Question

What is sludge? Explain how it is treated.

Answer 1

Hint:Sludge is a residue form from wastewater treatment. In sewage treatment plants, the residue that accumulates is called sludge. It is treated by anaerobic bacteria.

Complete answer:
First we should know about sewage to answer this question. Sewage is considered wastewater released from houses. As sewage consists of toxins and dangerous microorganisms that contaminate the water and cause water causing diseases in humans, raw sewage should not be dumped untreated into the sea.
The semi-solid, solid, or slurry residual content formed as a by-product of wastewater treatment operations is sewage sludge.
Using a skimmer, sludge is collected and then transported to a tank where it is decomposed for biogas processing by anaerobic bacteria.

Additional information: This residue is generally categorized into primary and secondary sludge. Chemical precipitation, sedimentation, and other primary processes produce primary sludge, while secondary sludge is the activated biomass of waste arising from biological treatment. Mixed sludge obtained from secondary wastewater treatment is moved via a dissolved-air flotation tank where solids lift to the surface and are skimmed off. The thickened sludge is mulched with steam, and transported to thermal hydrolysis where, under heat and pressure, large molecules such as proteins and lipids are broken down. A flash tank moves through the hydrolyzed sludge, where a rapid decrease in pressure allows cells to rupture, and then to anaerobic digestion, where bacteria turn dissolved organic matter into biogas.

Note:Biogas is a mixture of gases generated in the lack of oxygen (anaerobic) by the breakdown of organic matter, consisting primarily of methane and carbon dioxide. This biogas is used to heat, cook, etc. as a low-cost fuel. It is used to generate electricity as well.