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Endüstri Mühendisliği Bölümü

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Browsing Endüstri Mühendisliği Bölümü by Subject "Anaerobic Digestion"

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    Citation Count: Uludag-Demirer, S.; Demirer, G.N.; Chen, S., "Ammonia removal from anaerobically digested dairy manure by struvite precipitation", Process Biochemistry, Vol.40, No.12, pp.3667-3674, (2005).
    Ammonia removal from anaerobically digested dairy manure by struvite precipitation
    (Elsevier Science LTD, 2005) Uludağ Demirer, Sibel; Demirer, G. N.; Chen, S.
    Ammonia is one of the most important contaminants impairing the quality of water resources. When this is considered along with the fact that the global demand for nitrogenous fertilizers is in constant rise, the need for recovery as well as removal of nitrogen is well justified. Crystallization of N and P in the form of struvite (MgNH4PO4 center dot 6H(2)O), which is a slow releasing and valuable fertilizer, is one possible technique for this purpose. This study investigated the removal of NR4+ through struvite precipitation from the effluents of one- (R1) and two-phase (R2) anaerobic reactors digesting dairy manure. To force the formation of struvite in the anaerobic reactor effluents, Ma(2+) ion was added by using both Mg(OH)(2) and MgCl2 center dot 6H(2)O. To prevent the effect of different total phosphorus (TP) concentration in the effluents of RI and R2, as well as to not limit the formation of struvite, an excess amount Of PO43- (0.14 M) was added in the form of NaHPO4. Different stoichiometric Mg2+:NH4+:PO43- ratios were tested to determine the required Mg2+ concentrations for maximum NH4+ removal by keeping NH4+:PO43- ratio constant for the effluents of reactors RI and R2. The results revealed that very high NH4+ removal efficiencies (above 95%) were possible by adding Mg 21 ions higher than 0.06 M concentration in the effluents from reactors RI and R2. It was also observed that the initial pH adjustment to 8.50 using NaOH did not result in any significant increase in the removal of NH4+ and the removal of NH4+ in the reactors treated with MgCl2 center dot 6H(2)O was higher than those treated with Mg(OH)(2) for the same Mg2+ concentration.
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    Citation Count: Uludağ-Demirer, S...et al (2008). Anaerobic digestion of dairy manure with enhanced ammonia removal. Journal of Environmental Management , 86(1), 193-200. http://dx.doi.org/10.1016/j.jenvman.2006.12.002
    Anaerobic digestion of dairy manure with enhanced ammonia removal
    (Academic Press Inc, 2008) Uludağ Demirer, Sibel; Demirer, Göksel N.; Frear, C.; Chen, S.; 45685
    Poor ammonia-nitrogen removal in methanogenic anaerobic reactors digesting animal manure has been reported as an important disadvantage of anaerobic digestion (AD) in several studies. Development of anaerobic processes that are capable of producing reduced ammonia-nitrogen levels in their effluent is one of the areas where further research must be pursued if AD technology is to be made more effective and economically advantageous. One approach to removing ammonia from anaerobically digested effluents is the forced precipitation of magnesium ammonium phosphate hexahydrate (MgNH4PO4 6H2O), commonly called struvite. Struvite is a valuable plant nutrient source for nitrogen and phosphorus since it releases them slowly and has non-burning features because of its low solubility in water. This study investigated coupling AD and controlled struvite precipitation in the same reactor to minimize the nitrogen removal costs and possibly increase the performance of the AD by reducing the ammonia concentration which has an adverse effect on anaerobic bacteria. The results indicated that up to 19% extra COD and almost 11% extra NH3 removals were achieved relative to a control by adding 1750 mg/L of MgCl2 6H2O to the anaerobic reactor.
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    Citation Count: Othman, M.Z.; Uludağ, Demirer S., Demirer, G.N. (2009). "Enhanced nutrients removal in conventional anaerobic digestion processes", World Academy of Science, Engineering and Technology, Vol. 58, pp. 1206-1212.
    Enhanced nutrients removal in conventional anaerobic digestion processes
    (2009) Othman, M.Z.; Uludağ, Demirer S.; Demirer, G.N.
    One of the main challenges for one phase anaerobic digestion processes is the high concentration of NH 4 + and PO 4 3- ions in the digested sludge supernatant. This project focuses on enhancing the removal of nutrients during the anaerobic digestion process through fixing both NH 4 + and PO 4 3- ions in the form of struvite (magnesium ammonium phosphate, MAP, MgNH 4PO 4.6H 2O) within the anaerobic sludge. Batch anaerobic digestion tests showed that Mg 2+ concentration in the range 279 - 812 mg/L had insignificant effect on CGP but incurred a slight increase in COD removal. The reactor that had soluble Mg 2+:NH 4 +:PO 4 3- at a molar ratio of 1.28:1:00:1:00 achieved the best performance enhancement of 8% increase in COD removal and 32% reduction in NH 4 + in the reactor supernatant. Overall, the results show that there is a potential to optimise conventional anaerobic digestion such that supernatant lean in P and N, and sludge rich in nutrients are obtained.
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    Citation Count: Uludağ-Demirer, S., Othman, M. (2009). Removal of ammonium and phosphate from the supernatant of anaerobically digested waste activated sludge by chemical precipitation. Bioresource Technology, 100(13), 3236-3244. http://dx.doi.org/10.1016/j.biortech.2009.02.030
    Removal of ammonium and phosphate from the supernatant of anaerobically digested waste activated sludge by chemical precipitation
    (Elsevier Science LTD, 2009) Uludağ Demirer, Sibel; Othman, Maazuza; 45685
    The removal of ammonium (NH(4)(+)) and phosphate (PO(4)(3-)) from supernatant of anaerobic digestion by magnesium ammonium phosphate (MAP) formation was Studied. To be able to find out the loss of NH(4)(+) by its transformation to NH(3), rates of NH(4)(+) removal by aeration and by MAP formation combined with aeration were compared. NH(4)(+) removal by aeration was found to be insignificant. The kinetics of MAP formation was fast. The removal rate of NH(4)(+) and Mg(2+) was the smallest and the largest, respectively based on rate constants calculated. The removal of NH(4)(+) showed sensitivity to Mg(2+) and PO(4)(3-) concentrations and controlled the purity of MAP precipitate. The removal of PO(4)(3-) was found to be Sensitive to mainly Mg(2+) ion. These results also indicated that as the supernatant Solution became more saturated in terms of MAP forming ions, the effect of pH increase became insignificant in the removal of ions from the solution