For the Ministry of Agriculture in Cyprus, LG Sound b.v installed 33 LG Sonic, ultrasonic devices in the Limassol water treatment plant, to prevent bad odour and taste to the water caused by geosmins in the water.
The earthy taste problem persisted during summer of 2010 and various physical, chemical and biological tests were done in order to check the process efficiency, which showed problems at various locations in and outside the plant:
Physical and chemical tests showed no significant deviation from standard values, except the higher dissolved oxygen in raw water which indicated excessive algal and macrophyte growth. Phytoplankton sample test in June confirmed that raw water had high phytoplankton biovolume.
Despite that WTP uses chlorination as a common method to deal with bacteria, fungi, algae, protozoa, and viruses - disinfection in this case seems not powerful enough. Upon inspection of the water treatment plant, a significant amount of algae and slimy film were noticed in flocculation chambers and sand filters.
To reduce the volume of algae coming from the main water reservoir as much as possible, LG Sonic devices where installed in the break-pressure tank.
However, the growth of blue-green algae throughout the whole water treatment plant had to be reduced, in order to minimize taste and odour problems. Because a significant amount of blue-green algae and biofilm had been found in the flocculation tanks and sand filters, these parts of the water treatment plant where treated, along with the treated water reservoir, because this is the last stage before the water is being transported.
LG Sonic Technology
The LG Sonic technology controls algae, biofilm and actinomycetes by sending ultrasonic sound waves of several specific frequencies into the water, which control the algae by resonance and sound pressure.
The ultrasound waves will travel through the water reservoir, bringing algal cells in vibration on its path. When brought into vibration these algal cells may rupture leading to the death of the algae.
Biofilm deteriorates under the specific frequencies and bacteria are inhibited to settle to a submerged surface.
After installation of the LG Sonic products in several of the tanks in the treatment plant, a great deal of the taste and odour problems of the treated water was solved. Besides that, in various tanks biofouling was reduced, leading to less maintenance.
After installing the LG Sonic devices in sand filters, these would clog less fast and stay free of biofouling. Also flocculation processes are improved because due to the ultrasonic soundwaves. Because less growth of algae and biofouling occurs, less chemicals are consumed within the water treatment plant.