Wastewater Dissolution Tank for High Solids MBR
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Solution Overview
Problem
Current membrane bioreactor (MBR) systems face inefficiencies in oxygen delivery, particularly at high solids concentrations, leading to impractical operation costs and limited capacity due to low oxygen dissolution efficiency and high energy requirements, making them unsuitable for wastewater treatment with solids concentrations above 3%.
Innovation Solution
A system that uses a dissolution tank with a pressure vessel and liquid spray nozzle to dissolve gases into wastewater, allowing for precise control of dissolved oxygen delivery directly into the bioreactor, reducing the need for deep basins and minimizing energy consumption by using supersaturated water to maintain aerobic conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coarse air bubbles are used for aeration in MBR systems, then membrane scouring is improved, but dissolved oxygen delivery efficiency deteriorates
Solution Approach 1:
The aeration function is segmented into two separate systems: coarse bubble aerators dedicated to membrane scouring and fine bubble aerators dedicated to dissolved oxygen delivery. This segmentation allows each system to optimize its specific function without compromising the other, resolving the contradiction between scouring effectiveness and oxygen delivery efficiency
Solution Approach 2:
A vacuum pump is introduced as an intermediary device to extract excess gas from the bioreactor headspace. This mediator prevents gas accumulation that would otherwise interfere with efficient oxygen transfer, enabling both coarse bubble scouring and fine bubble aeration to work more effectively together
2Use of energy by moving object
If fine bubbles are used for aeration, then dissolved oxygen delivery is improved, but membrane scouring capability deteriorates
Solution Approach 1:
The aeration system is divided into two distinct components: fine bubble aerators positioned away from membranes for optimal oxygen transfer, and coarse bubble aerators positioned near membranes for effective scouring. This spatial and functional segmentation allows each type to perform its specialized function without compromise
Solution Approach 2:
Different regions of the bioreactor are provided with different bubble characteristics: fine bubbles in regions prioritizing oxygen transfer and coarse bubbles in regions prioritizing membrane scouring. This local differentiation of quality allows simultaneous optimization of both functions in different locations
3Use of energy by moving object
If deeper basins are used to increase oxygen dissolution, then oxygen delivery efficiency is improved, but device complexity and construction cost worsen
Solution Approach 1:
The system changes the key parameter of bubble size from coarse to fine for the oxygen delivery function. This parameter change dramatically increases the surface area-to-volume ratio of bubbles, enabling efficient oxygen dissolution in shallow basins without requiring increased depth
Solution Approach 2:
Instead of solving the oxygen dissolution problem by increasing vertical dimension (basin depth), the system transitions to solving it through surface area expansion via fine bubble generation. This dimensional shift from vertical to surface-based approach eliminates the need for deep basins
4Productivity
If high solids concentration wastewater is treated in MBR systems, then treatment capacity is improved, but oxygen dissolution efficiency deteriorates
Solution Approach 1:
The system changes the bubble size parameter to fine bubbles, which maintain higher dissolution efficiency even in high solids concentration environments. The small size and high surface area of fine bubbles allow them to overcome the mass transfer limitations imposed by high solids content more effectively than coarse bubbles
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 enhances oxygen delivery efficiency at high solids concentrations, reduces operational costs, and allows for a more compact MBR design, enabling effective treatment of wastewater with higher solids concentrations while maintaining optimal aerobic conditions for biological processes.
Implementation Method 1
a dissolution tank that includes a pressure vessel which provides a pressurized gas head space into which gas is being dissolved
Implementation Method 2
using supersaturated water to maintain aerobic conditions
Implementation Method 3
a pressure vessel which provides a pressurized gas head space above the wastewater or water into which gas is being dissolved
Data Source
AI summary
Disclosed is a system and method for treating wastewater. The system includes a bioreactor which defines a basin for receiving wastewater to be treated; a membrane module in fluid communication with the bioreactor; and a dissolution tank. The tank includes a pressure vessel that contains a portion of the wastewater to be treated and provides a regulated, pressurized gas head space above the wastewater. The tank also includes at least one liquid spray nozzle that permits passage of the wastewater into the gas head space of the pressure vessel and an outlet for discharging the wastewater having a desired gas concentration from the pressure vessel. The system also includes a pumping mechanism for supplying the wastewater to the spray nozzle of the tank such that fluid droplets are formed in the gas head space and the gas contained within the pressurized head space is dissolved into the wastewater.