Nitrification in the presence of sulfide and organic matter in a sequencing moving bed biofilm reactor (SMBBR) with zeolite as biomass carrier

BACKGROUND: The biological nitrification process is inhibited in the presence of sulfide and organic matter (OM). The use of immobilized biomass on inert carriers may help to decrease this inhibition. Thus, the main goal of the present work was to develop a sequencing moving bed biofilm reactor (SMBBR) using zeolite as biomass carrier and to determine its performance in presence of sulfide and OM. RESULTS: The use of zeolite as biomass carrier improves both the total ammonia nitrogen (TAN) oxidation and nitrate accumulation, allowing the system to be able to treat higher nitrogen loading rates. The SMBBR with zeolite in presence of sulfide and OM performed nitrification better than a sequencing batch reactor (SBR), by keeping the TAN and chemical oxygen demand (COD) removal efficiency at >90% for both inhibitory conditions. The SMBBR also is able to degrade COD by ≤98%. Finally, biomass with zeolite settled faster than biomass without zeolite, improving the sludge volume index (SVI) by 53.8%. CONCLUSIONS: It was possible to develop a SMBBR system using zeolite as biomass carrier. The SMBBR could maintain a nitrifying system under inhibitory conditions, allowing efficiencies of TAN and COD removal as high as 90%. © 2019 Society of Chemical Industry

Elemental sulfur-based autotrophic denitrification in stoichiometric S0/N ratio: Calibration and validation of a kinetic model

The inclusion of S0 hydrolysis in a kinetic model of autotrophic denitrification has been recently proposed; however the model has not been calibrated or validated yet. Thus, a new methodology was developed and applied to calibrate and validate this kinetic model for the first time. An inoculum adapted from a poultry wastewater treatment plant at stoichiometric S0/NO3− ratio was used. The model was calibrated with batch data (initial nitrate concentrations of 50 and 6.25 mg NO3−-N/L) at an S0/N ratio = 2.29 mg S/mg N and validated with seven different batch data. The sensitivity analysis showed that the most sensitive parameters are related to S0 hydrolysis. The kinetic model was successfully calibrated with the new methodology and validated, with Theil inequality coefficient values lower than 0.21. Thus, the proposed model and methodology were proved to be well suited for the simulation of elemental sulfur-based autotrophic denitrification in batch systems