The reduction in the Spectral Absorption Coefficient (SAC 254 nm) correlates with the removal rate of organic substances, hence micropollutants, in wastewater. Therefore, this coefficient can be applied as a sum parameter for micropollutants and is suited to monitor the reduction of the indicator substances and the treatment efficiency of the PAC-stage. Experience has shown that with an effective SAC254 reduction by 40%, an average removal of 80% of indicator substances can be achieved during the PAC adsorption process1.

光譜吸收係數 (SAC 254 nm) 的降低與污水中有機物質（即微污染物）的去除率有相關聯。因此，此係數可作為微污染物的總和參數，適合監測指標物質的減少量和PAC階段的處理效率。經驗顯示，在PAC吸附過程中，當 SAC254 指數下降40%，平均可去除80%的指標物質 註1。

 

Kressbronn-Langenargen WWTP has applied one UVAS probe in the effluent of the clarifier from the biological step and another one in the effluent of the sand filter to measure SAC254. The measurement points can be seen in Figure 4. These probes have been installed since 2011 and are still operating with little maintenance. The instrumentation is connected to the SC1000 controller which can show measurement data and curves of each parameter in real-time. Another measuring method considered by the WWTP is to use DR6000 to measure the absorption coefficient in the laboratory as a reference value. Figure 5 shows recorded data of the online measured SAC254 by the two UVAS probes and the resulting ΔSAC254. It can be seen that the elimination rate drops to 20% a few times in the recorded period. Those events correlated with rainfall.

Kressbronn-Langenargen 污水處理廠在生物處理步驟的澄清池排放水口安裝一個 UVAS 有機物感測器，以及在砂濾池的排放水口安裝另一個 UVAS 有機物感測器來測量 SAC254。測量點如圖 4 所示。感測器與SC1000控制主機連接，可即時顯示各參數的測量數據和曲線。污水處理廠考慮的另一種測量方法是使用DR6000分光光度計在實驗室測量吸收係數作為參考值。圖 5 顯示以兩個 UVAS 有機物感測器線上測量 SAC254 的記錄數據以及所得的 ΔSAC254。可以看出，在記錄期間內，去除率曾多次下降至20%。這些事件與降雨有關。

 

1 Roessler et al. (2016): Application of SAC254 measurement for the assessment of micropollutant removal in the adsorptive treatment stage of a municipal wastewater treatment plant

 

Considerations
In order to protect sensitive water bodies from pollution wastewater treatment plants should be upgraded with the adsorptive treatment step to prevent the discharge of organic micropollutants. With the construction of a completely new treatment stage using powdered activated carbon at the Kressbronn-Langenargen WWTP in 2011, new challenges with monitoring and control came up. To understand the processes within this treatment stage, Hach provided instrumentation for monitoring and control from the point of influent to the effluent.

為保護敏感水體不受污染，污水處理廠升級吸附處理步驟，以防止排放有機微污染物。 2011 年，隨著 Kressbronn-Langenargen 污水處理廠採用粉狀活性碳建造全新的水處理階段，監控方面有了新的挑戰。為了解此處理階段的流程，Hach提供從進水口到排放水口的監控儀器方案。

 

As the reduction rate of SAC254 correlates with the elimination rate of micropollutants, online monitoring of this parameter with UVAS plus provides the customer with the real-time information about the efficiency of the adsorption and if the target is achieved.

Therefore, this customer plans to use SAC254 to fit the operation to the dynamic load in the PAC process in the future. Measuring TSS with Solitax helps the customer to keep the PAC concentration balanced in the treatment cycle. The Solitax for Turbidity is applied in the effluent of the sedimentation tank and of the sand filter to detect any PAC loss. The improved performance of the Phosphorus reduction could be tracked by Phosphax Sigma.

由於 SAC254 的降低率與微污染物的去除率相關，因此使用 UVAS plus 分析儀線上監測相關參數，為客戶提供有關吸附效率以及是否達到目標的即時資訊。
因此，客戶計劃未來使用SAC254來因應PAC過程中的動態負荷量。使用 Solitax 濁度/懸浮固體線上分析儀測量 TSS懸浮固體以協助客戶在污水處理循環中保持 PAC粉狀活性碳濃度平衡。Solitax for Turbidity  濁度線上分析儀安裝於沉澱池和砂濾池的排放水口，以監測是否有 PAC 耗損。 Phosphax Sigma 分析儀則可以追蹤水中磷濃度降低的效能改善。

 

The customer at the Kressbronn-Langenargen WWTP operates this adsorption stage with using the reliable solution from Hach from the beginning since 2011 and it has proved to be a beneficial tool for process monitoring and control. The high quality of the instrumentation could hold out against the abrasive characteristics of activated carbon and requires low maintenance.

Kressbronn-Langenargen 污水處理廠的客戶自 2011 年起使用Hach儀器方案來監測操作該吸附階段，實據證明了其為水處理過程監控的有效工具。

 

The Hach solution for controlling adsorption with powdered activated carbon is implemented not only at Kressbronn-Langenargen WWTP but also at several other wastewater treatment plants in Germany and Switzerland and can also be applied for monitoring and control of adsorption with granular activated carbon as well as ozonation.
監控粉狀活性碳吸附的Hach水質監測儀器方案除了安裝於 Kressbronn-Langenargen 污水處理廠，也安裝於德國和瑞士的其他幾個污水處理廠，並且可用於監控顆粒活性碳吸附和臭氧化。