Anaerobic ammonium nitrogen oxidation and sulphate reduction in psychrophilic conditions

Investigations of simultaneous removal of ammonium and sulphate were carried out in anaerobic laboratory bioreactor - upflow anaerobic filter (UAF). The bioreactor was filled with the anaerobic activated sludge from WWTP Bielsko – Biała. The process was operated in psychrophilic conditions. Temperature was maintained constant at 20± 2° C. Synthetic wastewater containing ammonium chlorine and sulphate magnesium was used as the feed for the bioreactor in experiment. The concentration range of ammonium and sulphate in the wastewater were kept at 22-27 and 80 – 130 mg/L , respectively . The analysis of the nitrogen and sulphur compounds in the liquid and gas phases indicated simultaneous ammonium and sulphate removal in the reactor. After star- up and acclimatization of this process for 30 days , the average effluent concentrations of ammonium and sulphate were 20 and 18 mg/L , respectively. About 80 % of the sulphate entering the reactor was removed from the liquid phase, of which 30 % appears as S – S2- in the effluent. During sulphate conversion were formation also S- H2S in the biogas and elemental S. Raman spectroscopy (RS) were performed to confirm the presence of sulphur in the sludge. Owing to the reduction sulphate and oxidation ammonium, about 20 % nitrogen initially present in the influent was removed appearing as N2 in the gas phase.