关键词:

焦化废水, 硫氰化物, 生物降解, 交互干扰

Abstract:

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.

Key words:

焦化废水, 硫氰化物, 生物降解, 交互干扰