Effect of process variables on the production of Polyhydroxyalkanoates by activated sludge
Tóm tắt
Polyhydroxyalkanoates are known to be temporarily stored by microorganisms in activated sludge, especially in anaerobic-aerobic processes. Due to the problems resulted from the disposals of plastic wastes and excess sludge of wastewater treatment plants, the production of polyhydroxyalkanoates by treating activated sludge and determining the effect of process variables were the main issues of this paper. In this research, an anaerobic-aerobic sequencing batch reactor was used to make microorganism adapted and a batch aerobic reactor was used for enriching them. The variables affecting polyhydroxyalkanoates production including aeration time, sludge retention time, and volatile fatty acids concentration of the influent in sequencing batch reactor, and also carbon to nitrogen ratio and cultivation time in polymer production reactor, were investigated using Taguchi statistical approach to determine optimum conditions. The maximum polymer production of 29% was achieved at sludge retention time of 5–10 days, aeration time of 2 hours, supplementation of 40% of volatile fatty acids in the influent and increasing of carbon to nitrogen ratio of polymer production reactor to above 25 g/g. Based on the results, in optimum conditions, the volatile fatty acids concentration which increased the production of polyhydroxyalkanoates up to 49% was the most effective variable. Carbon to nitrogen ratio, sludge retention time and aeration time were ranked as the next affecting parameters. Although the polyhydroxyalkanoates content achieved in present study is much lower than that by pure culture, but the proposed method may still serve well as an environmental friendly means to convert waste into valuable product.
Tài liệu tham khảo
Lee SY: Bacterial poly-hydroxyalkanoates. Biotechnol Bioeng. 1996, 49: 1-14. 10.1002/(SICI)1097-0290(19960105)49:1<1::AID-BIT1>3.3.CO;2-1.
Zinn M, Witholt B, Egli T: Occurrence Synthesis and Medical Application of Bacterial Polyhydroxyalkanoate. Adv Drug Delivery rev. 2001, 53: 5-21. 10.1016/S0169-409X(01)00218-6.
Khanafari A, Akhavan Sepahei A, Mogharab M: Production and recovery of Poly-Β-Hydroxybutirate from whey Degradation by Azotobacter. Iran. J. Environ. Health. Sci. Eng. 2006, 3 (3): 193-198.
Anderson AJ, Dawes EA: Occurrence, metabolism, metabolic role, and industrial uses of bacterial poly-hydroxyalkanoates. Microbiol Rev. 1990, 54: 450-472.
Doi Y: Microbial polyesters. 1990, New York: VCH, ISBN 978-0-444-50563-7
Matsuo T, Hanaki K, Takizawa S, Satoh H: Advances in Water and Wastewater Treatment Technology. 2001, London: Elsevier Sci, 249-260.
Ayorinde FO, Saeed KA, Price E, Morrow A, Collins WE, Mclnnis F, Pollack SK, Eribo BE: Production of Poly (ß-hydroxybutyrate) From Saponified Vernonia Galamensis Oil by Alcaligenes Eutrophus. J Ind Microbiol Biotechnol. 1998, 21: 46-50. 10.1038/sj.jim.2900555.
Hejazi P, Vasheghani FE, Yamini Y: Supercritical Fluid Disruption of Ralstonia eutropha for Poly (β-hydroxybutyrate) Recovery. Biotechnol Progr. 2003, 19: 1519-1523. 10.1021/bp034010q.
Yamane T: Yield of poly-D (−)-3Hydroxybutyrate from various carbon sources A theoretical study. Biotechnol and Bioeng. 1993, 41: 165-170. 10.1002/bit.260410122.
Salehizadeh H, Van Loosdrecht MCM: Production of Polyhydroxyalkanoates by mixed culture: recent trends and biotechnological importance. Biotechnol Adv. 2004, 22: 261-279. 10.1016/j.biotechadv.2003.09.003.
Gonzalez-Lopez J, Pozo C, Martinez-Toledo MV, Rodelas B, Salmeron V: Production of polyhydroxyalkanoates by Azotobacter chroococcum H23 in wastewater from olive oil mills (alpechin)”. Int Biodeterior Biodegrad. 1996, 38: 271-276. 10.1016/S0964-8305(96)00060-1.
Ramos-Cormenzana A, Monteoliva-Sánchez M, López MJ: Bioremediation of alpechín. Int Biodeterior Biodegrad. 1995, 35: 249-268. 10.1016/0964-8305(95)00033-2.
Liu Y, Tay J: Strategy for minimization of excess sludge production from the activated sludge process. Biotech Adv. 2001, 19 (2): 97-107. 10.1016/S0734-9750(00)00066-5.
Takdastan A, Mehrdadi N, Azimi AA, Torabian A, Nabi Bidhendi GR: Investigation of intermittent chlorination system in biological excess sludge reduction by sequencing batch reactors. Iran. J. Environ. Health. Sci. Eng. 2009, 6 (1): 53-60.
Wang W, Jung Y, Kiso Y: Excess sludge reduction performance of an aerobic SBR process equipped with a submerged mesh filter unit. proceesBiochemistry. 2006, 41: 745-751.
Mino T, Van Loosdrecht MCM, Heijnen JJ: Microbiology and biochemistry of the enhanced biological phosphate removal process. Water Sci Technol. 1998, 32: 3193-3207.
Satoh H, Mino T, Matsuo T: PHA production by activated sludge. Int J Biol Macromol. 1999, 25: 105-109. 10.1016/S0141-8130(99)00021-5.
Chua ASM, Takabatake H, Satoh H, Mino T: Production of polyhydroxyalkanoates (PHAS) by activated sludge treating municipal wastewater: effect of pH, sludge retention time (SRT), and acetate concentration in influent. Water Res. 2003, 37: 3602-3610. 10.1016/S0043-1354(03)00252-5.
Cai M, Chua H, Zhao Q, Sin NS, Ren J: Optimal production of Polyhydroxyalkanoates (PHA) in activated sludge fed by volatile fatty acids (VFAs) generated from alkaline excess sludge fermentation. Bioresource Technol. 2009, 100: 1399-1405. 10.1016/j.biortech.2008.09.014.
Yan S, Tyagi RD, Surampalli RY: Polyhydroxyalkanoates (PHA) production using wastewater as carbon source and activated sludge as microorganisms. Water Sci Technol. 2006, 53: 175-180.
Hosnani E, Nosrati M, Shojasadati SA: Role of Extracellular Polymeric Substances in Dewaterability of Untreated Sonicated and Digested Waste Activated Sludge. Iran. J. Environ. Health. Sci. Eng. 2010, 7 (5): 395-400.
Takabatake H, Satoh H, Mino T, Matsuo T: Recovery of biodegradable plastics from activated sludge process. Water Sci Technol. 2000, 42: 351-356.
APHA, AWWA, WEF: Standard Methods for the Examination of Water and Wastewater. 1998, Washington DC, USA: Amer. Public Health Assoc, 20
Braunegg G, Sonnleitner B, Lafferty RM: A Rapid Gas Chromatographic Method for the Determination of Polyhydroxybutiric Acid in Microbial Biomass. Eur J Appl Microbiol Biotechnol. 1978, 6: 29-37. 10.1007/BF00500854.
Roy RK: A Primer on the Taguchi Method. 1990, New York; Van No strand Reinhold, 40-99.
Mokhtarani N, Ganjidust H, Vasheghani Farahani E, Khaleghi Sarnamy M: Effect of VFAs in the production of Polyhydroxyalkanoates by activated sludge. Iranian J. of Polym. Sci. & Technol. 2008, 21: 83-90.
Metcalf and Eddy Inc: Wastewater Engineering, Treatment and Reuse. 2003, New York: McGraw-Hill, 565-566. 4
Dionisi D, Majone M, Ramadori R, Beccari M: The storage of acetate under anoxic conditions. Water Res. 2001, 35: 2661-2668. 10.1016/S0043-1354(00)00562-5.