(Source: Crini & Lichtfouse, 2019)
Incineration
The sludge stabilization procedure that gives the largest volume decrease is incineration. Incinerators may accept sludge from many treatment facilities and are often larger in size. Through burning in the presence of extra oxygen, sludge incineration eliminates organic compounds and harmful organisms (Schnell et al., 2020). Carbon, sulphur, and hydrogen, which are present as fat, carbohydrates, and proteins, are the combustible components found in sludge (Dmitrienko et al., 2020). Water vapour, carbon dioxide, Sulphur dioxide, and inert ashes are the byproducts of full sludge combustion. The quantity of oxygen required for full combustion of organic materials may be calculated using the organic components’ identification (Stasta et al., 2006). Due to the high price and complex operations required, incinerators are only used in sludge treatment in wastewater treatment plants serving big urban areas.
Landfill disposal
Landfilling is a process for safely disposing of solid urban garbage onto soil with minimal health risks and environmental implications, employing engineering approaches to confine the discarded waste to the lowest feasible area and volume, covered by a soil layer (Wang et al., 2010). Landfilling is likely the easiest approach in terms of management and materials handling (Oyedele et al., 2013). Landfilling now compares favorably to other alternatives in terms of cost. Landfilling, from an environmental aspect, inhibits the discharge of any sludge-borne contaminants or pathogens by concentrating the sludge in one place. The benefits and drawbacks of landfill disposal are summarized here (Table 11).
Table 11 . Advantages and disadvantages of landfill disposal