結論與建議

5-1 結論

1. 增加快混 G 值可提升濁度去除率且有一最適 Gt 值範圍(9×10⁴~ 1.2×10⁵)，超出範圍時，增加快混 G 值反而更加速微膠羽破碎，

不利膠羽生長，導致濁度去除率降低。

2. 增加快混 G 值有助於 DOC 之去除，同樣有一最適快混 Gt 值範圍 (6×10⁴~ 4.8×10⁵)且範圍較去除濁度之最適 Gt 值範圍大。

3. 電性中和機制下形成之膠羽結構較易受水流剪力作用，增加快混 G 值可提升膠羽強度及破碎膠羽回復率，兩者呈正相關性。反之，

沉澱掃除機制下形成之膠羽結構不易受水流剪力作用而改變，膠羽強度受快混 G 值影響變化不大且破碎膠羽回復率隨快混 G 值增加而變差。

4. 膠羽強度及破碎膠羽回復率與混沉過濾效能皆無太大相關性，唯獨膠羽大小關係著濁度去除率進而影響上澄液過濾性。

5. 低濁水混沉後上澄液過濾性受快混 G 值之影響趨勢最為明顯，增加快混 G 值可提升上澄液過濾性。

6. 各淨水場原水經管柱快混設備處理後，其處理水混沉後可明顯提升濁度去除及上澄液過濾性，但對 DOC 去除之助益並不明顯。

故可藉由提高快混G 值達到減少加藥量之目的。

5-2 建議

1. 新竹第二淨水場混沉處理低濁水(20 NTU)及高濁水(150 NTU) 時，均有過量加藥之情形發生，原水混凝快混操作應先維持現有的G 值，但應可減少混凝劑量以評估實場混沉及過濾效能是否改變，以確認在現有G 值操作條件下，混凝劑減量是否可達到設定的標準，以避免實場混凝操作發生過量加藥之情形。

2. 豐原第二淨水場混沉處理低濁水(15 NTU)及高濁水(200 NTU) 時，其快混操作G 值建議應增加至 800 s^-1或 1000 s^-1，可提升混沉及過濾操作效能並藉此減少混凝劑量。

3. 建議水場可考慮在快混操作發生問題或困難之淨水場裝設管中快混設備，以有效提升水場混沉及過濾效能。

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附錄 A 槳驅動輪(propellers)、渦輪槳翼(turbine impellers)以及翼片槳翼(paddle impellers)。螺旋槳翼通常為 2 ~ 3 片，其與另外兩種葉片之差異在於其翼片些微傾斜，因此轉動時會產生軸向螺旋水流，其轉速範圍約在 400 ~ 1750 rpm，較渦輪及翼片槳翼來得快；渦輪槳翼之直徑通常為 30 ~ 50%快混池直徑或寬度，渦流槳翼之轉速約為 10 ~ 150 rpm；翼片槳翼通常有2 ~ 4 個翼片，槳翼直徑通常為 50 ~ 80%快混池直徑或寬度，轉速約為20 ~ 150 rpm(Reynolds and Richards, 1996)。一般淨水場通常以翼片槳翼為主，因槳翼的投影面積大，能產生較大的紊流及混合效

水躍式混合

出水室水躍區進水室

反應區面積

混合池

出水進水

H

水躍式快混槽俯視圖及剖面圖

管中混合

機械式攪拌為水場常使用之攪拌方式，但淨水場可能因槽體過大或槳葉太小之因素，增加攪拌時間亦無法使混凝劑能均勻分散，因此水場經常過量加藥25 ~ 30%之混凝劑，藉此達到沉澱掃除之機制，以確保供水之水質。為此，管中混合之方式即被提出，管中混合應用於快混單元時，顆粒聚集速率常數與水中濁度變化之關係如(6)式：

n

dt Kapp

dTur

  (6)

式中

dTur/dt 為顆粒聚集時濁度變化之速率，Kapp 為顆粒聚集速率常

速率愈快(Mhaisalkar et al., 1991)。其快混G 值可由(7)式求得。

V g

a C



  ^







G 2 (7) 式中

C

_d為常數；a 代表噴嘴孔面積；ν 為通過噴嘴之流速；γ 為流體比重量(水的比重量為 9810 N/m³)；g 代表單位質量重(9.81 N/kg)；μ 為動力黏滯係數(20℃，水的動力黏滯係數為 10^-3 N．sec/m²)；V＝

0.13．d³，式中d 為噴嘴管內徑(Monk and Trussel, 1991)。

附錄B

Concentration (mmole/L as Al)

0.00 0.02 0.04 0.06 0.08 0.10 0.12

Absorbance

0.0 0.2 0.4 0.6 0.8

y=6.736x + 0.015 R

=0.997

Al-Ferron 逐時螯合比色法檢量線

附錄 C

Dosage (mg/L as Al)

0 1 2 3 4 5 6

Residual T urbidity (NT U )

Dosage (mg/L as Al)

0 1 2 3 4 5 6

Res idual Turbi d it y ( N TU)

Dosage (mg/L as Al)

R esid ua l T u rb id ity (N T U )

1 Dosage (mg/L as Al)

0 2 4 6 8 10

R esid u al T ur bid ity (N T U )

(新竹第二淨水場；原水濁度：150 NTU；淨水場混凝劑量：2.43 mg/L) (a) 0.45 µm

(b) 1 µm

Dosage (mg/L as Al)

R es id u al T u rb id it y (N T U )

Dosage (mg/L as Al)

0 1 2 3 4 5 6

R esid u al T u rb id ity ( N T U )

Dosage (mg/L as Al)

R esid u al T u rb id it y ( N T U )

Dosage (mg/L as Al)

0 2 4 6 8 10

R es id u al T u rb id it y ( N T U )

0

(豐原第二淨水場；原水濁度：200 NTU；淨水場混凝劑量：3.33 mg/L) (a) 0.45 µm

(b) 1 µm

附錄 D Case 1

清水流速：1.2739 m/s

取兩點計算壓力損失

P = 666 – 167 = 491 Pa = 491 N/m²

Case 2

清水流速：4.0340 m/s

取兩點計算壓力損失

P = 6610 – 0.617 = 6609.383 Pa = 6609.383 N/m²

Case 3

清水流速：5.9448 m/s

取兩點計算壓力損失

P = 12600 – 0.617 = 12599.383 Pa = 12599.383 N/m²

V

Power number = 9.8×0.00108×50.102 = 0.5302 10 4501

Power number = 9.8×0.00108×674.388 = 7.1377 16514

Power number = 9.8×0.00108×1285.612 = 13.6069 22802

1.2739 4501 4.0340 16514 5.9448 22802

附錄E

Velocity Gradient (s ^-1 )

100 1000

F loc Si ze d 50

( m)

100

150 s^-1 400 s^-1 600 s^-1 800 s^-1 1000 s^-1

Velocity Gradient (s ^-1 )

100 1000

F loc Si ze d 50

( m) ¹⁰⁰

150 s

^-1

400 s

^-1

600 s

^-1

800 s

^-1

1000 s

^-1

圖1 不同快混強度下之膠羽強度 (a) 20 NTU

(b) 150 NTU

Velocity Gradient (s ^-1 )

100 1000

F loc Si ze d 50

( m)

100

200 s^-1 400 s^-1 560 s^-1 800 s^-1 1000 s^-1

Velocity Gradient (s ^-1 )

100 1000

F loc Si ze d 50

( m)

¹⁰⁰

200 s^-1 400 s^-1 560 s^-1 800 s^-1 1000 s^-1

圖2 不同快混強度下之膠羽強度 (豐原第二淨水場)

(a) 15 NTU

(b) 200 NTU

在文檔中快混強度對天然濁水混凝效能之影響 (頁 63-83)

Aggregation: Measurement, Modeling and Simulation. Butterworth-Heinemann Ltd.,

Polymers. Ed. by Finch, C. A. Royal Society of Chemistry, London, 62-75.

and Operation of Water Treatment Facilities. John Wiley and Sons, New York,

Water Res. 32, 2660-2668.

Wat. Sci. Tech. 28(1), 233-242.

Res. 38, 486-494.

Res. 25, 43-52.

Colloid Interface Sci. 154, 351-358.

Operation and Processes in Environmental Engineering. PWS Publish Company

Works Assoc. 63, 52-58.

Tech. 26, 996-1001.

Miner. Process. 73(2-4), 251-259.

反應區面積

n

dt Kapp

dTur

dTur/dt 為顆粒聚集時濁度變化之速率，Kapp 為顆粒聚集速率常

V g

a C

C

Concentration (mmole/L as Al)

Absorbance

y=6.736x + 0.015 R

=0.997

Dosage (mg/L as Al)

Residual T urbidity (NT U )

Dosage (mg/L as Al)

Res idual Turbi d it y ( N TU)

Dosage (mg/L as Al)

R esid ua l T u rb id ity (N T U )

1

Dosage (mg/L as Al)

R esid u al T ur bid ity (N T U )

Dosage (mg/L as Al)

R es id u al T u rb id it y (N T U )

Dosage (mg/L as Al)

R esid u al T u rb id ity ( N T U )

Dosage (mg/L as Al)

R esid u al T u rb id it y ( N T U )

Dosage (mg/L as Al)

0 2 4 6 8 10

R es id u al T u rb id it y ( N T U )

0

V

Velocity Gradient (s -1 )

100 1000

F loc Si ze d 50

( m)

100

Velocity Gradient (s -1 )

100 1000

F loc Si ze d 50

( m) 100

150 s

400 s

600 s

800 s

1000 s

Velocity Gradient (s -1 )

F loc Si ze d 50

( m)

Velocity Gradient (s -1 )

F loc Si ze d 50

( m)

Velocity Gradient (s ^-1 )

Velocity Gradient (s ^-1 )

( m) ¹⁰⁰

Velocity Gradient (s ^-1 )

Velocity Gradient (s ^-1 )