bulking control in complete-mixed activated sludge process using combination of metallic coagulants and static magnetic fields

Metallic coagulants have been used for more coagulation and flocculation of flocs in many wastewatertreatment plants (wwtps) in all parts of the world. the integration of different methods to improve thewastewater treatment process has been considered in recent years. in this case-control study, the effects offour main coagulants (ferric chloride, ferric sulfide, alum, and poly-aluminum chloride) on sludge volumeindex (svi) with and without exposure of static magnetic fields (smfs) have been investigated. bothmethods significantly reduced svi (ml/g), but the combination of smfs and coagulants was more effective.ferric chloride could control bulking or reduce svi to less than 150 ml/g at concentrations of 0.0625 to2 g/l when the smfs intensity of 15 mt was used. the control of bulking in other coagulants happenedwhen smfs were added to coagulants at 0.0625-0.125 g/l concentration of coagulants (p < 0.05). with theapplication of smfs, the highest reduction of svi belonged to ferric sulfide (43.60%), followed by ferricchloride (18.40%), poly-aluminum chloride (pacl) (20.19%), and alum (19.80%). without the applicationof smfs, the highest reduction of svi belonged to ferric chloride (38.36%), followed by alum (34.94%),pacl (25.43%), and ferric sulfide (6.69%).