Investigation of hospital wastewater treatment plant efficiency in north of Iran during 2010-2011

Hospital wastewater contains pathogenic agents and hazardous compounds; so, it will cause many risks on environmental and human health of different communities. The aim of this research was to investigate the efficiency of hospital wastewater treatment plant in north of Iran. This cross-sectional descriptive research was done on four hospital wastewater treatment plant in north of Iran during 2010 to 2011. A total of 100 grab sample were taken from the influent and effluent of each wastewater treatment plant. Collected sample were sent to laboratory and analyzes for PH, TSS, BOD, COD and Total Coliforms (TC) according to standard methods. The mean value of PH, TSS, BOD, COD and TC in influent wastewater of all studied hospitals was 7.5, 296, 400, 616 mgL -1 and 3.1×105 MPN per 100 ml and in effluent was 7.4, 78, 84, 150 mgL -1 and 831 MPN per 100 ml, respectively. The mean free chlorine residual in the effluent of these hospitals was reported to be 0.2 mgL -1 . The mean removal of TSS, BOD, COD and TC in mentioned hospitals wastewater treatment plant was 74.3, 79.6, 76.5 and 99.7%, respectively. According to the results of this research, the concentration of TSS, BOD, COD and TC in the effluent of the studied hospitals was more than the Iranian reuse standard which indicates inefficient removal of pollutants in mentioned hospital wastewater treatment plant. Thus, for effluent reuse in irrigation more efficient wastewater treatment process is required.