Vai trò của chỉ số SVI trong xử lý nước thải

**The SVI Index in Wastewater Treatment** The SVI (Sludge Volume Index) is a crucial parameter used to assess the settling ability of sludge in wastewater treatment systems. Understanding the role of SVI helps operators detect issues early and make timely adjustments. Let’s explore the impact of the SVI index on wastewater treatment efficiency and how it is calculated. --- ### **Table of Contents** - What is the SVI Index? - How to Calculate the SVI Index in Wastewater - The Role of the SVI Index in Wastewater Treatment - Methods to Adjust the SVI Index - When SVI is High - When SVI is Low --- ### **What is the SVI Index?** The SVI index, or Sludge Volume Index, is a measurement that indicates the settling characteristics of activated sludge in a biological treatment system. It is expressed in milliliters per gram (mL/g) and is determined by measuring the volume of settled sludge after 30 minutes in a graduated cylinder. SVI provides valuable information about the density, settling ability, and cohesion of the sludge. A low SVI value suggests that the sludge settles quickly and forms a compact layer, which is typically a good sign for the treatment process. On the other hand, a high SVI value may indicate sludge bulking or poor settling, leading to floating sludge in the clarifier and reduced effluent quality. --- ### **How to Calculate the SVI Index in Wastewater** To calculate the SVI index, you measure the volume of sludge that settles in a 1000 mL graduated cylinder after 30 minutes, then divide that volume by the concentration of mixed liquor suspended solids (MLSS) in grams per liter (g/L). $$ \text{SVI} = \frac{\text{Volume of Settled Sludge (mL)}}{\text{MLSS (g/L)}} $$ This method gives an accurate indication of sludge behavior. However, it can be time-consuming and prone to human error during reading and calculation. --- ### **The Role of the SVI Index in Wastewater Treatment** The SVI index plays a vital role in monitoring the performance of the activated sludge process. Here's what different SVI values indicate: | **SVI Value (mL/g)** | **Condition** | |----------------------|---------------| | < 50 | Potential pinfloc – potential for sludge bulking | | 50–100 | Optimal sludge condition | | 100–150 | Filamentous growth – possible sludge bulking | | 150–200 | Bulking at high flows – increased sludge volume | | > 200 | Severe bulking – poor settling and cloudy effluent | An ideal SVI range is generally between 100–200 mL/g. A lower SVI means better settling and denser sludge, while a higher SVI indicates poor settling and potential operational problems. By monitoring the SVI, operators can identify issues early and take corrective actions to maintain efficient wastewater treatment. --- ### **Methods to Adjust the SVI Index** #### **When SVI is High (SVI > 120 mL/g)** **Symptoms:** - Large, swollen flocs - Poor settling and excessive sludge **Impact:** - Reduced removal efficiency of COD, TN, and ammonia - Sludge aging and floating sludge **Solutions:** - Remove excess sludge - Add nutrients and aerobic microorganisms - Maintain SV30 between 300–500 mL/g - Keep MLSS between 3–5 g/L #### **When SVI is Low (SVI < 50 mL/g)** **Symptoms:** - Small flocs and slow settling - Low SV30 **Impact:** - Lower removal efficiency of contaminants **Solutions:** - Add more seed sludge and aerobic microorganisms - Maintain SV30 between 300–500 mL/g - Keep MLSS between 3–5 g/L --- ### **Conclusion** The SVI index is a key indicator of sludge performance in wastewater treatment. By understanding and managing this parameter, operators can ensure stable and efficient treatment processes. If you need help measuring or adjusting your SVI, contact **Môi Trường Song Phụng** for expert support and guidance. --- ### **Related Services from Môi Trường Song Phụng** - On-site chemical dosing system installation - Replacement of filter media in water filtration systems For more information or assistance, feel free to reach out. We’re here to help you achieve optimal wastewater treatment results.

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