Effect of Ultrasound on Algae

Published on by in Technology

How exactly does ultrasound affect the algae in lakes?

What happens to algae on the molecular level?

Which frequencies are used and how do they affect the aquatic life and other microorganisms?

 

Taxonomy

11 Answers

  1. Excessive algae is a symptom of imbalance in the lake's eco-system; typically low D.O. levels. When we treat a symptom, it tends to relieve the visible problem and if that's your goal then that's great. Unfortunately, dead algae cells precipitate to the benthic zone where vertebrates and invertebrates can feed on them. Unfortunately, nature's clean-up organisms (aerobic bacteria) also begin to metabolise the biomass but to do this, they need lost of D.O. As a result of this demand, the D.O. is stripped from the lake and anaerobic bacteria take over resulting in their noxious by-products.

    Killing the algae does not get to the root cause which is low D.O. levels in the water.

  2. Within a body of water, physicochemical parameters, water ow, and microorganisms present can differ. The type of algae can vary and even change during the season. To use ultrasonic waves effectively, it is important that specific ultrasonic frequencies be used. LG Sonic uses scientifically proven ultrasonic frequencies to control many types of algae. The size of an algae cell, its morphology, and the general water quality determine the frequency necessary to control algae. It is therefore very important to monitor the water quality (Chlorophyll a, Phycocyanin, Turbidity, DO, pH, Redox, temp) to predict an algal bloom and to identify what kind of algae is growing and effectively base the ultrasonic treatment on that.

    The MPC-Buoy provides a complete overview of the water quality by collecting the following parameters every 10 minutes: Chlorophyll α (green algae), Phycocyanin (blue-green algae), pH, Turbidity, Dissolved Oxygen, and Temperature. The collected data is delivered in real time via radio, GPRS, or 3G to a web-based software platform. Based on a developed algorithm, LG Sonic is able to modify the ultrasonic program to the specific water conditions and predict an algal bloom a few days ahead. Depending on the information received, the ultrasonic program can be modi ed to address the water conditions and type of algae present. In this way, it is possible to eliminate existing algae and prevent the growth of new algae. Each MPC-Buoy system can control algae in areas up to 500m/1600ft in diameter.

    The ultrasonic sound waves create an ultrasonic pressure in the top layer of the water. This ultrasonic sound barrier prevents the algae from rising to the surface and absorbing light for photosynthesis. Therefore, algae are no longer capable of growing further. The algae will die while the cell wall remains intact, preventing the release of toxins from the algae into the water. The algae will sink to the bottom of the water reservoir, where it is degraded by the bacteria present.

    The University of Portsmouth, UK; UNICET Catania, Italy; and BOKU, Austria found that LG Sonic units are safe for fish. LG Sonic devices have been tested to determine their effect on zooplankton, and no negative effect was found.

  3. In May 2016, we introduced our ultrasonic algae control device called a Quattro-DB and branded as Hydro BioScience, Eco Driven Solutions.  It is currently patent pending.  It has two frequency bandwidths.  The lower bandwidth is from 24 to 58 kilohertz and it produces 1565 frequencies there.  The upper bandwidth is from 195 to 205 kHz with 17 frequencies.  The upper target is blue-green algae and was chosen based on research done at that frequency range for effectiveness on Microcystis, a troublesome species that shuts down many lakes worldwide.  In the lower bandwidth, used by most companies in our industry, the primary target is green algae and diatoms where an internal cell wall (plasmalemma) is caused to tear from a contractile vacuole (think pump) and this disables the algae by disrupting internal fluid flow.  Most blue-greens have gas vesicles (hundreds per cell) that are a protein layer thick and provide buoyancy.  The cells have a density very close to that of water and daily photosynthesis provides hydrocarbon ballast that allow these algae to sink to the bottom where phosphates and other nutrients are higher in concentration.  Cell division is usually done during this cycle as well.  In about three days, gas from the vesicles diffuses through the outer cell wall and the cell becomes permanently heavier than water, sinking to the bottom where insufficient light will finally cause it to die.  The outer cell wall is NOT RUPTURED as has been incorrectly reported.  Our device does not create cavitation and was specifically designed not to do so for safety reasons.  Some devices do create a small amount of cavitation, but the effect does not go beyond a few inches from the device.

    The Quattro-DB has two piezos for generating sound and each emits sound in two directions.  They are arranged at right angles to each other to cause sound output in four directions simultaneously.  Sound output is 0.4 seconds on and 0.6 seconds off with the maximum instantaneous power at 50 watts.  On average, our device uses a meager 12.5 watts.  Most people think that wattage is important when selecting a device.  It is not.  What is important is choosing the correct piezo material and dimensions for the application and providing head and tail masses to it to spread out its effective operating range.  Our piezo was strategically selected to operate in two very different ranges as mentioned above.  In the name, Quattro is for four way output and DB is for dual bandwidth.

    With four way output and generating about 185 dB sound level across our operating range, our device has a green algae radial control range of 150 meters range (17.5 acre) and 400 meter range for blue-green algae with gas vesicles (120 acres).

    The device does not kill bacteria, but can cause anaerobic bacteria to suspend colonization close to the device.  This is attributed to creating a sound vibration that to these type of bacteria resembles water turbulence where they cannot effectively create a colonial biofilm layer.  This is effectively used in water treatment facilities to reduce bacterial growth on walls and reduces Chlorine consumption and disinfection by-product generation of THM's (trihalo methanes) and HAA's (halo acetic acids) which are carcinogens and regulated by the EPA.

    The technology works via a phenomenon called critical structural resonance, much like what happens when a crystal glass breaks due to response to its on natural vibrating frequency.

    Most algae problems occur due to high nutrient levels, primarily phosphate.  Our general recommendation is to find the source of the nutrients and stop them from entering your water system if possible.  In natural systems, we recommend beneficial bacteria and aeration along with ultrasound to create a healthy water body.  We generally refer to this technique as The Water Trifecta®.

    Ultrasound is safe for fish.  In hatcheries of catfish and trout, we have reports that turning the ultrasound off during feeding cycles improves the food intake and growth of the fish.  Catfish have been found to grow faster with ultrasound present and also off-flavor (musty taste in the fish from algae) has been effectively reduced thus increasing the marketability of the fish.

    Hopefully this helps clear up how the device operates. 
    George Hutchinson, President AlgaeControl.US LLC,
    email: george@algaecontrol.us

  4. Why not harvest algae through rotating algae biofilm reactor (RABR) and convert it to BIo-fuel.

  5. Laurence Hutchinson. I agree fully.

    Excessive algae is a symptom of biological imbalance in the water body normally resulting from one or all of the following; low D.O. levels, excessive nutrients, thermal stratification and warm waters.

    Killing the algae with ultrsound is simply treating a symptom. Imagine a hole in the roof and it rains. Symptom is a wet floor. Put a bucket/container to catch the drips and you've treated the symptom but the cause still remains.

    Best solution is to solve the causal issues leading to the symptoms...

    Mix the water, add oxygen, oxidise excess nutrients and provide sufficient D.O. throughout the water column to allow the eco-system to balance itself.

  8. Sonochemists have studied from 20 kHz to 2mhz.

    At very low freq. Effect from stress response on inhibitory messenger molecule algal releases.

    At higher freq.effects from cavitation and cell lysis from rupturing vavuoles..confirmed in TEM studies.

    Intensity ranges too studied with increase in effects from intensities

  9. Ultrasound works on algal blooms by rupturing the vacuoles that are used for flotation and are integral to the diurnal rise and fall of oxygen/carbon dioxide cycle (Blue-Green algae--cyanobacteria). With the vacuoles ruptured the algal cells settle on the bottom of a lake where they provide a food source for bottom feeders in the pond or lake.  Contrary to frequent popular speculation they are not harmful to fish, turtles, and other biota living in the pond, as it doesn't function like sonar on ships.  Most companies that make ultrasonic systems do not release or publish their frequency spectrum as they consider them proprietary and to give out the frequency would be akin to giving money to a competitor to mimic their design.

     

  10. destroying algal species just adds to the nutrient load, probable the reason algal species proliferate in the first place, killing them does not solve all of the problems.

  11. Peter, see: http://www.sciencedirect.com/science/article/pii/S1568988311000710

    Ultrasound can declump algae and at higher frequencies, causes structural breakdown at cellular level.

    2 Comments

    2. Use aeration and mixing which is Natures way of removing algae without causing problems for fish and gives them more oxygen with which to feed and grow faster. An 'Aquaerator' on the bed also ensures destratification.