If the grit in grit chambers is 4.5 million litres per day, its cleaning is done

ANS:A - manually

Cleaning grit chambers manually involves physical labor by workers to remove the accumulated grit from the chambers. Here's an explanation of the manual cleaning process:

1. Accessing the Grit Chamber: Workers must first gain access to the grit chamber, which may involve opening access doors or hatches leading to the chamber. Safety precautions, such as wearing appropriate personal protective equipment (PPE), are often necessary.
2. Manual Removal of Grit: Once inside the grit chamber, workers manually scoop or shovel the accumulated grit from the bottom of the chamber. This process requires physical effort as workers must handle and lift heavy loads of grit.
3. Transportation and Disposal: After removing the grit from the chamber, workers transport it to a designated disposal area. This may involve loading the grit onto carts, wheelbarrows, or other equipment for transportation. Depending on local regulations and practices, the disposed grit may be sent to a landfill, incinerator, or used for other purposes such as landfill cover or construction materials.
4. Cleaning and Maintenance: After the grit is removed, workers may need to clean and inspect the interior surfaces of the grit chamber to remove any remaining debris or buildup. Regular maintenance of the chamber, including repairs to any damaged or deteriorated components, may also be necessary to ensure continued functionality.
5. Safety Considerations: Manual cleaning of grit chambers can be physically demanding and potentially hazardous. Workers must follow safety protocols to minimize the risk of injury, such as using proper lifting techniques, wearing appropriate PPE, and avoiding contact with hazardous substances or equipment.

While manual cleaning can be effective, it is often labor-intensive and time-consuming compared to mechanical or automated methods. However, in some situations where mechanical equipment is not available or feasible, manual cleaning may be the preferred option for maintaining the performance of grit chambers in wastewater treatment systems.