Waste-Activated Sludge Treatment Processes

Waste-Activated Sludge Treatment Processes

Chin Heng Gan (Universiti Tunku Abdul Rahman, Malaysia) and Siew Hoong Shuit (Universiti Tunku Abdul Rahman, Malaysia)
DOI: 10.4018/978-1-7998-0369-0.ch011
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Biological processes are the most common methods to treat wastewater but they produce huge amounts of waste-activated sludge (WAS) as a by-product. WAS generated during wastewater treatment must be stabilized sufficiently prior to ultimate disposal. The most common methods of sludge stabilization are biological processes (aerobic or anaerobic digestion) due to simplicity of the operation, and lower operating and maintenance costs for similar wastes. Anaerobic digestion remains the principal process for the stabilization of sludge solids as organic waste is converted into methane-rich biogas and fertilizer in an oxygen-free environment. However, WAS treatment processes are often a challenging problem. Therefore, the characteristics of WAS are discussed to have a better understanding so as to treat it efficiently. Various kinds of treatment processes such as physicochemical treatment, biological treatment, and combined treatment are the focus of this chapter; however, many concepts developed in this chapter apply to anaerobic digestion to stabilize the WAS.
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Overview Of Wastewater Treatment Processes

Activated sludge, aerated lagoons, rotating biological contactors and trickling filters are the most common wastewater treatment processes being used in Malaysia (“Sewage,” 2016). In an activated sludge system, the wastewater first passes through the preliminary process (screening, grease and grit removal), followed by primary clarifier, aeration, secondary clarifier, filtration and eventually disinfection process before being discharged as show in Figure 1.

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