Sequential Biological Reactor Nitrogen Removal
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Solution Overview
Problem
Processing nitrogen-concentrated effluents poses challenges due to high ammonium concentrations, which can cause environmental damage and require costly revamping of treatment facilities, and existing methods struggle with optimizing nitrite production and reduction reactions in variable flow rate and concentration conditions, especially in anaerobic digester supernatants, gas processing condensates, and landfill leachates.
Innovation Solution
A method utilizing a sequential biological reactor (SBR) with fractionated feed, aeration, and anoxia phases, adjusted by real-time measurements to optimize nitrite production and denitrification, involving the evaluation of nitrogenous feed and minimum liquid volume to inhibit nitrating bacteria and promote nitrite-producing biomass, while controlling aeration and pH to maintain efficient nitrogen removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional nitrification/denitrification is used to process nitrogen-concentrated effluents, then nitrogen removal is achieved, but oxygen inputs and biodegradable carbon inputs are excessively high
Solution Approach 1:
The nitrification process is segmented into two distinct stages: first, ammonium is oxidized to nitrites by ammonium-oxidizing bacteria (AOB) under controlled aeration; second, nitrites are denitrified to nitrogen gas in an anoxic phase. This segmentation allows the system to bypass complete nitrification to nitrates, reducing oxygen consumption by approximately 25% compared to conventional processes while maintaining effective nitrogen removal.
2Quantity of substance
If conventional nitrification/denitrification is used to process nitrogen-concentrated effluents, then nitrogen removal is achieved, but biodegradable carbon inputs and heterotrophic sludge production are excessively high
Solution Approach 1:
The process extracts and removes nitrites from the system before they can be fully nitrified to nitrates. By stopping nitrification at the nitrite stage and immediately transitioning to an anoxic denitrification phase, the system eliminates the need for large amounts of biodegradable carbon that would otherwise be required for complete denitrification, reducing carbon input by approximately 40% and associated heterotrophic sludge production.
3Productivity
If the inflow volume is poured into the reactor in a single batch, then processing efficiency is high, but ammonium concentration inhibits nitriting bacteria
Solution Approach 1:
The influent flow is segmented and introduced into the reactor in multiple controlled portions rather than as a single batch. This segmentation dilutes the ammonium concentration in each portion, preventing inhibition of nitriting bacteria while maintaining continuous processing efficiency. The reactor receives incremental feeds that allow biological processes to proceed without being overwhelmed by toxic ammonium levels.
4Quantity of substance
If ammonium concentration in effluent is high, then nitrogen removal is necessary, but it causes environmental damage and requires costly infrastructure upgrades
Solution Approach 1:
The process changes key operational parameters including dissolved oxygen concentration (maintained at low levels during aeration), pH control, and aeration duration to optimize the nitrite shunt pathway. By carefully controlling these parameters, the system achieves effective nitrogen removal from high-ammonium effluents using existing infrastructure, avoiding the need for costly revamping while meeting stringent discharge limits.
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 approach allows for high ammonium conversion rates, reduced oxygen and carbon inputs, self-regulation of pH, and optimized anoxia phase management, resulting in efficient nitrogen removal with significant cost savings and improved reliability in processing nitrogen-concentrated effluents.
Implementation Method 1
the ammonium is oxidized in two steps in aerated conditions, first to nitrites
Implementation Method 2
then to nitrates
Implementation Method 3
is finally reduced to nitrogen gas in anoxic conditions
Data Source
AI summary
The invention relates to a method for processing nitrogen-concentrated effluents by ammonia oxidation into nitrites followed by nitrite denitritation in a gaseous nitrogen in a sequential biological reactor (1) consisting in pouring a processable effluent volume in to the reactor by successive volume fractions, in dividing the entire processing cycle into successive sub cycles, wherein each sub-cycle comprises a feeding phase, an aeration phase for nitrification and an anoxia phase along which a carbon-containing source is introduced into the reactor for converting nitrites into nitrogen. The inventive method also consists in evaluating a nitrogenous volume charge in the effluent to be processed, mainly by measuring the effluent conductivity (X) and the flow rate (Q) and in determining the number of feeding phases of the entire cycle according to nitrogenous charge and to a minimum volume of liquid in the reactor in such a way that an injected nitrogen concentration is diluted in the liquid volume, wherein the volume phase nitrogenous charge is however sufficient for producing a single shot or peak of the ammonia charge favourable for a nitrating biomass formation in the reactor.