Around the world, wastewater is most commonly treated using the activated sludge process. This process involves mixing incoming wastewater with activated sludge, a refined bacterial suspension optimized for biological wastewater treatment. The physical properties of the activated sludge are crucial for the efficiency of many energy-demanding processes in wastewater treatment plants. For example, the settling properties of sludge determine how easily it can be separated from the cleaned water in the final stage of treatment. Additionally, the dewatering properties of sludge are important for the cost of sludge disposal and polymer dosage.
Currently, the most frequently used methods for characterizing sludge settling properties are the Sludge Volume Index (SVI) and the Diluted Sludge Volume Index (DSVI). In both methods, 1 liter of mixed sludge is allowed to settle for 30 minutes in a standard 1-liter laboratory measuring cylinder. Afterward, the sludge volume (SV) is measured, and the indexes can be calculated if the sludge suspended solids concentration is known. The only difference between SVI and DSVI is that the sludge in DSVI is diluted to ensure unhindered settling. However, since the sludge often only settles unhindered for about 15 minutes, the remaining time involves more compression or hindered settling. In other words, SVI and DSVI are mixed parameters influenced by different physical sludge properties, such as settling speed and compression.
The Sludge Physics Analyser allows you to measure SVI, DSVI, free/unhindered settling speed, and compression separately, providing much more direct and process-relevant data. Due to the significant impact of sludge physical properties, there is a strong focus in the scientific community on developing methods to test these properties and determine which ones are important. However, the implementation of these methods in routine plant management is still lagging behind. Therefore, we have developed the Sludge Physics Analyser, which is suitable for routine laboratory applications in wastewater treatment plants.
Read more about the Sludge Physics Analyser here.
