert foulants into a form suitable for return to the bioreactor, resolving the contradiction between maintaining filtration stability and preventing foulant accumulation.
2Quantity of substance
If backwash effluent is discharged to the outside, then foulant accumulation in the bioreactor is reduced, but MLSS concentration falls excessively and biodegradation ability is reduced
Solution Approach 1:
The patent converts the harmful foulants in the backwash effluent into beneficial substances through ozone treatment. The treated foulants are transformed into a form that can be effectively utilized by the activated sludge in the bioreactor, turning what would be waste material into a resource that supports biodegradation processes.
3Quantity of substance
If additional effluent treatment facility is located to treat backwash effluent, then foulant management is improved, but system complexity and operational cost increase
Solution Approach 1:
The patent merges the backwash effluent treatment process with the existing bioreactor system. By using ozone treatment and returning the processed effluent to the bioreactor, the system eliminates the need for separate effluent treatment facilities, reducing overall system complexity while maintaining effective foulant control.
Solution Approach 2:
The patent makes the backwash effluent treatment system multi-functional by integrating it with the bioreactor's existing processes. The treated effluent serves multiple purposes: it maintains MLSS concentration, provides substrate for biodegradation, and controls foulant accumulation, thereby eliminating the need for dedicated treatment facilities.
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 ensures stable membrane filtration performance, maintains active biodegradation ability, and eliminates the need for additional effluent treatment facilities by keeping MLSS concentration within a desired range, while reducing operational costs through controlled ozone use.
Implementation Method 1
ozone treatment of backwash effluent to reduce foulants to sizes smaller than the membrane pore size
Implementation Method 2
using a ceramic monolithic membrane with circular or polygonal cross-section channels
Implementation Method 3
organic substances are subjected to biodegradation with microorganisms in a bioreactor
Data Source
AI summary
The invention provides a side stream type membrane bioreactor process which does not cause an excessive fall in the MLSS concentration in a bioreactor, does not require any additional effluent treatment facility for discharging a backwash effluent, and can further ensure the stability of the membrane filtration performance of a separation membrane. Thus, according to the invention, in a side stream type membrane bioreactor process, a backwash effluent containing foulants that are generated by backwashing a separation membrane 2 is collected in a backwash effluent tank 7, and then subjected to ozone treatment, and the resultant is returned to a bioreactor 1. By this ozone treatment, the foulants close to the membrane pore size of the separation membrane are made fine or are made into a state be easily taken into activated sludge flocs. Therefore, even when the treated effluent is returned to the bioreactor 1, the membrane filtration performance of the separation membrane is not deteriorated. Moreover, the returned sludge makes it possible to maintain the MLSS concentration at an effective level in the bioreactor.