Cultivating Chlorella vulgaris and Scenedesmus quadricauda microalgae to degrade inorganic compounds and pesticides in water

This work evaluates the possibility of cultivatingScenedesmus quadricauda and Chlorella vulgarismicroalgae in wastewater from the hydroponic cultivationof tomatoes with the aim of purifying the water.S. quadricauda and C. vulgaris were also used in purificationtests carried out on water contaminated by the followingactive ingredients: metalaxyl, pyrimethanil, fenhexamid,iprodione, and triclopyr. Fifty-six days after the inoculumwas placed, a reduction was found in the concentration ofnitric nitrogen, ammonia nitrogen, and soluble and totalphosphorus. The decrease was 99, 83, 94, and 94 %, respectively,for C. vulgaris and 99, 5, 88, and 89 %, respectively,for S. quadricauda. When the microalgae were present, allthe agrochemicals tested were removed more quickly fromthe water than from the sterile control (BG11). Theincrease in the rate of degradation was in the ordermetalaxyl>fenhexamid>iprodione>triclopyr>pyrimethanil.It was demonstrated that there was a real degradation offenhexamid, metalaxyl, triclopyr, and iprodione, while in the case of pyrimethanil, the active ingredient removed fromthe substrate was absorbed onto the cells of the microalgae.It was also found that the agrochemicals used in the testshad no significant effect on the growth of the twomicroalgae. The experiment highlighted the possibility ofusing cultivations of C. vulgaris and S. quadricauda as purificationsystems for agricultural wastewater which containseutrophic inorganic compounds such as nitrates and phosphatesand also different types of pesticides.