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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 Effect of iron hydroxide on phosphate removal during anaerobic digestion of activated sludge(2004) Stabnikov, Victor; Tay, Stephen; Tay, Joo; Ivanov, Volodymyr M.Addition of ferric hydroxide to the reactor of methanogenic fermentation of activated sludge followed microbial reduction of Fe (III) and formation of ferrous ions, which precipitated phosphate. It was shown that 66.6 – 99.6 % of dissolved phosphate with initial concentration of 1000 – 3500 mg РО43-/l can be removed by the addition of ferric hydroxide in concentration of 6420 mg Fe (III)/l and anaerobic sludge with iron-reducing activity. Optimal ratio of added Fe(III): removed dissolved phosphate, ensured not less than 95 % removal of phosphate was 2. These data could be used in a new technology of anaerobic treatment of wastewater with simultaneous removal of phosphate.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 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.