Performance Investigation of the Primary Clarifier-Case Study of Castiglione Torinese

In this study, to investigate removal efficiency of the primary clarifier at Castiglione Torinese water resource recovery facility (WRRF), 20 consecutive day sampling campaign was conducted. The data are partitioned per weather conditions and relations between influent total chemical oxygen demand (CODT), soluble chemical oxygen demand (CODs), total suspended solids (TSS), ammonium (NH4) and phosphate (PO4) concentrations and their corresponding removal efficiencies are investigated. Significant differences in removal efficiencies between various parameters and unexpected increasing of concentrations of CODs, NH4, PO4 are observed. The analysis revealed the possibility of establishment of empirical relations between influent concentrations and their corresponding removal efficiencies of the primary clarifier in Castiglione Torinese in case of availability of high frequency data. To reason out increasing of CODs, NH4, PO4 concentrations, initially the impact of surface overflow on removal efficiencies are studied. The results show that removal efficiencies are not notably influenced by changing of the surface overflow. Secondly, manipulating the sludge pumping patterns, the effect of primary sludge blanket height (SBH) on removal efficiencies are analysed and considering the available data frequency, conclusions were drawn. Finally, according to findings and detail specifications of sewer system and the treatment plant, hypotheses were proposed for justification of increasing concentrations.