Effects of some operating parameters on the efficiency of a sequencing batch reactor system for treatment of textile wastewater containing acid dyes

摘要

The purpose of this research was to find the optimal treatment conditions of a sequencing batch reactor (SBR) system for treatment of various types of textile wastewater (TWW) and synthetic textile wastewater containing acid red 18 and acid blue 9 dyes. Experiments were carried out under various BOD_5:TN ratios of 100:5, 100:10, 100:15, and 100:20, with mixed liquor suspended solids of 3,000 mg/L, and at hydraulic retention times (HRT) of 5, 7.5, and 10 d in order to determine the highest removal efficiency. Also, glucose, starch industrial wastewater (SWW), and noodle industrial wastewater were tested for their suitability as a carbon source. The results showed that mixed acid dyes had no significant effect on hetero-trophic bacteria, but strongly repressed denitrifying bacteria activity. The SBR system with two times diluted TWW containing 1,480 mg/L glucose demonstrated high removal efficiencies for color, chemical oxygen demand (COD), biochemical oxygen demand (BOD_5), and TN (75.9 ± 2.1, 89 ± 7, 92 ± 1, and 90.9 ±2.8%, respectively). Regarding the effect of nitrogen concentration and HRT, the highest color, COD, BOD_5, and TN removal efficiencies (91.1 ±0.3, 96 ±1, 97 ±3, and 86.9 ±0.4%, respectively) were observed with one time diluted TWW containing 1,480 mg/L glucose and 344 mg/L urea (BOD_5:TN of 100:10) at HRT of 10 d. For future applications, noodle or SWWs could be used as a carbon source instead of glucose, without any significant difference in color removal efficiency. This study suggests that the SBR system could be applied for treatment of TWW after one-time dilution with water and supplemented with carbon and nitrogen sources at organic loading and BOD_5:TN ratio of 0.17-0.23kg BOD_5/m~3d and 100:10, respectively.