Single Reactor Wastewater Nutrient Removal via Electrochemical Control
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Solution Overview
Problem
Conventional wastewater treatment plants face challenges in efficiently removing carbon, phosphorus, and nitrogen nutrients from effluents in a single reactor, leading to environmental hazards due to eutrophication, and require costly infrastructure and energy for simultaneous nutrient removal.
Innovation Solution
A process using a single reactor with an aluminum anode and cathode, applying an electric current density of 15-20 A/m², intermittent ON/OFF electrical exposure, and maintaining an oxidation-reduction potential between -150 to +150 mV, creating anoxic and aerobic conditions to activate specific bacteria for substantial removal of carbon, nitrogen, and phosphorus, achieving high removal efficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional biological reactors are used to remove carbon, phosphorus and nitrogen, then nutrient removal is achieved, but multiple reactors or zones are required increasing device complexity and infrastructure costs
Solution Approach 1:
The patent combines multiple nutrient removal functions (carbon removal via aerobic oxidation, phosphorus removal via EBPR, and nitrogen removal via nitrification-denitrification) into a single reactor by applying electrochemical methods. Electric current is used to create alternating aerobic and anoxic zones within one reactor, enabling simultaneous C, P, and N removal without requiring multiple separate reactors or complex zoned configurations.
Solution Approach 2:
The patent changes the oxidation-reduction potential (ORP) parameter by applying electric current to transform the reactor environment. By controlling ORP fluctuations between aerobic and anoxic conditions through electrochemical reactions, the system enables different biological processes to occur sequentially or simultaneously within the same reactor space, resolving the contradiction between removal efficiency and reactor complexity.
2Reliability
If multiple biological reactors working at different operating conditions are used, then optimal removal of each individual nutrient is achieved, but energy consumption and infrastructure costs increase
Solution Approach 1:
The patent employs electrochemical reactions driven by electric current to automatically create the necessary aerobic and anoxic conditions for different nutrient removal processes. The electric field itself serves as the mechanism to generate oxygen demand variations and ORP fluctuations, eliminating the need for separate aeration systems, mechanical mixing devices, or complex control mechanisms that would consume additional energy in conventional multi-reactor systems.
Solution Approach 2:
By controlling the electric current density and ORP parameters, the system optimizes energy consumption. The electrochemical method allows precise control of redox conditions to match the specific needs of different nutrient removal processes, avoiding the energy waste associated with maintaining separate reactors at different operating conditions.
3Reliability
If carbon source is added into the anoxic reactor to sustain heterotrophic denitrifiers, then nitrogen removal is achieved, but operational costs increase
Solution Approach 1:
The patent uses the wastewater's own organic matter as the carbon source for denitrification. The electrochemical process stimulates endogenous respiration of microorganisms, releasing intracellular carbon compounds that serve as electron donors for heterotrophic denitrifiers. This eliminates the need to add external carbon sources, reducing operational costs while maintaining effective nitrogen removal.
Solution Approach 2:
The patent converts the typically harmful effect of endogenous respiration (which consumes organic matter and can lead to carbon loss) into a beneficial process. By controlling ORP and electrochemical conditions, the system channels the carbon released during endogenous decay directly to denitrification, transforming what would be a waste pathway into an efficient nitrogen removal mechanism without requiring external carbon addition.
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 over 97% removal of carbon, nitrogen, and phosphorus in a single reactor, enhancing nitrification potential by 50% through anammox activation, while reducing energy consumption and infrastructure costs, and improving sludge characteristics.
Implementation Method 1
N was transformed into nitrogen gas through electrically changing of the oxidation-reduction potential (ORP) between -150 to 150 mV to promote the simultaneous nitrification/denitrification processes in the reactor
Implementation Method 2
Carbon (C) removal through the oxidation of the organic materials by the microbial biomass
Implementation Method 3
Phosphorus (P) removal involves the recycling of biomass into anaerobic and aerobic zones in order to promote the accumulation of phosphate by micro-organisms in a process known as enhanced biological phosphorus removal (EBPR)
Data Source
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AI summary
There are provided processes for treating wastewater. The processes can comprise treating a mixture comprising the wastewater and an activated sludge, in a single reactor, with an electric current having a density of less than about 55 A/m2, by means of at least one anode and at least one cathode that define therebetween an electrical zone for treating the mixture; exposing the mixture to an intermittent ON/OFF electrical exposure mode to the electric current in which an OFF period of time is about 1 to about 10 times longer than an ON period of time; and maintaining an adequate oxidation-reduction potential in the single reactor. Such processes allow for substantial removal of carbon, nitrogen and phosphorus from the wastewater in the single reactor of various forms and for obtaining another mixture comprising a treated wastewater and solids.