Pedosphere 21(4): 454--463, 2011
ISSN 1002-0160/CN 32-1315/P
©2011 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Kinetic adsorption of ammonium nitrogen by substrate materials for constructed wetlands |
ZHU Wen-Ling1,2, CUI Li-Hua 1,3, OUYANG Ying4, LONG Cui-Fen1 and TANG Xiao-Dan1 |
1 College of Natural Resources and Environmental Science, South China Agricultural University, Guangzhou 510642 (China);
2 Urban Drainage Monitoring Station of Guangzhou City, Guangzhou 510010 (China);
3 Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642 (China);
4 Department of Water Resources, St. Johns River Water Management District, Palatka, Florida 32178 (USA) |
| ABSTRACT |
| Constructed wetlands (CWs) are engineered systems that utilize natural systems including wetland vegetations, soils, and their associated microbial assemblages to assist in treating wastewater. The kinetic adsorption of ammonium nitrogen (NH4+-N) by CW substrate materials such as blast furnace slag (BFS), zeolite, ceramsite, vermiculite, gravel, paddy soil, red soil, and turf, was investigated using batch experiments and kinetic adsorption isotherms. Both Freundlich and Langmuir isotherms could adequately predict the NH4+-N adsorption process. The maximum adsorption capacities of NH4+-N, estimated from the Langmuir isotherm, ranked as: zeolite (33 333.33 mg kg-1) > turf (29 274.01 mg kg-1) > BFS (5 000 mg kg-1) > vermiculite (3 333.33 mg kg-1) > gravel (769.23 mg kg-1) > paddy soil (588.24 mg kg-1) > red soil (555.56 mg kg-1) > ceramsite (107.53 mg kg-1). Some properties of the substrate materials, including bulk density, specific gravity, hydraulic conductivity, uniformity coefficient (K60), curvature coefficient (Cc), organic matter, pH, exchangeable (or active) Cu, Fe, Zn and Mn, total Cu, and Fe, Mn, Zn, Cd, Pb and Ca, had negative correlations with NH4+-N adsorption. Other properties of the substrate materials like particle diameter values of D10, D30 and D60 (the diameters of particle sizes of a substrate material at which 10%, 30% and 60%, respectively, of the particles pass through the sieve based on the accumulative frequency), cation exchange capacity (CEC), exchangeable (or active) Ca and Mg, and total K and Mg had positive correlations with NH4+-N adsorption. In addition, active K and Na as well as the total Na had significant positive correlations with NH4+-N adsorption. This information would be useful for selection of suitable substrate materials for CWs. |
| Key Words: ammonia removal, kinetic adsorption capacity, Langmuir isotherm, physicochemical properties, substrate materials |
| Citation: Zhu, W. L., Cui, L. H., Ouyang, Y., Long, C. F. and Tang, X. D. 2011. Kinetic adsorption of ammonium nitrogen by substrate materials for constructed wetlands. Pedosphere. 21(4): 454-463. |
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