Petersburg: A Russian water supply utility has "hired" the crustaceans, Australian red claw crayfish, to test quality of treated wastewater before it is dumped into the Neva Bay.
Experts at St Petersburg`s water supply company-- Vodokanal water supplier -- will observe crayfish`s condition and heartbeat to determine the quality of wastewater that gets treated at the South-western Wastewater Treatment Plant.
Bio-electronic control is a new technology developed and used by St.Petersburg scientists.
For almost six years, Astacus leptodactylus, or narrow-clawed crayfish, have been used for this purpose at St. Petersburg`s water-supply stations. However, the temperature of water for them should not exceed 22-23 degrees Celsius.
Since in summer, the temperature of wastewater can be as high as 26-30 degrees, it was necessary to use more thermophilic species.
Specialists therefore chose the Australian red claw crayfish (Red Claw Cherax quadricarinatus), but the species work seasonally and would thereby be replaced back to narrow-pawed crayfish when the summer months end.
Crayfishes are kept in a tank through which cleaned wastewater is circulated. If its quality deteriorates, sensitive crayfish will respond immediately, giving scientists a signal through a fiber-optic sensor attached to their shells.
If the heartbeat of all six crayfishes simultaneously increases 1.5-2 times, the red signal will go on to warn the operator.
After some of the facilities in the city`s sewerage system are completed this year, St. Petersburg will clean 95 percent of wastewater dumped into the Neva Bay.
Before 1997, all wastewater in St. Petersburg was dumped into the Bay of Finland untreated.
About two billion USD have been invested in the construction of wastewater treatment facilities over the past 30 years, which helped reduce environmental damage six-fold.
Currently, 85 percent of wastewater in the city is cleaned. The main danger for marine life comes from blue-green algal blooms caused by such biogenes as nitrogen and phosphorus. (Itar-Tass)
PTI
