Assessment of aluminum bioavailability in alum sludge for agricultural utilization

Inorganic aluminum ions, [Al(H₂O)₆]³⁺, [Al(OH)(H₂O)₅]²⁺, and [Al(OH)₂(H₂O)₄]⁺, are toxic to a number of crops. The aim of this study was to estimate the danger of soil contamination of bioavailable aluminum and heavy metals forms because of alum sludge which was a by-product of water, and wastewater treatment technology using aluminum coagulant is introduced into the soil. Aluminum and selected heavy metal fractionation was carried out in the post-coagulation sludge collected at a water treatment plant (where aluminum was used as a coagulant), fermented sewage sludge at a municipal wastewater treatment plant (which did not apply aluminum coagulant), and soil from water treatment plant as well as the mixtures of sludge and soil. It has been found that post-coagulation sludge used as natural fertilizer is a secondary source of bioavailable aluminum, especially when aluminum coagulants are used during water and wastewater treatment. The evaluation of applicability of the sludge to very weak acidic and acidic agricultural soils was carried out. The authors shall debate the question whether, in this case, the Regulation of EU and Polish Government on sewage sludge should also take the bioavailable aluminum into account and add to the list of the elements whose allowable contents are limited.     

Biosorption of chromium (VI) from aqueous solutions and ANN modelling

The use of sustainable, green and biodegradable natural wastes for Cr(VI) detoxification from the contaminated wastewater is considered as a challenging issue. The present research is aimed to assess the effectiveness of seven different natural biomaterials, such as jackfruit leaf, mango leaf, onion peel, garlic peel, bamboo leaf, acid treated rubber leaf and coconut shell powder, for Cr(VI) eradication from aqueous solution by biosorption process. Characterizations were conducted using SEM, BET and FTIR spectroscopy. The effects of operating parameters, viz., pH, initial Cr(VI) ion concentration, adsorbent dosages, contact time and temperature on metal removal efficiency, were studied. The biosorption mechanism was described by the pseudo-second-order model and Langmuir isotherm model. The biosorption process was exothermic, spontaneous and chemical (except garlic peel) in nature. The sequence of adsorption capacity was mango leaf > jackfruit leaf > acid treated rubber leaf > onion peel > bamboo leaf > garlic peel > coconut shell with maximum Langmuir adsorption capacity of 35.7 mg g^?1 for mango leaf. The treated effluent can be reused. Desorption study suggested effective reuse of the adsorbents up to three cycles, and safe disposal method of the used adsorbents suggested biodegradability and sustainability of the process by reapplication of the spent adsorbent and ultimately leading towards zero wastages. The performances of the adsorbents were verified with wastewater from electroplating industry. The scale-up study reported for industrial applications. ANN modelling using multilayer perception with gradient descent (GD) and Levenberg-Marquart (LM) algorithm had been successfully used for prediction of Cr(VI) removal efficiency. The study explores the undiscovered potential of the natural waste materials for sustainable existence of small and medium sector industries, especially in the third world countries by protecting the environment by eco-innovation.     

Empirical Estimation of Virtual Point Source Height Over a Bank of Coke Ovens

This paper addresses an empirical method of assessment of the height of a virtual point source. In order to achieve such assessment, three planes defining the location of a virtual point source in a space are created and formulas describing the geometry of observer’s sight and plume orientation are used. Data for calculations are obtained on a basis of plume photographs. The final position of a virtual emission point is described by a set of its coordinates in the Cartesian coordinate system. Presented method may be applied as a means to verify and validate the existing formulas describing the rise of plume above the stack exit or as a tool enabling acquisition of information for the sake of creating new formulas of this type. The calculation of the location of a virtual point source ascribed to the point emission from the roof of the bank of coke oven is presented and illustrated with photographs which reveal position of plume, adequate planes, axes and characteristic objects.     

Development and Testing of 2D Finite Difference Model in Open Channels

This study develops a depth-averaged two-dimensional (2D) numerical model using a finite difference method (FDM) on a staggered grid. The governing equations were solved using the Marker and Cell method that was developed at the Los Alamos laboratories by Harlow and Welch in 1965. In the paper, an explicit FDM was used to solve the governing equations. A first-order approximation was used for the temporal derivative. Second-order central difference approximations were used for space discretization. The time step is limited by the Courant–Friedrichs–Lewy (CFL) condition. The time step used in this study depends on the grid spacing and velocity components in the x- and y-directions. The study is divided into two steps: the first step is to develop a depth-averaged 2D numerical model to simulate the flow process. The second constructs a module to calculate the bed load transport and simulate the river morphology in the areas that have steep slopes, torrents, and mountain rivers. Developed model was applied to the artificial channel and a flood event in the Asungjun River section of the mountainous Yangyang Namdae River (South Korea). General simulation results showed that the developed model was in good agreement with the observed data.     

Investigation of polyhydroxyalkanoates (PHAs) biosynthesis from mixed culture enriched by valerate-dominant hydrolysate

The production of polyhydroxyalkanoates (PHAs) with a high fraction of 3-hydroxyvalerate (3HV) and 3-hydroxy-2-methylvalerate (3H2MV) from mixed culture enriched by valerate-dominant hydrolysate was evaluated in this study. After long-term enrichment, the culture showed strong ability to synthesize 3HV and 3H2MV, even with acetate-dominant substrate. The ultilization of single or mixed iso-/n-valerate by the enriched culture showed that the mixture of iso-valerate and n-valerate was more efficient substrate than any single in terms of balancing microbial growth and PHAs synthesis. Besides, through comparing the kinetics and stoichiometry of the tests supplying valerate and propionate, the enriched culture with equivalent valerate and propionate (1:1 molar ratio) exhibited superior PHAs production performances to pure valerate or propionate, attaining more than 70 mol% of 3HVand 3H2MV. The above findings reveal that valerate-dominant hydrolysate is a kind of suitable substrate to enrich PHAs producing culture with great capability to synthesize 3HV and 3H2MV monomers, thus improving product properties than pure poly(3-hydroxybutyrate) (P3HB); also 3HV and 3H2MV production behaviors can be regulated by the type of odd-carbon VFAs in the substrate.

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Cancer risk from gaseous carbonyl compounds in indoor environment generated from household coal combustion in Xuanwei,China

Airborne carbonyls were characterized from emitted indoor coal combustion. Samples were collected in Xuanwei (Yunnan Province), a region in China with a high rate of lung cancer. Eleven of 19 types of samples (58%) demonstrated formaldehyde concentrations higher than the World Health Organization exposure limit (a 30-min average of 100 μg m^?3). Different positive significant correlations between glyoxal/methylglyoxal and formaldehyde/acetaldehyde concentrations were observed, suggesting possible different characteristics in emissions between two pairs of carbonyl compounds. A sample in the highest inhalation risk shows 29.2 times higher risk than the lowest sample, suggesting different coal sampling locations could contribute to the variation of inhalation risk. Inhabitants in Xuanwei also tend to spend more time cooking and more days per year indoors than the national average. The calculated cancer risk ranged from 2.2–63 × 10^?5, which shows 13 types of samples at high-risk level. Cumulative effect in combination with different carbonyls could have contributed to the additive actual inhalation cancer risk. There is a need to explicitly address the health effects of environmentally relevant doses, considering life-long exposure in indoor dwellings.     

Preparation of biochar catalyst with saccharide and lignocellulose residues of corncob degradation for corncob hydrolysis into furfural

This paper presented a novel process for production of furfural by hydrothermal degradation of corncob over biochar catalyst, in which it was prepared with the recycling degradation solution and lignocellulosic solid residues. The biochar catalyst was papered by lignocellulose residues and concentrated saccharide solution, and then impregnated in 0.5 mol/L sulphuric acid at room temperature for 24 h assisted by the ultrasonic vibration. In the system of recycling, 8.8 % lignocellulose residues and 100 % concentrated saccharide solution from corncob hydrolysis have been recycled. Hydrolysis of corncob was carried out at 180 °C for duration of 170 min over the biochar catalyst. The experimental results have shown that the furfural yield of up to 37.75 % and overall corncob conversion rate of 62.00 % could be achieved under optimum operating conditions for the catalysts preparation and the corncob hydrolysis. It is believed that the acid density of 4.27 mmol/g of biochar catalyst makes the SO₃H groups cleave β-1,4 glycosidic linkages effectively and hydrolyze the cellulose and hemicellulose to water-soluble sugars, as well as to facilitate dehydration of xylose to give the product of furfural.     

Facile Preparation of Chitosan Films for High Performance Removal of Reactive Blue 19 Dye from Aqueous Solution

This study aimed at finding effective strategies for high-performance removal of reactive blue 19 (RB19) dye from aqueous solution. Chitosan (CS) films had been prepared by using solvent casting with mild drying for this purpose. The CS films were characterized by X-ray diffraction, field-emission scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy. The performance of RB19 removal using CS were evaluated by varying contact time, solution pH, initial dye concentration, and adsorbent dosage. Adsorption isotherms, kinetics, and desorption were investigated by batch experiments. Results showed that CS films exhibited the optimal adsorption performance for RB19 removal and high maximum adsorption capacities of RB19, which were 799 and 822.4 mg g^?1 at 20 and 40 °C, respectively. Adsorption kinetic data were well described by the pseudo-second-order kinetic model. FTIR analyses further indicated that interactions between RB19 and the CS film occurred during adsorption. The CS films also exhibited satisfactory desorption of RB19 at about 80 % after 30 min of desorption at pH 11. Our study demonstrated that the CS films can be easily prepared and applied for effective removal of RB19 in treatment of wastewater.     

Urinary levels of phthalate metabolites and associations with demographic characteristics in Korean adults

The objective of this study is to assess human exposure to phthalates and its associations with demographic characteristics of the subjects in the Korean National Human Biomonitoring Survey. The subjects aged between 18 and 69 were selected through nationwide stratified sampling. A total of 1874 urine samples were collected and stored at ?20 °C until measurement for ten selected metabolites of phthalates (MnBP, MiBP, MBzP, MCHP, MnOP, MEHP, MEOHP, MEHHP, MiNP, and MiDP) using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The difference in the level of urinary phthalate metabolites by the characteristics of the subjects was tested for statistical significance using SAS Surveyreg procedure. The coefficients and standard errors from multiple linear regressions were exponentiated to estimate the adjusted proportional change (APC) and 95% CIs compared with a referent level. The proportion of data above LOQ was less than 20% for MCHP, MnOP, MiNP, and MiDP. Geometric means of creatinine-adjusted concentrations (unit: μg/g creatinine) of six other phthalate metabolites among Korean adults were 41.7 (95% CI 39.6–43.9) for MnBP, 17.1 (95% CI 16.1–18.1) for MiBP, 15.7 (95% CI 14.4–17.1) for MBzP, 8.65 (95% CI 8.10–9.22) for MEHP, 17.5 (95% CI 16.8–18.3) for MEOHP, and 38.1 (95% CI 36.2–40.2) for MEHHP. Urinary level of phthalates tended to be higher among subjects with older age, females, and those with vigorous daily physical activity and tended to be lower among drinkers and those with higher income. Our results suggest that the level of phthalate exposure is significant among Korean adults and thus warrants further studies to identify major source and route of exposure to phthalates.