Treatment-based hospital wastewater characterization and fractionation of pollutants

Abstract

This study investigated detailed characterization of hospital wastewater, size distribution of major organic pollutants and COD fractionation. In order to estimate the amount of wastewater, water consumption values and number of patients from 1156 hospitals were assessed statistically, and hourly water consumption data of a middle size hospital were recorded. Significant differences were observed in the total water consumption of the hospitals even among the ones having similar bed capacities. The average daily water consumption per hospital was about 140 m3, while the 1st and 3rd quartile were 25 m3 and 150 m3 respectively. Pollutant size distribution (PSD) analysis provided specific fingerprints for COD, BOD, colour and AOX parameters of hospital wastewater. Size distribution analyses resulted that about 20% of the AOX was in size range smaller than 1 kDa which might be attributed to adsorbable iodinated compounds (AOI) generated in iodinated X-ray process. According to the PSD results, it can be estimated that up to 85-90% of the total COD and 75-80% of the total AOX can be removed by direct filtration process using an ultrafiltration-sized membrane. COD fractionation experiments revealed that hospital wastewater has more soluble inert COD content than domestic wastewater with a similar COD concentration. Therefore, slightly higher COD concentrations can be expected at the biological treatment effluent of hospital wastewater compared to domestic wastewaters with similar COD concentrations. The difference may be attributed to the use of various chemicals and cleaning agents of inert properties.