Pilot Trial of Combined BCB Process for Chemical Wastewater Treatment

摘要

The wastewaters from phenol and rubber synthesis were treated by activated sludge process in a large-scale chemical factory in Shanghai, but the final effluent quality cannot fit in with the local discharge limit if without using the river water for dilution. Therefore, this chemica lfactory had to upgrade its wastewater treatment plant. For fully using the present buildings and equipments during upgrading the chemical factory's wastewater treatment plant and saving operation cost, a sequential biological pre-treatemnt, chemical oxidation, and biological post-treatment (or BCB for short) process had been proposed and investigated in a pilot trial. The pilot trial results showed that about 80% COD in the chemical wastewater could be removed through anoxic and aerobic degradation in the biological pre-treatemnt section, and the residual COD in the effluent of biological pre-treatment section belongs to refractory chemicals which cannot be removed by normal biological process. The refractory chemicals were partial oxidized using Fenton reagent in chemical oxidation section to improve their biodegradability; subsequently the wastewater was treated by SBR process in the biological post-treatment section.And the final effluent COD can reach the first grade discharge limit (<100mg/L) of Chinese Notational Integrated Wastewater Discharge Standard (GB8978-1996) even if without using any dilution water. Compared with the original dilution and biological process, the operation cost of BCB process just increased about 0.5 yuan (RMB) per cubic meter wastewater, but about 1,240,000 m 3 /a dilution water could be saved and the COD emission could be cut down by 112 ton each year.