Seasonal effects in endotoxin concentration at different sections of a sewage treatment plant, Delhi

The aim of present study is to assess the seasonal effects during five different seasons on endotoxins levels at various sections (aeration tank, sludge bed, grit chamber and final settlement tank) of a sewage treatment plant. Samples for endotoxins were collected using a three-stage cascade impactor. The sampler collects particulate matters in three different sizes, viz. PM1, PM2.5 and PM10. We mainly focused on the detection of endotoxins associated with the coarse particles (PM10-2.5) and fine particles (PM2.5-1.0). ANOVA was employed to understand whether the difference in airborne endotoxins concentrations (EU/m(3)) was significant at p < 0.05 in different sections and during different seasons. The endotoxin concentration was found highest (125.67 +/- 7.89 EU/m(3)) at the aeration tank in summer season and lowest (11.25 +/- 2.62 EU/m(3)) at FST during winter season in the size range of (PM10-2.5), both are significant. Same trends were followed for fine particulate matter (PM2.5-1.0) associated endotoxin. The endotoxin concentration was found significantly different (p < 0.05) in summer and winter season, but no significant (p > 0.05) difference was found in monsoon and autumn seasons at all the sections.