Continuous Flow Reactor for Nitrogen and Phosphorus Recovery

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Solution Overview

Problem

Conventional reactors for recycling nitrogen and phosphorus from wastewater using magnesium ammonium phosphate (MAP) crystallization face challenges such as complex processes, low treatment capacity, turbulence issues, and low recovery ratios, leading to inefficient treatment of high-concentration nitrogen and phosphorus wastewater.

Innovation Solution

A continuous flow reactor design featuring a cylindrical coagulation crystallizer, conical static settler, and wall-attached inclined plate settler, with a funnel type protective baffle and sawtooth slots to enhance coagulation and settling, along with pH regulation, to improve the recovery of nitrogen and phosphorus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional sequencing batch fluidized bed reactors are used for MAP crystallization, then nitrogen and phosphorus recovery is achieved, but the process becomes complex and treatment capacity is low

Engineering Contradiction:

Improvewastewater treatment capacityVSAvoidprocess complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The reactor is divided into distinct functional zones: a coagulation zone at the top where Mg2+ is added and mixing occurs, and a settling zone at the bottom where MAP crystals settle. This segmentation allows simultaneous coagulation and settling operations, improving treatment capacity while maintaining process simplicity through continuous flow operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coagulation zone is designed to perform preliminary mixing and crystal formation before the slurry enters the settling zone. Mg2+ is pre-added and mixed in the coagulation zone to form MAP crystals, which then settle in the dedicated settling zone, separating the coagulation and settling functions for more efficient continuous operation.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If high flow rate wastewater is used to improve treatment capacity, then productivity increases, but turbulence increases and adversely affects reaction effect

Engineering Contradiction:

Improvewastewater treatment capacityVSAvoidturbulence

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The reactor separates high-flow coagulation in the upper zone from settling in the lower zone. The coagulation zone can handle high flow rates with adequate mixing, while the settling zone operates at lower velocities to minimize turbulence and promote crystal settling, allowing the system to process high volumes without compromising reaction or settling efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The reactor uses vertical zonation to resolve the conflict between flow rate and turbulence. The coagulation zone handles high horizontal flow, while the settling zone uses vertical settling motion, effectively separating the dimensional requirements for high productivity from those requiring low turbulence.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If conventional top-in bottom-out or bottom-in top-out sequencing batch fluidized beds are used, then MAP crystallization occurs, but sludge-water separation is difficult and recycling purity is low

Engineering Contradiction:

ImproveMAP recycling purityVSAvoidslag-water separation difficulty

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The reactor clearly segments the coagulation and settling functions into separate zones. The settling zone at the bottom provides a dedicated area for sludge-water separation with a sludge discharge outlet, while the coagulation zone handles crystal formation. This segmentation improves MAP crystal purity by separating the crystallization process from the settling and discharge process, making sludge-water separation more effective.

Inventive Principle:

Principle #1Segmentation

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 reactor achieves a high recovery ratio of nitrogen and phosphorus, with concentrations reduced to below 200 mg/L, improving treatment efficiency and reducing turbulence-related issues, while maintaining stable pH for optimal MAP crystallization.

Implementation Method 1

cylindrical coagulation crystallizer

Methodology Applied

Scientific EffectCoagulation: Coagulation

Implementation Method 2

magnesium ammonium phosphate (MAP) crystallization

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 3

conical static settler, and wall-attached inclined plate settler, with a funnel type protective baffle for static settling

Methodology Applied

Scientific EffectSedimentation: Sedimentation

Data Source

PatentUS8702992B2Continuous flow reactor and method of using the same for treating nitrogen and phosphorus-containing wastewater

Publication Date: 2014.04.22 NANJING UNIV

AI summary

A continuous flow reactor, including a cylindrical coagulation crystallizer, a funnel type protective baffle for static settling, and a conical static settler. A lower end surface of the cylindrical coagulation crystallizer is connected with an upper end surface of the conical static settler, and the funnel type protective baffle for static settling is connected with an inner wall of the cylindrical coagulation crystallizer.