Raw Water Treatment Bypass Control for Nitrogen and Phosphorus Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing raw water treatment methods combining biological treatment with membrane separation activated sludge treatment face challenges in suppressing the elution of nitrogen and phosphorus into treated water, particularly when treating wastewater with high nitrogen content, due to complex systems, instability in measurements, and increased operational management load.
Innovation Solution
A raw water treatment method and device that controls the flow rate of raw water bypassing the biological treatment tank and flowing into the activated sludge treatment tank based on nitrogen and phosphorus concentrations in treated water, with optional addition of nitrogen and phosphorus sources and inorganic coagulants to maintain optimal treatment conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a separate oxygen-free tank is provided to conduct denitrification treatment, then nitrogen fraction is reduced, but installation space increases and treatment system becomes more complex
Solution Approach 1:
The patent merges the denitrification function into the existing aerobic biological treatment tank by controlling dissolved oxygen concentration to fluctuate between 0.2-2.0 mg/L. This allows simultaneous occurrence of nitrification and denitrification processes in the same tank, eliminating the need for a separate oxygen-free denitrification tank and reducing system complexity while effectively reducing nitrogen fraction in treated water
2Measurement precision
If solid fraction in organic wastewater is large, then measurement stability deteriorates and precision is unattainable, but appropriate operational control is difficult to achieve
Solution Approach 1:
The patent changes the measurement parameter from total wastewater load to soluble BOD concentration specifically. By measuring only the soluble fraction rather than total BOD including suspended solids, the measurement stability and precision are significantly improved even when solid fraction is large, enabling appropriate operational control
3Quantity of substance
If high concentration wastewater is measured, then sensor maintenance and configuration requires considerable effort, but operational management load increases
Solution Approach 1:
The patent measures soluble BOD concentration rather than total BOD in high concentration wastewater. This parameter change reduces sensor fouling from suspended solids, decreasing maintenance frequency and operational management load while still providing sufficient information for treatment control
4Productivity
If sludge generated in latter-stage biological treatment tank is reduced, then BOD volume load is reduced, but nitrogen elutes into treated water causing nitrogen standard to be exceeded
Solution Approach 1:
The patent dynamically controls dissolved oxygen concentration to fluctuate between 0.2-2.0 mg/L rather than maintaining constant high levels. This dynamic control allows the system to adaptively balance BOD removal efficiency with nitrogen suppression, achieving both high productivity and low nitrogen elution through optimized aeration patterns
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
Effectively suppresses the elution of nitrogen and phosphorus into treated water by stabilizing the biological and activated sludge treatment processes, ensuring high-quality treated water output even with fluctuations in raw water composition.
Implementation Method 1
a biological treatment tank (10) containing a carrier (36) supporting an aerobic microorganism
Implementation Method 2
a membrane separation device (34) that subjects second treated water that has undergone biological treatment in the activated sludge treatment tank to a membrane treatment
Implementation Method 3
an activated sludge treatment tank (32) containing an activated sludge
Data Source
AI summary
A raw water treatment method includes: treating raw water using a raw water treatment device provided with a biological treatment tank that contains a carrier holding an aerobic microorganism, and a membrane separation active sludge treatment unit provided with an active sludge treatment tank into which first treated water biologically treated in the biological treatment tank flows, and which stores active sludge, and a membrane separation device that subjects second treated water biologically treated in the active sludge treatment tank to membrane treatment; and causing a portion of the raw water to flow into the active sludge treatment tank while bypassing the biological treatment tank.