Thiocyanate (SCN-) is one of the main contaminants in coking wastewater and has non-neglectable contribution to COD

chroma and NH+4-N value.The interactive inhibitory reaction of SCN- with other pollutants would affect the selection of treatment technology and the draining water quality control.In this study

the SCN- degradation kinetics was investigated using activated sludge of coking wastewater.Effects of phenol on SCN- degradation and SCN- on nitrification were also studied in order to assess the interaction of SCN- with other pollutants.Under specified culture condition

the degradation rate of SCN- reached up to 20.15 mg SCN-·(g MLSS)-1·h-1 and the sludge activity was not significantly affected by the initial concentration of SCN-.The SCN- degradation process follows the Michaelis-Menten model.Experiment results indicated that phenol has toxic inhibition on SCN- degradation

with 738 mg·L-1 phenol

the complete degradation time of 108 mg·L-1 SCN- was delayed from 1.5 h to 20 h.On the other hand

SCN- also inhibits the nitrification of NH+4

especially for the conversion of nitrite to nitrate

which resulted in the accumulation of NO-2.Hence

the inhibitory interactions of thiocyanate with phenol and ammonia make the treatment of coking wastewater more complicated and difficult.Thus

for the pollution control of coking wastewater

it should identify the interaction effects among main contaminants

consider the adaptation of sludge activity with pollutants concentrations from the point of co-substrate effect or poisonous effect

which would give help in establishing an optimized biological treatment technology.