Effluent Phosphorus Removal via pH Adjustment and Centrifugal Separation
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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 the separation of effluents into acidic and alkaline portions, adjusting the pH of the acidic portion to alkaline using an alkaline agent, precipitating phosphorus as a phosphate salt, and using centrifugal forces to separate the precipitate, thereby reducing phosphorus content in the effluent.
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 conditions. By adjusting pH above 9 using alkaline substances, phosphorus precipitates as calcium phosphate, enabling effective phosphorus removal without requiring expensive tertiary treatment facilities or specialized microorganisms.
Solution Approach 2:
The invention uses inexpensive alkaline substances (such as calcium oxide, calcium hydroxide, or sodium hydroxide) to adjust pH and precipitate phosphorus. These are cheap, readily available materials that replace expensive specialized treatment systems, achieving cost-effective phosphorus removal.
2Reliability
If phosphorus-concentrating microorganisms are used in anaerobic media to reduce phosphorus, then phosphorus removal is achieved, but operational complexity increases and specific treatments are required
Solution Approach 1:
The invention replaces complex biological systems (anaerobic microorganisms requiring controlled environments) with a simple chemical precipitation process. By adding alkaline substances to adjust pH, phosphorus precipitates automatically, eliminating the need for complex anaerobic digestion systems and specialized operational procedures.
Solution Approach 2:
The effluent system itself provides the phosphorus removal function through natural chemical precipitation when pH is adjusted. The calcium and phosphorus already present in the effluent combine to form precipitate, eliminating the need for external specialized treatment systems or microorganisms.
3Reliability
If pH is adjusted to alkaline conditions to precipitate phosphorus, then phosphorus removal effectiveness is improved, but energy consumption and operational simplicity may be affected
Solution Approach 1:
The invention uses cheap, readily available alkaline substances (calcium oxide, calcium hydroxide, sodium hydroxide) to adjust pH. These inexpensive materials can be added directly to effluent streams without requiring complex energy-intensive processing systems, achieving cost-effective phosphorus precipitation.
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 the recovery and reprocessing of the phosphorus precipitate, 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 using centrifugal forces 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 using centrifugal forces the precipitate 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.