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Nyborg Bartlett opublikował 5 miesięcy, 2 tygodnie temu
A set of parameters for the rotary jet process was obtained when the in situ stabilization experiment was carried out.The n-octanol/water partition coefficient (logKow) is widely used in the environmental, agricultural and pharmaceutical fields for the risk evaluation and application of organic chemicals. In this work, grounded on atomic distribution matrices, a norm index-based QSPR model was built for organic chemicals with 18 kinds of diverse structures. The statistical results (R2 = 0.9037, RMSE = 0.4515) showed that the QSPR model for describing the logKow of organics was fitted well. Various validation results showed that the model had good robustness, good predictability and wide applicability. These satisfactory results indicated that the model was applicable for the logKow description of organic chemicals and that norm descriptors were reliable and general for the description of organic structures. The model was relatively better at describing logKow for aromatics, alcohols, nitriles, esters, amides, halogenated compounds, acids and amine compounds. The intensity of spatial branching and the space charge distribution intensity descriptors could have a greater impact on the logKow value of a compound.Pakistan is ranked among the most climate change adversely affected countries of the world due to facing higher frequency of extreme natural hazards events as floods, drought, and earthquakes. Inadequate mitigation measures regarding severity and consecutive events of floods have badly affected millions of households’ livelihoods. Pakistan has experienced five consecutive floods in the current decade from 2010 to 2015. These floods severely affected the mostly districts of Punjab province among these three most flood-affected districts Rahim Yar Khan, Muzaffargarh, and Rajanpur were selected for this research work. This study used the cross-sectional data of 840 flood-affected households from these three districts. Empirical estimates indicated the study area households major adaptation measures were foundation strengthen, elevated ground floor, precautionary saving, and construction of the house with reinforced material. Probit model estimates signified age, gender, location, and family size; monthly income, physical disability, education, and house ownership were major factors influencing mitigation strategies of households’ level. Limited resources, inadequate planning for land use, lack of advanced and early warning system, and inadequate sound financial status were major obstacles regarding households’ level adaptation of mitigation strategies. In addressing household level obstacles regarding advanced adaptation measures, development requires for local disaster policies such as ample spatial planning, codes of house building, practices of building infrastructure, propagation and forecasting updated flood information, and advanced and updated early warning system.Green waste (GW) management is a key issue due to its high production rate and its variety of physical properties and chemical composition. Composting is a promising alternative for GW treatment and valorization. However, the presence of recalcitrant components such as lignin and cellulose increase the processing time. Strategies such as addition of co-substrates and operative modifications have improved the processing time and compost quality. Therefore, in this study, three strategies have been implemented (i) addition of unprocessed food (UF) and processed foods (PF) as co-substrates for GW to improve the nutrients composition of the substrates at the beginning of the process, (ii) addition of phosphate rock (PR) to improve product quality, and (iii) the use of two-stage composting (TSC) to accelerate the degradation. For this purpose, three treatments with the same mixture (48% GW + 21% UF + 18% PF + 13% sawdust (SW)) were conducted (i) TA (TSC + 15% PR), (ii) TB (traditional composting +15% PR), and (iii) TC (traditional composting). TSC did not show significant differences compared with TC regarding the process and compost quality, while the addition of PR increased the phosphorus content of the product. However, TC produced the compost with the highest quality according to the Colombian legislation for soil amendment.In this study, a new adsorbent of silicon-doped magnesium oxide (SMG) was developed for the recovery of nutrients from wastewater. The adsorption conditions including adsorbent dosage, initial solution pH, contact time, coexisting substances, N/P molar ratios, and reaction temperature were investigated. Analysis of field emission scanning electron microscopy-energy dispersive spectrometer (FESEM-DES) and specific surface areas (BET) showed that SMG was a mesoporous adsorbent with SBET of 108.31 m2/g. The recycled sediment (RS) was identified as almost pure struvite via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The recovery efficiencies of SMG reached 43.25% of ammonia nitrogen and 97.31% of phosphate at dosage of 0.3 g/L, initial solution pH of 7.0, contact time of 20 min, and temperature of 298 K. Under the optimal reaction conditions, the maximum adsorption capacities of SMG were 170.93 mg/g of ammonia nitrogen and 420.89 mg/g of phosphate at N/P molar ratio of 1.51. Coexisting humic acid (HA), calcium (Ca2+), acetic acid (AA), and ferric ions (Fe3+) in nutrient solution hindered the struvite ordered precipitation. The adsorption process followed pseudo-second-order and Elovich kinetic models and was well described by both the Langmuir and Freundlich isotherms at room temperature. All results indicated that the most likely mechanism of nutrients recovery from wastewater was chemical precipitation and proved that SMG was a high-efficiency adsorption material in a wide pH range of 3.0-9.0 for simultaneous recovery of nutrients from wastewater.In many developing countries, rising pollution and FDI inflows are positively correlated. This paper explores the existence of pollution haven hypothesis in Pakistan by employing the autoregressive distributed lag (ARDL) bounds test on yearly data from 1971 to 2014 for foreign direct investment inflow and four pollutants, i.e., CO2 emissions, CO2 emissions from solid fuels, SO2 emissions, and GHG emissions. In each case, eight different models are tested by incorporating different explanatory variables with foreign direct investment inflow. The outcome of this study shows that in some of the models a positive long-term relationship exists between FDI inflow and CO2 emissions, CO2 emissions from solid fuels, and GHG emissions and a negative long-term relationship between FDI inflow and SO2 emissions. Overall, we found no conclusive evidence of the existence of the pollution haven hypothesis for Pakistan. As Pakistan is taking active measures to attract more FDI, it is essential to introduce appropriate environmental policies and institutional reforms that do not hinder FDI inflows.Transport of environmental pollutants in groundwater systems can be greatly influenced by colloids. In this study, the cotransport of Pb2+ and silica (SiO2) colloids at different Pb2+ concentrations was systematically investigated by batch adsorption and saturated sand column experiments. Results showed that SiO2 colloids had low adsorption capacity for Pb2+ (less than 1% of the input) compared with sands. In saturated porous media, SiO2 colloids showed a high mobility; however, with the increase of Pb2+ concentration in the sand column, the mobility of SiO2 colloids gradually decreased. Notably, SiO2 colloids could facilitate Pb2+ transport, although they did not serve as effective carriers of Pb2+. Under the condition of low Pb2+ concentration, SiO2 colloids promoted the Pb2+ transport mainly through the way of „transport channel,” while changing the porosity of the medium and masking medium adsorption sites were the main mechanisms of SiO2 colloid-facilitated Pb2+ transport under the condition of high Pb2+ concentration. The discovery of this non-adsorption effect of colloids would improve our understanding of colloid-facilitated Pb2+ transport in saturated porous media, which provided new insights into the role of colloids, especially colloids with weak Pb2+ adsorption capacity, in Pb2+ occurrence and transport in soil-groundwater systems.In the present study, PANI-TiO2 nanocomposites have been used in suspended and immobilized form for photocatalytic degradation of Acid Yellow 17 (AY-17) dye under visible light. PANI-TiO2 nanocomposites were immobilized in polystyrene cubes to form PANI-TiO2 @ polystyrene cubes. The nanocomposites were found to be visible light active both in suspended and immobilized form. PANI-TiO2 nanocomposite with 13% TiO2 loading was found to be the optimum in terms of maximum degradation of AY-17. The efficiency of floating bed photoreactor (FBR) operated in liquid recycle mode using PANI-TiO2 @ polystyrene cubes was studied. In this reactor, around 89% degradation of 1 L of AY-17 with an initial concentration of 10 mg/L could be achieved with 2.83 g/L per pass of immobilized catalyst. The FBR operated with PANI-TiO2 @ polystyrene cubes has exhibited good performance as a photocatalytic reactor and may be recommended over other conventional photo reactors for treatment of wastewater contaminated with synthetic dyes. The kinetics of degradation of AY-17 by photocatalysis under visible light with suspended PANI-TiO2 and PANI-TiO2 @ polystyrene cubes followed first-order kinetics. The values of apparent kinetic parameter for degradation by immobilized photocatalysts are lower than the corresponding kinetic parameter for suspended photocatalysts. It confirms the existence of diffusional limitations in photocatalysis by PANI-TiO2 @polystyrene cubes.The effluents of municipal wastewater treatment plant (WWTP) contain excessive nitrogen and phosphorus compared with the concentration in rivers or lakes. To reduce the pollutant load placed on aqueous environments, constructed wetland (CW) technology has been widely applied to advanced wastewater treatment. Packing substrates in CW could remove various pollutants. Steel slag, yellow earth, kaolin, volcanic rock, anthracite, and ceramsite could effectively remove phosphorus (P); volcanic rock, ceramsite, zeolite, yellow earth, manganese sand, and activated carbon have an affinity for ammonia nitrogen (NH4+-N). After 24 h reactions with the WWTP standard 1B synthetic wastewater, four packing substrates, i.e., volcanic rock and anthracite (11), volcanic rock and yellow earth (21), zeolite and yellow earth (21), and manganese sand and activated carbon (13), could remove over 56% and 30% of NH4+-N and phosphorus respectively. In addition, anthracite and volcanic rock (13), anthracite and activated carbon (140), anthracite and manganese sand (15), and anthracite and zeolite (14) effectively purified NH4+-N and phosphorus in secondary WWTP effluent, with removal efficiency exceeding 39% and 27%, respectively. A sequential experiment was performed to optimize packing substrates ratios in CW with volcanic rock and anthracite, ceramsite and yellow earth, and manganese sand and activated carbon. When the quantity of the substrate was doubled, most packing substrates adsorb more than 50% phosphorus and NH4+-N of the standard 1B WWTP synthetic wastewater. Considering the removal efficiency of packing substrates on phosphorus and NH4+-N, it is suggested that manganese sand and activated carbon (13), volcanic rock and anthracite (21), and yellow earth are appropriate substrates for CW in WWTP effluent advanced treatment.