Changes of microbial substrate metabolic patterns through a wastewater reuse process, including WWTP and SAT concerning depth.
In this study, changes of microbial substrate metabolic patterns by BIOLOG assay were discussed through a sequential wastewater reuse process, which includes activated sludge and treated effluent in wastewater treatment plant and soil aquifer treatment (SAT), especially focussing on the surface sand layer in conjunction with the vadose zone, concerning sand depth. A SAT pilot-scale reactor, in which the height of packed sand was 237 cm (vadose zone: 17 cm and saturated zone 220 cm), was operated and fed continuously by discharged anaerobic-anoxic-oxic (A2O) treated water. Continuous water quality measurements over a period of 10 months indicated that the treatment performance of the reactor, such as 83.2% dissolved organic carbon removal, appeared to be stable. Core sampling was conducted for the surface sand to a 30 cm depth, and the sample was divided into six 5 cm sections. Microbial activities, as evaluated by fluorescein diacetate, sharply decreased with increasing distance from the surface of the 30 cm core sample, which included significant decreases only 5 cm from the top surface. A similar microbial metabolic pattern containing a high degree of carbohydrates was obtained among the activated sludge, A2O treated water (influent to the SAT reactor) and the 0-5 cm layer of sand. Meanwhile, the 10-30 cm sand core layers showed dramatically different metabolic patterns containing a high degree of carboxylic acid and esters, and it is possible that the metabolic pattern exhibited by the 5-10 cm layer is at a midpoint of the changing pattern. This suggests that the removal of different organic compounds by biodegradation would be expected to occur in the activated sludge and in the SAT sand layers immediately below 5 cm from the top surface. It is possible that changes in the composition of the organic matter and/or transit of the limiting factor for microbial activities from carbon to phosphorus might have contributed to the observed dramatic changes in SAT metabolic patterns.
Department of Environmental Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 6158540, Japan; Recycling Research Team, Materials and Resources Research Group, Public Works Research Institute, 1-6 Minamihara, Tsukuba, Ibaraki 305-8516, Japan. Electronic address: yu-takabe@pwri.go.jp.
Yugo
Y
Takabe
Department of Environmental Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 6158540, Japan; Tokyo Engineering Consultants Co., Ltd., 3-7-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-0013, Japan.
Ippei
I
Kameda
Department of Environmental Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 6158540, Japan.
Ryosuke
R
Suzuki
Department of Environmental Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 6158540, Japan.
Fumitake
F
Nishimura
Department of Environmental Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 6158540, Japan.
Sadahiko
S
Itoh
D018407:Bacterial Physiological Phenomena; D019149:Bioreactors / Q000382:microbiology*; D060587:Groundwater / Q000382:microbiology*; D010865:Pilot Projects; D012988:Soil Microbiology; D014865:Waste Disposal, Fluid; D018508:Water Purification; D060753:Water Quality
Activated sludge; BIOLOG assay; Microbial substrate metabolic pattern; Soil aquifer treatment; Surface sand layer; Wastewater reuse