EFFECT OF NITRITE TO SULFIDE RATIOS ON THE PERFORMANCE OF ANOXIC SULFIDE OXIDIZING REACTOR

摘要

The present study reports the operation of a laboratory-scale anoxic sulfide oxidizing (ASO) reactor to investigate the effects of influent nitrite to bisulfide molar ratios of 0.58, 1.45, and 1.75 upon the simultaneous bisulfide and nitrite removal rates from the synthetic wastewater. For all tested ratios, very high bisulfide removal percentages (above 99 %) were observed. The mass balance analysis suggested that the bisulfide oxidation was incomplete. The sulfate formation decreased with the increasing influent sulfide concentrations. An influent bisulfide concentration above 1400 mg S /I accompanied by high effluent nitrite might have some inhibitory effect on the complete sulfide oxidation to sulfate. Nitrite removal percentage for the 0.58 ratio was in the range of 71.89-86.86 %, showing some fluctuations in the working performance of the ASO reactor. Nitrite removal at the 1.45 ratio ranged from 72.70-87.30 %. Comparatively higher nitrogen removal (78-94 %) was observed for the 1.75 ratio. The application of an influent nitrite to sulfide molar ratio of 1.75 would be a better choice for higher nitrite and bisulfide removal efficiencies in an ASO reactor.