Worm Control in Membrane Aerated Biofilm Reactors
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Solution Overview
Problem
Large populations of worms, such as nematodes, in membrane aerated biofilms can be detrimental to nitrifying biomass, leading to poor effluent quality due to their potential consumption of nitrifying bacteria or alteration of oxygen levels within the biofilm.
Innovation Solution
Temporarily discontinuing all oxygen sources to the biofilm reactor for periods ranging from 3 to 48 hours to reduce or prevent excessive worm populations, with longer durations being more effective in killing worms, and potentially using additional chemical agents to ensure complete removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen is continuously supplied to the biofilm reactor, then nitrifying biomass is maintained, but worm populations grow excessively and harm the biofilm
Solution Approach 1:
The patent implements periodic interruption of oxygen supply to the biofilm reactor. Oxygen is supplied for a first period to maintain nitrifying biomass, then interrupted for a second period to kill worms. This periodic cycling between oxygen supply and interruption resolves the contradiction by alternating between conditions favorable for nitrifiers and conditions lethal to worms.
2Object-affected harmful factors
If oxygen supply is interrupted to kill worms, then worm populations are reduced, but nitrifying biomass is compromised
Solution Approach 1:
The patent implements periodic interruption of oxygen supply to the biofilm reactor. Oxygen is supplied for a first period to maintain nitrifying biomass, then interrupted for a second period to kill worms. This periodic cycling between oxygen supply and interruption resolves the contradiction by alternating between conditions favorable for nitrifiers and conditions lethal to worms.
Solution Approach 2:
The patent applies preliminary action by maintaining nitrifying biomass under continuous oxygen supply before interrupting oxygen to kill worms. The nitrifiers are prepared and established in the biofilm while oxygen is available, so when oxygen is interrupted to kill worms, the nitrifying biomass is already in place and can recover quickly when oxygen is restored.
3Object-affected harmful factors
If worms are controlled through chemical agents, then worm populations are reduced, but system complexity and chemical usage increase
Solution Approach 1:
The patent applies self-service by using the oxygen supply system itself as the control mechanism for worms. Instead of introducing external chemical agents or additional equipment, the existing oxygen supply is periodically interrupted to create lethal conditions for worms. This resolves the contradiction by using the system's own resources to control worms without adding complexity.
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 method effectively controls worm populations, maintaining biofilm efficiency and improving effluent quality by ensuring sufficient nitrification and reducing total nitrogen concentrations in treated wastewater.
Implementation Method 1
supplies of oxygen to the biofilm, including oxygen dissolved in incoming water, are removed
Data Source
AI summary
An overgrowth of worms can reduce the effluent quality of a membrane aerated biofilm reactor. A method of controlling the growth of worms in a membrane aerated biofilm includes discontinuing all oxygen sources to a tank containing the biofilm and fluid flows flow into the tank. The tank is maintained in this idle condition for a period of time sufficient to kill at least some of the worms living in the biofilm. The method may be applied periodically to inhibit the formation of an excessive population of worms or retroactively to reduce an already excessive population of worms.