Combined Fe0/air and Fenton process for the treatment of dinitrodiazophenol (DDNP) industry wastewater

Abstract Treatment of dinitrodiazophenol (DDNP) industry wastewater by combining Fe 0 /air and Fenton process was investigated to decompose the refractory pollutants (i.e., DDNP and its by-products) and improve the biodegradability. Two control experiment systems (i.e., Fe 0 /air system and Fenton system) were set up to confirm the synergistic reaction between Fe 0 /air and Fenton process. In addition, effect of initial pH (1.5–8.0), Fe 0 dosage (10–50 g/L), air aeration (0–2.0 L/min), treatment time and hydrogen peroxide (H 2 O 2 ) dosage (0–50 mmol/L) on the treatment efficiency of the combined process was studied, respectively. The results show that the maximum COD (78%) and chromaticity (98%) removal efficiencies were obtained under the optimal conditions. Meanwhile, BOD 5 /COD ratio was enhanced from 0 to 0.27, which suggest that its biodegradability was improved. Furthermore, DDNP concentration was detected by HPLC, and the degradation of DDNP industry wastewater was analyzed by UV–vis and Fourier transform infrared spectra (FTIR). The results suggest that DDNP removal efficiency reached 99.83%, and benzene-ring, nitro-group (NO 2 − ) and diazo ( N N ) of DDNP had been decomposed and transferred into the smaller molecules organic compounds. Therefore, a good treatment of DDNP industry wastewater could be obtained by the combined Fe 0 /air and Fenton process.