Algae is a growing problem in all sorts of water and wastewater facilities — reservoirs, lagoons, ponds, water storage tanks and more.

The problem grows more acute as the climate warms, making conditions more hospitable for green and blue-green algae to proliferate. Water utilities are looking for ways to control algae that are cost-effective and sustainable.

WaterIQ Technologies offers what it calls next-generation ultrasonic algae defense systems. They function without chemicals and in many cases with battery-backed solar energy. The company offers Pulsar family ultrasonic units suitable for a range of applications, from smaller facilities like ponds and wastewater treatment plant clarifiers, on up to large reservoirs and wastewater lagoons.

They are highly configurable with various AC/DC power supplies, power cable lengths and plug-ins for different geographies. The basic devices can be upgraded to integrate internet of things (IoT) and telemetry technologies to enable remote monitoring. George Hutchinson, chief technology officer, and Lawrence Field, founder and president, talked about the systems in an interview with Treatment Plant Operator.

In the most basic sense, how do the Pulsar units work?

Hutchinson: The different versions all basically do the same thing. They put out sounds at a certain intensity level over a span of frequency bandwidths. The user places them in a body of water where there is a need to control algae or biofilm. There are different effective ranges for different types of algae. For blue-green algae, the range is about 400 meters — that’s about 120 acres of coverage. For green algae and diatoms the range is smaller.

How does the sound actually control the algae?

Hutchinson: For green algae and diatoms, it causes the inner cell wall to vibrate. At the correct frequency, you achieve what we call critical structural resonance. When this occurs, it creates enough stress to cause that inner cell wall to tear, so that the cell loses pressure control and the ability to transfer fluid within the cell. It also opens an avenue for bacteria to enter. The bacteria then start eating the algae cell from the inside.

Is the mechanism the same with blue-green algae?

Hutchinson: Blue-green algae are totally different organisms. They use gas vesicles as a means to go up and down in the water column. The sound breaks those vesicles; the gas then migrates to the outer cell wall and slowly diffuses out, like a balloon leaking air over time. Once enough of that gas escapes, the cells can’t get back up to the surface to get sunlight for photosynthesis, and they eventually die.

How can ultrasonic technology help control biofilm?

Hutchinson: Biofilm consists of bacteria that create colonies on equipment surfaces. Our technology covers frequencies in two bandwidths. By alternating those frequencies we create a sensation similar to water turbulence. Anaerobic bacteria can’t create colonies in turbulent water, and so they go into stasis. We have one frequency set centered around 42 kHz and one around 200 kHz. Inside water process plants, the impact of eliminating biofilm is huge. Not only do you eliminate THM and HAAs, you keep the equipment clean and trouble-free. It saves money just in the people it takes to manage and maintain the equipment.

How does Pulsar differ from other ultrasonic systems for algae control?

Field: Pulsar units have been engineered to produce the right frequencies at the right decibel levels. We have 2,000 frequencies that are substantially different in killing power, and our frequency sets run 24/7. It takes about 34 minutes to run through the 2,000 frequencies. They pulse 0.4 seconds on and 0.6 seconds off. The idea behind the large number of frequencies is to kill more species more precisely.

Are there also differences in the physical construction of the devices?

Field: Yes. Typically, when you place a device in water that contains algae, it becomes covered in algae after two or three weeks, and you have to clean it. We apply a material called Sharklet to our units. It mimics shark skin, which does not attract bacteria; it’s used in hospitals and in medical implants. Because our units are covered with the Sharklet material, they don’t accumulate biofilm or algae. They last without having to be cleaned.

What has been done with the product to provide durability?

Field: Earlier transducers were put together with a conductive glue. We do not use glue at all. We use one mold and a specific type of screw to hold the piezos and the units together. So we experience no field failures.

How are units powered when deployed in larger bodies of water?

Field: For drinking water reservoirs, for example, we power them with a solar unit that is highly efficient. At installations near the equator, it is often cloudy, so we have a solar panel that is about 50% more efficient. We think it’s the most efficient solar panel on the market.

What kind of battery backup do these solar-powered units have?

Hutchinson: It’s a 24-volt, deep-cycle type marine-type battery. It will run the unit for almost a week even with no sun at all.

How can these units be controlled and monitored?

Field: For our larger units, we offer the latest in remote monitoring technology and interface that takes the information into the cloud, so that engineers can look at the data real time. We measure seven parameters for water quality, and we also have also two types of algae sensors. So users are able to look at their water quality every single day, measure algae on a daily basis and see the decrease.

What is driving the demand for ultrasonic control technologies?

Field: Issuers of requests for proposals are saying they want algae remediation systems that are chemical-free. So we are seeing a really strong demand for nonchemical solutions where they don’t have to pour copper sulfate into their water to get rid of the algae. This is the biggest trend I have seen in the last year among governments and municipalities.