Removal capacity of fecal streptococci, fecal and total coliforms from the artificial surface flow wetland of the Aurora II pilot plant

Abstract

The capacity of the artificial surface flow wetland of the Aurora II pilot plant is significant in the removal of fecal streptococcus, fecal and total coliforms, as well as compliance with the fecal coliforms/fecal streptococcus (FC/FS) ratio of the affluent water. The average value at the exit of fecal streptococcus was 2,78x10⁷ MLN/100cm3 representing 58 % of removal, 5,78x10¹⁰ MLN/100cm³ for fecal coliforms representing 98 % of removal and 7,15x10¹¹ MLN/100cm³ for total coliforms which represents the 71% of removal, therefore, it’s necessary to implement a tertiary treatment to comply with the maximum permissible limit of fecal coliforms established by the “Acuerdo Gubernativo 236 – 2006” which is the Guatemalan regulation. For this case, it is recommended to continue with the reuse of the effluent for agricultural irrigation in general as a tertiary treatment, according to the classification, Type I, established in article 35 of the same regulation. The FC/FS ratio obtained was of 11 000:1, which differs from the typical value of 4,4:1 obtained from the literature.