NAMS 2002 Workshop - ICOM 2008

Drinking and Wastewater Applications V – 2
Friday July 18, 3:00 PM-3:30 PM, Maui
Treatment Performance and Detoxification of Coke Plant Wastewater Using
an Anaerobic-Anoxic-Oxic Membrane Bioreactor System
W. Zhao (Speaker), Div. of Water Environment, Dept, of Environmental Science and Engineering,
China - xhuang@tsinghua.edu.cn
X. Huang, Div. of Water Environment, Dept, of Environmental Science and Engineering, China
D. Lee, Chemical Engineering Department, National Taiwan University, Taiwan
M. He, Div. of Water Environment, Dept, of Environmental Science and Engineering, China
Coke plant wastewater is a kind of complex industrial wastewater generated in
the iron and steel industry during coal carbonization and fuel classification. Its
quantity and quality may vary fairly widely, depending on coal quality, coking
temperature, and by-product recovery processes. The major contaminants in a
typical coke plant wastewater consist of high concentration ammonia, toxic
substances (such as cyanide, thiocyanate, phenols), and biologically inhibitory
organic compounds. The conventional activated sludge process is usually not
potent enough for removal and detoxification of these pollutants. Due to
increasingly stringent regulations for receiving water bodies and industrial
wastewater reuse strategies, achieving effective and safe control of this kind of
wastewater is imperative. In this study, an anaerobic-anoxic-oxic membrane
bioreactor (MBR) system was proposed to treat coke plant wastewater.
Treatment performance at different hydraulic retention times (HRTs) was
investigated. Acute toxicity test was applied to evaluate the toxicity change
during the MBR system, and transformation of organic pollutants in the system
was also analyzed.
The MBR system consisted of an anaerobic reactor (A1), an anoxic reactor (A2)
and an oxic reactor (O) with a submerged hollow fibre polythene membrane
(nominal pore size: 0.4 μm, membrane area: 0.2 m 2 , Mitsubishi, Japan). The
anaerobic reactor was packed with soft media. The anoxic and oxic reactors
were completely mixed tanks, and the mixed liquor recirculation was from the
oxic one to the anoxic one. Compared conventional anaerobic-anoxic-oxic
activated (CAS) system was operated at the same condition with MBR system.
Raw coke plant wastewater was collected from Beijing Steel Company. Acute
toxicity of wastewater was assessed by luminescent bacteria growth inhibition
test, using Zn 2+ as the toxicity reference substance. Transformation of organic
pollutants in the system was analyzed by fluorescence excitation- emission
matrix (EEM). The MBR process was operated in a constant mode. When the
transmembrane pressure (TMP) reached around 0.3MPa, off line physical (with
tap water) and chemical (with HCl, NaOH, NaClO) cleaning of the membrane