Lighvan hot spring and Toptapan mineral spring are located in the Eastern Azarbaijan, NW of Iran. The host rocks of Lighvan hot spring are dacite, andesite and Quaternary volcanic tuffs. Their main rock forming minerals are quartz, plagioclase, biotite and rarely amphibole. The host rocks of Toptapan mineral water spring are Cretaceous and Jurassic sandstone, shales and carbonate sedimentary rocks. Their main rock forming minerals are quartz, calcite, dolomite and clays. Due to the deposition of mineral water springs, travertine is the main Quaternary sediments around the springs. Water samples were collected from Toptapan mineral spring and Lighvan hot spring in July (dry season). The sampling method was according to standard methods for geochemical analysis. Field parameters such as PH, temperature, and EC were measured in situ, and samples were analyzed by ICP-OEC and ICP-MS in the laboratory of the Geological Survey of Iran. The measuring data showed that pH varies between 6.1 to 6.4. The surface temperature varies from 20.1˚C to 32.8˚C. The concentration of anions and cations in the Piper diagram show calcic bicarbonate type for Toptapan mineral spring and sodic bicarbonate type for Lighvan hot spring respectively. According to Lunglier – Ludwig diagram, the dissolution of carbonate and silicate minerals is the most important factor in increasing calcic cation. The Cl-Li-B diagram shows that the dissolution of sodic minerals and clays and ionic exchange are also the most important factors for increasing sodium in these springs. These data are in agreement to the host rocks, their mineralogy and their chemical composition. Based on the Ca-Mg-K geothermometer diagram, the geothermal reservoir temperature for Lighvan hot spring is 95-100 ˚C with a depth of about 2Km and for Toptapan mineral spring is 65-85 ˚C with a depth of less than 1Km. Also, high concentrations of chlorine show a deep geothermal primary reservoir in the Lighvan hot spring. These geochemical data show that these cold and hot springs are not polluted and not harmful for environmental point of views.

In most developing nations, municipal wastewater treatment is limited to aerobic secondary treatments, expensive and ineffective in removing nutrients from treated effluents before discharge, resulting in eutrophication and imbalance in receiving bodies. As a result, the effectiveness of Chlorella vulgaris for primarily treated wastewater collected from a sewage treatment plant during an 8-hour detention time was investigated in this study. Microalgae have been found to efficiently remove organics and nutrients to levels far below the desired limit in the present research. After algal treatment concentration of COD, phosphate and ammonia reduced to 12.43 mg/L (93.75%), 0.04 mg/L (98.40%) and below detectable limit (100%) respectively. In addition, remarkable reduction was found in solids (TSS, TS and TDS) and EC concentration. The use of microalgae resulted in an increase in DO concentration. As a result, introducing Chlorella vulgaris into a wastewater treatment system can lower nutrient and organics contents without any additional treatment.

The goal of this research was to investigate the efficacy photocatalysis with natural solar radiation and artificial UV radiation for disinfecting total coliforms in biologically treated wastewater.   The effect of TiO2 dosage and irradiation time on total coliform inactivation as measured by log reduction values (LRV), removal of BOD, COD, turbidity, and effluent properties as measured by pH and conductivity was investigated. Two sets of experimental equipment were constructed, one for using solar UV light and the other for using artificial UV light. After four hours of irradiation with 60 mg/L TiO2, photocatalysis achieved LRVs of 1.4 and 1, respectively, under UV and solar radiation. COD and BOD were reduced by 67% and 50% respectively under UV and solar radiation after two hours of irradiation with 60 mg/L TiO2. Turbidity was reduced by 71%. Both conductivity and acidity of the effluent were reduced as TiO2 concentration was increased. Photocatalysis with natural solar radiation produced disinfection results that were comparable to that of efficient UV light exposure. Artificial UV light and natural solar radiation can be combined in photocatalysis process to form a hybrid process.

The objective of this study was to identify the correlation between NOx concentration and envi-ronmental variables at photocatalytic concrete pavements containing TiO2 by direct monitoring in field. In order to confirm the NOx concentration according to various environmental variables of the photocatalytic concrete pavements, humidity, temperature, light intensity, and NOx concen-tration were measured continuously for 3 days at photocatalytic pavement, concrete pavement, and atmospheric conditions, respectively. We identified the NOx concentration at all measurement sites and calculated the NOx removal efficiency of the photocatalytic pavements. As a result, the NOx concentration of the photocatalytic pavement was 0.086 ppm on the 1st day, 0.125 ppm on the 2nd day, and 0.106 ppm on the 3rd day, which was mostly lower than that of the concrete pavement and the atmospheric conditions. When the NOx removal efficiency of the photocatalytic pavement on days 1–3 was examined by time, the NOx removal efficiency was evidently higher in the order of 0–6 h > 18–24 h or 6–12 h > 12–18 h for all three measurement days. In addition, the relationship between NOx removal efficiency and environmental variables was analyzed. As a result of corre-lation analysis between NOx removal efficiency and environmental variables of the site, relative humidity showed a positive (+) correlation, while temperature and light intensity showed a negative (-) correlation. Based on our results, we summarize some considerations for evaluating the NOx removal performance of photocatalytic pavements applied in the field.

Constructed wetland (CWs) systems offer an economical alternative to wastewater (WW) treatment in developing countries. So this study investigated lab-scale hybrid constructed wetlands (HCWs) with plant species Canna indica and Typha latifolia in mono and mixed culture for removing organic matter and nutrients from municipal wastewater (MWW) under arid climatic conditions. A HCW system consists of a storage tank feeding four series of vertical flow constructed wetlands (VFCWs) followed by horizontal flow-constructed wetlands (HFCWs). The results indicate that the planted beds performed better in removing suspended solids (TSS) (89.93% by Typha latifolia), biochemical oxygen demand (BOD5) (95.01% by mixed-culture), chemical oxygen demand (COD) (90.77 by Typha latifolia), nitrite (NO2-) (89.99% by mixed-culture), ammonium nitrogen (NH4+) (99.98 % by mixed-culture), and orthophosphate (PO43-) (87.22% by Typha latifolia) as compared to the unplanted bed for the same parameters (87.85%, 92.87%, 77.35%, 85.30%, 99.75%,  and 80.95%), respectively. The nitrate (NO3−) concentration in the effluent recorded the highest increase in the VFCW unit planted with mixed culture from 0.44 to 0.999 mg/l and decreased in the second stage to 0.588 mg/l at the HCW outlet. The mean values of the testing parameters in different HCW systems were not significant between the mono and mixed culture (P > 0.05), with a significant difference (P <0.05) between the VFCWs and HFCWs. The finding of this study demonstrated that Canna indica and Typha latifolia have been effective in WW treatment by HCW systems.

The development of suitability species models look for the availability to growth in a study area. These models can be used for different targets. In this research, a suitability model of Eucalyptus has been developed to soils contaminated by trace elements management. Guadiamar Green Corridor has been selected due to the huge data available regarding trace elements, forestry species and so on. Logistic regression (LR) and Random Forest (RF), as popular machine learning model, were applied in a geodatabase from Guadiamar Green Corridor with more of 20 years of data. This database is composed by soil physical and chemical variables, climate (temperature min and max, annual precipitation), forestry species. The results show the poor performance of LR and RF applied directly over the unbalanced training set. However, when Up-sampling or SMOTE are applied, both procedures improve its sensitivity, however, RF show more improve that LR. The methodology applied can help to determine the potential distribution of Eucalyptus in similar Mediterranean areas and extended to different areas according to Soil, Climate and Trace Elements data. Finally, the models developed under this research work can be used to reduce human and environmental health by trace elements taking into account local conditions but also climate change scenarios.

Perfluorinated chemicals (PFCs) are widely used in industrial and commercial applications, leading to their release into the environment. The rapid industrialization and growing population in India make it a suitable case study to investigate PFOS contamination in environmental matrices. The purpose of this study is to investigate PFOS concentrations in river water and groundwater from several locations along the Bharathapuzha river basin and estimate PFOS intakes through drinking water. The highest PFOS level detected in the surface water is 1.3 ng/L and groundwater is 1.0 ng/L, which is significantly lower than the level of PFOS detected in major rivers of many developed countries. It is possible to attribute the low PFOS concentration to factors such as high annual precipitation, reduced industrial and municipal wastewater discharge, and relatively low emissions per capita in a region where agriculture is a major part of the economy. In addition, the daily intake of PFOS through drinking water in all age groups was below the safety threshold for cancer risk.

Discharge of synthetic dyes from industries without treatment leads to major environmental problems. Present research highlighted the Mn-doped ZnO along with UV-induced photo degradation of Congo red (CR) dye through batch study. The synthesized Mn-doped ZnO (MDZO) was characterized by Transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). The results revealed that MDZO along with UV exposure degraded the CR dye up to 99.3% at concentration 4 mg/L, pH (7), adsorbent dose (0.6 g/L) and contact time (30 min). The degradation data nicely fitted with pseudo-secondary kinetics and the thermodynamic study suggest the said reaction is exothermic in nature. A statistical method, central composite design (CCD) was used to screen out the optimized condition of dye degradation. The interactions of main factors and optimal conditions were also evaluated by 3D surface plots. The statistical output clearly demonstrates that the dye degradation data is nicely fitted with very high goodness of fit and F value (86.19). Present research clearly suggested that Mn-doped ZnO along with UV could be an effective treatment towards degradation of Congo red dye.

We analyzed 125 samples collected from Joypurhat district, Bangladesh, in this study. Average inorganic arsenic (IAs) content obtained from collected polished rice, tomato, potato, radish, and arum leaves 0.31 - 0.91, 0.24 - 0.61, 0.49 - 0.88, 0.40 - 0.93, and 0.30 - 0.69 mg/kg, respectively. This report summarized that almost every agronomic sample contains arsenic; the As contents remain within the permissible limit set by FAO/WHO’s guideline (1.00 mg/kg) except for the rice sample. The As concentration for the rice sample was significantly higher (0.31 - 0.91) than the prescribed limit (0.20 mg/kg). But, the As level for water (mean range, 0.10 - 0.72 mg/l), sediment (0.13 - 0.53 mg/kg), and soil samples (24.1 - 43.1 mg/kg) also significantly surpassed the permissible level. The present study is alarming for water samples, where the highest IAs concentration (0.72 mg/l) is 72 times [14 times] higher than WHO/FAO’s [Bangladesh’s] allowable limit (0.01mg/l) [0.05 mg/l]. All agronomic fields contain higher IAs (25.50 - 43.10 mg/kg) than the world standard limit (10 mg/kg). Statistical Igeo confirmed the moderate pollution of the entire agronomic field of Joypurhat except for the river’s sediment. Again, EF values ensured the anthropogenic pollution by the moderately severe enrichment of As for the 65% agronomic field and significant enrichment of As for the 35% agronomic field. Hazard estimation results revealed the privileged possibility of non-carcinogenic [carcinogenic] health hazards to regular polished rice [water] consumers. So, present study suggests that authorities should take necessary steps to prevent contamination/upcoming health risks.

The simulation of photocatalytic reactor is conducted using computational fluid dynamics. Turbulence is described by using the RNG k-ε turbulence model. The DO radiation model is used to simulate the irradiance distribution in the photocatalytic reactor. The effects of operating parameters on the performance of photocatalytic reactor are considered. Results show that the degradation rate of oxalic acid decreases with the increase of inlet flow. The degradation efficiency decreases from 50% to 40% when the flow rate changes from 2.5 m3 h−1 to 10 m3 h−1. The degradation rate of oxalic acid can be improved by increasing the irradiance of the lamp. The degradation efficiency of oxalic acid in the photocatalytic reactor first reaches a maximum degradation efficiency with the increase of titanium dioxide concentration, and then decreases with the increase of titanium dioxide concentration. An optimal concentration of catalysts exists. The maximum degradation efficiency is 27% for the catalyst concentration of 20 µgL−1.