Bilge Özbay

This study investigates the utilization of the biodrying process, which is an eco‐friendly approach for sewage sludge management to produce a fuel‐like product. Biodrying tests were conducted for six trials containing different amounts of bulking agents (straw and sawdust). Higher volatile matter removal was achieved for trials with sawdust as a result of better porosity conditions. Consequently, biodrying indexes were higher for straw containing trials (7.73–30.85) with straw than those trails with sawdust (6.94–13.99). Trials with straw resulted in biodried materials with lower moisture content and higher calorific value due to lower water holding capacity of straw. However, sawdust provided better fuel quality due to the higher bulk density of the product. Thus, fuel value indexes determined for trials with sawdust (81.62–152.17) were remarkably higher than those of trials with straw (16.02–68.97). Furthermore, biomass characterization indexes (>25.000) indicated that products with sawdust can be used as promising alternatives to biomass such as wood chips and wood chunks in combustion facilities.

The objective of this study was to investigate the variations and correlations of the air pollutants during Covid-19 pandemic lock-down period for an industrialized city of Turkey. With this aim, air quality data measured at four different stations in the period March–June 2020 were used. Results of the study demonstrated that lock-down period caused significant decreases in pollution levels in urban, industrialized, and rural sites. In the city center (Station 2), reduction determined for PM10 and NO_x levels were 32.95% and 58.26%, respectively whereas in the industrialized site (Station 3) decrease ratios of these pollutants were 17.11% and 47.87%, respectively. Obtained reduction ratios may indicate that industrial and traffic activities have more significant contributions to NO_x emissions in the region. A strong positive correlation between CO and NO_x (r = 0.87) may also be evidence for traffic-related pollution in the city center while positively correlated NO_x and SO₂ levels indicate the importance of point sources for Stations 1 and 3. Coherent with the literature, O₃ emissions showed increasing tendency both in moderately industrialized (Station 1) and rural sites (Station 4). When average concentrations of the pollutants were compared for May 2019 and May 2020 periods, the most significant variation was noted for the industrialized region with 50.07% reduction in NO_x values.

In this study, multilayer perceptrons (MLPs) and conventional isotherm equations were used to model bisorption of nickel using terrestrial moss. Characterization of the biosorbent was examined by scanning electron microscopy and Fourier transform infrared spectroscopy analyses. Batch biosorption tests were performed to examine the impacts of different experimental conditions. Thermodynamic calculations were made to evaluate the feasibility of the biosorption. All of the experimental data (total 86 data-sets) were used for MLP modeling purposes whereas equilibrium data were used in Langmuir, Freundlich, and Temkin models. Adsorption kinetic data were tested using pseudo-first-order and second-order kinetic models. Performances of the models were evaluated considering calculated R² and mean standard error (MSE) values. Related isotherm and kinetic parameters were also calculated for conventional biosorption equations. In multilayer perceptron (MLP) modeling studies, network architecture with three hidden layers provided highest prediction efficiency. Although both MLPs and conventional models are regarded to be useful, perceptron models are thought to provide more representative information as all factors are evaluated simultaneously.