BACTERIAL LOAD OF BOVILLA RESERVOIR DURING MASSIVE RAINFALL

Bovilla reservoir is situated 15 km North-East of Tirana the capital city of Albania and is the main source of drinking water supply for this city. The reservoir is fed mainly from Terkuza River with an annual average flow 3.3 m/s. Approximately 1800 l/s of raw water is abstracted from the reservoir and is delivered toward Bovilla Water Treatment Plant. The beginning of rain season or massive rainfall, frequently are accompanied with an increase of turbidity due to runoff from Terkuza River. Therefore, is expected an increase of bacterial load. The purpose of this paper is the determination of Bovilla’s bacterial load during massive rainfall and comparison with bacterial load in normal condition. This study was conducted from October 2010 until April 2012. Water samples were collected near the withdrawal tower in 15 m deep, which corresponds with the depth of water that is abstracted for treatment for human consumption. The samples were taken weekly and were analyzed for some physical-chemical and microbiological parameters such as: water temperature, pH, turbidity, ammonium, nitrates, nitrites, ferrous, total coliforms, fecal coliforms, faecal streptococci, bacterial microflora in 220C and bacterial microflora in 360C. Results have shown that during rainfall the values of turbidity, ammonia and ferrous differed clearly from the values obtained for samples in normal conditions. Most of microbiological parameters investigated increased considerably during massive rainfall events.