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Öğe Accumulation of arsenic in plants from arsenic contaminated irrigation water(PAMUKKALE UNIV, 2017) Ozturk, Mustafa; Aslan, Sukru; Demirbas, AhmetArsenic occurs naturally in the earth's surface and is widely distributed in the environment. Arsenic is commonly encountered in groundwater in different parts of the world due to natural processes as well as from anthropogenic activities. Groundwater and surface water contamination by arsenic has been reported from many countries including Turkey. Chronic health effects of arsenic are lesions (spotted keratosis, melanosis, dorsal keratosis, hyper pigmentation, hyper keratosis and gangrene). Long-term exposure to arsenic may cause bladder, lung, skin, kidney, liver and prostate cancer. Due to the high toxic effects on the human health, the maximum contaminant level of arsenic in drinking waters was limited to 10 mu g/L by the United States Environmental Protection Agency and World Health Organization. Arsenic level in drinking water was established as 10 mu g/L in 2008 in Turkey. Arsenic-contaminated groundwater is also used for irrigation for the growing plants and livestock watering as well as the use of drinking water sources. Contaminated water, used in irrigation, could cause dangerous conditions in soil and product quality. Elevated arsenic levels in irrigation water were found to inhibit seed germination and seedling establishment of crops. A number of studies have reported a large variability in arsenic levels in foods, waters, and soils from different countries. Animals can accumulate arsenic via intake of contaminated feed, soil, water and then these animal tissue containing residues of arsenic can be harmful to human health who consumes the meat, visceral organs, and milk. Arsenic accumulation differs between plant species and individuals. The results showed that the trend of arsenic concentration in the plant tissues are root>stem>leaf/fruit. Concentration of arsenic in plants is much higher than the soil and water and it has toxic effects to the other organisms. In this review article accumulation of arsenic in plants and harmful effects on the human health are evaluated.Öğe Ammonium oxidation via nitrite accumulation under limited oxygen concentration in sequencing batch reactors(ELSEVIER SCI LTD, 2009) Aslan, Sukru; Miller, Lindsey; Dahab, MohamedIn this study, the effects of sludge retention time (SRT) on NH(4)-N oxidation and NO(x)-N accumulation in the nitritation reactors were studied. The gradually decrease of SRT also caused long reaction time to achieve 99% NH(4)-N removal. Although the target NH(4)-N removal was achieved in a short reaction time at 40 days of SRT, decreasing of SRT from 40 to 30, 25, 20 days, increase the reaction time from 168 to 240 and 265 h, respectively. The inlet NH(4)-N was almost oxidized and the concentration of NO(2)-N accumulated to a high level of 177 mg/l, while NO(2)-N/(NO(3)-N + NO(2)-N) ratio was about 0.9 at SRT of 40 days. However, the concentration of NO(3)-N increased slightly and NO(2)-N/(NO(x)-N) ratio dropped to 0.8 when the SRT was lower than 40 days. During the operation in a cycle, free ammonia concentration in the SBR was decreased from 2.8 to 0.7 mg/l which is below the lowest concentration causing inhibition of nitrite oxidizing bacteria (NOB). It was assumed that combined dissolved oxygen limitation and NH(3)-N inhibition on NOB caused NO(2)-N accumulation under the experimental conditions. (c) 2008 Elsevier Ltd. All rights reserved.Öğe ASSESSMENT OF THE ADSORPTION KINETICS, EQUILIBRIUM AND THERMODYNAMICS FOR THE POTENTIAL REMOVAL OF NI2+ FROM AQUEOUS SOLUTION USING WASTE EGGSHELL(VILNIUS GEDIMINAS TECH UNIV, 2015) Aslan, Sukru; Polat, Ayben; Topcu, Ugur SavasIn this study, Ni2+ sorption onto the waste eggshell was investigated under different operational conditions. Results indicated that the eggshell could be successfully used to remove Ni2+ ions from the water. Quick sorption process reached to equilibrium in about 2 hours with maximum sorption at pH 7.0. Based on the experimental data, Langmuir isotherm model with the q(m) value of 1.845mg Ni2+/g eggshell was observed. The pseudo-second-order model provided the best correlation coefficient in comparison with other models. The calculated q(e) values derived from the pseudo-second-order for sorption of Ni2+ ions were very close to the experimental (q(exp)) values. Such thermodynamic parameters as G degrees, H degrees, and S degrees were determined in order to predict the nature of adsorption. Results indicated that the adsorption of Ni2+ onto the eggshell was endothermically supported by the increasing adsorption of Ni2+ ions with temperature.Öğe Biological denitrification of drinking water in a slow sand filter(ELSEVIER SCIENCE BV, 2007) Aslan, Sukru; Cakici, HaticeBiological removal of nitrate from drinking water was studied in a slow sand filter. Optimum carbon to nitrogen ratio (C/N) was found to be 1.8 when using acetic acid in batch tests. The filtration rates impact on NO3-N removal through the sand filter was assessed for 22.6 mg NO3-N/l concentrations while keeping C/N ratio as 1.8 for acetic acid. The filtration rates varied from 0.015, 0.02, 0.03, 0.04,0.05, and 0.06 m/h, respectively, corresponding to an overall average NO3-N removal efficiency of 94%. Although increasing filtration rates decreased NO3-N removal, effluent NO3-N concentrations at the effluent port were lower than the limit value. The slow sand filter process was unable to provide NO3-N removal rate more than 27.1 N/(m(2) day) (0.05 m/h flow rate). The NO3-N removal efficiency slightly dropped from 99% to 94% when the loading rate increased from 27.1 to 32.5 g/(m(2) day), but the effluent water contained higher concentration of NO2-N than the standard value. (C) 2007 Elsevier B.V. All rights reserved.Öğe Biological nitrate removal in a laboratory-scale slow sand filter(WATER RESEARCH COMMISSION, 2008) Aslan, SukruThis research evaluated removal of nitrates from drinking waters in a slow sand filter (SSF). Batch experiments were performed to determine optimum carbon to NO3-N (C/N) ratio for the filtration experiments. The filter column was filled with filter sand of an effective diameter of 0.5 mm and uniformity coefficient of 1.23. The filter was operated at filtration rates of between 0.02 to 0.120 m/h and 0.01 to 0.25 m/h with concentrations of 22.6 and 45.2 mg NO3-N/l, respectively, and effluent samples of the SSF were taken at 6 depths of 10, 15, 20, 40, 60, 80 cm, and the bottom. Optimum C/N ratio was found to be 1.5 when using ethanol in batch tests when the removal efficiencies of NO3-N and C were higher than 90%. Although increasing filtration rates decreased NO3-N removal, effluent NO3-N concentration at the effluent port of the SSF was lower than the limit value. Most of the NO3-N removal was carried out at the upper layer of (10 cm) the filter bed. Concentration of NO3-N, NO2-N, and C were not detected at the 60 cm depth of the SSF through the study for the inlet concentrations of 22.6 mg NO3-N/l. As expected, increasing influent NO3-N concentration to 45.2 mg/l increased NO 3-N, NO2-N, and C concentrations in the effluent water. The SSF process was unable to provide NO3-N removal rate of more than 228 g N/m(3) center dot d (0.2 m/h flow rate, 217g N/m(2)center dot d of surface loading rate). The NO 3- N removal efficiency dropped slightly from 96 to 95% when the loading rate increased from 228 to 285 g/m(3) center dot d, but the effluent water contained higher concentrations of NO2-N (8.4 mg/l) than the standard value. The results of the SSF experiment demonstrated that averaged nitrogen conversion to volatile solids was about 0.77 mg VS/ mg NO3-N.Öğe Biosorption of Cu2+ and Ni2+ ions from aqueous solutions using waste dried activated sludge biomass(DE GRUYTER POLAND SP ZOO, 2018) Aslan, Sukru; Yildiz, Sayiter; Ozturk, MustafaAdsorption of Cu(II) and Ni(II) ions onto the waste powdered activated sludge biomass (PWB), which was obtained from the biological wastewater treatment plant, was investigated in this experimental study. The effects of contact time, pH, temperature, initial sorbate and sorbent concentrations on the adsorption were determined. The BET surface area, pore volume, and pore diameter of PWB were found to be about 0.51 m(2)/g, 0.0053 cm(3)/g, and 41.4 nm, respectively. Considering the R-2 value, q(exp) and q(cal), the Langmuir and Freundlich models were well described for Cu(II) and Ni(II) adsorption, respectively. The adsorption mechanism of Cu(II) and Ni(II) onto the PWB could be better simulated by the pseudo-second-order kinetic mechanism than the pseudo-first-order, intra particle diffusion and Elovich models. Thermodynamic aspects of the adsorption of heavy metals were also investigated. Considering the applied desorbing agents for reuse of PWB for Ni(II) recovery, desorption cycle is not feasible due to the deterioration of the PWB structure.Öğe Biosorption of Cu2+ from synthetic wastewater by tea waste sorbent: kinetics, equilibrium and thermodynamics(Pamukkale Univ, 2021) Aslan, Sukru; Yildiz, Sayiter; Ozturk, MustafaThe biosorption of Cu2+ onto the tea wastes (TW) was investigated by performing the batch experiments. The removal efficiency and biosorption capacity (q(e)) of TW was investigated as a function of pH, contact time, initial Cu2+ concentration, temperature, and TW dose. The q(e) value of 7141 increased with the increase of solution temperatures. According to the R-2 value, q(exp) and q(coa), the adsorption equilibrium was well described by the Langmuir isotherm model The highest sorption of Cu2+ onto TW was observed at the initial pH value and temperature of 6.0 and 55 degrees C, respectively. Experimental results confirming that the biosorption reaction of Cu(2+)on the TW was thought to be endothermic. By the comparison of kinetic models, results demonstrated that the system was best described by the pseudo secondorder kinetic model The negative Delta G degrees value indicated that the Cu2+ sorption onto the TW is feasible.Öğe Cancer risk assessment in drinking water of Izmir, Turkey(SPRINGER, 2007) Aslan, Sukru; Turkman, Aysen; Mothersill, C; Mosse, I; Seymour, CIn this study, the occurrence of trihalomethanes (THMs) of the tap water in Izmir City was investigated and the lifetime cancer risk of THMs through oral ingestion, dermal absorption, and inhalation exposure were estimated. The total THMs in samples taken from the Tahtali and Ball;ova Water Treatment Plants (TWTP, BWTP), which are the major water sources of the Izmir City were about 72 and 88 mu g/L, respectively. Chloroform existed at the highest concentrations in samples. Although the cancer risk evaluation of CHBr3 through oral route for both sexes was below the EPA level, the highest lifetime cancer risk was originating due to CHCl2Br; 5.2 x 10(-5) and 4.3 x 10(-5) for males and 4.76 x 10(-5) and 5.8 x 10(-5) for females, for the samples from BWTP and TWTP, respectively. While overall the average lifetime cancer risks through oral route, dermal absorption, and inhalation exposure for THMs were higher than the EPA acceptable risk of 10(-6) by about 87, 340, and 5.7 times in the samples from TWTP and 99, 390, and 7.9 times in the samples from BWTP, respectively. The average lifetime cancer risk for THMs in both sources was in decreasing order, CHCl2Br, CHCl2Br, CHCL3, and CHBr3 for both sexes.Öğe CH4 production potential of autotrophic nitrification bacteria produced in the submerged nitrification bioreactor in the laboratory and kinetic analysis(Taylor & Francis Ltd, 2024) Aslan, Sukru; Alhraishawi, Ali; Ozturk, MustafaIn this study, CH4 production capacity of nitrification bacteria (NB) obtained from the submerged biofilter in the laboratory was investigated. Biochemical methane potential (BMP) test was carried out with the NB amount of zero (control, CR), 5% (R1), 10% (R2), and 15% (R3) at a temperature of about 37 +/- 0.5 degrees C. Compared to the CR, significantly higher cumulative CH4 volume of about 290, 490, and 715 mL were determined in the R1, R2, and R3, respectively. All the applied kinetic models gave good results (R-2 >= 0.97), while the Transference Function and First-order models provided the better R-2 values. The delay phase (lambda) was not observed in the AD process, and CH4 production started immediately on the first day of operation. The predicted k value of 0.133 day(-1) was high in CR, while it was approximately between 0.078 and 0.112 day(-1) for the higher amount of NB containing BMP units, which indicated that the AD required long reaction time.Öğe Effect of low microwave temperature on the physical and chemical properties of waste activated sludge(Modestum, 2024) Alhraishawi, Ali; Aslan, SukruIn this study, the effect of microwave (MW) irradiation at a target temperature of 80 °C with a heating rate of two °C/min and a holding time of five minutes on the physicochemical properties of activated sludge was studied. The results showed that subjecting biosludge to MW pretreatment resulted in a reduction in particle size to 14.5, 44.6, and 72.8 for d10, d50, and d90, respectively and an increase in the specific surface area of the biosludge to 235.9 m2/kg. Pretreatment resulted in an increase in soluble oxygen demand, sugar, and protein concentrations to 2,380.0 mg/L, 66.5 mg/L, and 1.81 g/L, respectively. A slight increase in the release of inorganic compounds, especially NH4-N and PO4-P, was observed in the disintegrated biosludge. While there was an increase in release of K and Zn, a decrease in concentrations of Na, Ca, Mg, and Al in the liquid was observed after MW irradiation. It was determined that the dewatering property deteriorated after biosludge disintegration, as it increased from raw sludge to disintegrated sludge by 21-fold. © 2024 by Author/s and Licensed by Modestum DOO, Serbia.Öğe The effect of petrochemical industry wastewater composition on the activated sludge microflora(PARLAR SCIENTIFIC PUBLICATIONS (P S P), 2006) Turkman, Aysen; Aslan, Sukru; Ozdurakoglu, NiluferIn this study, the effect of wastewater composition on the activated sludge microflora has been evaluated. Wastewater samples from the aeration tank of a petrochemical industry wastewater treatment plant were taken and analyzed during a four-months period. The results of analysis indicate that the density of floc-forming, microorganims was higher than that of filamentous ones in the activated sludge tank, when sludge volume index (SVI) was lower than 150 ml/g. During the study, pH values of the mixed liquor were very high for fungal growth. Consequently, lower amounts of fungal species than floc-forming microorganisms were observed. Increasing, protozoan concentration in activated sludge process (ASP) caused lower amounts of suspended solids (SS), washed out especially at low dissolved oxygen (DO) concentration. Food/microorganisms (F/M) ratios were varying between 0.3-0.7 g BOD5/g mixed liqior suspended solids (MLSS) in the process. Even when influent wastewater contained low nitrogen and phosphorus levels, high BOD5 removal rates were observed, provided by filamentous microorganisms dominating in the unit. When the organic loading was higher than 14 g/m(3) /d, influent COD concentrations were higher than 2100 mg/L, and thus Pseudomonas spp. in the ASP were affected negatively.Öğe Effects of microwave irradiation at various temperatures on biosludge disintegration(Taylor & Francis Ltd, 2024) Aslan, Sukru; Alhraishawi, Ali; Ozturk, MustafaThe waste biological sludge disintegration by using microwave irradiation was investigated at a ramping rate of 2 degrees C/min and 5 min holding time at various target temperatures. Significant disintegration of biosludge was observed and the highest disintegration degree was determined about 82% at the temperature of 110 degrees C. Increase of target temperature elevated the energy needs to 98, 123 and 148 kWh/kg TS at the temperatures of 75 degrees C, 90 degrees C and 110 degrees C, respectively. The gradual increase of sugar and protein in the sludge slurry with increasing temperatures indicates successful degradation. The microwave pretreatment increased the specific surface area of the sludge by particle size reduction. The specific surface area of raw sludge was 70 m2/kg and rose to approximately 253.7 m2/kg at 110 degrees C with an increment ratio of 260%. Although a significant NH4-N release was not observed, PO4-P concentrations increased from 11.0 mg/L to 16.3, 20.7 and 29.2 mg/L at the temperatures of 75 degrees C, 90 degrees C, 110 degrees C, respectively. While the specific filter resistance of waste biological sludge was about 1.0 x 1013, increasing the microwave target temperature, the ability of dewatering decreased and the highest SFR value of 5.1 x 1014 was observed at the temperature of 110 degrees C.Öğe Individual and combined effects of nickel and copper on nitrification organisms(ELSEVIER SCIENCE BV, 2017) Aslan, Sukru; Sozudogru, OnurIndividual and combined effects of Ni2+ and Cu2+ concentrations on the nitrification process were investigated in a submerged biofilter. The activity of nitrification organisms was inhibited by high concentrations of Cu2+. However, low concentrations of Cu2+ promoted NOB activity. There were no observable stimulation effects of Ni2+. The presence of 0.2-4.0 mg/L Ni2+ caused a decrease in the rate of nitrification. Although the inhibition of Cu2+ on the nitrification organisms started at a concentration of 0.5 mg/L, it started at 0.2 mg/L for Ni2+. Ni2+ had stronger inhibitory effect on the nitrification organisms than Cu2+. Using a mixture of Ni2+ and Cu2+, inhibition level drastically increased to 32% and 49% at concentrations of 2.0 and 3.0 mg/L, respectively. At the same concentrations, individual inhibition by Ni2+ and Cu2+ was much lower, about 12-15% and 18-24%, respectively. (C) 2016 Elsevier B.V. All rights reserved.Öğe Influence of Operational Parameters and Low Nickel Concentrations on Partial Nitrification in a Submerged Biofilter(HUMANA PRESS INC, 2011) Aslan, Sukru; Gurbuz, BurhanettinThe effect of Ni(2+) concentrations on ammonium oxidation was studied in a batch and partial bionitrification reactor (PBNR). The nitrification rates up to the concentration of 0.1 mg Ni(2+)/l were close to those without Ni(2+). After testing the operational conditions in the PNBR, the highest NO(2)-N/NO (x) -N ratio was achieved at the DO concentrations of 2.0 mg/l and pH 9.00. The PNBR was operated at steady state (NH(4)-N loading rate and NO(2)-N/NO (x) -N ratio were 405 g m(-3) day(-1) and 0.74, respectively) before exposure to Ni(2+). The removal efficiency of NH(4)-N and NO(2)-N/NO (x) -N ratio in the effluent waters was increased by adding low concentrations of heavy metals to the PBNR. The average number of aerobic mesophilic bacteria at the biofilm surface and in the water in the void volume of PNBR were 1.0 x 10(4) CFU/g and 1.4 x 10(5) CFU/ml, respectively.Öğe Influence of salinity on partial nitrification in a submerged biofilter(ELSEVIER SCI LTD, 2012) Aslan, Sukru; Simsek, ErdalPartial nitrification under various concentrations of NaCl (0-40 g/l) at a constant operational condition was investigated in a submerged biofilter reactor. The highest NO2-N/NOx-N ratio (0.76) was achieved at the NLR of 830 g NH4-N/m(3) day with salt free wastewater. Small increase the salt content led to higher activities and the NH4-N removal efficiency increased from 92% to 95% at 1 g/l NaCl concentration. Over this concentration, each NaCl addition provoked the NH4-N oxidation and a sharp increase of inhibition was observed. The total oxidized NH4-N was achieved at the nitrogen loading rate (NLR) and surface loading rate (SLR) of 0.754 kg/m(3) day and 3.23 g/m(2) day, respectively without salt in the feed wastewater and it was decreased to 0.322 kg/m(3) day and 1.38 g/m(2) day at the salinity of 40 g/l in the PNBR. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Methane Production and Nutrient Recovery After Applying Microwave Technology in Sewage Sludge Pretreatment(Springer Int Publ Ag, 2024) Alhraishawi, Ali; Aslan, Sukru; Ozturk, MustafaThis study investigates the effect of microwave treatment on the disintegration of municipal activated sludge. Sludge samples underwent heating at a targeted temperature of 90 degrees C for 35 min, with a 5-min retention time. Soluble chemical oxygen demand, sugars, proteins, nitrogen, and phosphorus exhibited notable increases compared to untreated samples. Results indicate a substantial (42-45%) rise in CH4 production during the anaerobic digestion process of the disintegrated sludge compared to the untreated counterpart CH4 production was estimated using a transference model, which showed the best fit compared to other models. Further experimentation involved testing digested sludge with excess soluble NH4-N and PO4-P for the recovery of struvite at a 1.50/1/1 (Mg/N/P) ratio. The findings reveal that up to 90.1% and 90.4% of PO4-P and NH4-N, respectively, can be efficiently removed from the solution. Despite the increased CH4 output, the energy recovered was insufficient to offset the electrical energy used by the microwave. There was a significant deterioration in sludge filter resistance due to the increase in fine particles and bound water after anaerobic digestion of the pretreated sludge.Öğe Methane Production and Struvite Recovery from Disintegrated Biosludge at Different Microwave Powers(Springer, 2025) Alhraishawi, Ali; Aslan, Sukru; Ozturk, MustafaThis study examined the impact of microwave (MW) irradiation on the disintegration of waste biological sludge (WBS) and CH4 production during anaerobic digestion (AD), alongside the recovery of NH4-N and PO4-P via struvite precipitation in AD tailings. MW treatment was conducted under controlled conditions (120 degrees C and 2 degrees C/min) at the power levels of 900 W and 1,800 W. The soluble chemical oxygen demand (sCOD) increased by factors of 465 and 432 at 900 W and 1,800 W, respectively, while sugar and protein concentrations rose by factors of 840-110 and 1.93-2.15 compared to the untreated WBS. However, MW irradiation was less effective for releasing NH4-N and PO4-P. The disintegration of WBS improved CH4 production in the biochemical methane potential (BMP) test by 26% and 35% at 900 W and 1,800 W, respectively, relative to the control. Despite these enhancements, the process was deemed uneconomical due to the high energy demand of MW irradiation compared to the energy gained from the increased CH4 yield. Additionally, the sludge dewatering properties, measured as sludge filter resistance (SFR), deteriorated significantly, increasing from 2.87 x 10(14) for the untreated WBS to 6.50 x 10(14) and 6.70 x 10(14) at 900 W and 1,800 W, respectively. Kinetic modeling of the BMP tests revealed that the Transference Function provided the best fit to the experimental data. In the struvite precipitation, the optimal recovery of NH4-N and PO4-P (96%) was achieved at a molar ratio of 1.25/1/1 for Mg/N/P. [GRAPHICS] .Öğe Nitritation and denitritation of ammonium-rich wastewater using fluidized-bed biofilm reactors(ELSEVIER SCIENCE BV, 2008) Aslan, Sukru; Dahab, MohamedFluidized-bed biofilm nitritation and denitritation reactors (FBBNR and FBBDR) were operated to eliminate the high concentrations of nitrogen by nitritation and denitritation process. The dissolved oxygen (DO) concentration was varied from 1.5 to 2.5 g/m(3) at the top of the reactor throughout the experiment. NH4-N conversion and NO2-N accumulation in the nitritation reactor effluent was over 90 and 65%, respectively. The average NH4-N removal efficiency was 99.2 and 90.1% at the NLR of 0.9 and 1.2 kg NH4-N/m(3) day, respectively. Increasing the NLR from 1.1 to 1.2 kg NH4-N/m(3) day decreased the NH4-N elimination approximately two-fold while NH4-N conversion to NO2-N differences were negligible. The NO2-N/NOx-N ratios corresponded to 0.74, 0.73, 0.72, and 0.69, respectively, indicating the occurrence of partial nitrification. An average free ammonia concentration in the FBBNR was high enough to inhibit nitrite oxidizers selectively, and it seems to be a determining factor for NO2-N accumulation in the process. In the FBBDR, the NOx-N (NO2-N+NO3-N) concentrations supplied were between 227 and 330 mg N/l (NLR was between 0.08 and 0.4 kg/m(3) day) and the influent flow was increased as long as the total nitrogen removal was close to 90%. The NO2-N and NO3-N concentrations in the effluent were 3.0 and 0.9 mgA at 0.08 kg/m(3) day loading rate. About 98% removal of NOx-N was achieved at the lowest NLR in the FBBDR. The FBBDR exhibited high nitrogen removal up to the NLR of 0.25 kg/m(3) day. The NOx-N effluent concentration never exceeded 15 mg/l. The total nitrogen removal efficiency in the FBBRs was higher than 93% at 21 +/- 1 degrees C. (C) 2007 Elsevier B.V. All rights reserved.Öğe OPTIMIZATION OF OPERATIONAL CONDITIONS FOR NITRITE ACCUMULATION IN A SUBMERGED BIOFILTER(GH ASACHI TECHNICAL UNIV IASI, 2017) Aslan, Sukru; Simsek, ErdalThe partial nitrification bioreactor (PNBR) was operated at a constant temperature and an influent synthetic wastewater pH of 35 degrees C and 8.5, respectively. The effects of dissolved oxygen concentrations (DO), hydraulic retention times (HRT), and the nitrogen loading rates (NLR) on the ammonium removal efficiencies and the NO2-N/NOx-N ratio were investigated. The activity of nitrite oxidizing bacteria was stimulated at high DO concentrations. The highest NO2-N/NOx-N ratio of 0.76 was obtained at the DO concentrations of 1.9 mg/L. The NLRs and HRTs significantly affect the NO2-N accumulation in the PNBR. Although the most of NH4-N (98%) was oxidized at the HRT of 10.3 h, the ratio of NO2-N/NOx-N [NO2-N/(NO2-N+NO3-N)] was too low (0.33). The removal efficiency of NH4-N descended to 92% while the ratio of NO2-N/NOx-N achieved the highest level of 0.74 at the HRT of 5.2 h. At the NLR of 830 g NH4-N/m(3). day, the ratio of NO2-N/NOx-N reached to the highest level of 0.76 under the operational conditions. However, the removal efficiency of NH4-N decreased from 94% to 92%. Further increased the NLR caused the deterioration of NH4-N oxidation and NO2-N/NOx-N ratio. The stable NO2-N production rate of about 810 g/m3. day (2.5 g/m(2). day) was obtained under the NLR and surface loading rate of 830 g NH4-N/m(3). day and 3.55 g/m(2). day, respectively.Öğe The removal of nitrate and pesticides from contaminated water(SPRINGER, 2006) Aslan, Sukru; Turkman, Aysen; Tellam, JH; Rivett, MO; Israfilov, RG; Herringshaw, LGA water-saturated biological denitrification system was employed to remove selected pesticides and nitrate from drinking waters. In the study, approximately 99% nitrate removal was observed, but most of the samples included nitrite. Up to 95% removal of pesticides was also observed. The lowest removal efficiency of nitrate (63%) was observed when the temperature dropped sharply from 18 T to 14 T. Despite such oscillations, high removal efficiencies for trifluralin, fenitrothion and endosulfan (alpha+beta) were observed and the highest nitrite concentration was 16 mg/l in the effluent of the reactor.
