Abstract
Recently reported virus contamination in natural waters is considered to be closely dependent upon insufficient virus removal in the sewage treatment process. Therefore, it is necessary to clarify the behavior of viruses in the treatment process.
This research was undertaken to elucidate the factors effecting virus behavior in an aeration tank in the activated sludge process. This process is at present the most popular biological sewage treatment method. The effects of MLSS concentration, temperature and pH on virus reduction were investigated in batch experiments using a vaccine strain of attenuated poliovirus type 1 (LSc, 2ab) as a model virus. The infectivity of virus was determined by the plaque assay using BGM cells.
The results indicated that the virus infectivity in a mixed liquor of activated sludge decreased exponentially with time. Regardless of MLSS concentration, temperature and pH, the time course of virus infectivity reduction could be expressed as two consecutive stages. The first stage decreased more rapidly than the second one while both were characterized by first-order kinetics. The reduction of virus infectivity was found to be proportional to MLSS concentration and effective for the condition of low pH and high temperature in the aeration tank.
