Batch tests were operated to investigate effects of initial pH (3,5,7,9,11) on anaerobic digestion of waste activated sludge under 0.6V direct electrical stimulation. Initial pH had a great influence on biogas production and VS removal efficiency. At the optimal initial pH of 9, maximum methane yield of 224mLCH4/g VS and VS removal efficiency of 38.1% were achieved after 32days digestion. Initial pH could accelerate hydrolysis and acidification process of waste activated sludge. Alkaline environment (pH 9, 11) enhanced SCOD and VFAs concentrations in suspensions, especially at pH 11. Acetic acid and butyric acid were dominant at pH 3and 11while acetic acid and propionic acid were main products at pH 5, 7 and 9. Initial pH facilitates release of ammonium from waste activated sludge and in acidic environment ammonium was released in excess.
Seggiani M, Vitolo S, Puccini M, et al. Cogasification of sewage sludge in an updraft gasifier[J]. Journal of Fuel, 2012,93: 486-491.
[2]
Khalid Azeem, Arshad Muhammad, Anjum Muzammil, et al. The anaerobic digestion of solid organic waste[J]. Journal of Waste Management, 2011,31:1737-1744.
Go¢mez X, Cuetos MJ, Cara J, et al. Anaerobic co-digestion of primary sludge and the fruit and vegetable fraction of the municipal solid wastes[J]. Journal of Renewable Energy, 2006, 31:2017-2024.
[5]
Feng Yinghong, Zhang Yaobin, Chen Shuo, et al. Enhanced production of methane from waste activated sludge by the combination of high-solid anaerobic digestion and microbial electrolysis cell with iron-graphite electrode[J]. Journal of Chemical Engineering, 2015,259:787-794.
[6]
Kotoyoshi Nakanishi, Hiroharu Tokuda, Takahiko Soga, et al. Effect of Electric Current on Growth and Alcohol Production by Yeast Cells[J]. Journal of Fermentation and bioenoineer, 1998,85(2):250-253.
[7]
She Peng, Song Bo, Xing Xin-Hui, et al. Electrolytic stimulation of bacteriaEnterobacter dissolvens by a direct current[J]. Journal of Biochemical Engineering, 2011,31:1737-1744.
Beschkov V, Velizarov S, Agathos S N, et al. Bacterial denitrification of waste water stimulated by constant electric field[J]. Journal of Biochemical Engineering, 2004,17(2):141-145.
[10]
Y G Chen, S Jiang, H Y Yuan, et al. Hydrolysis and acidification of waste activated sludge at different pHs[J]. Journal of Water Research, 2007,41(3):683-689.
Cai M L, Wei Y S, Liu J X. Enhanced biohydrogen production from sewage sludge with alkaline pretreatment[J]. Journal of Environment Science and Technology, 2004,38:3195-3202.
FU W G, Mathews A P. Lactic acid production from lactose by Lactobacillus plantarum: kinetic model and effects of pH, substrate, andoxygen[J]. Journal of Biochemical Engineering, 1999,3(3):163-170.
Chen Yinguang, Jiang Su, Yuan Hongying, et al. Hydrolysis and acidification of waste activated sludge at different pHs[J]. Journal of Water Research, 2007,41:683-689.
Rajinikanth Rajagopal, Daniel I Massé, A critical review on inhibition of anaerobic digestion process by excess ammonia[J]. Bioresource Technology[J]. 2013,143:632-641.
[20]
Orhan Yenigün, Burak Demirel. Ammonia inhibition in anaerobic digestion: A review[J]. Journal of Process Biochemistry, 2013,48:901-911.
