The preparation of an adsorbent from mixtures of sewage sludge and coal-tar pitch using an alkaline hydroxide activation agent

The increasing generation of sewage sludge and its subsequent treatment are very sensitive environmental problems. For the more stable and sanitary treatment of this sewage sludge, there have been many studies, including the recent attempt to prepare an adsorbent from sewage sludge via recycling. In this study, of the adsorbent preparation methods, chemical activation was utilized, and in order to find the optimum conditions, several variables were tested, such as the activation agent concentration, activation temperature and activation time. The activation agents used in this study were alkaline hydroxides: KOH and NaOH. The properties of prepared adsorbent were also measured by analyzing the iodine adsorptivity and surface area. In addition, the prepared adsorbent, the BOD, COD, SS, T-N and T-P removal efficiencies from the effluent water of a sewage treatment plant were examined via column test. From the test, the optimum conditions for KOH-activation were 1 mol/l, 800 °C and 1.5 h for the activation agent concentration, activation temperature and activation time, respectively; whereas those for NaOH-activation were 1.25 mol/l, 850 °C and 1.5 h. From the application of the prepared adsorbent to the effluent water of the sewage treatment plant, the measured BOD, COD, SS, T-N and T-P removal efficiencies, the P1-800 adsorbent had the highest efficiencies for BOD, COD and SS of 56.68, 57.76 and 81.45%, respectively.