TRANSFORMATIONS OF ORGANIC MATTER AND BIOFILM SPATIAL CHARACTERISTICS IN SUBSURFACE WASTEWATER INFILTRATION SYSTEM

摘要

A pilot-scale subsurface wastewater infiltration (SWI) system for river landscape water treatment has been steadily operated for more than one year. The purpose of the study was to investigate the transformations of organic matter and biofilm spatial characteristic in SWI system. In addition, the transformations of volatile organic compounds (VOC), dissolved organic matter (DOM), fluorescent dissolved organic matter (FDOM) were examined by Gas ChromatographyMass Spectrometer (GC-MS), Gel Filtration Chromatography (GFC) and three-dimensional Excitation–Emission Matrix (EEM) respectively. Results showed that the average removal rates of COD and BOD were 43.3% and 66.5%, respectively, at the hydraulic loading of 0.2 m3/(m2·d). Results indicated that most of VOCs could be removed and the majorities of DOM whose molecular weights were more than 1000 kDa were degraded by SWI system. The viable cell quantities in the vertical section of SWI system were measured in the study. And the minimum of viable cell number were observed in the top left section of the system and the maximum was in the bottom right section, ranging from 140.7 to 328.8×107 cells/g filler. In addition, the biofilm spatial characteristics were examined by the evaluation of Scanning Electronic Microscope (SEM) and EEM fluorescence spectroscopy.