Slaughterhouse wastewater treatment by combined anaerobic baffled reactor and UV/H2O2 processes

Combined processes of biological anaerobic baffled reactor (ABR) and UV/H2O2 at a laboratory scale were studied to treat a synthetic slaughterhouse wastewater. In this study, the total organic carbon (TOC) loadings of 0.2–1.1 g/(L day) were used. The results revealed that combined processes had a higher efficiency to treat the synthetic slaughterhouse wastewater. Up to 95% TOC removal was obtained for an influent concentration of 973.3 mgTOC/L at the hydraulic retention time (HRT) of 3.8 days in the ABR and 3.6 h in the UV photoreactor. Meanwhile, up to 97.7% and 96.6% removal of chemical oxygen demand (COD) and 5-day carbonaceous biochemical oxygen demand (CBOD5) were observed in the ABR for the same influent concentration, respectively. Comparatively, for an influent concentration of 157.6 mgTOC/L, the UV/H2O2 process alone with the TOC loading of 0.06–1.9 g/(L h) was also studied, in which, up to 64.3%, 83.7%, and 84.3% of TOC, COD, and CBOD5 removal were observed, respectively, at the HRT of 2.5 h with hydrogen peroxide (H2O2) concentration of 529 mg/L. It was found that individual ABR and UV/H2O2 processes enhanced the biodegradability of the treated effluent by an increased CBOD5/COD ratio of 0.4 to 0.6. An optimum H2O2 dosage of 3.5 (mgH2O2)/(mgTOCin h) was also found for the UV/H2O2 process.

Research highlights▶ ABR-UV/H2O2 exhibit higher efficiency for slaughterhouse wastewater treatment. ▶ Maximum TOC, COD, and CBOD5 removal efficiencies were >90% in ABR-UV/H2O2. ▶ CBOD5/COD ratio was increased in individual ABR and UV/H2O2 processes. ▶ Optimal H2O2 dosage was 3.5 (mgH2O2)/(mgTOCin h) for UV/H2O2 process.