Industrial-scale biological treatment of Chinese nutgall processing wastewater by combined expanded granular sludge bed and bio-contact oxidation

Abstract

The industrial-scale biological treatment of Chinese nutgall processing wastewater was conducted with a 200 m 3 expanded granular sludge bed reactor and a 900 m 3 bio-contact oxidation reactor. The temperature of the two reactors was controlled under mesophilic conditions (32 -40˚C), through changing the proportion of the dilution water, which was composed of steam condensation water and residual circulating water. The effluent COD, gallic acid, chroma, total nitrogen, total phosphorus levels and pH of both the expanded granular sludge bed and bio-contact oxidation reactors were monitored. In addition, the redox potential in the expanded granular sludge bed was recorded. The total COD removal efficiency was 87.257% when the influent COD concentration was 14 251±3 148 mg/L, and the ratio of wastewater: dilution water was 1:5. The removal efficiencies of gallic acid, chroma, total nitrogen, and total phosphorus were 72.221%, 43.940%, 64.151% and 39.316%, respectively. The effluent pH increased in either the expanded granular sludge bed reactor or the bio-contact oxidation reactor during the operation. The redox potential in the expanded granular sludge bed varied between -367 mV and -435 mV. The results indicate that the combined process was suitable for treating Chinese nutgall processing wastewater.

Nitrogen Removal along Vertical direction by Plant Biological Membrane System

“…In the experiment, the bio-film was formed after the 34 th day. It took more time than any other researches for bio-film forming and stable phase entering [9] because of the natural bio-film forming without inoculation or air aeration of the system. With the bio-film forming and the increase of inflow concentration, there was obvious purification phenomenon occurred in different layers of the PBMS.…”