Decontamination of alachlor herbicide wastewater by a continuous dosing mode ultrasound/Fe(2+)/H2O2 process.

We used a ultrasound/Fe(2+)/H2O2 process in continuous dosing mode to degrade the alachlor. Experimental results indicated that lower pH levels enhanced the degradation and mineralization of alachlor. The maximum alachlor degradation (initial alachlor concentration of 50 mg/L) was as high as 100% at pH 3 with ultrasound of 100 Watts, 20 mg/L of Fe(2+), 2 mg/min of H2O2 and 20°C within 60 min reaction combined with 46.8% total organic carbon removal. Higher reaction temperatures inhibited the degradation of alachlor. Adequate dosages of Fe(2+) and H2O2 in ultrasound/Fe(2+)/H2O2 process not only enhance the degradation efficiency of alachlor but also save the operational cost than the sole ultrasound or Fenton process. A continuous dosing mode ultrasound/Fe(2+)/H2O2 process was proven as an effective method to degrade the alachlor.