Two-Stage MAP Crystal Recovery via Aerobic-Anaerobic Segmentation
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Solution Overview
Problem
Current methods for recovering magnesium ammonium phosphate (MAP) from sludge have limitations in achieving a high phosphorus recovery rate, particularly in efficiently precipitating and separating MAP crystals from sludge, as they often rely on anaerobic treatment and pH increase methods that are not optimized for maximum crystal formation and separation.
Innovation Solution
A two-stage process utilizing a first reaction tank with an aerobic environment and a second reaction tank with an anaerobic environment, where sludge is recirculated to facilitate phosphorus redissolution and crystal growth, using aeration and magnesium chloride to enhance MAP crystal formation and separation, with a conical design and aerator devices to grade crystal size and facilitate extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If anaerobic treatment and pH increase methods are used to precipitate MAP crystals, then phosphorus recovery is achieved, but the phosphorus recovery rate is limited and crystal separation is inefficient
Solution Approach 1:
The process is divided into two distinct reaction stages: an aerobic first reaction tank for initial MAP crystal formation, and an anaerobic second reaction tank for phosphorus redissolution and further crystal growth. This segmentation allows each stage to be optimized for its specific function, improving overall recovery rate and crystal quality for separation
Solution Approach 2:
The patent changes the environmental parameters (aerobic/anaerobic conditions, pH levels) between the two reaction tanks to optimize MAP crystal formation and growth. The first tank operates under aerobic conditions with pH control for initial precipitation, while the second tank uses anaerobic conditions for phosphorus release and subsequent crystal growth, thereby improving both recovery rate and separability
2Reliability
If standard separation techniques are used for MAP crystals, then separation is possible, but macrocrystals are difficult to separate from sludge
Solution Approach 1:
The first reaction tank performs preliminary MAP crystal formation under aerobic conditions before the sludge enters the second reaction tank. This preliminary action creates initial crystal nuclei that will grow into larger, more separable macrocrystals during the anaerobic phase, making subsequent separation more effective
Solution Approach 2:
The patent employs periodic alternation between aerobic and anaerobic conditions in the two-stage process. This periodic action promotes repeated cycles of crystal formation and growth, resulting in larger macrocrystals that are more easily separated from sludge using standard techniques
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 significantly increases the phosphorus recovery rate by promoting further MAP crystal formation and growth, allowing for effective separation of macrocrystals from sludge, which are difficult to separate using standard techniques, thereby improving the overall efficiency of phosphorus recovery.
Implementation Method 1
an aerobic environment prevails and in which the sludge is guided in a cycle supported by aeration
Implementation Method 2
to increase its pH value by CO2 stripping
Implementation Method 3
magnesium ammonium phosphate crystals (MAP crystals) precipitated from the sludge
Implementation Method 4
heavy MAP particles are passed into a lower funnel of the device and extracted from there
Data Source
AI summary
The invention relates to a method and an assembly for recovering magnesium ammonium phosphate from slurry supplied to a reaction container (10) in which an aerobic milieu that is alkaline as a result of CO2-stripping is present and in which the slurry is guided in a circuit with the aid of ventilation. Cationic magnesium, such as magnesium chloride, is added to the slurry, and magnesium ammonium phosphate crystals which are crystallized out of the slurry are removed via a removal device (30) provided in the base region of the reaction container. The slurry is supplied from the first reaction container (10) to a second reaction container (12) via a first line (14), wherein an anaerobic milieu is set in the second reaction container in order to redissolve the phosphate, and MAP crystals crystallized in the second reaction container are supplied to the first reaction container.