Comparative study between polyaluminiumchloride and aluminiumtrichloride as coagulants for municipal waste water.

Type:
eindwerk
Titel:
Comparative study between polyaluminiumchloride and aluminiumtrichloride as coagulants for municipal waste water.
Auteur:
Hogeschool West-Vlaanderen. GKG; Demolder, Lies
Jaar:
2008
Taal:
Engels
Uitgever:
Kortrijk : GKG, 2008
Paginering:
60 p. + bijl. : ill.
Plaatsnummer:
GKG.ARCHIEF.EW.MIL.2008/4 (Graaf Karel de Goedelaan Kortrijk)
Samenvatting:
Eindwerk industrieel ingenieur milieukunde, One of the most used operative chemical species in the coagulation/flocculation process is aluminium. Adding aluminiumions (Al3+) to the waste water causes a reaction with the hydroxide ions such that aluminium hydroxide is formed. These gelatinous flocs settle slowly and cause the suspended solids in the waste water to sweep out. Polyaluminiumchloride (PAC) and aluminiumtrichloride (AlCl3), both containing aluminium in their compound, are used as coagulants in these experiments. The utilized flocculant is Flocan 23, a medium charged anionic polyacrylamide. In water, this polyelectrolyte forms a soft gel that causes the particles to bind together via interparticle bridging. Because of this, the three-dimensional floc grows in size and can be removed much easier by sedimentation. To determine the optimum amount of the coagulants PAC (14 % Al3+) and AlCl3 (14 % AlCl3) and the flocculant Flocan 23 (1 g/l), the Jar test was executed. This is a lab-scale simulation of the coagulation/flocculation process whereby the pH, the mixing speed, the retention time, the temperature, the type of chemicals and the sequence of their addition are the most important parameters. After the treatment of the waste water, the following tests are performed to compare the effects of the different amounts of the coagulants and the flocculant: - determination of the amount of sludge by using the Imhoff cone - determination of the amount of suspended solids (SS) in the clarified liquid by means of a vacuum filtration - determination of the chemical oxygen demand (COD) of the superior liquid through the micro COD method using prepared digestion vials
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