What are some common methods for sludge disposal?

All of the mentioned methods—landfilling, incineration, and land application as fertilizer—are common techniques for sludge disposal, making the comprehensive option correct.

Landfilling involves the disposal of sludge in a landfill, where it is buried and isolated from the environment. This method is straightforward but requires careful management to prevent groundwater contamination.

Incineration is another method employed to reduce the volume of sludge significantly and eliminate pathogens present in it. The process involves burning the sludge at high temperatures, which transforms it into ash, flue gases, and heat. This method is efficient for volume reduction and can also harness energy from the combustion process when designed as a waste-to-energy facility.

Land application as fertilizer utilizes the nutrient content of treated sludge, which can enrich soil and support agricultural practices. However, this method requires careful regulation to ensure that the application does not pose risks to human health or the environment.

Since all of these disposal techniques play significant roles in managing wastewater sludge, recognizing their applicability in different contexts is essential for effective wastewater management practices.