Harsonic, using low-energy, environmentally-friendly technology, is a new innovative solution to avoid biofilm as an alternative to harmful chemical cleaning. It’s been effectively applied to farmer’s boreholes in the Koo Valley of South Africa’s Klein Karoo.
The clogging of borehole systems, due to iron oxide, manganese oxide and calcium carbonate contamination in the soil — severely affecting pump efficiency — is a worldwide problem.
Recent tests with the application of ultrasonic devices, supplied by the Belgium-based Harsonic company, have proven that a long-term solution for this problem is available.
It has been discovered that the majority of these deposits are the result of bacteriological-induced oxidation processes. In these oft complex reactions, bacteria plays a big role, requiring a so-called biofilm matrix to propagate. This slimy layer provides bacteria with an ideal environment to breed or spread.
In the past, chemicals were used to kill bacteria. This method has proved to be inefficient and often costly. But Harsonic’s ultrasound solution attacks the problem from a completely different angle.
Specific ultrasound waves and resonance frequencies removes the binding cells (which forms the biofilm matrix). In doing so, the smooth biofilm surface disintegrates and flushed out with the water flow, which is inherent to a borehole in production. By washing out the bacteria caught in the biofilm, it eliminates the root cause of the bacteriological mineral deposits.
“The success of the application relates to the fact that the mineral depositing process largely relies on the initial development of biofilm in boreholes and pumps. If you can prevent the formation of biofilm, you can prevent the possibility of mineral-related deposits and clogging,” says Leon Geustyn, a consulting engineer and head of Parac, the South African agent for Harsonic.
He says this method uses water as the carrying medium for the ultrasound waves. “It has been proven that these waves can go through open check valves and through the pump head. In this way, ultrasound waves, which are emitted by an above-ground ultrasound transducer, does the job in the underground borehole and screen.”
For more than 10 years, ultrasonic devices have been implemented globally to successfully prevent the development of biofilm in various applications, such as on ship hulls, in cooling systems and small diameter water distribution systems. The company soon realised that it could also solve the borehole clogging problem.
HARSONIC SUCCESS IN SA FARMING COMMUNITY
In 2017, Parac, along with the local irrigation board (supervised by chairman and local farmer Marais Rossouw), conducted the first Harsonic trials in the Koo Valley, a farming community in the Cape Winelands known for the quality of its apples, pears, apricots and peaches.
Here, the soils are rich with iron oxide. This causes a build-up of iron bacteria deposits in borehole pipes, with severe clogging that drastically reduces pumping efficiency. Groundwater remains an all-important resource for the region’s producers.
WATCH: Local Koo Valley farmers shows WineLand Media the extent of its iron oxide problem, and how it’s affecting boreholes, threatening producer’s water resources. Harsonic has provided a cost-effective solution to the problem.
The clogging problem is severe and often, farmers experience approximately 90% reduction in pumping efficiency within the first three months. “Over the years, several products have been applied to address this problem with little to no success,” Leon says. “Pumps have to be removed from the boreholes and cleaned on a regular basis”
After the Harsonic device was installed in a test borehole, the results showed zero reduction in pumping efficiency over an eight-month period of continuous pumping. After this, the pump was removed from the borehole for inspection with no evidence of deposits or clogging. Both the pump and delivery line were as good as new.
This borehole has now been performing at the same efficiency for three years. Six more boreholes were fitted over a three-year period, showing similar results. All of the tested boreholes are 250 m in depth with yields varying between 4 000 and 5000 l/hour.
Now, more than 14 installations have been successfully implemented in areas such as Hermanus, Piketberg and Montagu, mainly on irrigation boreholes, as well as a large, potable water supply borehole near Calitzdorp.
Internationally the Harsonic devices have been implemented at more than 60 borehole sites in the USA, Canada, France, The Netherlands and Germany. These boreholes vary in size but mainly comprise of high yield suppliers for irrigation. In France, for example, the Harsonic device was used for cooling water to a power generation plant.
A significant installation was completed in Burkina Faso recently, where calcium carbonate is a severe problem. In this case the clogging problem was completely solved, and water turbidity was reduced from 18.8 NTU to 0.82 NTU (nephelometric turbidity units).
This very important water quality parameter was the only parameter for which the water did not perform as per WHO standards. After the usage of Harsonic the water became potable in terms of WHO standards.
From a practical perspective on the smaller boreholes the ultrasonic devices are installed in line with a y-piece on the feeder pipe directly before the bend into the borehole.
These devices use very low power – in the order of 6 Watt. It will be applicable for boreholes up to 250 m depth and 63 mm diameter. On larger boreholes of up to 400 m depth 250 mm diameter well head a more powerful device is required and could either simply be attached to the feeder pipe if it is metal or installed in line on non-metal feeder pipes. In this scenario the power usage is in the order of 20 Watt.
There is no maintenance requirement and the devices are guaranteed to remain fully operational for at least five years, but the expected lifetime is more. In the case of the irrigation boreholes the return on investment is calculated to be between one and two years. That mainly relates to pump efficiency and related costs and does not take into account the hassles with pump removal and cleaning as well as down time.
All-in-all the ultrasonic solution to prevent the clogging of boreholes has now been proven to be successful as originally anticipated.
The ultrasound-based technology cleans in real-time, 24/7 and avoids clogging of pipelines, cooling-systems, heat-exchangers, strainers, etc. This reduces maintenance and production costs as well as bacterial contamination. Harsonic cleans much deeper than chemicals as it also removes the contamination in the micro cracks and corners where chemicals have no impact. A 100% sustainable alternative for standard chemical disinfection.