Seasonal variations of the growth of filamentous bacteria in Kuwait’s wastewater treatment plants

If not controlled, excessive sludge bulking can lead to a complete failure of the entire wastewater treatment process. Selection of an appropriate control measure requires information about the filaments type, level of dominance and the most probable causes. The main aim of this paper is to present the filamentous bacteria identified in Kuwait’s wastewater treatment plants and to compare their seasonal levels of dominance. Wastewater samples were collected weekly from Riqqa and Um-Al-Haiman activated sludge systems in Kuwait for eight months. Vermicon identification technology, a molecular method, was used for the identification and quantification of the following six filamentous bacteria: Type 1851, H. hydrossis, Nocardioform, Type 021N/Thiothrix, N. Limicola and M. parvicella. The obtained results indicated that the rapid growth of the filaments was triggered by the sharp drop in water temperature during winter (January). Further, most of the filaments dominate the systems almost all through the year. Furthermore, Microthrix was found to have the highest rate of fluctuations.