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Документ Improvement of sludge quality by iron-reducing bacteria(2004) Ivanov, Volodymyr M.; Wang, J.-Y.; Stabnikov, Victor; Xing, Zikun; Tay, JooSewage sludge can be used in agriculture as organic fertilizer. However, one of the obstacles for this use is the high concentration of heavy metals and the presence of sulphides (acidifying soil or compost). The aim of this research was to develop the biotechnology for improving the quality of sewage sludge that would be used as organic fertilizer. Microbial reduction of inexpensive sources of Fe(III) in anaerobic digester is proposed as a means of preventing the accumulation of sulphide and of enhancing the accumulation of phosphate in sewage sludge. Industrial grade iron hydroxide can serve as a suitable source of Fe(III) The results show that almost all dissolved phosphate is recovered by the reaction with Fe2+. Additionally, the activity of iron-reducing bacteria inhibits the production of sulphide by sulphate-reducing bacteria and the growth of these bacteria in anaerobic digesters.Документ Application of iron-reducing bacteria for phosphate removal from returned liquor of municipal wastewater treatment plant(2005) Ivanov, Volodymyr M.; Stabnikov, Victor; Tay, Stephen; Tay, JooThe aim of this research was to examine efficiency of enrichment culture and isolated strains of iron-reducing bacteria for the removal of phosphate from return liquor of municipal wastewater treatment plant (MWWTP) with ferric hydroxide as a source of Fe (III). Bacterial reduction of ferric hydroxide enhanced phosphate removal from return liquor. The obtained data could be used for the design of a new biotechnology of anaerobic removal or recovery of phosphate from return liquor of MWWTP.Документ Phosphate removal from return liquor of municipal wastewater treatment plant using iron-reducing bacteria(2005) Ivanov, Volodymyr M.; Stabnikov, Victor; Zhuang, W. Q.; Tay, Joo; Tay, StephenThe application of iron-reducing bacteria (IRB) for phosphate removal from return liquor (liquid fraction after activated sludge digestion and anaerobic sludge dewatering) of municipal wastewater treatment plant was studied. Methods and Results: Enrichment culture and two pure cultures of IRB, Stenotrophomonas maltophilia BK and Brachymonas denitrificans MK identified by 16S rRNA gene sequencing, were produced using return liquor of WWTP as carbon and energy source and iron hydroxide as oxidant. The final concentration of phosphate increased from 70 to 90 mg l-1 in control and decreased from 70 to 1 mg l-1 in experiment. The mass ratio of removed P to produced Fe(II) was 0.17 g P g-1 Fe(II). S. maltophilia BK showed the ability to reduce Fe(III) using such xenobiotics as diphenylamine, m-cresol, 2,4-dichlorphenol and p-phenylphenol as sole source of carbon under anaerobic conditions. Bacterial reduction of ferric hydroxide enhanced phosphate removal from return liquor. Significance and Impact of Study: An ability of facultative anaerobes Stenotrophomonas maltophilia BK and Brachymonas denitrificans MK to reduce Fe(III) was shown. These bacteria can be used for anaerobic removal of phosphate and xenobiotics by bacterial reduction of ferric ions.Документ The effect of various iron hydroxide concentrations on the anaerobic fermentation of sulfate-containing model wastewater(2006) Stabnikov, Victor; Ivanov, Volodymyr M.Addition of ferric hydroxide and iron-reducing bacteria in anaerobic treatment of sulphate-containing wastewater reduced sulphate reduction and production of sulphide, increased removal of total organic carbon (TOC) and methane production. Influence of ferric addition on sulphate-containing wastewater treatment depended on Fe(III) dosage, which can be determined as a molar ratio of Fe(ІІІ)/SO42-. Concentration of sulphide constantly increased and consisted on 15 day 91 mg/l and 45 mg/l at ratio of Fe(ІІІ)/SO42- 0.06 and 0.5. However, no production of dissolved sulphide was observed at ratio Fe(ІІІ)/SO42- 1 and 2. Maximum rates of total organic carbon removal were 0.75, 1.15, 1.39, 1.55 g TOC/g of volatile suspended solids (VVS) per hour; rates of methane production were 0.039, 0.047, 0.064 and 0.069 ml/g VVS per hour; contents of methane in biogas were 25, 41, 55 and 62 vol. % at the ratios of Fe(ІІІ)/SO42- 0.06, 0.5, 1 and 2, respectively. These data could be used for the development of a new technology for anaerobic treatment of sulphate containing wastewater.Документ The removal of phosphorus from reject water of municipal wastewater treatment plant using iron ore(2009) Guo, Cheng Hong; Stabnikov, Victor; Kuang, Shengli; Ivanov, Volodymyr M.BACKGROUND: Reject water (return liquor) from dewatering of anaerobically digested activated sludge in municipal wastewater treatment plants contains from 10 to50%of the phosphorus load when being recycled to the aeration tank. Phosphorus removal from reject water could be an effective way to decrease phosphorus loads entering the aeration tank. An innovative approach involves the replacement of iron salts, which are commonly used for phosphorus removal, with ferrous ions produced by iron-reducing bacteria from iron ore. The aim of the research was to examine the feasibility of phosphorus removal from return liquor using bioreduction of iron ore.RESULTS: Ferrous production, phosphate and organic carbon removal rates were determined as a function of different iron ore particle sizes in batch experiments. Iron-reducing bacteria ensured the production of ferrous ions from iron ore up to concentrations of 550 mg L−1. The ferrous production rate was linearly dependent on the calculated specific surface area of the iron ore particles. The phosphorus concentration in the reject water was reduced by 90% during bioreduction of iron ore. The phosphorus removal rate did not depend on specific surface area of iron ore particles when the particle size of iron ore was smaller than 7 mm. The organic carbon removal rate did not seem to be dependent on iron ore particle size. CONCLUSION: Removal of phosphate using iron ore can be more economical than conventional chemical precipitation of phosphate using iron salts because of the lower cost of iron ore.Документ Iron-mediated removal of ammonia from strong nitrogenous wastewater of food processing(2004) Ivanov, Volodymyr M.; Wang, J.-Y.; Stabnikova, Elena; Krasinko, Victoria; Stabnikov, Victor; Tay, Stephen; Tay, JooThe combination of microbial reduction and further microbial oxidation of iron was applied to the treatment of food-processing wastewater and recovery of ammonium. Fe2+ ions were formed by iron-reducing bacteria under anaerobic conditions. Ammonium was recovered by co-precipitation with negatively charged iron hydroxides produced during oxidation of Fe2+ by iron-oxidizing bacteria under microaerophilic conditions. The value-added by-product of this process can be used as a slowly released ammonium fertilizer.