Abstract:
The research was aimed to study on the cyanide removal efficiency by sequencing batch reactorsystem (SBR). The experiment was concerned on the effect of thiocyanate concentration (0.08, 0.10,0.16, 0.17, 0.18, 0.19, 0.20, 0.26 and 0.33 mg cyanide/l) on the efficiency of SBR system. And alsothe effect of hydraulic retention time (3, 5, 7 and 10 days) on the efficiency of the system withthiocyanate containing wastewater was investigated to compare with non-thiocyanate containingwastewater. And the wastewater from electroplating industrial factory was also tested with the SBRsystem.The results showed that the COD, BOD5, TKN and cyanide removal efficiency were decreased withthe increase of thiocyanate concentration. The system showed the highest COD, BOD5, TKN andcyanide removal efficiency of 98.8, 91, 84.1 and 95.8 % respectively at the lowest thiocyanateconcentration of 0.08 mg cyanide/l. In addition, the effluent ammonium, nitrite, nitrate and sulfatewere increased with the increase of thiocyanate concentration similar to increase the thiocyanateloading of the system.To study the effect of hydraulic retention time of the system (3, 5, 7 and 10 days) the syntheticthiocyanate containing synthetic wastewater was used. The results showed that the removalefficiency was increased with the increase of hydraulic retention time (HRT) in both thiocyanateand non-thiocyanate containing synthetic wastewater. The highest COD, BOD5, TKN and cyanideremoval efficiency of 96.1, 72, 49.7 and 82.2 % respectively with thiocyanate containing syntheticwastewater was given with HRT of 10 days. While, the highest COD, BOD5 and TKN removalefficiency of 97.5, 93.3 and 80.3 % respectively with non-thiocyanate containing syntheticwastewater was given with HRT of 10 days. In addition, the effluent ammonium, nitrite, nitrate andsulfate were decreased with the increase of HRT due to the increase of organic loading.The COD, BOD5, TKN and cyanide removal efficiencies of the system with the wastewater fromelectroplating industrial factory were 90.2, 86.4, 52.2 and 88.9 %, respectively and the effluentnitrite, nitrate and sulfate were 0.9, 0.2 and 10.8 mg/l, respectively. From the results above, it could