Advanced Phosphorus Removal from Membrane Filtrate and Filter Filtrate Using Packed Columns with Different Adsorptive Media

This study investigated the potential of applying adsorptive media to further remove phosphorus in secondary and tertiary effluent to levels lower than the current limits of technologies in practice. On-site short-term bench scale adsorption column tests treating membrane microfiltration effluent were conducted in parallel with three different commercial adsorptive media including US filter GFH, ResinTech ASM-10-HP and Purolite Arsenex, at the city of Coeur d'Alene wastewater treatment plant. At influent TP concentrations ranging from 0.014 - 0.43 mg/L, effluent TP of 0.005-0.008 mg/L was achieved. Phosphorus fractionation analysis of influent and effluent through the column showed that soluble non-reactive P (sNRP), which likely consists of acid-hydrolysable P (poly-P) and dissolved refractory organic P (rDOP), is the dominant form of P in the membrane microfiltration (tertiary) effluent at a TP concentration of 0.014 mg/L. The particular P in the column effluent was negligible (<0.002 mg/L) for all tests, while effluent soluble P (sTP) ranged from 0.004 to 0.007 mg/L and consisted of 0.001 to 0.005 mg/L soluble non-reactive P (sNRP) and 0.002 mg/L ortho-P. The results demonstrated that the adsorption column process can effectively remove both soluble reactive ortho-P and soluble non-reactive P, such as dissolved refractory organic P in the wastewater. The three different adsorptive media tested exhibited comparable performance in terms of effluent P concentrations and fractionations, despite their composition differences. Addition of oxidants such as hydrogen peroxide to the influent seemed to negatively affect P removal via adsorption, and the final effluent TP concentrations were higher (0.013-0.017 mg/L) than those observed without any hydrogen peroxide addition (0.005-0.008 mg/L). P fractionation analysis showed that the effluent ortho-P remained the same (0.002 mg/L) compared to tests without pre-oxidation, whereas the effluent sNRP and sTP increased due to decreased removal efficiency of sNRP after H2O2 addition to the influent feed for all three media. A long-term pilot scale test with Kemira's CFH12 media-packed column was performed at the City of Las Vegas Water Pollution Control Facility for 6 months. The results demonstrated the potential of applying adsorption as a final polishing step to further reduce the effluent P to lower levels (TP