title: Evaluation of a Ca-modified porphyritic andesite for ammonium removal in the anaerobic digestion process.
abstract: In this study, a Ca-modified porphyritic andesite (wheat-rice-stone (WRS)) was developed for the anaerobic digestion of ammonium-rich wastes. The Ca-modified WRS was obtained with integrated Ca-salt treatment and calcination. Scanning electron microscope and Brunauer-Emmett-Teller surface area analyses were performed to characterize the Ca-modified WRS, and adsorption isotherms and kinetics were investigated to clarify the adsorption mechanism. The ammonium adsorption process was explained well with a pseudo-second-order kinetic model. The specific surface area of the Ca-modified WRS was determined to be 4.56 sq. m/g, and the maximum NH4(+)-N adsorption capacity was determined to be 45.45 mg/g. These values are improvements over those of natural WRS. The ammonium adsorption capacity remained constant at a pH range from 5.0 to 9.0, which indicates that Ca-modified WRS is a promising material for various applications. The methane-production and chemical oxygen demand-removal aspects of anaerobic digestion were much improved with the addition of Ca-modified WRS. Therefore, Ca-modified WRS could be developed into a viable ammonium adsorbent for the anaerobic digestion of ammonium-rich wastes.
authors.affiliation: Graduate School of Life and Environmental Science, University of Tsukuba, Tsukuba, Japan. wangqhqh@yahoo.cn
authors.forename: Qinghong
authors.initials: Q
authors.lastname: Wang
authors.forename: Yingnan
authors.initials: Y
authors.lastname: Yang
authors.forename: Dawei
authors.initials: D
authors.lastname: Li
authors.forename: Zhenya
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D002118:Calcium / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D008903:Minerals; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D002118:Calcium