Hydrocyclone Crystal Separation for Sludge Phosphorus Recovery
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Solution Overview
Problem
Current methods for treating anaerobically digested sludge result in high nitrogen and phosphorus concentrations in wastewater, leading to pipe blockages and inefficient phosphorus recovery, with existing techniques focusing on phosphorus removal rather than recovery and often producing impure MAP crystals.
Innovation Solution
A crystal separation apparatus using a hydrocyclone and crystallization reactor to separate and recover MAP crystals from sludge, with a return pipe system to maintain crystal concentration and prevent blockages, and a screen residue removal process to enhance purity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If digested sludge is transported through sewers to collective treatment facilities, then treatment efficiency and scale economy are improved, but pipe blockages occur due to MAP precipitation
Solution Approach 1:
The patent applies preliminary action by precipitating MAP crystals from digested sludge before transportation through sewers. The crystallization reactor converts dissolved phosphorus into solid MAP crystals that can be easily separated and removed, preventing blockages during subsequent sewer transportation while maintaining treatment efficiency.
Solution Approach 2:
The patent extracts the harmful MAP crystals from the sludge stream using a hydrocyclone separator. The hydrocyclone separates the heavy MAP crystals from the lighter sludge liquid, allowing the crystals to be removed before sewer transportation, thus eliminating the blockage problem while preserving the beneficial phosphorus recovery.
2Reliability
If phosphorus is removed from sludge to prevent blockages, then pipe flow is maintained, but phosphorus recovery is inefficient
Solution Approach 1:
The patent converts the harmful effect of MAP precipitation (which causes blockages) into a beneficial process by controlling the crystallization to occur in a reactor before sewer discharge. The same MAP that would cause blockages is now systematically precipitated and recovered as a useful phosphorus product, transforming a problem into a solution.
Solution Approach 2:
The patent introduces a crystallization reactor as an intermediary device between sludge production and sewer transportation. This intermediary facility controls the MAP precipitation process, allowing phosphorus recovery while preventing blockages in the sewer system, thus mediating between the conflicting requirements of phosphorus removal and recovery.
3Quantity of substance
If conventional aeration treatment is used to generate MAP, then phosphorus concentration decreases, but MAP purity is low and recovery is impure
Solution Approach 1:
The patent applies parameter changes by controlling the crystallization conditions in the reactor, including pH, temperature, and chemical additives. By optimizing these parameters, the patent achieves high-purity MAP crystal formation while maintaining effective phosphorus removal, overcoming the limitation of conventional aeration treatment.
Solution Approach 2:
The patent replaces conventional mechanical aeration treatment with a chemical crystallization process. Instead of relying solely on biological aeration, the system uses controlled chemical precipitation to form pure MAP crystals, which are then easily separated by the hydrocyclone, achieving both high phosphorus removal and high crystal purity.
4Productivity
If hydrocyclone is used to separate MAP crystals, then separation efficiency is improved, but blockages occur when crystal concentration is high
Solution Approach 1:
The patent implements feedback control by monitoring the concentration of MAP crystals in the hydrocyclone inlet and adjusting the process parameters accordingly. When crystal concentration becomes too high and poses a blockage risk, the system reduces the feed rate or adjusts crystallization conditions to maintain optimal separation efficiency while preventing hydrocyclone blockages.
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
The apparatus achieves high-purity MAP recovery, prevents hydrocyclone blockages, and maintains stable treatment processes, effectively reducing phosphorus load in wastewater and enabling efficient phosphorus recovery.
Implementation Method 1
a hydrocyclone for separating the crystals from the sludge or separated water introduced into the hydrocyclone
Implementation Method 2
a crystallization reactor for precipitating the crystals by adding a chemical to the sludge or separated water
Data Source
AI summary
In a system for separating crystals from sludge, or from separated water generated when sludge is subjected to a concentration process or a dewatering process, aspects of both phosphorus removal and phosphorus recovery can be satisfied, MAP having a high degree of purity can be recovered, and stable treatment can be performed such that the MAP recovery rate is high and blockages of a hydrocyclone do not occur. An aspect of the present invention is a crystal separation apparatus for separating crystals from sludge, or from separated water generated when sludge is subjected to a concentration process or a dewatering process, comprising a hydrocyclone for separating the crystals from the sludge or separated water introduced into the hydrocyclone, and a return pipe A for returning the sludge or separated water which flows out from an overflow riser of the hydrocyclone to a sludge or separated water introduction portion of the hydrocyclone.