Treatability evaluation of domestic wastewater for a rational selection of treatment processes for wastewater treatment and reuse

Impurities in the domestic wastewater were divided into suspended and dissolved matters using a 0.45μm membrane and organic and inorganic matters by ignition method. A water quality matrix was thus formed for classifications of each kind of impurity. As a result, more than 60% of the BOD and COD were found to be of suspended state in the raw wastewater, as well as half of TP and 20% of TN. The treatability of impurities in each category was evaluated by enhanced primary treatment, secondary treatment, and advanced treatment using GAC adsorption with pre-ozonation. It was noticeable that the enhanced primary treatment was equally effective as the advanced treatment and better than the secondary treatment in removing most of the suspended matter, although it was less effective to remove most of the dissolved matter. Complete removal of dissolved phosphorous was another important feature of the enhanced primary treatment. The characteristics of these processes in removing dissolved organic matter of different kinds and in different molecular weight range were also compared. The results of this study can provide useful information for the selection of suitable treatment techniques for wastewater treatment and reuse.