The combination of zerovalent iron (ZVI) with anaerobic sludge for enhancing reductive transformation and dechlorination of 4-chloronitrobenzene (p-ClNB) was investigated in the study. The p-ClNB was quickly reduced into 4-chloroaniline (p-ClAn) and subsequently dechlorinated into aniline (AN) in the complex system, and the strengthening factor for pseudo-first-order transformation rate constant of p-ClNB (Q, kZVI+sludge/(ksludge+kZVI)) was up to 3.698. Subsequently, the dechlorination efficiency of p-ClAn by anaerobic sludge was also significantly enhanced. The synergistic effect was obviously affected by the ZVI's type as well as ratio of the ZVI to sludge. Results showed that the Q values for the synergistic effect of different type of ZVI with sludge was followed: Reduced ZVI (RZVI) > Industrial ZVI (IZVI) > Nanoscale ZVI (NZVI). Increasing dosage of ZVI could promote the p-ClNB transformation, but the p-ClAn dechlorination rate and Q value were not enhanced. Furthermore, the NZVI and high concentration of RZVI inhibited p-ClAn dechlorination. With the sludge biomass incresing, the dechlorination rate of p-ClAn was significantly enhanced, and the Q value had positive relation with the mass ratio of anaerobic sludge to RZVI, which suggested that the anaerobic biological reaction maybe the rate-determining step in the combined ZVI-anaerobic sludge system.

Enhanced transformation and dechlorination of p-Chloronitrobenzene in the combined ZVI-anaerobic sludge system

245th National Meeting (2013)

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