Pneumatic flocculation in water treatment

Kazi, N.M., 1995. Pneumatic flocculation in water treatment. PhD, Nottingham Trent University.

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The removal of turbidity by flocculation is based on the amount of the temporal mean velocity gradient. Many means are available to produce the velocity gradients and one of these is pneumatic flocculation.

This thesis describes an investigation of the development of a technique of air diffusion that generates a specific temporal mean velocity gradient to enhance the flocculation of suspended materials. Three types of synthetic turbidity namely kaolin, lycopodium and polyvinyl chloride (PVC) were coagulated with aluminium sulphate and ferric sulphate. Each material was flocculated under constant and step-down agitation using a diffused air model treatment process. Four air diffusion pads with different sizes of orifice 1.0, 1.5, 2.0 and 3.0 mm in diameter were used in order to investigate the optimum orifice size and the optimum air flow rates.

The best turbidity removal was obtained with an orifice diameter of either 1.5 mm (78.00% to 94.81% removal) or 2.0 mm (83.18% to 96.00% removal). The optimum range of air flow rate per unit area of the flocculator was found to be 0.077 to 0.618 and 0.077 to 0.463 cc/ for the diffusion pads of orifice sizes of 1.5 and 2.0 mm respectively.

Removal of soluble iron, aluminium and nitrogenous matter in the process of coagulation followed by pneumatic flocculation through forming the hydroxide which is a non soluble matter and other physicochemical processes which might occur during the flocculation and settling processes.

A mathematical relationship has been established to describe the kinetics of the pneumatic flocculation in terms of the process variables.

The pneumatic flocculator required 1/16 of the power required for the mechanical flocculator in order to obtain the same degree of treatment.

Item Type: Thesis
Creators: Kazi, N.M.
Date: 1995
ISBN: 9781369312874
Divisions: Schools > School of Science and Technology
Record created by: Linda Sullivan
Date Added: 28 Aug 2020 09:37
Last Modified: 08 Jun 2023 10:13

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