| A new index, called efficiency index, has been developed to evaluate solid-liquid separation in order to consider the phosphorus removal efficiency and the properties of the solid fraction produced. According to the index, compared to a screw press, centrifuge decanters are the most effective separators, which means that they remove phosphorus and produce a solid fraction that is concentrated in dry matter and nutrients. To optimize the centrifuge decanter, laboratory manipulations tested chemical additives: Ca(OH)2 , CaCO3, FeCl3, Al2(SO4) 3 and four (4) polymers. Results show that chemical additives, combined with centrifugation, enhance phosphorus removal. However, the analysis of the data with the efficiency index illustrates a general trend: the treatments with additives have a lower efficiency index than the controls, indicating a lower concentration of dry matter in the solid fraction. The efficiency index suggests the use of some polymers, at their optimal dosage, will perform better than the controls. |
