In-situ formation and immobilization of biogenic nanopalladium into anaerobic granular sludge enhances azo dyes degradation.
Azo dyes are toxic and recalcitrant wastewater pollutants. An innovative technology based on biogenic nanopalladium (Bio-Pd) supported anaerobic granular sludge (AGS) was developed for azo dyes reduction. In-situ formation of Bio-Pd in the AGS was observed by Scanning Electron Microscopy coupled with Energy Dispersive Spectrometer (SEM-EDS). The Pd associated AGS (Pd-AGS) showed enhanced decolorization rates to the three azo dyes of Congo Red, Evans Blue and Orange II, with the degradation kinetic constants increased by 2.3-10 fold compared to the control AGS in the presence of electron donor formate. Impacts of different electron donors on Orange II decolorization were further investigated. Results showed that formic acid, formate, acetate, glucose, ethanol and lactate could serve as electron and hydrogen donors to stimulate Orange II decolorization by the Pd-AGS, and their activities followed the order: formic acid > formate > ethanol > glucose > lactate > acetate. Most of the Bio-Pd was bound with microbes in the AGS with a small fraction in the extracellular polymer substances (EPS). Transmission Electronic Microscopy analysis revealed that the Bio-Pd formed in the periplasmic space, cytoplasm and on the cell walls of bacteria. This study provides a new concept for azo dye reduction, which couples sludge microbial degradation ability with Bio-Pd catalytic ability via in-situ formation and immobilization of Bio-Pd into AGS, and offers an alternative for the current azo dye treatment technology.
Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: xchquan@bnu.edu.cn.
Xiangchun
X
Quan
Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
Xin
X
Zhang
Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
Hengduo
H
Xu
D001391:Azo Compounds / Q000737:chemistry* / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000378:metabolism; D004396:Coloring Agents / Q000737:chemistry* / Q000378:metabolism; D007220:Industrial Waste; D053768:Metal Nanoparticles; D008854:Microscopy, Electron; D010165:Palladium / Q000737:chemistry*; D012722:Sewage / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism
D001391:Azo Compounds; D004396:Coloring Agents; D007220:Industrial Waste; D012722:Sewage; D014874:Water Pollutants, Chemical; D010165:Palladium
Anaerobic granular sludge; Azo dye; Biogenic nanopalladium; Decolorization; Reduction