Brine Waste Water Treatment via Membrane Segmentation and Crystallization
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Solution Overview
Problem
Existing brine waste water treatment processes in the coal chemical engineering industry face challenges such as high energy consumption, membrane contamination, poor stability of membrane units, and inability to achieve zero release of waste water, leading to inefficient salt recovery and high operational costs.
Innovation Solution
A method involving a two-stage reverse osmosis treatment process combining intermediate pressure reverse osmosis and high pressure reverse osmosis, followed by biochemical treatment using salt-tolerant microbial inoculum, and electrodialysis with circulating crystallization to recover high-purity salts, ensuring zero release of waste water and improving membrane stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If membrane separation techniques are used for brine waste water treatment, then water recovery efficiency is improved, but membrane contamination occurs leading to reduced service efficiency and service life
Solution Approach 1:
The patent applies preliminary action by implementing a multi-stage pretreatment process before membrane separation. This includes coagulation, flocculation, and sedimentation stages that remove suspended solids, organic matter, and nitrogenous contaminants beforehand. By performing these preparatory treatments, the patent prevents membrane contamination before it occurs, thereby extending membrane service life while maintaining high water recovery efficiency.
Solution Approach 2:
The patent segments the treatment process into multiple distinct stages: pretreatment (coagulation, flocculation, sedimentation), membrane separation (reverse osmosis, nanofiltration), and post-treatment. This segmentation allows each stage to be optimized independently, with pretreatment specifically designed to protect membranes from contamination while membrane separation focuses on water recovery, thus resolving the contradiction between productivity and reliability.
2Productivity
If thermal evaporation techniques are used for brine waste water treatment, then water recovery is achieved, but energy consumption is huge
Solution Approach 1:
The patent replaces the thermal evaporation process with membrane separation techniques (reverse osmosis and nanofiltration). Instead of using thermal energy to evaporate water, the patent uses mechanical pressure-driven membrane processes that operate at lower energy consumption levels while achieving the same water recovery objective. This substitution directly addresses the high energy consumption problem of thermal evaporation.
3Manufacturing precision
If multiple separation and purification methods are used to obtain high-purity single salts, then salt quality meets criteria for sale, but process complexity increases and cost rises
Solution Approach 1:
The patent applies local quality by using different membrane types (reverse osmosis membranes for general separation, nanofiltration membranes for specific ion rejection) at different stages of the process. Each membrane is selected for its specific separation characteristics suited to the local requirements of that treatment stage, achieving high-purity salt recovery without requiring an excessively complex multi-method process.
Solution Approach 2:
The patent changes operational parameters (pressure, flow rate, membrane selection) to optimize salt purification at each stage. By adjusting these parameters and selecting appropriate membranes for specific separation tasks, the patent achieves high-purity single salt recovery through a streamlined process rather than through increased process complexity.
4Productivity
If membrane units operate continuously for high productivity, then water treatment output increases, but membrane contamination accelerates reducing operational stability
Solution Approach 1:
The patent implements preliminary action through comprehensive pretreatment (coagulation, flocculation, sedimentation) that removes contaminants before they can reach and contaminate the membranes. This preventive approach allows membrane units to operate continuously at high productivity while maintaining stability, as the pretreatment barrier protects the membranes from degradation over time.
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 method achieves stable operation of membrane units for extended periods, reduces operational costs, and effectively recovers high-quality salts, realizing near-zero release of waste water while enhancing salt recovery efficiency.
Implementation Method 1
a reverse osmosis membrane separation process comprising the following steps: (1) pretreatment: the pretreatment includes softening, coagulation and sedimentation, rough filtration and ultrafiltration procedures, and the water outputted is treated by reverse osmosis treatment
Implementation Method 2
the water outputted from the biochemical treatment is treated by softening, coagulation and sedimentation, rough filtration and ultrafiltration treatment, and then is treated by electrodialysis
Implementation Method 3
the third concentrated water produced in the electrodialysis is treated by circulating crystallization
Data Source
AI summary
The present invention relates to a method for zero-release treatment of brine waste water, comprising: (1) pretreatment; (2) reverse osmosis treatment; (3) advanced oxidation treatment; (4) biochemical treatment; (5) electrodialysis concentration; (6) circulating crystallization. Compared with the prior art, the method for zero-release treatment of brine waste water provided in the present invention realizes zero release or near zero release of waste water, improves salt recovery efficiency, can recover high-quality sodium sulfate, mirabilite and sodium chloride, and turns crystalline salts into a resource; the membrane treatment unit can operates stably in the process for a long operation period at a low cost, and the entire process has high economic efficiency.