Treatment of ammonium in slaughterhouse wastewater by UASB technology combined with EGSB using anammox and PVA gel

Abstract

Slaughterhouse wastewater (SWW) possesses very high organic and nutrient concentrations and its residues are moderately solubilized, which leads to pollution affecting the environment and human health. The objective of this study was to investigate the effective removal of ammonium in slaughter wastewater by up flow anaerobic sludge blanket (UASB) technology combined with an expanded granular sludge bed (EGSB) using anammox and PVA gel as the biomass carrier. Ammonium loading rates (NLRs) increased from 0.25 kg N-NH₄⁺/m³.d to 0.75 kg N-NH₄⁺/m³.d with hydraulic retention times (HRTs) of 12, 6, and 4 h. The system was operated in 2 phases. In phase 1, the removal of ammonium by employing the combination of UASB technology and EGSB using anammox was examined. The removal efficiencies of nitrite were 52% (NLRs=0.25 kg N-NH₄⁺/m₃.d), 69% (NLRs=0.5 kg N-NH₄⁺/m³.d) and 64% (NLRs=0.75 kg N-NH₄⁺/m³.d). On the other hand, the removal efficiencies of ammonium were about 37% (NLRs=0.25 kg N-NH₄⁺/m³.d), 64% (NLRs=0.5 kg N-NH₄⁺/m³.d) and 55% (NLRs=0.75 kg N-NH₄⁺/m³.d). In phase 2, a PVA gel was supplied to the EGSB as the biomass carrier for growing the anammox sludge. The result showed that the removal efficiencies of nitrite were about 55% (NLRs=0.25 kg N-NH₄⁺/m³.d), 77% (NLRs=0.5 kg N-NH₄⁺/m³.d), and 73% (NLRs=0.75 kg N-NH₄⁺/m³.d). In addition, the removal efficiencies of ammonium were about 56% (NLRs=0.25 kg N-NH₄⁺/m³.d), 68% (NLRs=0.5 kg N-NH₄⁺/m³.d), and 60% (NLRs=0.75 kg N-NH₄⁺/m³.d).