本研究使用中部某造紙廠廢水處理場之活性污泥，以同一污泥樣品進行十次接續重複(consecutive repetitions)量筒沉降試驗，以了解在重複試驗時，是否會因污泥之膠羽(floc)遭受破壞而影響試驗結果之複現性。接者使用10,000 mL之均勻混合樣品，分成十組進行平行重複(parallel repetitions)試驗，以利於評估是否可以接續重複試驗取代平行重複試驗。每次試驗約進行30分鐘，並於適當時間以目視方式讀取污泥沉降界面，所得數據可繪出沉降曲線(Ht vs. time)，並以圖解分析法，求取初始沉降速度(v)。沉降試驗完成後，取樣進行懸浮固體(SS)分析，接續試驗共進行3 重複，而平行試驗每一沉降筒進行一次SS分析共10 重複，據以計算固體通量(SF= v ×X)。研究結果顯示接續重複試驗的沉降速度平均值為1.91 cm/min，變異係數(Cv)為2.6%，平均SS濃度為468 mg/L，平均固體通量值為12.8 kg/m2-d；平行重複試驗結果顯示，沉降速度之平均值為1.92 cm/min，變異係數為0.5%，平均SS濃度為410 mg/L，平均固體通量值為11.3 kg/m2-d，顯示接續重複試驗可以取代平行重複試驗，唯前10分鐘之沉降界面高度變動較大。實場之固體通量操作值為87.5 kg/m2-d(SS濃度為4000 mg/L)與兩種重複試驗之差異甚大，顯示批次量筒試驗，受限於管壁效應，不宜將其試驗結果直接應用於實場。後續宜開發即時監控界面沉降管柱，以便獲得更接近實場之數據，作為評估現場連續試驗之參考。
This study conducted 10 consecutive and 10 parallel reproducible settling tests by using 1000-mL graduated cylinders on activated sludge obtained from a pulp-making wastewater treatment plant located in Central Taiwan. Each test took about 30 minutes, during which the height of sludge interface was read so that the entire settling could be obtained (Ht. Vs. time). The initial velocity was obtained with the initial linear tangent on the settling curve. At the completion of the test, supernatant sample was taken for the determination of suspended solid (SS, X), so that the solid flux (SF) could be computed (SF = v ？？X). The results of 10 consecutive tests show an average of initial velocity of 1.91 cm/min (Cv = 2.6%) at an average SS of 468 mg/L and SF of 12.8 kg/m2-d, while the parallel tests give an average initial velocity of 1.92 cm/min (Cv = 0.5%) at an average SS of 410 mg/L and SF of 11.3 kg/m2-d. This suggests that the consecutive test can be used to replace the parallel test for reducing requirement of sample size. However the consecutive test yielded a larger variation during the first 10 minutes. Comparing with the full-scale operation data (SF of 87.5 kg/m2-d and SS of 4000 mg/L), this study underestimates the SF. This is likely due to the low SS and wall effect associated with the graduate cylinder used for the settling test. An on-line settling column with larger surface area is under designed and will be used to improve the settling test in the future.
