Effect of organic compounds on nitrite accumulation during the nitrification process for coking wastewater

摘要

Coking wastewater is one of the most toxic industrial effluents since it contains highnconcentrations of ammonia and toxic organic compounds. Nitrification might be upset bynthe inhibitory effect of organic compounds during the biological treatment of the wastewater. In thisnstudy, shortcut nitrification was obtained in a sequencing batch bioreactor (SBR) and the inhibitoryneffect of organic compounds on the nitrification was examined when temperature was 30 ^ 18C,npH was 7.0–8.5, and dissolved oxygen concentration was 2.0–3.0mg L21n. The inhibitory effect ofnorganic compounds was presumed to be one of the main factors to obtain satisfactory nitritenaccumulation. The effect of organic compounds on nitrification was examined in the SBR with initialninhibitor concentrations ranging from 0 to 80mg L21n, including phenol, pyrocatechol, resorcin,nbenzene, quinoline, pyridine and indole. The inhibitory effect became stronger with the increase innthe concentration, and it was presumed to take place through a direct mechanism resulting fromnbiological toxicity of the inhibitor itself. Furthermore, the inhibitory effect on ammonia oxidationnwas slighter than that on nitrite oxidation, and the nitrite accumulation ratio during the nitrificationnwas determined by the difference between the reaction rates of above two processes.