Effect of cations Ca2+ and Mg2+ on the removal efficiency of humic acid by UV/TiO2

زمینه و هدف: اسید هیومیک (HA) از تجزیه عناصر گیاهی و حیوانی آزاد می شود. مواد هیومیکی به عنوان پیش ساز محصولات جانبی گندزدایی در فرآیند کلرزنی نقش دارند. هدف از مطالعه حاضر بررسی اثر کاتیون های Ca2+،Mg2+ بر کارآیی حذف اسید هیومیک توسط UV/TiO2 بود. روش بررسی: در این مطالعه نیمه تجربی تأثیر پارامترهای pH، زمان تماس، غلظت دی اکسید تیتانیوم (TiO2)، غلظت Ca2+و غلظت Mg2+بر میزان حذف اسید هیومیک با استفاده از روش UV/TiO2 بر روی آب سنتتیک و آب خام زاینده رود اصفهان بررسی شد. یافته ها: غلظت بهینه کاتالیست نانو ذره دی اکسید تیتانیوم جهت حذف اسید هیومیک g/L1 بدست آمد. تحت شرایط اسیدی (3pH=) در زمان تماس 60 دقیقه بالاترین راندمان حذف به دست آمد. کارآیی حذف HA به روش UV/TiO2 با افزایش زمان تماس کاهش یافت. در حضور یون های Ca2+ و Mg2+ میزان حذف HA به روش UV/TiO2 افزایش یافت. نتیجه گیری: فرآیند فتوکاتالیستی نانو ذره دی اکسید تیتانیوم منجر به کاهش قابل ملاحظه ای از مواد هیومیکی موجود در آب می شود. اگر آب یا فاضلاب حاوی میزان بالایی از ترکیبات مقاوم و سختی باشند، می توان با یک تصفیه فتوکاتالیتیکی مقدماتی این ترکیبات را شکسته و به محصولات جانبی قابل تجزیه تغییر شکل داد

Quantitative and qualitative land suitability assessment for rice cultivation, north of Iran

Evaluation of arable lands and agricultural potential to support current and future agricultural uses is one of the best agricultural policies for food security in developing countries. Hence, studies related to land suitability evaluation can lead to sustainable land use. The aims of this research were qualitative land suitability evaluation, land production potential prediction and quantitative land suitability evaluation on the basis of the FAO model for rice in Sangar region, northern Iran. Qualitative evaluation was carried out using the maximum limitation and parametric methods. Land production potential was determined by the agro-ecological zoning (AEZ) model. Land suitability classes according to maximum limitation, Storie and square root parametric methods are determined S3, S3-N1 and S2-S3, respectively. Rice radiation-thermal production potential was calculated as 7.65 t/ha; mean land production potentials, using Storie and square root formulas were predicted respectively, as 3.69 and 4.52 t/ha and mean actual yield was estimated as 2.81 t/ha. The results of this study showed that use of the square root formula is more appropriate than Storie formula as far as land production potential calculation is concerned. Soil limitations and weak management level have caused majority of land units to have moderate quantitative suitability (S2) for rice cultivation. Comparison between qualitative and quantitative suitability classes demonstrates that quantitative suitability classes are significantly increased due to crop adaptation with climate agents

Evaluating the interaction of 308-nm xenon chloride excimer laser with human dentin and enamel hard tissues

Background: The pulsed output of the 308 nm XeCl laser and its photoablation action rather than photothermal action offers the ability to remove dental hard tissues with minimal generation of heat in the tissue. Materials and Methods: A total of 20 human molar teeth (ten teeth used as enamel samples and ten teeth used as dentin samples after removing the enamel tissue from their crowns) were irradiated by the laser. The crown of each sample was regarded as a cube which its lateral sides were exposed in 2Hz frequency without water cooling. Also, 18 holes for all enamel samples and 18 holes for all dentin samples were obtained. Three different amounts of energy were selected as a variable factor with 6 different numbers of pulses in each energy. The images of these holes were prepared by optic and computer combining, and the amounts of the ablation depth and effective ablation area were calculated using the MATLAB software. Results: The amounts of ablation depth were increased with increasing the number of pulses for both enamel and dentin tissues. The amounts of ablation depth were also increased with increasing the amounts of energy for both enamel and dentin tissues. The greater amounts of ablation depth and effective ablation area were observed in the dentin tissue rather than the enamel tissue. The borders of created holes were reported sharp and clear. Conclusion: The application of the XeCl laser for hard tissue removal and cavity preparation can be possible after some certain modifications

Estimation of landfill gas generation in a municipal solid waste disposal site by LandGEM mathematical model

Anaerobic decomposition of organic compounds in landfills is responsible for generation of greenhouse gases. The present study aimed to determine the total gas and methane emission from a landfill located in Hamedan (west of Iran) from 2011 to 2030. LandGEM 3.02 model was used to estimate the gas emission with the volumetric methane percent of 60%, production potential of 107, and methane generation rate of 0.2. Spatial distribution of annual methane and total landfill gas emission rate in the study area at three decades were provided through ArcGIS software. The results showed that organic and food wastes had the maximum amounts in the solid waste stream (over 75%). The results showed that 4.371×108 m3 methane would be produced after 20 years, mostly (4.053×106m3) in the first year. In addition, methane production capacity in Hamedan landfill site was 107 m3/Mg. According to the results, the maximum and minimum gas generation rates are in summer (the hottest season) and winter (the coldest season) respectively. The results of the LandGEM model represented that the total gas and methane generation rates will be significant in the first 10 years. The potential of rapidly degradable organic compounds for gas emission will be higher than that of slowly degradable organic compounds. The results obtained in the present study can be beneficially used in planning for energy production and other applications in landfill sites

Risk assessment of sari fatemeh zahra hospital using failure mode effect analysis, individualized rapid assessment tool, and preliminary hazard analysis

Abstract Background and purpose: Identification of risk in hospital waste management have a major role in reducing the cost of surplus and preventing the spread of diseases. In this quantitative analysis, we aimed at determining waste components, evaluating hospital waste management, and prioritizing the risks in Sari Fatemeh Zahra Hospital. Materials and methods: We performed a descriptive-cross-sectional study in 2015. Tchobanoglous method was used for quantitative-physical analysis of the waste. The individualized rapid assessment tool was applied to evaluate waste management. Preliminary Hazard Analysis and failure mode and effect analysis models were used to identify and prioritize the risks. Results: Total waste production, general waste, infectious wastes, and sharp objects were 1011.54, 600.45, 384.94, and 26.15 kg/day, respectively. Plastics, organic materials, and textiles constituted the highest amount of waste products. According to the individualized rapid assessment tool, the score obtained by the hospital was 82.15% indicating an excellent waste management. In preliminary hazard analysis, failure mode, and effect analysis models, 23 errors were observed, of which 9 had a priority number greater than 100. Conclusion: The models studied showed that mixing the sharp waste material with other garbage, disposal of non-infectious and semi-household waste in infectious bins and vice versa are of high risk and need corrective measures. Keywords: hospital waste management,quantitative analysis, risk assessment,preliminary hazard analysis, Hazard Analysis and Failure mode

Landfill site selection using a hybrid system of AHP-Fuzzy in GIS environment: A case study in Shiraz city, Iran

Landfilling with simplicity and economic advantages is the most common element for waste management in both developed and developing countries. Landfill site selection in a proper way is an important municipal planning process which prevent environmental issues including water pollution imposed for insanitary landfills. The present research was developed to exhibit a simplified method of multi criteria decision making (MCDM) and Fuzzy memberships in GIS environment to ascertain best landfill sites for Shiraz county, located south of Iran. 15 most common sub-criteria, documented in literature and implicated by Iranian environmental protection organization (IEPO) including surface water, ground water, land use, distance to well, soil type, slope, protected area, fault in environmental group, residential area, road, airport, village, infrastructure, historical area, wind direction in socio-economical group were selected and the weight of each criterion was determined based on expert's knowledge with use of analytical hierarchy process (AHP). The results of the present research are as follows: � Distance to residential area and groundwaters with weight of 0.36 and 0.28 were recognized as the most important criteria for landfill site selection. � The six suitable areas for landfill in Shiraz county is 1.003 of total area equal to 8710 ha. � AHP and Fuzzy memberships has a great potential and ability for landfill site selection. © 2019 The Author(s

Studying the efficiency of a biological aerated filter (BAF) with oyster Media on improving the quality of effluent produced by treatment plants

A biological aerated filter (BAF) is an economical, flexible and effective bioreactor for effluent treatment that needs less area than the conventional biological processes. Media materials choice is an essential parameter in the design and operation of a BAF to get the limit determined by environmental standard organization. In this study, oyster shells were used as filter media for the BAF reactor to enhance the quality of the effluent produced by Qom wastewater treatment plant. The BAF reactor was placed at the output of the treatment plant and the effect of hydraulic loading change was investigated. Hydraulic loadings equal to 0.3, 0.6 and 0.9 m3/m3.day were discussed. The results of this study revealed that oyster shells as BAF filter media reached TBOD5, TSS, COD, TKN, NH4-N, TP, TC and FC removal rates of 49.5, 48.2, 52.2, 47.3, 45.4, 45.7, 59.4 and 62%, respectively, at a hydraulic loading equal to 0.3 m3/m3.day. In addition, BAF efficiency was decreased for all parameters at a hydraulic loading equal to 0.9 m3/m3.day and as the hydraulic loading increased, the filter efficiency decreased consequently. Generally, the efficiency of the filter was higher in ammonia removal with regard to the other parameters. Oyster shells BAF acted as an advanced treatment method for achieving effluent quality requirements

Catalytic decomposition of 2-chlorophenol using an ultrasonic-assisted Fe3O4-TiO2@MWCNT system: Influence factors, pathway and mechanism study.

As a reusable sonocatalyst, magnetically separable Fe3O4-TiO2@MWCNT (FMT) was synthesized by an ultrasound-assisted wet impregnation method and was evaluated in the removal of 2-chlorophenol (2CP). Physical and chemical properties of the catalyst composite materials were investigated by all catalysts were systematically characterized using Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive X-ray Analysis (EDX), Dynamic light scattering (DLS), and N2-physisorption. The efficiency and kinetics of 2CP removal by FMT-assisted sonocatalysis (FMT-US) was systematically investigated under various operational parameters i.e. pH, FMT and 2CP concentration, temperature and ultrasonic power. The results indicated that 0.4gL-1 FMT dosage, pH 5, temperature of 35°C as well as 50 w ultrasound power are the most favorable conditions for the degradation of the 2CP. Furthermore, both of the superoxide and hydroxyl radicals were produced in the reaction, however, superoxide radicals were assumed to be the dominating reactive species for the 2CP degradation, according to the scavenging tests and electron paramagnetic resonance tests. Moreover, the FMT catalyst exhibited a high reusability and stability in the US/FMT system during the five repetitive experiments. The intermediate products were identified by GC-MS, thereby a possible degradation pathway is proposed. The chemical oxygen demand (COD) and corresponding total organic carbon (TOC) removal efficiencies were 64.9% and 56.7%, respectively. Finally, toxicity tests showed that the toxicity of the solution increased during the first 5min and then decreased significantly with the progress of the oxidation. The mechanisms of ultrasound irritation enhanced FMT activation were also proposed. Copyright © 2017 Elsevier Inc. All rights reserved