The correct answer is: B. Percentage of sludge by volume to percentage of total solids by weight.
Sludge volume index (SVI) is a measure of the settling characteristics of activated sludge. It is defined as the volume of sludge (in milliliters) that is produced by 1 gram of dry solids after 30 minutes of settling at 20°C.
SVI is an important parameter in wastewater treatment because it is a measure of the sludge’s ability to settle and compact. A high SVI indicates that the sludge is difficult to settle and compact, which can lead to problems with sludge handling and disposal.
There are a number of factors that can affect SVI, including the type of wastewater being treated, the operating conditions of the wastewater treatment plant, and the type of sludge conditioning agent being used.
SVI can be reduced by a number of methods, including:
- Increasing the dissolved oxygen concentration in the wastewater treatment plant
- Increasing the hydraulic retention time in the wastewater treatment plant
- Using a sludge conditioning agent
- Increasing the temperature of the wastewater treatment plant
SVI is an important parameter that should be monitored regularly in wastewater treatment plants. A high SVI can lead to problems with sludge handling and disposal, so it is important to take steps to reduce SVI if it is too high.
Here is a brief explanation of each option:
- Option A: Percentage of sludge by volume to percentage of suspended solids by weight. This is not the correct definition of SVI. SVI is defined as the volume of sludge (in milliliters) that is produced by 1 gram of dry solids after 30 minutes of settling at 20°C.
- Option B: Percentage of sludge by volume to percentage of total solids by weight. This is the correct definition of SVI.
- Option C: Percentage of suspended solids by weight to percentage of sludge by volume. This is not the correct definition of SVI. SVI is defined as the volume of sludge (in milliliters) that is produced by 1 gram of dry solids after 30 minutes of settling at 20°C.
- Option D: Percentage of total solids by weight to percentage of sludge by volume. This is not the correct definition of SVI. SVI is defined as the volume of sludge (in milliliters) that is produced by 1 gram of dry solids after 30 minutes of settling at 20°C.