Aerobic Membrane Bioreactor and Anaerobic Digester Integration
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Solution Overview
Problem
Existing biological wastewater treatment systems face challenges in achieving near complete removal of organic and inorganic compounds, such as CBOD, TSS, TN, and TP, due to high capital and operating costs, variable performance, and increased complexity, which are not adequately addressed by current technologies.
Innovation Solution
The integration of an aerobic membrane bioreactor system with an anaerobic digester, where wasted solids are sent to the anaerobic digester and effluent is returned to the aerobic bioreactor, maintaining a solids retention time that supports biomass growth while minimizing decay, and incorporating phosphorus and ammonia removal processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional biological treatment systems are used to remove organic and inorganic compounds, then treatment capacity is maintained, but capital and operating costs increase significantly
Solution Approach 1:
The patent combines the aerobic bioreactor and anaerobic digester into an integrated system where the anaerobic digester serves dual purposes: treating wasted solids from the aerobic reactor and functioning as a denitrification reactor. This merging eliminates the need for separate denitrification equipment and reduces overall system complexity while achieving near-complete removal of CBOD, TSS, TN and TP.
Solution Approach 2:
The anaerobic digester is designed to perform multiple functions simultaneously: it processes wasted solids from the aerobic reactor, provides denitrification by converting nitrate to nitrogen gas, and produces biogas as a valuable byproduct. This multi-functionality reduces the number of separate units needed and lowers both capital and operating costs.
2Quantity of substance
If chemical addition is used to achieve complete TP removal, then nutrient removal efficiency is improved, but residual solids generation increases
Solution Approach 1:
The system uses biological processes to remove phosphorus through enhanced biological phosphorus removal (EBPR) mechanisms within the anaerobic-aerobic system configuration. Microorganisms naturally accumulate phosphorus during aerobic phases and release it during anaerobic phases, enabling phosphorus removal without chemical addition and minimizing residual solids generation.
3Quantity of substance
If system upgrades are implemented to meet stringent effluent regulations, then treatment performance is improved, but operating costs increase due to energy and chemical usage
Solution Approach 1:
The system converts the wasted solids from the aerobic reactor, which would normally be a disposal burden requiring energy-intensive aerobic digestion, into a valuable resource. These solids are fed to the anaerobic digester where they produce biogas (methane) that can be used for energy generation, thereby converting a waste stream into an energy source and reducing overall energy consumption.
4Stability of the object's composition
If aerobic digestion is used for wasted solids treatment, then solids stabilization is achieved, but energy consumption increases
Solution Approach 1:
Instead of using energy-intensive aerobic digestion to treat wasted solids, the system inverts the approach by using anaerobic digestion. This reverses the conventional wisdom that aerobic conditions are always better for solids stabilization, demonstrating that anaerobic conditions can achieve effective stabilization while producing biogas and consuming less energy.
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 configuration enhances the efficiency and cost-effectiveness of wastewater treatment, achieving near complete removal of undesirable contaminants with reduced residual solids generation and energy consumption, while simplifying the treatment process and reducing operational costs.
Implementation Method 1
a time needed to achieve growth of organisms suitable for converting carbonaceous biochemical oxygen demand (CBOD) into cell mass
Implementation Method 2
wasting a volume fraction of organic cell mass from an aerobic membrane bioreactor to an anaerobic digester system
Data Source
AI summary
A wastewater treatment system is provided including an aerobic membrane bioreactor and an anaerobic digester system connected to receive wasted solids continuously from the aerobic membrane bioreactor and also connected to return effluent from the anaerobic digester system continuously to the aerobic membrane bioreactor. Further, a process is provided for treating wastewater including the step of wasting a volume fraction of organic cell mass from an aerobic membrane bioreactor to an anaerobic digester system and maintaining a solids retention time (SRT) in the bioreactor that is (1) greater than a time needed to achieve growth of organisms suitable for converting carbonaceous biochemical oxygen demand (CBOD) into cell mass and (2) less than a time at which substantial decay of the organisms occurs. The system and process may further include optional pretreatment and/or phosphorus and/or nitrogen removal downstream of the membrane bioreactor system.