A Study of the Horizontal Roughing Filter Efficiency to Improve the Quality of Effluent from Boukan Polishing Pond Following Aerated Lagoons

The need to improve the quality of lagoon effluent is one of the environmental priorities for
wastewater projects. Thus, the study objective was to investigate horizontal roughing filter (HRF)
performance to improvement total suspended solides (TSS), chemical oxygen demand (COD), turbidity
and fecal coliform in the effluent from polishing pond following aerated lagoons in order to provide
national standards.
Methods: The pilot-scale experimental study was carried out on-site wastewater treatment plant of
Boukan, Iran. Design, manufacture and installation of horizontal roughing filter pilot was performed
according to Wegelin guidelines. HRF Performance for removal of TSS, COD, turbidity and fecal
Coliform was studied in three filtration rates 0.5, 1 and 1.5 m3/m2.hr. The results were analyzed by
analysis of covariance (ANCOVA) using SPSS 16.
Findings: The mean of TSS, COD, turbidity and fecal coliform in the horizontal roughing filter effluent
had the significant difference within various hydroulic loading rates (P<0.001). Accordingly, in hydroulic
loading rate of 0.5 m3/m2.hr as optimum loading rate, the HRF reduced TSS, COD and turbidity of the
effluent from the polishing pond following aerated lagoons to 21 mg/L, 35 mg/L and 8.33 NTU.
Conclusion: The HRF can be used as appropriate option, due to high efficiency and easy operation, to
improve the quality of effluent from the polishing pond following aerated lagoons in order to provide
national standards