(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