Characterization of Treatment Processes and Mechanisms of COD, Phosphorus and Nitrogen Removal in a Multi-Soil-Layering System

• Published in: Soil science and plant nutrition (Tokyo) Vol. 51; no. 2; pp. 213 - 221
• Main Authors: Sato, Kuniaki, Masunaga, Tsugiyuki, Wakatsuki, Toshiyuki
• Format: Journal Article
• Language: English
• Published: Oxford, UK Taylor & Francis Group 01.04.2005; Blackwell Publishing Ltd
• Subjects: Multi-Soil-Layering method; nitrogen and phosphorus removal; organic matter removal; processes of wastewater treatment
• ISSN: 0038-0768; 1747-0765
• DOI: 10.1111/j.1747-0765.2005.tb00025.x

Characteristics of the treatment processes inside a MSL system were investigated by using a laboratory-scale MSL system, which was set up in a D10 ×W50 ×H73 cm acrylic box enclosing "soil mixture blocks" alternating with permeable zeolite layers. For the study of the treatment processes inside the system, wastewater, with mean concentrations (mg L −1 ) of COD: 70, T-N: 12, T-P: 0.9, was introduced into the system at a loading rate of 1,000 L m −2 d −1 . Treatment processes in the MSL system were different for the COD, P and N pollutants. Eighty percent of COD was removed in the 1st soil layer among the 6 layers, and the removal rate increased as water moved down and finally reached 90% in the last layer of the system. Phosphorus concentration was lower under the soil mixture layers than under the permeable layers, presumably because P was adsorbed mainly by soil and mixed iron particles. The P concentration in water gradually decreased in the lower layers of the system. The concentration of PO 4 3- -P was generally lower in the aerated MSL system than in the non-aerated one. NH 4 + -N was adsorbed and nitrified in the upper part of the system. The NO 3 − -N concentration was lower in water under the soil mixture layers than under the permeable layers, indicating that denitrification mainly occurred in the soil mixture layers.