Beril Salman Akin

Biological removal of carbon, nitrogen, and phosphorus in a sequencing batch reactor.

Abstract In this research the process performance of enhanced biological phosphorus removal was investigated in a sequencing batch reactor (SBR) having a new operational mode. The SBR system used in this study had simultaneous feeding and decanting conditions. The laboratory scale reactor (10 L) was operated for 392 days. The system was operated under 4 different sets each having 2 cycles per day. In each cycle, fill (4 h), anoxic (0.5 h), aerobic (7 h) and settling phases were present. In the fill phase, wastewater was fed from the bottom and the anoxic/anaerobic conditions were established in the settled sludge. During filling, the water left the system by water displacement. The system provided nitrification, denitrification as well as phosphorus and organic removal. High COD (90–98%), PO4-P (77–100%), and NH4-N (90–95%) removals were achieved by this system.

Excess molar volumes, viscosity, refractive index, and Gibbs energy of activation of binary biodiesel + benzene, and biodiesel + toluene mixtures at 298.15 and 303.15 K

Excess molar volumes (VE), viscosities, refractive index, and Gibbs energies were evaluated for binary biodiesel + benzene and toluene mixtures at 298.15 and 303.15 K. The excess molar volumes VE were determined from density, while the excess Gibbs free energy of activation G*E was calculated from viscosity deviation Δη. The excess molar volume (VE), viscosity deviation (Δη), and excess Gibbs energy of activation (G*E) were fitted to the Redlich-Kister polynomial equation to derive binary coefficients and estimate the standard deviations between the experimental data and calculation results. All mixtures showed positive VE values obviously caused by increased physical interactions between biodiesel and the organic solvents.

ENHANCED PHOSPHORUS REMOVAL BY GLUCOSE FED SEQUENCING BATCH REACTOR

In this study an anaerobic/aerobic sequencing batch reactor was used for an enhanced biological phosphorus removal. These conditions were tested by a laboratory scale reactor (14 liter) with a synthetic feed, glucose being the sole carbon source. However, enhanced biological phosphorus removal (EBPR) was not achieved during this study. A series of batch tests were conducted with various substrates; acetic acid, glucose and the mixture of acetic acid and glucose. High phosphate removal was obtained when acetate was the substrate (68.7%). It was observed that when the acetic acid was used as a sole substrate, the bacteria growing in the alternating anaerobic/aerobic system removed the organic substrate under anaerobic conditions. However, in case of the glucose feed most of the COD removal took place under not truly anaerobic conditions. This also coincides with low phosphate removal (37.8%). These results are in consistent with the results of the continuous operation. When the acetic acid–glucose mixture was used, the phosphate removal decreased down to 60.8%. This was thought to be due to the glucose that reduced the dependency on poly-P as an energy source.

Serum heavy metal and antioxidant element levels of children with recurrent wheezing

STUDY OBJECTIVES The aim of the study is to investigate the levels of toxic heavy metals related with environmental pollution and trace elements involved in antioxidant system in children suffering from recurrent wheezing. STUDY DESIGN One hundred children with recurrent wheezing (at least three recurrences) between the ages from 1 to 6 years took part in the study, and also 116 age- and sex- matched healthy children were involved in the study as a control group. Venous blood samples were collected and serum mercury, lead, aluminium, zinc, selenium, and copper levels were studied using ICP-MS. RESULTS Serum lead (0.76±0.15 vs. 0.27±0.01, p:0.001) and mercury levels (1.31±0.15 vs 0.71±0.05, p<0.001) were higher in wheezy group than those acquired from the control group. Serum zinc (69.4±1.65 vs. 78.9±2.78, p:0.005) and selenium (115.6±1.87 vs. 125.4±2.94, p:0.008) levels were lower in wheezy group than those acquired from the control group. Serum zinc levels were found to be correlated with number of ARTIs (r(p):-0.332, p:0.001) and the number of wheezy attacks (r(p):-0.776, p<0.001) during the previous year in the wheezy group. CONCLUSION Elevated levels of serum lead and mercury and low levels of zinc and selenium may suggest some disturbances in the antioxidant system in children with recurrent wheezing. This means that children with recurrent wheezing are much more susceptible to environmental pollutants and respiratory tract infections than healthy children and this heavy metal-antioxidant relationship may play a role as a contributing factor in the pathogenesis of recurrent wheezing in children.