Abstract :
The algal species Secenedesmus quadricauda was used to remove nickel ions from contaminated water (under laboratory conditions). It was exposed to different concentrations of nickel (2, 4, 6 and 8) ppm in order to measure it capacity to remove and tolerate this metal. The results showed that the alga was able to remove this metal with percentages of 98, 53.5, 55.33 and 43% for the concentrations 2, 4, 6 and 8 ppm, respectively, in the eighth days of the experiment period, while this ability was decreased in the fourteen days of the experiment period to: 80, 43.25, 36.83 and 26.62 % for the concentrations 2, 4, 6, and 8, ppm respectively, as a result of death for some algal cells. So, it was concluded that this alga can tolerate nickel till 6 ppm, because it can remove more than 50 % from its concentration till the eighth day of the experiment period (8 days represents the life cycle of the studied alga according to some related references and most of the studies which used the same alga). This means that the algal cells of this species can tolerate and live till the end of the life cycle with the 6ppm of nickel (this concentration-6ppm- usually exceed the acceptable values of nickel in water -0.05ppm- according to Iraqi rivers protection system.No.251967).
