Sulfide removal from industrial wastewaters by lithotrophic denitrification using nitrate as an electron acceptor

摘要

Sulfide is present in wastewaters as well as in biogas and can be removed by severalnphysicochemical and biotechnological processes. Nitrate is a potential electron acceptor, readilynavailable in most wastewater treatment plants and it can replace oxygen under anoxicnconditions. A lab-scale reactor was operated for treatment of sulfide containing wastewater withnnitrate as an electron acceptor and is used to evaluate the effects of volumetric loading rates,nhydraulic retention time (HRT) and substrate concentrations on the performance of thenlithotrophic denitrification process for treating industrial fermentation wastewaters. Sulfide isnremoved more than 90% at the loading rates between 0.055 and 2.004 kg S22n/m3nd, when theninfluent sulfide concentration is kept around 0.163 kg/m3nand the HRT decreased from 86.4 to 2 h.nNitrogen removal differed between 23 and 99% with different influent NO3n2-N concentration andnloading rates of NO3n2/S22nratio. The stoichiometry of sulfide oxidation with nitrate is calculatednassuming different end-products based on thermodynamic approach and compared withnexperimental yield values. The calculated maximum volumetric and specific sulfide oxidationnrates reached 0.076 kg S22n/m3nh and 0.11 kg S22n/kg VSS h, respectively. The results are obtained atnindustrially relevant conditions and can be easily adapted to either biogas cleaning process or tonsulfide containing effluent streams.