Efficiency Evaluation of Two Combined Processes for Treating Tannery Wastewater

Two processes used to treat organic wastewater discharged from a tannery are discussed and their treatment efficiencies are compared. The results show that the process of sequencing the batch reactor (SBR) combined with the contact oxidation (O-SBR) is more realistic than that of SBR combined with the hydrolysis acidification (H-SBR). With HRT contact oxidation for 24h and sewage aeration for 5—7h in the SBR, the average removal of 83% for COD and 74% for ammonia are achieved in the O-SBR process. The COD and ammonia in the effluent of the O-SBR process are about 273mg/L and 42mg/L, respectively. With HRT contact oxidation for 24h and the same sewage aeration in the SBR, the average removal of COD and ammonia are only 70% and 5%, respectively, in the H-SBR process. Though the COD is less than 500 mg/L, the ammonia is as high as 163mg/L in the effluent. Furthermore, an attached process to the H-SBR has to be constructed for fetor collection, transfer and treatment.