(Source: Kwarciak-Kozłowska, 2019)
Sludge Transformation Methods
Adoption of sludge treatment and disposal options inside the wastewater treatment plant area, such as incineration and moist air oxidation, is rising because to increased competition for space in landfills, disposal prices, legislative limits, and incentives to sludge recycling countries (Kelessidis & Stasinakis, 2012). Sludge combustion, on the other hand, raises severe problems about air pollution and the proper disposal of remaining ashes. The following sludge transformation processes are covered in this section with their advantages and disadvantages:
Thermal Drying
Thermal drying is a very adaptable procedure for making pellets for agricultural reuse, sanitary landfill disposal, or incinerated. Heat is used to remove the moisture in the sludge (Andres, 2011). The pellets generated can be utilized to power boilers, industrial heaters, cement kilns, and other appliances. Thermal air heaters, tray dryers, and a condenser are used in the drying process. It has the following benefits and drawbacks (Table 9).
Table 9. Advantages and disadvantages thermal drying process in sludge transformation