ประสิทธิภาพการกำจัดสีของสีรีแอกทีฟชนิดอะโซโดยระบบเอสบีอาร์แบบแอโรบิกและแอนแอโรบิก-แอโรบิกภายใต้ภาวะการปฏิบัติการที่ต่างกัน / อำพล เตโชวาณิชย์ = Color removal efficiency of a reactive azo dye by aerobic and anaerobic-aerobic SBR systems under different operating conditions
In this research, the effects of color intensity, anaerobic time and type of substrate on the organic carbon, phosphorus and color removal were studied by using three SBR bench scale models with 16 L tank capacity. The systems were operated at 8-day total sludge age and 12-hour cycle time with different anaerobic+aerobic times of 0+11 (aerobic process), 2+9, 4+7 and 8+3 hrs. (which were anoxic+anaerobic+aerobic process with predenitrification process taking part in the early stage of the anarobic step). The synthetic wastewaters were prepared to have 500 mg/l COD, 50 mg/l nitrogen, 15 mg/l phosphorus (100:10:3) as well as, 10, 40 and 80 mg/l reactive diazo Remazol Black B dye. The COD removal efficiency of the aerobic and EBPR systems at 2, 4 and 8 hour anaerobic times was 96.3, 96.1, 96.9 and 95.9 percent, respectively, at the 10 mg dye/l condition and 93.0, 94.6 and 93.6 percent for the aerobic and 2 and 4 hour anaerobic system at 40 mg/ dye/l condition and 88.6 percent for the 4 hour anaerobic system at 80 mg dye/l condition. This showed that the color intensity had very little effect on the organic carbon removal. The TKN removal efficiency was 97.7, 97.7, 97.8 and 97.3 percent, respectively, at the 10 mg dye/l condition and 96.2, 95.8 and 95.8 percent for the aerobic and 2 and 4 hour anaerobic system at 40 mg dye/l condition and 93.3 percent for the 4 hour anaerobic system at 80 mg dye/l condition; the dye effect was therefore similar to the COD scenario. The phosphorus removal efficiency was 59.2, 98.7, 98.7 and 98.0 percent, respectively, at the 10 mg dye/l condition and 58.8, 97.4 and 99.3 percent for the aerobic and 2 and 4 hour anaerobic system at 40 mg dye/l condition and 97.4 percent for the 4 hour anaerobic system at 80 mg dye/l condition. This demonstrated that the aerobic system, as expected, could not satisfactorily reduce color while the BPR process could. Also, the dye concentration up to 80 mg/l, or the color intensity, did not have much effect on the PAO. The color removal efficiency in SU unit was 18.3. 36.8, 62.8 and 62.5 percent, respectively, at the 10 mg dye/l condition and 14.6, 35.2 and 52.7 percent for the aerobic and 2 and 4 hour anaerobic system at 40 mg dye/l condition and 54.5 percent for the 4 hour anaerobic system at 80 mg dye/l condition. The anaerobic+aerobic systems had obviously a better color removal than the aerobic system. High decolorization level could be achieved with long anaerobic time, while it decreased with the dye concentrations. It is not necessary that the systems with the same phosphorus removal efficiency had to decolorize at the same degree, i.e., PAO were not the sole primary decolorizing organisms.
