Reaction kinetics of sequencing aerobic sludge blanket reactors treating an inhibitory substrate

• Main Authors: Hsiang-Lien Chang Chien, 張簡祥聯
• Other Authors: Ju-Sheng Huang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/19444309153014061771

碩士 === 崑山科技大學 === 環境工程研究所 === 100 === A kinetic model (incorporating intrinsic kinetics) and an empirical model (incorporating apparent kinetics) that can be used for simulating variations in inhibitory substrate residual concentration with different operating conditions in the SASB reactor are formulated. Two SASB reactors were also used to treat an inhibitory substrate phenol by varying four different organic loading rates (OLRs = 2, 4, 6 and 8 kg COD/m3-d) to generate experimental data. In order to promote granulation of biomass in the reactor, one phenol-fed SASB reactor (reactor A) was supplemented with a designate amount of glucose (decreased gradually from 200 to 0 mg COD/L) whereas the other phenol-fed SASB reactor (reactor B) was added into a fixed amount of calcium chloride (60 mg CaCl2). Thus, not only the performance and granule characteristics of SASB reactors treating an inhibitory substrate can be evaluated but the associated mass transfer and reaction kinetics can also be elucidated. The proposed kinetic and empirical models were all validated by experiments. Each SASB reactor was operated with a cycle length of 240 min. One cycle consisted of 2 min of feeding, 231 min of aeration (superficial air velocity = 0.0277 m/s, DO＞5 mg/L), 5 min of settling, and 2 min of discharging. When reactors A and B were maintained at the OLRs of 2–8 kg COD/m3-d, not only the COD removal efficiency of greater than 93% can be reached, but fairly good sludge granulation/settling can also be achieved. Noting that when reactor B was maintained at the OLR of 8 kg COD/m3-d, such a high loading rate and large granule diameter can disintegrate biomass granules, resulting in a high VSS concentration in the effluent. With an increase in OLR, the average granule diameter (dp) and its specific gravity increased whereas the average microbial density decreased. At the same OLR, the average granule diameter of reactor B (1.08–2.81 mm) was larger than that of reactor A (0.91–2.5 mm). With an increase in OLR, the specific oxygen utilization rates of reactors A and B increased (31–66 mg O2/g VSS-h; 34–53 mg O2/g VSS-h). With an increase in OLR, solids retention time (SRT) of reactor A decreased whereas SRT of reactor B increased. From the batch experiments, the obtained Haldane kinetic parameter intrinsic k values (5.0–5.3 mg phenol/mg VSS-d) are larger than the apparent k'' values (4.5–5.0 mg phenol/mg VSS-d). The apparent K''s values (109–172 mg phenol/L; increases with increasing OLR) are larger than the intrinsic Ks values (85–147 mg phenol/L). The apparent Ki'' values (277–300 mg phenol/L; increases with increasing OLR) are larger than the intrinsic Ki values (260–285 mg phenol/L). By using the validated kinetic model, the calculated mass transfer parameter values (??2 = 8–54, Bi = 10–44, ?? = 0.36–0.66) reveal that the internal mass transfer rate is an important factor that affects the overall substrate removal rate in the SASB reactors. The influencing effect of internal mass transfer resistance on overall substrate removal rate in the reactor B is greater than that in the reactor A. The calculated COD removal efficiencies using kinetic and empirical models are only 3% deviated from the experimental results. The variations of the simulated results using kinetic and empirical models are within 2.6%.