Source : Hach US

 

Reliable Monitoring of Adenosine Triphosphate (ATP) in Water Reuse and Reverse Osmosis Treatment

Hach® EZ7300 Adenosine Triphosphate (ATP) Analyzer Successfully Used as a Measurement Surrogate for Log Removal Value to Monitor Reverse Osmosis Performance and Integrity

Hach® EZ7300 水中三磷酸腺苷 (ATP) 線上分析儀成功用於作為對數去除值的替代測量，來監測RO逆滲透的效能以及完善程度

 

背景介紹

Orange County Water District’s Groundwater Replenishment System (GWRS) is the largest indirect potable reuse facility in the world, producing 100 million gallons per day of highly purified water to replenish groundwater (which is the region’s primary drinking water supply) and to maintain a local underground seawater intrusion barrier. The GWRS Advanced Water Purification Facility utilizes a multiple-barrier approach to recycle secondary-treated wastewater through treatment by microfiltration (MF), reverse osmosis (RO), and ultraviolet disinfection with hydrogen peroxide addition (UV/H2O2)

美國加州橘郡水務局的地下水補給系統 Orange County Water District’s Groundwater Replenishment System(GWRS) 是世界上最大的間接飲用水回收設施，每天生產1 億加侖高純淨水，以補充地下水（這是該地區的主要飲用水供應）並維持作為當地地下海水入侵水源的屏障。 GWRS 先進水淨化廠採用多屏障方法，透過微過濾 (MF)、逆滲透 (RO) 以及加入過氧化氫的紫外線消毒 (UV/H2O2) 來回收二級處理後的污水。

Orange County Water District Potable Water Reuse Facility (Fountain Valley, CA)

 

回收水的逆滲透處理
To comply with local regulations and demonstrate effective treatment of wastewater, potable reuse facilities in California are required to demonstrate a high log removal value (LRV) for their overall treatment scheme. This LRV ensures that effective treatment removes bacteria, giardia, cryptosporidium, viruses, and other harmful contaminants.

為遵循加州當地法規標準並證明能有效處理污水，加州的飲用水回收處理設施必須證明其整體水處理方案具有高對數去除值 (LRV)。 LRV 可確保有效處理去除細菌、賈第鞭毛蟲、隱孢子蟲、病毒和其他有害污染物。

RO is a widely accepted treatment technology in reuse scenarios, serving as a physical barrier to pathogens and most dissolved constituents. However, for potable reuse, pathogen removal credit for RO systems is dependent upon proving continuous integrity of the membranes, usually through online monitoring of a surrogate for virus rejection.
逆滲透是回收水領域當中被廣泛接受的一種處理技術，可作為病原體和大多數溶解成分的物理屏障。 然而，對於飲用水的再利用，逆滲透系統的病原體去除程度取決於能證明膜的持續完善程度，通常是透過線上監測病毒排斥的替代物質。

 

Traditional surrogates, such as total dissolved solids and total organic carbon (TOC), demonstrate only 1-2 logs of removal credit. These values are much lower than the 6 logs of virus removal demonstrated by RO in past studies. In order to obtain greater log removal credits, new surrogates are necessary.

傳統的替代監測指標 : 例如總溶解固體和總有機碳 (TOC)，僅顯示 1-2 個對數的去除積分。 而這些數值遠低於 RO 在過去研究中所證明的 6 個病毒去除對數。 為獲得更大的對數去除積分，需要監測新的替代物質。

 

Currently, not all promising surrogates have an effective online monitor as an alternative to laboratory grab sample methods. In some cases, a same-day lab analysis may be a viable alternative, however the water district wanted to demonstrate that a higher LRV could be shown for their RO system through the use of an effective online monitoring strategy.

目前並非所有可能的替代物質都能透過有效的線上監測儀來取代實驗室取樣方法。 在某些情況下，同一天的實驗室分析也許是可行的方案，但橘郡水務局希望能夠透過使用有效的線上監測方案證明其 RO 系統可顯示出更高的 LRV。

 

Therefore, a study was initiated to determine whether Adenosine Triphosphate (ATP) could serve as this new, effective surrogate for membrane integrity monitoring. Goals of this pilot study were to:

於是，研究計畫啟動，以確定三磷酸腺苷 (ATP) 是否可以做為這種新的、有效的膜完善程度監測替代物質。 此項試驗研究的目標是：
• Identify better, more representative surrogates for use in monitoring RO performance for potable reuse  鑑別出更好、更具代表性的替代物質 - 用於監測再生飲用水的逆滲透效能
• Understand the measurable permeate concentrations of the surrogates, including free ATP 了解替代物質的可測量滲透濃度，包括遊離 ATP
• Identify a cost effective, reliable online monitor of RO membrane integrity  鑑別出具有成本效益、可靠的逆滲透膜完善程度的線上監測儀器
•  Achieve higher log removal credits than conductivity and TOC  達到比導電度和 TOC 還更高的對數去除積分

 

Free ATP was measured every 30 minutes for approximately 5 months. In contrast to cellular ATP bound inside bacterial cells, free ATP is dissolved in the extracellular portion of the water sample, and was chosen over cellular ATP as the primary analyte for use for LRV monitoring due to the need to demonstrate high removal of (large) molecules dissolved in water.

大約 5 個月內，每 30 分鐘測量一次遊離 ATP。 與結合在細菌細胞內的細胞 ATP 不同，遊離 ATP 溶解在水樣的細胞外部分，由於需要證明高度去除溶解在水中的(大)分子，證明（大量）的高去除率，因此選擇細胞 ATP 為 LRV 監測的主要分析物。

 

Figure 1 shows free ATP in the RO feed (yellow) and RO permeate (green) and calculated LRVs (blue). Over 5 months of continuous online free ATP analysis, the free ATP average was 3.03, with minimum value of 2.60 and maximum value of 3.30.

圖 1 顯示 RO 進水(黃色)和 RO 滲透水(綠色)中的遊離 ATP 以及計算的 LRV(藍色)。 超過5個月時間的連續線上遊離ATP分析，遊離ATP平均值為3.03，最小值為2.60，最大值為3.30。

 

The pilot study successfully showed that free ATP was removed by the RO treatment process as evidenced by the difference between free ATP values between the RO feed and RO permeate.

初步研究成功顯示，RO 處理過程去除了遊離 ATP，從RO 進水和 RO 滲透水之間遊離 ATP 值之間的差異證明了這一點。

Figure 1. Continuous online free ATP measurements collected every 30 minutes. Average LRV = 3.03. Min LRV = 2.60; Max LRV = 3.30. Note: Data
gap in November 2019 was due to pilot source water not being available. 2020 project data gap was result of Covid-19 pandemic.

 

結論
The results of the pilot study and the performance of the EZ7300 ATP analyzer provide a new approach for the water district to demonstrate the continuous integrity of the RO process, which is a critical step in the water purification process. Continuous monitoring by the analyzer provided these additional benefits:

試驗研究的結果和 EZ7300 ATP 分析儀的效能為加州橘郡水區提供了新方法，證明 RO 程序的持續完善程度，這是水淨化過程中的關鍵步驟。 分析儀的連續監測並且提供以下額外的優點：
• Online monitoring of free ATP across the RO system yields a higher LRV than the traditional surrogates TOC and electrical conductivity.  線上監測整個RO 系統中的遊離ATP 可產生比傳統替代TOC 和導電度更高的LRV。
• Improved monitoring of RO integrity may allow greater pathogen log reduction regulatory credits (LRV).  改良的RO 完善監控可能帶來更大的病原體對數減少監管積分(LRV)。
• Higher LRV increases confidence, from both the industry and public, in RO’s ability to remove high levels of pathogens.  更高的LRV 數值同時提升產業以及公眾對於逆滲透去除高濃度病原體能力的信心。
• The self-cleaning routine of the analyzer ensures that sample carryover and instrument contamination does not occur.  EZ7300 ATP分析儀的自清潔程序確保不會發生樣品殘留和儀器污染。

EZ7300 ATP Analyzer installed

 

This study demonstrated that Adenosine Triphosphate (ATP) is continuously present in treated wastewater, as a naturally occurring compound of biological origin. It is present in high concentration in the RO feed and in measurable concentrations in RO permeate; this combined with its high removal by RO makes free ATP an excellent candidate for LRV demonstration.
Free ATP concentrations in the RO feed and permeate can be successfully and continuously monitored by the EZ7300 online analyzer.