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 formulated rinsate of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] from an agricultural chemical formulation facility. The SBBR was inoculated with Agrobacterium bacteria strain J14a. Hydraulic residence times (HRTs) and different carbon sources were varied to determine their effects on the rate of degradation of atrazine and chemical oxygen demand (COD) by 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 temperature of 22°C. The first order degradation rate 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.