The performance of a wastewater treatment system consisting of an anaerobic pond followed by a high-rate algal pond (HRAP) is presented. The results allowed establishment of a statistical model for HRAP design in similar climatic conditions. The results also allowed the determination of the first-order constant of faecal coliforms (FC) die-off. This constant was found to be 24.7 and 0.97 d-1, respectively, in the hot and the cold seasons. Also, some results are presented on the comprehension of the biological processes which take place in a homogeneous HRAP. They indicate that BOD and FC removals are separated in the time and that BOD removal always precedes FC die-off. Finally the results show that the helminth eggs were completely removed within an overall hydraulic retention time of 8.2 days.

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