Investigation of metal pollution in Moryayla (Erzurum) and surrounding stream sediments,Turkey

The enrichment factor (EF), geochemical index (Igeo), pollution factor (Cf), and pollutant load index (PLI) were calculated using average shale metal concentration values to determine metal pollution in Moryayla and surrounding stream sediments. It was determined that the average concentration values are above the world average shale values. According to the results obtained, the mean accumulation levels of heavy metals in the study area were Mn > Zn > Cu > Pb > As > Cr > Ni > Sb. Considerable degree of enrichment was observed because the elements As, Cu, and Pb are at EF > 5 at locations 47, 53, 70, and 71. The values obtained from the Igeo, Cf, and PLI are a wide range of pollutants (from unpolluted to moderately polluted to extremely polluted to) for the various elements studied.     

Surface modification of <Emphasis Type="Italic">Nizimuddinia zanardini</Emphasis> and <Emphasis Type="Italic">Stoechospermum marginatum</Emphasis> using 4-phenyl-3-thiosemicarbazide to improve heavy metals biosorption from water

Surface modification of two algal biomasses, Nizimuddinia zanardini and Stoechospermum marginatum, using 4-phenyl-3-thiosemicarbazide ligand was performed to investigate the consequences on the adsorption of heavy metals from aqueous solution. Stabilization of amino group of 4-phenyl-3-thiosemicarbazide on the surface of biomasses was confirmed using Fourier transform infrared spectroscopy. Chemical modification was found to exert significant positive effects on biosorption. Adsorption capacities for Pb(II), Cd(II) and Cr(VI) using modified N. zanardini were observed to be 19.3, 16.75 and 15.75 mg/g, respectively, compared to 17.48, 14.18 and 11.85 mg/g for raw N. zanardini biomass. Also, adsorption of Pb(II), Cd(II) and Cr(VI) by the modified S. Marginatum was found to be 17.54, 15.62 and 14.77 mg/g, respectively, in comparison with that of the raw biomass which were 16.86, 12.9 and 11.2 mg/g. The obtained results of the equilibrium adsorption were studied through different isotherm models of Langmuir, Freundlich and Temkin, where the Langmuir model was observed to agree well with the results. Prevalent kinetic models including pseudo-second order and intra-particle diffusion were applied, and the pseudo-second order was found to describe the adsorption kinetics data adequately. Intra-particle model was also utilized in order to show penetration of metal ions, where it was realized that the biosorption took place in two or three steps including film diffusion, molecular diffusion and chemical reaction.     

A novel continuous magnetic nano-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/perlite fixed bed reactor for catalytic wet peroxide oxidation of dyes: reactor structure

In the present work, a continuous catalytic wet peroxide oxidation fixed bed reactor was employed to treat a simulated wastewater sample with malachite green dye, as a contaminant. Natural perlite particle-supported nano-Fe₃O₄ catalyst was used as a fixed bed inside a reactor, and it was immobilized by a persistent magnetic field. The range of (perlite) particle sizes was from 100 to 1000 nm. The effects of various operating parameters, including temperature of the reactor, pH, initial hydrogen peroxide concentration and initial dye concentration, were investigated on the percentage removal of malachite green dye. Load of catalyst of 2 g and volumetric flow rate of 1 L/h were selected for all the tests. Maximum malachite green degradation was 99.5 ± 0.3%. This removal percentage was attained at temperature of 80 °C, pH = 6, initial dye concentration of 6 mg/L and initial hydrogen peroxide concentration of 100 mg/L. The process was isotherm, and the catalyst showed high catalytic activity in the steady-state condition. The loss of catalyst was less than 0.3%.     

Potency of constructed wetlands for deportation of pathogens index from rural,urban and industrial wastewater

Pathogen removal is essential for wastewater treatment and its potential reuse in agriculture. Three field-scale wastewater treatment systems consisting of free surface flow were operated around 1.5 years receiving water from urban domestic, rural domestic and industrial sources. The study was conducted to evaluate seasonal performance of constructed wetland systems in removing Escherichia coli, Enterococci and total coliforms under continuous hydraulic flow. Results displayed that all three wetlands gain recognition in removing pathogen load with high removal efficacy till water reaches output ports. Removal efficiencies were even higher, 66–93, 78–92 and 80–94% for E. coli, Enterococci and total coliforms, respectively, within constructed wetlands. Remarkably at shorter temporal scales in CW-A, greater homogeneity of pathogen concentrations was assessed at wetland outlet sites. In outlet ports, results displayed a highly effective removal of E. coli concentration 80–90% (June 2015), 86–92% (October 2015) and 79–92% (February 2016), Enterococci 80–94% (June 2015), 83–94% (October 2015) and 80–94% (February 2016) and total coliforms 85–93% (June 2015), 87–95% (October 2015) and 88–96% (February 2016). Positive correlation was observed between bacterial indicators (E. coli–Enterococci, r = 0.038; p < 0.01 and E. coli–total coliforms, r = 0.142; p < 0.01). Removal of bacterial indicators in constructed wetland was also displayed by PCA in which three-component analysis of variance was 98.39% and showed a clear decrease in measured parameter gradients toward samples from outlet ports. Constructed wetlands provide cost-effective treatment systems for reducing the pathogen load in wastewater in variable agro-climatic conditions and thus improve water quality.     

Comparison of different models of water quality index in the assessment of surface water quality

The method of water quality index is widely used in evaluation of the surface water quality because of its capability to summarize a number of water quality parameters into one numeric value, along with defined scale of water quality range. The current investigation includes application of modified model for calculating water quality index values, generated using experimental data and literary models. Software was created using modular design. Fourteen physical, chemical and biological parameters representing water quality state along with the assigned weights were elected. Comparison between models generated based on Serbian and American models of water quality index was done. Selected parameters differ mutually in number of parameters used in calculation of index, as well as in values of the weighting factors. In order to enable an efficient water quality analysis and to reconcile the requirements of both Serbian and American model, two software solutions were generated and processed on the example of the water quality of the Danube River in Serbia. Danube water quality was assessed at seventeen measuring locations along the river flow. Index values obtained from the two generated software applications were compared with the results of the official Serbian online calculator. Water quality determined using new generated models shows stricter approach and one class lower water quality compared to the existing Serbian model. Therefore, modular and open-generated simulation software is of great significance for the comparison and testing of different water quality models, not just those two shown in this study.     

Heavy metal exposure from co-processing of hazardous wastes for cement production and associated human risk assessment

This study was carried out to determine the concentration of heavy metals (Cd, Ni, Pb, Cr, Ni and Zn) in ordinary Portland cement (OPC) produced from the co-processing with hazardous waste in comparison with OPC produced using natural raw materials. The results showed that the concentration of heavy metals in cement produced from natural raw material was in the order of Zn > Pb > Cr > Ni > Cu > Cd. Zn and Cd were the highest and the lowest concentrations, respectively, in cements produced from the co-processing activity. The difference between heavy metals concentrations in OPC produced with and without co-processing was found to be statistically significant. The concentration of heavy metals in the cement produced is generally factory dependent. The human risk assessment associated with the heavy metals for non-carcinogenic and carcinogenic risks has been evaluated. The calculated hazard index (HI) and total lifetime cancer risks (LCR) were lower than the acceptable threshold reference values, HI < 1 and LCR < 1 × 10^?4, respectively. Thus, it is anticipated that there is no potential of non-carcinogenic and carcinogenic risks for both adult and children. However, the findings indicated that there is a need for regulatory monitoring. The exposure pathway for both non-carcinogenic and carcinogenic risks are both in the order of ingestion > dermal > inhalation.     

Management of shock loads wastewater produced from water heaters industry

Water heater manufacturing represents one sector of household electrical appliance industry. It includes several batch processes which resulted in a highly polluted wastewater as shock loads. The objective of this study was to manage the shock loads wastewater with a simple and cost-effective approach prior to final discharge into municipality. To achieve this objective, two approaches were studied. The first approach was the chemical treatment of the accumulated shock loads wastewater using alum and an anionic polymer. Although this approach produced a very high-quality effluent, it was economically and technically infeasible. The second approach was a controlled release of the shock loads to the normal daily discharge in a way that guarantees the compliance of the end-off-pipe with the National Regulatory Standards. This solution required establishment of an equalization tank for normal daily flow and a holding tank for controlled release of the shock loads. Mathematical calculations were carried out to determine the most violating parameters in order to calculate the mixing ratio the of shock loads with the normal daily flow. Full engineering design of the proposed solution was carried out. This approach was implemented and proved to be simple, easy to operate, cost-effective and can be replicated in similar batch processing manufacturing plants.     

Improving the indoor air quality using the individual air supply system

Indoor air quality attracts great interest. Many dwellings are ventilated naturally. The article presents the gravity system conversion into individual air supply system, which can be equipped with air fan. This solution’s impact on the interior microclimate was analyzed. The proposed solution uses the lower natural ventilation ducts sections, which are not normally used as air supply channels to bring air to the housing. Exhaust grilles were located in the adjacent rooms. Individual air supply system with switched off fan improves indoor air quality insufficiently; however, switching on the device causes a very significant change. A large carbon dioxide concentration reduction (which was used as an air quality indicator) has been confirmed by rigorous statistical analysis, the results of which were presented in the article.     

Water stress index and its implication for agricultural land-use policy in Thailand

Land-use change and expansion for agriculture significantly affect freshwater resource availability which in turn results in different levels of water scarcity and competition among users in different areas and time. The study uses the water stress index as an indicator for determining the potential impact of water use considering water deprivation potential. Considering the case of Thailand, the temporal aspects of water withdrawal and availability have been analyzed and characterized as the monthly water stress index for the 25 watersheds in the country. Wide variations of monthly water stress index are obtained; extreme water stress is observed in the areas of the Chao Phraya and Tha Chin watersheds (the central region) during the dry season because of the large areas cultivating second rice (rice planted in dry season). The target of the Thai government on agricultural land-use change and zoning toward the conversion of about 0.37 M·ha of the upland paddy fields with low productivity to sugarcane was evaluated showing serious implications on the monthly water stress index of the relevant watersheds and the water scarcity footprint potentials of rice and sugarcane production. The results reveal that proper policy can help reduce the amount of water requirement for agriculture in June, July, August and September by about 60–220 M·m³, which in turn results in the decrease in monthly water stress index values. Nevertheless, appropriate measures of water resource management for agriculture still need to be designed to avoid water competition as well as protect the ecosystem.     

Removal of diazinon pesticide from aqueous solutions using MCM-41 type materials: isotherms,kinetics and thermodynamics

In this research, ordered mesoporous silica, including MCM-41, was synthesized via sol–gel process and a propyl methacrylate-modified ordered mesoporous silica (MPS-MCM-41) was successfully synthesized via a postsynthesis grafting process. Then both MCM-41 and MPS-MCM-41 were characterized using FTIR, XRD, SEM and BET techniques. The synthesized materials were utilized as adsorbent for removal of diazinon pesticide from aqueous solutions. The effects of pH, contact time, adsorbent dose, initial concentration and temperature have been evaluated using removal efficiencies. Also, the kinetic, thermodynamic and isotherm models of diazinon adsorption were studied for the both MCM-41 and MPS-MCM-41. The results showed that the maximum adsorption capacities are 142 and 254 mg g^?1 for the MCM-41 and MPS-MCM-41, respectively, at the initial concentration of 50 mg L^?1, temperature of 298 K and adsorbent dose of 0.1 g L^?1. The highest percentages of diazinon removal are 56.4 and 87.2 (at adsorbent dose of 2 g L^?1 and the temperature of 318 K) for the MCM-41 and MPS-MCM-41, respectively. The Freundlich and Langmuir models are more compatible for describing equilibrium data of the diazinon adsorption capacity on the MCM-41 and MPS-MCM-41, respectively. Thermodynamic study indicated that the adsorption process of diazinon onto MCM-41 and MPS-MCM-41 is exothermic and has a spontaneous nature. The higher adsorption capacity and higher spontaneous nature of MPS-MCM-41 in comparison with MCM-41 might be due to the presence of the both hydrogen bonding and hydrophobic interaction between surface functional groups of MPS-MCM-41 (hydroxyl and propyl methacrylate) and diazinon functional groups.