Modification of natural zeolite and its application to advanced recovery of organic matter from an ultra-short-SRT activated sludge process effluent

摘要

Natural adsorbent was optimized from four natural adsorption materials (kaolin, bentonite, diatomite, and natural zeolite) through the comparison of their ability to recover organic matter from an ultra-short-sludge-retention-time (ultra-short-SRT) activated sludge process effluent. Natural zeolite was modified by the loading of three types of chemical coagulants (Fe-2(SO4)(3), Al-2(SO4)(3), and ZnSO4) and was used for the study of the advanced recovery of organic matter. The results of Brunauer-Emmett-Teller surface area (S-BET) measurements, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses showed that natural zeolite was successfully modified, with decrease in the specific surface area of the modified zeolite (MZ), but some metal ions/metal oxides were loaded onto the surface of natural zeolite. Compared with chemical coagulant and natural zeolite, the organic recovery efficiency from the effluent of the MZs improved, and after the optimization process, the organic recovery efficiency of MZ4 (Zeolite:Fe-2(SO4)(3) = 4:1), MZ9 (Zeolite:Al-2(SO4)(3) = 4:1), and MZ13 (Zeolite:ZnSO4 = 2:1) reached 72.0%, 67.6%, and 61.2%, respectively. The MZs can allow a significant amount of recovery of soluble chemical oxygen demand (SCOD) from the effluent, with SCOD recovery efficiencies for MZ4, MZ9, and MZ13 of 44.8%, 44.3%, and 39.4%, respectively. The E-4/E-6, UV253/UV203, and SUVA analyses after the organic recovery experiments indicated that the generation potential of disinfecting by products or halogenated products was reduced in the treated effluent by the MZs. The mechanism can be considered in two ways: the coagulation effect of the loaded metal ions/metal oxides and the physical and chemical adsorption effect based on the hydrogen bond and pi-pi bond between the MZ and organic matter. This study facilitated the application of organic recovery from wastewater and the advanced treatment of effluent. (C) 2018 Elsevier B.V. All rights reserved.