Load of Infectious Microorganisms in Hospital Effluent Treatment Plant in Madurai

Hospital effluent is often regarded as an important source of pathogenic microorganisms like bacteria, viruses and parasitic ova. Counts of all these microorganisms were enumerated in various stages of effluent treatment plant (ETP) such as equalisation tank (ET), aeration tank (AT), settling tank (ST), chlorination tank (CT), polishing tank (PT) and sludge dry beds. The microbial parameters includes total viable count (TVC), total coliforms (TC), faecal coliforms (FC), faecal Streptococci (FS), Staphylococci, Pseudomonas, Salmonella and Shigella. The raw sewage contains 35 % of 19.6 X 10² CFU/mL of bacteria as coliforms and E. coli as a typical faecal flora. There was a substantial reduction (> 2 log) noticed for the effluent in settling tank. Mass of the bacteria in the hospital effluent remains tightly attached to the solid particles. These are removed by aeration and clarification or settling by physical processes like flocculation. The treated effluent still contains sizeable counts or loads of bacteria even though disinfection procedures like chlorination are followed. Bacteria in sludge dry beds are exceedingly rigorous and higher concentration of chlorine is required for decontamination and other disinfection procedures such as UV radiation, Ozonization and sunlight disinfection are required for the reduction. Further work will be carried out to design and construct a portable low cost disinfection unit for the disinfection of harmful pathogenic microbes.