Chemical Drying of Struvite Using Calcium Oxide
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Solution Overview
Problem
Conventional methods for producing dry struvite from wastewater treatment effluents require energy-intensive heat treatment to remove associated free water, making them costly and inefficient.
Innovation Solution
A method involving the combination of a material with associated free water, a magnesium source, and a phosphate source, along with ammonium and/or potassium ions, to chemically react and produce struvite, thereby removing free water without heating, resulting in a substantially dry product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If heat treatment is used to remove free water from wet struvite, then the struvite can be dried and made suitable for handling and transport, but the process becomes energy consumptive and costly
Solution Approach 1:
The invention changes the drying mechanism from thermal evaporation to chemical absorption. By adjusting the chemical parameters (adding calcium oxide or calcium hydroxide) and changing the physical state of water from free water to chemically bound water in the form of calcium hydroxide, the process achieves drying without energy-intensive heating
Solution Approach 2:
The invention replaces the thermal field (heat treatment) with a chemical field (chemical reaction). Instead of using thermal energy to evaporate water, the process uses chemical reaction between calcium oxide/hydroxide and water to produce calcium hydroxide, thereby substituting a mechanical/thermal system with a chemical system
2Quantity of substance
If conventional heat treatment drying is used, then free water can be removed from struvite, but the process becomes costly and inefficient
Solution Approach 1:
The invention enables the struvite material to dry itself through a chemical reaction that occurs at ambient conditions. The calcium oxide or calcium hydroxide added to the mixture reacts with free water to form calcium hydroxide, allowing the material to remove its own free water without requiring external energy input or complex drying equipment
Solution Approach 2:
The invention performs preliminary chemical preparation by adding calcium oxide or calcium hydroxide to the wet struvite mixture before any drying step. This preliminary chemical action creates the conditions for spontaneous water absorption, eliminating the need for subsequent energy-intensive drying operations
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 method effectively reduces the water content in struvite from 10-90% to less than 5% by weight, producing a dry struvite product suitable for use as a fertilizer, while avoiding the energy costs and environmental impact of heat treatment.
Implementation Method 1
combining a material having associated free water with a magnesium source and a phosphate source in quantities sufficient to consume the associated free water to produce struvite
Data Source
AI summary
Methods and compositions for chemical drying and for producing struvite.