Which of the following process is not involved in sludge thickening?
(a) Gravity thickening
(b) Vacuum filter
(c) Air flotation
(d) Centrifugation
I had been asked this question in class test.
I'd like to ask this question from Sludge Thickening, Sludge Dewatering in section Sewage Filtration and Activated Sludge Process of Environmental Engineering