2.3. Methodology Sampling and analysis began in June of the first year, 2 months afterthe establishment, and continued until
the end of Novemberof the second year, so influent and effluent samples were collected from each bed once every month overan 18-month period. Samples were analysed to determine the reduction in concentrations of BOD, COD, TSS, total and faecal coliforms bacteria and faecal streptococci bacteria