Sukru Aslan

Ammonium oxidation via nitrite accumulation under limited oxygen concentration in sequencing batch reactors.

In 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.

Nitritation and denitritation of ammonium-rich wastewater using fluidized-bed biofilm reactors

Fluidized-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. NH(4)-N conversion and NO(2)-N accumulation in the nitritation reactor effluent was over 90 and 65%, respectively. The average NH(4)-N removal efficiency was 99.2 and 90.1% at the NLR of 0.9 and 1.2 kg NH(4)-N/m(3)day, respectively. Increasing the NLR from 1.1 to 1.2 kg NH(4)-N/m(3)day decreased the NH(4)-N elimination approximately two-fold while NH(4)-N conversion to NO(2)-N differences were negligible. The NO(2)-N/NO(x)-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 NO(2)-N accumulation in the process. In the FBBDR, the NO(x)-N (NO(2)-N+NO(3)-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 NO(2)-N and NO(3)-N concentrations in the effluent were 3.0 and 0.9 mg/l at 0.08 kg/m(3)day loading rate. About 98% removal of NO(x)-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 NO(x)-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.

Influence of salinity on partial nitrification in a submerged biofilter

Partial nitrification under various concentrations of NaCl (0-40 g/l) at a constant operational condition was investigated in a submerged biofilter reactor. The highest NO(2)-N/NO(x)-N ratio (0.76) was achieved at the NLR of 830 g NH(4)-N/m(3) day with salt free wastewater. Small increase the salt content led to higher activities and the NH(4)-N removal efficiency increased from 92% to 95% at 1 g/l NaCl concentration. Over this concentration, each NaCl addition provoked the NH(4)-N oxidation and a sharp increase of inhibition was observed. The total oxidized NH(4)-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.

Kinetic and isotherm study of cupper adsorption from aqueous solution using waste eggshell

AbstractThe sorption of Cu2+ ions from aqueous solutions by eggshell was investigated in a batch experimental system with respect to the temperature, initial Cu2+ concentrations, pH, and biosorbent doses. The adsorption equilibrium was well described by the Langmuir isotherm model with the maximum adsorption capacity of 5.05 mg Cu2+/g eggshell at 25 °C. The value of qe increased with increasing the temperature while also increases the release of Ca2+ and HCO−3 ions from the eggshell. The highest sorption of Cu onto the waste eggshell was determined at the initial pH value of 4.0. The results confirming that the adsorption reaction of Cu2+ on the eggshell was thought to be endothermic. A comparison of the kinetic models such as pseudo first and second-order kinetics, intraparticle diffusion, and Elovich on the sorption rate demonstrated that the system was best described by the pseudo second-order kinetic model.

Assessment of the adsorption kinetics, equilibrium and thermodynamics for the potential removal of Ni2+ from aqueous solution using waste eggshell

AbstractIn 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 qm value of 1.845 mg Ni2+/g eggshell was observed. The pseudo-second-order model provided the best correlation coefficient in comparison with other models. The calculated qe values derived from the pseudo-second-order for sorption of Ni2+ ions were very close to the experimental (qexp) values. Such thermodynamic parameters as ΔG°, ΔH°, and ΔS° 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.

Biosorption of Cu2+ and Ni2+ Ions From Aqueous Solutions Using Waste Dried Activated Sludge Biomass

Abstract Adsorption 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 m2/g, 0.0053 cm3/g, and 41.4 nm, respectively. Considering the R2 value, qexp and qcal, 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-fi rst-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.

Evaluation of Alfalfa Plants Growth Irrigated with Arsenic Contaminated Water

In Mexico, the society in general lacks the habit and ethics of properly disposing garbage or in taking care of the environment. This paper focuses on analyzing and disposing garbage in an automated way. The present study also seeks to create and promote care for the planet. The minicomputer (GreenScanProcess) is an automated system whose process is based on an algorithm that stands out for its functionality. GreenScanProcess has sensors that allow the analysis and scanning of garbage. It also measures the weight and humidity of the garbage. The minicomputer also examines the garbage to know its composition. Likewise, GreenScanProcess takes the garbage to the container according to the garbage. The benefits obtained when conducting the research were: environmental, economic, technological, and educational.

Cancer Risk Assessment in Drinking Water of Izmir, Turkey

In 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 Balçova Water Treatment Plants (TWTP, BWTP), which are the major water sources of the Izmir City were about 72 and 88 μg/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 × 10 −5 and 4.3 × 10−5 for males and 4.76 × 10−5 and 5.8 × 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.

THE REMOVAL OF NITRATE AND PESTICIDES FROM CONTAMINATED WATER

A 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 C to 14 C. Despite such oscillations, high removal efficiencies for trifluralin, fenitrothion and endosulfan (α+β) were observed and the highest nitrite concentration was 16 mg/l in the effluent of the reactor.