|Abstract: ||本研究除了建立回分式好氧污泥床(SASB)反應器處理抑制性基質之動力模式(incorporating intrinsic kinetics)及經驗模式(incorporating apparent kinetics)外，亦使用二組SASB反應器在有機負荷率2、4、6及8 kg COD/m3-d之操作條件下處理抑制性基質(酚)以獲得實驗數據，為促進SASB反應器之污泥顆粒化，一組SASB反應器(反應器A)啟動初期添加葡萄糖(由200 mg COD/L逐漸降低至未添加)，另一組SASB反應器(反應器B)則添加氯化鈣(60 mg CaCl2/L,即22 mg Ca2+/L)。據此，不僅可瞭解回分式好氧污泥床處理抑制性基質之效能及好氧污泥顆粒特性，亦可釐清基質降解動力及質傳效應，最後以實驗數據驗證動力模式與經驗模式之適用性。
二組SASB反應器之操作方式皆為廢水注入時間2 min，曝氣時間231 min (氣體表面流速0.0277 m/s，溶氧維持5 mg/L以上)，沉澱時間5 min，排水時間2 min，一次回分操作時間為240 min。二組SASB反應器在有機負荷率2~8 kg COD/m3-d操作條件下，反應器內污泥顆粒化穩定且沉降性良好，COD去除率可達93%以上。反應器B在有機負荷率為8 kg COD/m3-d處理酚基質時，因污泥顆粒較大與高負荷造成污泥解體致使出流水VSS增加。反應器A及B之污泥顆粒平均粒徑及比重都隨著有機負荷率之提高而增大，但平均生物密度則隨著有機負荷率之增加而減小。在相同有機負荷率條件下，反應器B之平均污泥顆粒粒徑(1.08~2.81 mm)明顯大於反應器A者(0.91~2.5mm)。反應器A及B之比攝氧率(31~66 mg O2/g VSS-h；34~53 mg O2/g VSS-h)皆隨著有機負荷率之增加而略為增加。反應器A之污泥齡隨著有機負荷率之增加而略為減短，惟反應器B之污泥齡隨著有機負荷率之增加而增長。
經由批次實驗求得酚好氧降解之Haldane intrinsic k值(5.0~5.3 mg phenol/mg VSS-d)大於apparent k'值(4.5~5.0 mg phenol/mg VSS-d)，apparent K's值(109~172 mg phenol/L)隨著有機負荷率之增加而增加，且都大於intrinsic Ks值(85~147 mg phenol/L)，apparent K'i值(277~300 mg phenol/L)亦隨著有機負荷率之增加而增加，且都大於intrinsic Ki值(260~285 mg phenol/L)。藉由動力模式求得之質傳參數(??2 = 8~54、Bi = 10~44 及η= 0.36~0.66)得知，污泥顆粒之內部質傳速率是影響SASB反應器整體基質去除速率之重要因素，反應器B之污泥顆粒內部質傳阻抗對整體基質去除率之影響大於反應器A者。本研究建立之動力模式及經驗模式模擬之COD去除率與反應器A及B處理酚基質實驗値之誤差在± 3%範圍內，且動力模式與經驗模式模擬值之間差異百分比亦僅2.6%範圍內。
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%.