Atrazine biodegradation in water by co-immobilized Citricoccus sp. strain TT3 with Chlorella vulgaris under a harsh environment

Abstract

With the extensive use of herbicides in agricultural production, the nearby waters are polluted by atrazine. The isolated Citricoccus sp. strain TT3 in our lab can transform atrazine into harmless cyanuric acid under natural conditions. However, this method is limited in practical use because of the weak resistance of bacteria to the harsh water environment. To solve this problem, Chlorella vulgaris was combined with atrazine degradation bacteria and co-immobilized in porous beads. The results demonstrated no significant difference in the atrazine removal rate between the free bacteria-microalgae mixture and the pure bacteria sample. Only 3.15 % and 4.35 % of atrazine in the acidic solution were removed by free bacteria and the bacteria-algae mixture. However, the degradation rate of immobilized bacteria and co-immobilized bacteria-microalgae under the same condition increased by 22.93 % and 40.57 %, respectively. Moreover, the inhibition effect of concomitant Mn2+, Cd2+, Co2+, and Cu2+ on the activity of Citricoccus sp. strain TT3 in beads was reduced. In addition, the long-term storage of immobilized beads still maintained a relatively stable degradation capacity, but its reusability needed to be improved. After being entrapped in microspheres, the enhancing effect of Chlorella vulgaris on the biodegradation of atrazine was pronounced under adverse environmental conditions. The study provided insight into the practical application of atrazine biodegradation technology.