Biological Phosphorus Removal via Pneumatic Sludge Recirculation
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Solution Overview
Problem
Existing wastewater treatment methods using activated sludge are inefficient in removing phosphorus and require significant space and energy, limiting their application in large-scale wastewater treatment plants.
Innovation Solution
Incorporating a separate tank for biological phosphorus elimination (P tank) hydraulically connected to the activated sludge tank, where thickened sludge from sedimentation tanks is introduced to mix with wastewater, allowing for phased operation and efficient phosphorus removal, utilizing compressed air for recirculation and mixing, and constructing the P tank as a circulation tank for enhanced mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate tank for biological phosphorus elimination is incorporated, then phosphorus removal efficiency is improved, but device complexity increases
Solution Approach 1:
The P tank is hydraulically connected to the B tank through openings, allowing the two tanks to function as an integrated system. The activated sludge flows from the B tank to the P tank and returns to the B tank, merging the phosphorus elimination function with the existing activated sludge process without requiring complete system redesign.
Solution Approach 2:
The P tank serves multiple functions: it acts as a phosphorus elimination reactor, a mixing tank for sludge and wastewater, and a recirculation chamber. By performing multiple functions in a single tank, the system achieves phosphorus removal without proportionally increasing device complexity.
2Reliability
If thickened sludge is recirculated from SU tanks to P tank, then phosphorus removal is enhanced, but energy consumption increases
Solution Approach 1:
Compressed air is introduced into the P tank to create hydraulic flow that recirculates the thickened sludge from the SU tanks back to the B tank. This pneumatic-hydraulic system replaces energy-intensive mechanical pumps, reducing overall energy consumption while maintaining effective sludge recirculation for phosphorus removal.
Solution Approach 2:
The system uses the own compressed air supply (already available for aeration in the B tank) to drive the sludge recirculation process in the P tank. The aeration system serves dual purposes: providing oxygen for biological processes and creating hydraulic flow for sludge recirculation, thereby eliminating additional energy requirements.
3Reliability
If the P tank volume is permanently mixed, then phosphorus elimination efficiency is improved, but energy consumption increases
Solution Approach 1:
Compressed air is used to create hydraulic flow and mixing within the P tank volume. The air bubbles rising through the tank create sufficient turbulence and circulation to achieve permanent mixing of the sludge and wastewater, eliminating the need for separate mechanical mixers and reducing energy consumption.
4Ease of operation
If the P tank is constructed as a circulation tank, then mixing efficiency is improved, but construction costs increase
Solution Approach 1:
The circulation tank design utilizes compressed air to create hydraulic circulation patterns that achieve thorough mixing. This approach replaces complex mechanical mixing equipment with a simpler pneumatic-hydraulic system, reducing construction and equipment costs while maintaining high mixing efficiency for effective phosphorus elimination.
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 achieves effective phosphorus removal with reduced energy consumption and costs, maintaining a balanced water level, and increasing the dry concentration of activated sludge, making it suitable for large-scale wastewater treatment plants with minimal additional construction costs.
Implementation Method 1
the volume of the P tank is mixed permanently or intermittently
Implementation Method 2
utilizing compressed air for recirculation and mixing
Implementation Method 3
the P tank is hydraulically connected with the B tank via one or more openings
Implementation Method 4
in the V phase the activated sludge is sedimented
Implementation Method 5
utilizing compressed air for recirculation and mixing, and constructing the P tank as a circulation tank
Data Source
AI summary
The invention relates to a method for carrying out biological purification of wastewater with the aid of activated sludge, in which the wastewater is introduced into an activated sludge tank (B tank) and then, in alternation, into one of a number of sedimentation and recirculation tanks (SU tanks) continuously connected hydraulically to the B tank and in which a number of operating cycles are carried out, including a sludge return phase, a mixing phase, a sedimentation phase and a draw-off phase (S phase, U phase, V phase, and A phase respectively), wherein the method further includes elimination of phosphor by using a tank for biological phosphor elimination (P tank), wherein the P tank is hydraulically connected with the B tank via one or more openings, wherein the wastewater is first introduced into the P tank and then subsequently transferred into the B tank, wherein in the S phase at least part of the thickened activated sludge is introduced from the SU tank into the P tank, and, wherein the volume of the P tank is mixed permanently or intermittently.