Membrane Bioreactor Phosphorus Removal via Gasification
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Solution Overview
Problem
Conventional phosphorus removal methods require sludge discharge and complex, area-intensive setups with separate facultative aerobic and aerobic zones, posing challenges in sludge management and maintenance.
Innovation Solution
A membrane bioreactor system with a membrane module where the lower part is intensively aerated to create an aerobic zone, a facultative aerobic zone, and an anaerobic zone, allowing phosphorus absorption and release without sludge discharge, utilizing phosphine-reducing bacteria to transform inorganic phosphorus into phosphine for removal through a gasification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sludge discharge is used to remove phosphorus, then phosphorus removal is achieved, but sludge management becomes difficult and occupies large area
Solution Approach 1:
The patent extracts phosphorus from the sludge system by converting it into phosphine gas through anaerobic digestion, then removes the phosphine gas from the system through air stripping. This separates phosphorus removal from sludge discharge, allowing phosphorus to be removed while retaining the sludge in the reactor.
Solution Approach 2:
The patent changes the chemical state of phosphorus from dissolved inorganic phosphorus to organic phosphorus in sludge, then transforms it to phosphine gas through anaerobic digestion. This parameter change enables phosphorus removal through gasification rather than sludge discharge.
2Reliability
If separate facultative aerobic and aerobic zones are used, then phosphorus removal is effective, but the process becomes complicated and occupies large area
Solution Approach 1:
The patent merges the facultative aerobic zone and aerobic zone into a single integrated membrane bioreactor system. The reactor contains both zones with different dissolved oxygen concentrations, eliminating the need for separate treatment systems and reducing overall complexity.
Solution Approach 2:
The patent creates different local zones within the same reactor based on dissolved oxygen concentration. The lower part has high dissolved oxygen (aerobic zone) while the upper part has low dissolved oxygen (facultative aerobic zone), allowing both zones to function simultaneously in a compact space.
3Reliability
If sludge is discharged to remove phosphorus, then phosphorus is removed from sewage treatment system, but the remaining sludge disposal becomes a difficult problem
Solution Approach 1:
The patent converts the harmful accumulation of sludge into a beneficial process by using anaerobic digestion to transform organic phosphorus in sludge into phosphine gas. This not only removes phosphorus but also stabilizes the sludge, turning a disposal problem into a resource recovery opportunity.
Solution Approach 2:
The patent introduces phosphine-reducing bacteria as intermediary organisms that facilitate the transformation of organic phosphorus to phosphine gas. These bacteria act as mediators between the sludge and the final phosphorus removal process, enabling phosphorus removal without sludge discharge.
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
Achieves effective phosphorus removal without sludge discharge, maintaining a dynamic equilibrium in the sludge population and achieving a 70% total phosphorus loss, while occupying a smaller area and simplifying maintenance.
Implementation Method 1
introducing sludge having a concentration of between 10,000 mg/L and 30,000 mg/L and having an organic loading of between 0.08 and 0.07 Kg (COD)/(Kg (MLSS) •d) into the membrane reactor so that phosphorus is absorbed in the aerobic zone, released in the facultative aerobic zone, and reduced by phosphine-reducing bacteria into phosphine
Implementation Method 2
phosphine-reducing bacteria in the sludge are filtered by a membrane material having a pore size of between 0.01 and 10 μm and retain in the membrane bioreactor
Implementation Method 3
aerating intensively the lower part of the membrane module while controlling dissolved oxygen concentration around the membrane module at more than 2 mg/L and dissolved oxygen concentration in the rest zone at less than 1 mg/L
Data Source
Figure 1
AI summary
A method for removing phosphorus having steps of a) providing a membrane bioreactor having a membrane module having a lower part; b) aerating intensively the lower part of the membrane module while controlling dissolved oxygen concentration around the membrane module at more than 2 mg/L and dissolved oxygen concentration in the rest zone at less than 1 mg/L so as to form an aerobic zone, a facultative aerobic zone, and an anaerobic zone; and c) introducing sludge having a concentration of between 10,000 mg/L and 30,000 mg/L and having an organic loading of between 0.08 and 0.07 Kg (COD)/(Kg (MLSS) •d) into the membrane reactor so that phosphorus is absorbed in the aerobic zone, released in the facultative aerobic zone, and reduced by phosphine-reducing bacteria into phosphine. The method for removing phosphorus does not include discharging sludge. An apparatus employed for the process does not take up much additional space.