| Title |
Studies on the Characteristics and Control of Stable Foam Formation in Wastewater Treatment Systems |
| Authors |
(A . R . Khan) ; (Kyung Sok Min) ; (Yong Jun Jung) |
| Abstract |
In continuation of our pervious work, a foam forming species, Rhodococcus rubra, and the biological samples from actual wastewater treatment plants with the history of foaming were investigated. The hydrophobicity and foaming potential of the samples were measured. Laboratory scale control measures were studied by using an antifoaming agent (dimethyl siloxane, DMS) and a surface modifying chemical (polyethylene glycol, PEG). Although, higher hydrophobicity is implicated with stable foam formation, yet no clear-cut relationship was found in the existing studies, however further work would be needed to confirm this fact. A relationship between hydrophobicity and foaming was found which too was not strictly followed. Nostocoida-dominated foam samples were although more hydrophobic compared to Gordona (formerly Nocardia) dominated samples, yet there were marked differences in their foam stabilities, Gordona-dominated being more stable compared to Nostocoida. These studies have indicated that the stability of foams dominated by the causative species was found in the order: Rhodococcus 〉 Gordona 〉 Microthrix 〉 Nostocoida. The studies related to the control measures of foams indicated that dimethyl siloxane was more effective antifoaming agent compared to polyethylene glycol. However, the optimum dose of this antifoam required to disrupt stable foams was so high that can not be used during foaming in actual treatment plants due to higher risk of the oxygen transfer. |