Violet Light Irradiation for Larval Settlement Prevention
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Solution Overview
Problem
In power plants using seawater as coolant, larvae of sessile invertebrates such as mussels and oysters settle inside intake and outfall structures, causing clogging and reducing cooling capacity, and existing methods like chlorine-based substances, photocatalysts, and laser beams are not entirely effective in preventing their settlement.
Innovation Solution
Irradiating light in the wavelength range of 400 to 440 nm, preferably using violet light, to cause larvae to close their shells and prevent swimming or crawling, which can be achieved using LED emitters, mercury lamps, or fluorescent tubes, without using laser beams or photocatalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chlorine-based substances are injected into the coolant to prevent settlement of marine invertebrates, then the settlement of larvae is reduced, but harmful effects on the marine environment and potential resistance development occur
Solution Approach 1:
The patent replaces chemical methods (chlorine-based substances) with a physical method (light irradiation in the blue-green spectrum range of 450-550 nm) to stop larval settlement. This substitution eliminates chemical harmful effects while maintaining effectiveness against sessile invertebrate larvae, including those resistant to chlorine.
2Reliability
If laser beams are used to prevent larval settlement, then settlement is effectively prevented, but the device complexity and cost increase
Solution Approach 1:
The patent replaces expensive, complex laser beam systems with inexpensive, readily available blue-green LED lights or other conventional light sources. These simpler light sources achieve the same larval stopping effect without requiring complex optical delivery systems, significantly reducing device complexity and cost.
3Area of stationary object
If broad-spectrum visible light is used to irradiate larvae, then coverage area increases, but energy consumption and loss increase
Solution Approach 1:
The patent applies the principle of local quality by using monochromatic or narrow-band light in the specific blue-green spectrum range (450-550 nm) that matches the absorption characteristics of larval photoreceptors. This targeted approach is more energy-efficient than broad-spectrum visible light, as it concentrates energy in the most effective wavelength range for stopping larval settlement.
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
Effectively prevents the settlement of mussel and oyster larvae by causing them to close their shells, thereby stopping them from swimming or crawling, with violet light showing higher transmittance and effectiveness in seawater, allowing for wider area coverage.
Implementation Method 1
irradiating light in a wavelength range including 400 to 550 nm, preferably 400 to 440 nm, to the larva in the settlement stage
Data Source
AI summary
The present invention provides methods of stopping a larva of a sessile invertebrate in a settlement stage from swimming or crawling in water, by means of irradiating violet light having a wavelength range of 400 to 550 nm to the larva in the settlement stage of the sessile invertebrate.