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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 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 The removal of phosphate from wastewater using anoxic reduction of iron ore in the rotating reactor(2009) Guo, Cheng Hong; Stabnikov, Victor; Kuang, Shengli; Ivanov, Volodymyr M.The removal of phosphorus from reject water, which is the liquid fraction produced after dewatering of anaerobically digested activated sludge on the municipal wastewater treatment plants (MWWTPs), can significantly reduce the phosphorus load to the main stream of the MWWTPs. Ferric or ferrous reagents can be used for this removal but the significantly cheaper option could be the production of ferrous reagent using bioreduction of iron ore. The removal of phosphorus from reject water using anoxic bioreduction of iron ore was studied in the rotating reactor, which was selected to avoid the clogging of the pores between iron ore particles. The highest phosphorus removal rate from reject water in the rotating reactor, i.e. the parameter which can be used in the design of the continuous process, was 25mg P/L day. Significant role in the iron ore bioreduction is playing the formation of the fine particles from initially loaded coarse particles of iron ore during rotation of the reactor.Документ The removal of nitrogen and phosphorus from reject water of municipal wastewater treatment plant using ferric and nitrate bioreductions(2010) Guo, Cheng Hong; Stabnikov, Victor; Ivanov, Volodymyr M.Reject water, which is the liquid fraction produced after dewatering of anaerobically digested activated sludge on the municipal wastewater treatment plants (MWWTPs), contributes up to 80% of the nitrogen and phosphorus loads to the MWWTP. It was proposed to combine the removal of nitrogen from reject water using the sequential biooxidation of and bioreduction of NO3- with precipitation of phosphate by Fe2+ ions produced due to bioreduction of Fe3+ in iron ore. Bioreduction of NO3- decreased Fe3+ bioreduction rate in reject water from 37 to 21 mg Fe2+/L d due to competition between NO3- and Fe3+ for electron donors. Addition of acetate as electron donor increased both bioreduction rates of Fe3+ and NO3- but acetate interfered with the competition between nitrate and phosphate anions reacting with ferrous cations decreasing efficiency of the phosphate removal from reject water. The stages of denitrification and ferric bioreduction/phosphate precipitation must be performed sequentially.