Effluent Phosphorus Removal via pH Adjustment and Filtration
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Solution Overview
Problem
Current methods for reducing phosphorus in effluents from chemical pulping processes, especially those involving acidic stages, are costly and operationally complex, such as tertiary treatment and the use of phosphorus-concentrating microorganisms, which are not effective in acidic conditions.
Innovation Solution
A method involving obtaining two portions of effluent or filtrate from acidic stages, adjusting the pH of one portion to alkaline using an alkaline agent, precipitating phosphorus as a phosphate salt, and separating it through filtration, then combining the purified effluent with the second portion, which can be done using various filtration methods including liquid-solid filtration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tertiary treatment or phosphorus-concentrating microorganisms are used to reduce phosphorus in effluent, then phosphorus removal effectiveness is improved, but investment cost and operating cost increase significantly
Solution Approach 1:
The invention changes the pH parameter of the effluent from acidic to alkaline by adding an alkaline agent. This parameter change causes phosphorus to precipitate as calcium phosphate, enabling effective phosphorus removal without requiring expensive tertiary treatment facilities or specialized microorganisms. The method achieves reliable phosphorus removal through a simple pH adjustment and precipitation process.
2Reliability
If phosphorus-concentrating microorganisms are used in anaerobic media to remove phosphorus, then phosphorus removal is achieved, but operational complexity increases and specific treatments are required
Solution Approach 1:
The invention replaces the complex biological system involving phosphorus-concentrating microorganisms operating in anaerobic media with a simple chemical precipitation process. By adding an alkaline agent to adjust pH and causing calcium phosphate precipitation, the method achieves phosphorus removal through straightforward chemical reactions rather than complex biological operations, significantly reducing operational complexity.
3Reliability
If phosphorus is precipitated and separated by filtration, then phosphorus content in effluent is reduced, but additional treatment steps and equipment are required
Solution Approach 1:
The invention merges the phosphorus removal process with the existing effluent treatment workflow. The pH adjustment and precipitation steps are integrated into the current treatment train, and the precipitated phosphorus is separated using existing filtration equipment. This combining approach achieves effective phosphorus content reduction without requiring entirely new treatment steps or specialized equipment, minimizing additional device complexity.
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 significantly reduces phosphorus content in effluents, is cost-effective with minimal equipment investment, and allows for efficient phosphorus precipitation even with small volumes of the first portion, suitable for integration into chemical pulping mill operations.
Implementation Method 1
adjusting pH of the first portion of the effluent or filtrate to alkaline with an alkaline agent
Implementation Method 2
allowing phosphorus to be precipitated in form of a phosphate salt
Implementation Method 3
separating the precipitate by filtration to produce purified effluent or filtrate
Data Source
Figure 1a~1h
Figure 2
AI summary
The invention relates to a method for reducing phosphorus in effluent or filtrate from a process which comprises at least one stage in which conditions are acidic, wherein the method comprises the steps of: a) obtaining a first portion of an effluent or filtrate from a stage in which conditions are acidic; b) obtaining a second portion of an effluent or filtrate from the same or different stage in which conditions are acidic; c) adjusting pH of the first portion of the effluent or filtrate to alkaline with an alkaline agent; d) allowing phosphorus to be precipitated in form of a phosphate salt; e) separating the precipitate by filtration to produce purified effluent or filtrate; and f) combining the purified effluent or filtrate with the second portion of the effluent or filtrate. The process may be a chemical pulping process in which pulp is cooked in a digestion apparatus (1), washed in a washing apparatus (2), bleached in a bleaching apparatus (3) in which an acidic bleaching stage (3') takes place, after which the pulp is separated in a separation apparatus (4) from an acidic effluent or filtrate which is divided into the first and second portions of effluent or filtrate. The invention also relates to the corresponding chemical pulping and purification apparatus.