Anammox Reactor Stage in Flow Equalization Process

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Solution Overview

Problem

Existing wastewater treatment processes face challenges in managing variable pollutant concentrations, volumes, and temperatures, particularly in industrial and municipal sewage, due to limitations in carbon to nitrogen ratio control and inhibition of anaerobic ammonium oxidation (anammox) by dissolved oxygen concentrations above 0.2 mg/L.

Innovation Solution

A multi-stage activated sludge process incorporating a flow equalization reactor with divided treatment zones, where an outflow from the first zone is mixed with an overflow from a nitritation reactor and fed into an anammox reactor, maintaining low dissolved oxygen levels and recycling nitrite to control biomass retention times, thereby optimizing the growth of anaerobic autotrophic ammonia oxidizing bacteria for nitrogen gas conversion without supplemental carbon sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If dissolved oxygen concentrations are increased to support aerobic nitrification, then ammonia oxidation is improved, but anammox bacteria are inhibited because DO concentrations above 0.2 mg/L inhibit the anammox process

Engineering Contradiction:

Improveammonia oxidation efficiencyVSAvoiddissolved oxygen inhibition to anammox

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The treatment system is divided into separate aerobic nitrification zones and anoxic anammox zones, allowing independent control of dissolved oxygen concentrations in each zone. This segmentation enables high DO levels in nitrification zones to support ammonia oxidation while maintaining low DO levels in anammox zones to prevent bacterial inhibition.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different dissolved oxygen conditions are applied to different spatial locations within the treatment system. The aerobic zones maintain high DO concentrations for nitrification, while the anammox zones maintain low DO concentrations (<0.2 mg/L) to protect anammox bacteria, creating locally optimized conditions for each biological process.

Inventive Principle:

Principle #3Local quality

2Productivity

If traditional nitrification-denitrification processes are used for nitrogen removal, then nitrogen removal is achieved, but supplemental carbon sources and oxygen transfer are required increasing process complexity and cost

Engineering Contradiction:

Improvenitrogen removal efficiencyVSAvoidprocess requirements for oxygen transfer and carbon dosing

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The anammox process enables the system to self-supply the electron donor (ammonia) needed for denitrification, eliminating the need for external carbon source addition. The process uses ammonia itself as the substrate for both nitrification and anammox reactions, reducing external chemical inputs and simplifying process operations.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system changes the operational parameters from traditional nitrification-denitrification to an anammox-based process, operating at lower dissolved oxygen concentrations and different temperature ranges optimized for anammox bacteria. This parameter change eliminates the need for supplemental carbon dosing and reduces oxygen transfer requirements.

Inventive Principle:

Principle #35Parameter changes

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 process significantly reduces oxygen transfer requirements and eliminates the need for supplemental carbon dosages, enhancing nitrogen removal efficiency and operational cost-effectiveness by maintaining low dissolved oxygen levels and optimizing biomass retention times in the anammox reactor.

Implementation Method 1

Bacteria mediating the direct conversion of nitrite and ammonium into nitrogen gas by the anaerobic ammonium oxidation (anammox) process

Methodology Applied

Scientific EffectAnaerobic ammonium oxidation (anammox):

Implementation Method 2

mixing a bypass flow Q1 from the flow equalization reactor and an overflow from the nitritation reactor to obtain a mixed liquor flow

Methodology Applied

Scientific EffectFluid mixing:

Implementation Method 3

receiving a wastewater inflow or a sewage inflow in a flow equalization reactor

Methodology Applied

Scientific EffectFlow equalization:

Data Source

PatentUS9567248B2Anammox reactor stage in a flow equalization reactor process

Publication Date: 2017.02.14 REID JOHN H

AI summary

A flow equalization reactor for a multi-stage activated sludge process for treating industrial wastewater and/or municipal sewage is divided into two or more treatment zones. An outflow from a first treatment zone is mixed with an outflow from the second treatment zone in a mixer and conveyed to a third stage reactor containing anaerobic, autotrophic ammonia oxidizing anammox bacteria for converting nitrite nitrogen to nitrogen gas. The relative amounts of the outflows from the first and second treatment zones are controlled to promote and optimize the growth and accumulation of the anammox biomass in the third stage reactor.