Treatment of formulated atrazine rinsate by Agrobacterium radiobacter strain J14a in a sequencing batch biofilm reactor

A sequencing batch biofilm reactor (SBBR) was developed to treat dilute for mulated rinsate of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-t riazine] from an agricultural chemical formulation Facility. The SBBR was i noculated with Agrobacterium bacteria strain J14a. Hydraulic residence time s (HRTs) and different carbon sources were varied to determine their effect s on the rate of degradation of atrazine and chemical oxygen demand (COD) b y the biomass. The degradation rate of atrazine by J14a was enhanced when a supplemental carbon source was added. An initial concentration of 30 mg/L of atrazine with citrate and sucrose as carbon sources was degraded to less than 1 mg/L within 12 h for a 2 d hydraulic residence time (HRT) at room t emperature of 22 degrees C. The first order degradation rare constant for 2 d HRT was approximately 0.44 +/- 0.03 h(-1) For a HRT of 7 d, more than 90 % of atrazine were degraded within 45 h. (C) 1999 Elsevier Science Ltd. All rights reserved.