EVALUATION OF FAECAL CONTAMINATION AND MICROBIAL DIE-OFF IN URINE SEPARATING SEWAGE SYSTEMS

摘要

An important feature for recirculated products from a sewage system is that the risk for transmission of disease is low. In a urine source separating system faeces may contaminate the collected urine through the toilet. The concentrations of faecal indicator organisms were measured in 14 urine collection tanks. The survival of these and some pathogenic microorganisms in source separated human urine was studied. Total coliforms, E. coli and clostridia were found in low concentrations while faecal streptococci occurred in concentrations up to 10~5/ml urine solution. The results from phenotyping of faecal streptococci and the high counts indicate growth within the system. The majority of the pathogenic microorganisms investigated had a rapid die-off. A higher temperature, a low degree of dilution and a pH far from neutral had a negative effect on survival. E. coli had a rapid die-off and is not suitable for indicating faecal contamination of the collected urine. Quantification of faecal sterols is a possible alternative to microbial analysis for this purpose. The amounts of coprostanol showed that the faecal contamination varied from not detected to up to 13.3 mg/ml urine solution with a concentration in the urine sludge of up to 417.5 mg/kg.