Application of immobilized biological fillers for the hydrolytic acidification and denitrification of sulfide-containing tannery wastewater

Abstract

This study investigated the application of immobilized biological fillers in the hydrolytic acidification (HA) and denitrification (DN) of actual sulfide-containing tannery wastewater (TWW) through pilot-scale systematic experiments, which provided technical insights for the engineering application of immobilized bio-filler in practical TWW treatment. HA fillers and DN fillers could effectively realize the enrichment and maintenance of functional flora even under long-term inhibition of high sulfide concentration. The HA fillers demonstrated efficient conversion of organic nitrogen. At a hydraulic retention time (HRT) in the range of 3–6 h, the HA reactor achieved an average organic nitrogen conversion concentration of about 100 mg/L, accounting for 56.2 %-68.5 % of the total organic nitrogen in the TWW. Under this condition, the highest average organic nitrogen conversion and mean chemical oxygen demand (COD) degradation efficiencies were achieved, at 32.95 mgNH4+-N/(L·h) and 179.42 mgCOD/(L·h), respectively. Free ammonia (FA) may contribute to pH stabilization in the HA reactor. Denitrification fillers could utilize the endogenous organic matter in the actual TWW hydrolyzed acidified solution, and realize stable biological nitrogen removal effect with no additional carbon source. The denitrification rate reached 76.3 mg NO3--N/(L·h) and the ΔC/ΔN of the denitrification ranged from 3 to 4.