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Sludge basics

Image of wet sludge, indicating gradual movement

What is sludge?

Sludge characteristics depend on both the original feedwater quality and the type of the unit operation from which the sludge is discharged.

For conventional municipal wastewater treatment, the two main sludge streams are from the primary sedimentation stage, producing primary sludge, and the secondary biological treatment stage, producing waste activated sludge (WAS) if the biological treatment is based on the activated sludge process.

More on sludge basics

Sludge processing: the basics Source: Judd Water & Wastewater Consultants / YouTube

Sludge processing: the basics

An introduction to sludge treatment − Simon Judd gives a brief overview to sludge processing in the context of wastewater treatment.

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Sludge processing explainers

Explore our content on sludge stabilisation, conditioning, thickening, dewatering, drying, and thermochemical processes

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Biosolids vs sewage sludge

Biosolids are usually considered to be the useful fraction of the sewage sludge. They are generally higher in solids concentration and lower in pathogen content, having gone through a stabilisation process such as chemical dosing, digestion and/or drying.

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