水中溶氧與分析
Why Monitor Dissolved Oxygen 為什麼要監測水中溶氧 ?
Dissolved oxygen is a measure of the amount of gaseous oxygen contained in water. Healthy waters that can support life must contain dissolved oxygen (DO). 溶氧是水中氣態氧含量的指標。能夠維持生命的健康水體必須含有溶氧（DO）。
In everything from aquariums to laboratories to beer breweries, the ability to quickly and accurately measure DO is crucial in the monitoring and maintenance of water quality. Improper DO levels can cause oxidation that damages equipment and compromises product. 從水族館、實驗室到啤酒廠，快速且準確地測量溶氧的能力對於水質的監測和維護是關鍵。不適當的溶氧濃度會引起氧化，進而損壞設備並損害產品。
Why Measure 為什麼要測量溶氧量 ?
There are numerous reasons to measure and maintain proper DO levels. While they vary across applications, the most common reasons are as follows 測量和維持適當的溶氧量的原因有很多。雖然不同應用有不同的溶氧量要求，但最常見的原因如下 :
- Quality: The DO concentration determines the quality of source water. Without enough DO, water turns foul and unhealthy affecting the quality of the environment, drinking water and other products. 品質：溶氧濃度決定源水的品質。如果沒有足夠的溶氧，水就會變得污濁不健康，進而影響環境、飲用水和其他產品的品質。
- Regulatory Compliance: To comply with regulations, wastewater often needs to have certain concentrations of DO before it can be dis-charged into a stream, lake, river or waterway. Healthy waters that can support life must contain dissolved oxygen. 遵循法規：為遵守法規，廢污水通常需要處理到一定濃度的溶氧量才能排入溪流、湖泊、河川或水道。能夠維持生命的健康水體必須含有溶氧。
- Process Control: DO levels are critical to control biological treatment of wastewater, the biofiltration phase of drinking water production, and determining the taste and shelf-life of beverages. In some industrial applications (e.g. power production) any DO is detrimental for steam generation and must be removed and its concentrations must be tightly controlled. 製程控制：溶氧量對於控制廢污水的生物處理、飲用水製造的生物過濾階段以及確定飲料的口感和保存期限很關鍵。在某些工業應用中（例如 : 發電），任何溶氧都會對蒸汽產生不利影響，必須將其去除，並且必須嚴格控制其濃度。
Which Processes Require the Monitoring of Dissolved Oxygen 哪些過程需要監測溶氧 ?
Wastewater Treatment 廢污水處理
Influent water entering a facility usually has a low DO concentration because it contains organics and microorganisms, which consume oxygen while feeding on the organics. 進入廢污水處理廠的進水通常溶氧濃度較低，因為其中含有有機物和微生物，微生物在吞食有機物的同時會消耗氧氣。
Monitoring DO helps promote efficiency in aeration basins. By using online DO measurement equipment, a facility can reduce energy costs by adjusting aeration to match the DO required by the organic load. Continuous measurement and adjustment ensure that the microorganisms have enough oxygen to consume organics while allowing the facility to conserve energy by reducing aeration when possible. 監測溶氧濃度有助於提高曝氣池的效率。藉由使用線上溶氧量監測設備，水處理廠可透過調節曝氣來匹配有機負荷所需的溶氧，進而降低電力成本。連續監測和調整確保微生物有足夠的氧氣來消耗有機物，同時允許水處理廠在可能的情況下透過減少曝氣來節約電力能源。
Industrial Steam Generation 工業蒸汽
Because DO causes corrosion in equipment, achieving low or no DO can prevent leaks, failures and shutdowns. 由於溶氧會導致設備腐蝕，因此達到低溶氧量或零溶氧量可預防廠區設備產生洩漏、故障和停機。
Monitoring of DO and the temperature of the source water can provide early warning for seasonal rise in manganese concentration. High levels of DO accelerates corrosion in water pipes. Low levels of DO can cause an increase in ferrous iron concentration, resulting in discoloration at the tap when water is aerated. 監測溶氧和水源水的溫度可以為季節性的錳濃度上升提供預警。高濃度的溶氧會加速水管的腐蝕。低濃度的溶氧會導致亞鐵濃度增加，導致在水暴露於空氣時變色。
It is important to maintain a balanced concentration of DO in finished water discharged into the distribution system. Balanced DO can improve the taste of drinking water. 對於要輸送到配水系統的飲用水，保持水中溶氧的平衡濃度非常重要。平衡的溶氧量可以改善飲用水的口感。
Drinking Water Treatment 飲用水處理
Monitoring of DO and the temperature of the source water can provide early warning for seasonal rise in manganese concentration. High levels of DO accelerates corrosion in water pipes. Low levels of DO can cause an increase in ferrous iron concentration, resulting in discoloration at the tap when water is aerated. 監測溶氧和水源水的溫度可以為季節性的錳濃度上升提供預警。高濃度的溶氧會加速水管的腐蝕。低濃度的溶氧會導致亞鐵濃度增加，導致在水暴露於空氣時變色。
Beverage Industry 飲料產業
Soft drink corporations set quality standards for DO levels to stabilize taste, to ensure shelf-life and to avoid corrosion in the packaged cans. 汽水飲料公司製定其飲料溶氧量的品質標準，以穩定口感、確保保存期限並避免包裝罐發生腐蝕。
Breweries monitor DO because fermentation requires oxygenation. However, for packaging, low DO levels are necessary to improve shelf-life and to stabilize taste/odor. (DO measurement in craft brewing) 啤酒廠監測溶氧，因為發酵需要氧合。然而，對包裝而言，低溶氧量是延長保存期限和穩定味道/氣味所必需的。 （精釀啤酒的溶氧測量）
Wine producers maintain low DO content by adding sulfites to the product to prevent oxidation, loss of aroma, discoloration, rapid aging and the growth of microorganisms. 葡萄酒製造商透過在產品中添加亞硫酸鹽來保持較低的溶氧量，以防止氧化、香氣流失、變色、快速熟化和微生物生長。
Juice producers maintain low DO to ensure flavor stability. 果汁生產商保持低溶氧以確保果汁風味穩定。
Aquaculture 水產養殖
In aquariums and fish farms, a minimum DO level of 4.5 mg/L is necessary to support fish life. Too much DO can result in promoting diseases. 在水族館和養殖漁場中，最低溶氧量必須達到 4.5 mg/L 才能維持魚類的生存。溶氧過多會引發疾病。
Environmental Monitoring 環境監測
Without a healthy concentration of DO, a body of water can experience hypoxia – a condition in which there is not enough oxygen to support aquatic life. 如果溶氧濃度不健康，水體就會出現缺氧現象，也就是沒有足夠的氧氣來維持水生生物的生存。
How is Dissolved Oxygen Monitored 如何監測水中溶氧 ?
As DO is a dissolved gas, it must be measured on site, ideally in the body of water. Drawing a grab sample introduces atmospheric oxygen and temperature changes interfering with the accuracy of the measurement. 由於溶氧是一種溶解氣體，因此必須在現場測量，最好是在水體中進行測量。抽取樣本會引入大氣中的氧氣和溫度變化，進而干擾測量的準確度。
Optical Sensors 光學感測器
This method uses light and luminescent material to measure DO. These electrodes require less maintenance, hold calibration, are not affected by hydrogen sulfide or other dissolved gases. They offer accuracy, stability and reproducibility at fast response times. 此方法使用光和光學材料來量測溶氧。這類分析電極(探頭)需要的維護較少，保持校正，不受硫化氫或其他溶解氣體的影響。在快速反應時間內提供準確度、穩定度和可重複性。
This method uses light and luminescent material to measure DO. These electrodes require less maintenance, hold calibration, are not affected by hydrogen sulfide or other dissolved gases. They offer accuracy, stability and reproducibility at fast response times. 此方法使用光和光學材料來量測溶氧。這類分析電極(探頭)需要的維護較少，保持校正，不受硫化氫或其他溶解氣體的影響。在快速反應時間內提供準確度、穩定度和可重複性。
Electrochemical Sensors 電化學感測器
This method utilizes Galvanic or Clark-type electrodes (anode and cathode in an electrolyte solution) to measure DO. To ensure accuracy the electrodes require frequent calibration and water samples must be gently stirred. 此方法利用伽伐尼電極或克拉克電極（電解質溶液中的陽極和陰極）來測量溶氧。為確保準確度，電極需要經常校正，並且必須輕輕攪拌水樣。
This method utilizes Galvanic or Clark-type electrodes (anode and cathode in an electrolyte solution) to measure DO. To ensure accuracy the electrodes require frequent calibration and water samples must be gently stirred. 此方法利用伽伐尼電極或克拉克電極（電解質溶液中的陽極和陰極）來測量溶氧。為確保準確度，電極需要經常校正，並且必須輕輕攪拌水樣。
Colorimetric Method 比色法
Indigo carmine reacts with the DO in the water producing a blue color proportional to the DO concentration. The blue color can be visually compared to a chart or read with a colorimeter or spectrophotometer. This method is portable and suitable for field-use but it has limitations. The water must be transparent and free of particulates. 靛藍胭脂紅與水中的溶氧反應，產生與溶氧濃度成比例的藍色。可以透過圖表直觀地比較藍色，或使用比色計或分光光度計讀取藍色。此方法方便攜帶且適合戶外或廠區使用，但也有其限制。水必須透明且不含微粒。
Indigo carmine reacts with the DO in the water producing a blue color proportional to the DO concentration. The blue color can be visually compared to a chart or read with a colorimeter or spectrophotometer. This method is portable and suitable for field-use but it has limitations. The water must be transparent and free of particulates. 靛藍胭脂紅與水中的溶氧反應，產生與溶氧濃度成比例的藍色。可以透過圖表直觀地比較藍色，或使用比色計或分光光度計讀取藍色。此方法方便攜帶且適合戶外或廠區使用，但也有其限制。水必須透明且不含微粒。
Winkler Titration 溫克勒滴定法
This method is performed by adding chemicals (manganese, iodide and hydroxide) to water samples to create a reaction with the DO that forms an acidic solution. The amount of alkali reagent required to neutralize the acid with titration, indicates how much DO was in the original water sample. Though it is considered a traditional method in some areas, it is time consuming and subject to human error. No online instrumentation exists for this method. 此方法透過在水樣中加入化學物質（錳、碘化物和氫氧化物）與溶氧反應，形成酸性溶液。用滴定法中和酸所需的鹼性試劑的量來顯示原始水樣中的溶氧量。儘管在某些領域被認為是一種傳統方法，但它很耗時且容易出現人為錯誤。此方法目前尚未有線上儀器。
This method is performed by adding chemicals (manganese, iodide and hydroxide) to water samples to create a reaction with the DO that forms an acidic solution. The amount of alkali reagent required to neutralize the acid with titration, indicates how much DO was in the original water sample. Though it is considered a traditional method in some areas, it is time consuming and subject to human error. No online instrumentation exists for this method. 此方法透過在水樣中加入化學物質（錳、碘化物和氫氧化物）與溶氧反應，形成酸性溶液。用滴定法中和酸所需的鹼性試劑的量來顯示原始水樣中的溶氧量。儘管在某些領域被認為是一種傳統方法，但它很耗時且容易出現人為錯誤。此方法目前尚未有線上儀器。
What is Dissolved Oxygen (DO) 什麼是溶氧 ?
Dissolved oxygen is a measure of the amount of gaseous oxygen contained in water. Healthy waters that can support life must contain dissolved oxygen (DO). 溶氧量是衡量水中氣態氧含量的指標。能夠維持生命的健康水體必須含有溶氧（DO）。
Dissolved oxygen is a measure of the amount of gaseous oxygen contained in water. Healthy waters that can support life must contain dissolved oxygen (DO). 溶氧量是衡量水中氣態氧含量的指標。能夠維持生命的健康水體必須含有溶氧（DO）。