Enhancement of atrazine removal by free and immobilized Arthrobacter sp. HB-5 in soil and wastewater.

摘要

In an attempt to remove atrazine in situ, high-efficiency atrazine-degrading Arthrobacter sp. strain HB-5 (HB-5) and HB-5 immobilized on sodium alginate were introduced into two atrazine-polluted soils that are representative of soils in North China. Soil and wastewater with and without (controls) HB-5 or immobilized HB-5 were incubated at 25 degrees C after the addition of atrazine. Soil samples were collected after 0 d, 1 d, 3 d, 5 d, 7 d, 10 d, and 13 d, and wastewater samples were collected after 0 d, 1 d, 3 d, 7 d, 14 d, 21 d, and 28 d. The residual atrazine was extracted from each sample and detected using gas chromatography. The half-life of the atrazine in the in soil samples was less than 3 d, and less than 7 d in the wastewater samples, treated with HB-5 or with immobilized HB-5. The immobilized HB-5 appears to exhibit better self-protection than the free bacteria at different pHs, and its ability to degrade atrazine was less affected by different conditions. Thus, in practice, immobilized HB-5 is better suited to incubations longer than 7 days because of its good adaptability. Both HB-5 and immobilized HB-5 exhibited better degradation of atrazine under conditions similar to the optimal living conditions of HB-5 than under other conditions. A small part of atrazine was removed by adsorption of organic matters, too. This study demonstrates the usefulness of these microorganisms in the bioremediation of soil and water systems polluted with triazine herbicides.