Aerobic Biological Fluidized-bed Technology Treatment of Coking Wastewater in Gasworks

Z.F.Ye, J.R.Ni, A.G.L.Borthwick

ABSTRACT: The coking wastewater in gasworks is difficult to purify by conventional biological treatment because of the high contents of its coal tar, ammonia-nitrogen, COD and phenol. In this study, a pilot-scale experiment has been conducted to treat the coking wastewater. With pretreatment of flocculation and sedimentation, this work highlights the aerobic biological fluidized-bed technology (ABFT) process, which is based on the use of immobilized microorganisms and enzymes on certain synthesized polymer carrier. The average contents of contaminants of the raw wastewater are approximately COD=4480mg·l-1, NH4+-N=531 mg·l-1, volatile phenol 237mg·l-1 and oils 126 mg·l-1 and they are as follows after treatment by the ABFT process: COD=57.7mg·l-1, NH4+-N=0.285 mg·l-1, volatile phenol 0.363 mg·l-1and oils 0.18mg·l-1. The results satisfy the demands addressed in China’s National First-grade Discharge Standard. The carrier employed to be fluidized media in the ABFT reactor has a porously reticular structure, and it exhibits excellent mechanical strength and chemical functions. The high-efficiency microorganisms BCP35 have been selected in this study, which can be immobilized on the carrier by chemical bonds. The result of the Kjeldahl-Gunning method for nitrogen determination indicates that the average immobilized biomass on the carrier is 32g·l-1(H2O) . Meanwhile, study on the process parameters of ABFT system shows that the maximum volume loads of ABFT reactor are 9.06kg COD·m-3·d-1  and 1.11 kg NH4+-N·m-3·d-1 as effluent holds COD≤100mg·l-1 and NH4+-N≤15mg·l-1.   The experimental investigations have shown that the ABFT process has an overwhelming advantage to treat high ammonia-nitrogen wastewater in comparison withSBR, BAF, contact oxidation and active carbon fluidizing tank, as well as its high efficiency and high resisting capacity of impact load.

Aerobic biological fluidized-bed technology (ABFT), immobilized microorganisms, coking wastewater, high-efficiency microorganisms BCP35