Showing papers in "Applied Water Science in 2021"

A critical review of synthesis parameters affecting the properties of zinc oxide nanoparticle and its application in wastewater treatment

Abstract: In this era, nanotechnology is gaining enormous popularity due to its ability to reduce metals, metalloids and metal oxides into their nanosize, which essentially alter their physical, chemical, and optical properties. Zinc oxide nanoparticle is one of the most important semiconductor metal oxides with diverse applications in the field of material science. However, several factors, such as pH of the reaction mixture, calcination temperature, reaction time, stirring speed, nature of capping agents, and concentration of metal precursors, greatly affect the properties of the zinc oxide nanoparticles and their applications. This review focuses on the influence of the synthesis parameters on the morphology, mineralogical phase, textural properties, microstructures, and size of the zinc oxide nanoparticles. In addition, the review also examined the application of zinc oxides as nanoadsorbent for the removal of heavy metals from wastewater.

Groundwater quality assessment using water quality index (WQI) under GIS framework

Abstract: Groundwater is an important source for drinking water supply in hard rock terrain of Bundelkhand massif particularly in District Mahoba, Uttar Pradesh, India. An attempt has been made in this work to understand the suitability of groundwater for human consumption. The parameters like pH, electrical conductivity, total dissolved solids, alkalinity, total hardness, calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride, fluoride, nitrate, copper, manganese, silver, zinc, iron and nickel were analysed to estimate the groundwater quality. The water quality index (WQI) has been applied to categorize the water quality viz: excellent, good, poor, etc. which is quite useful to infer the quality of water to the people and policy makers in the concerned area. The WQI in the study area ranges from 4.75 to 115.93. The overall WQI in the study area indicates that the groundwater is safe and potable except few localized pockets in Charkhari and Jaitpur Blocks. The Hill-Piper Trilinear diagram reveals that the groundwater of the study area falls under Na+-Cl−, mixed Ca2+-Mg2+-Cl− and Ca2+- $${\text{HCO}}_{3}^{ - }$$ types. The granite-gneiss contains orthoclase feldspar and biotite minerals which after weathering yields bicarbonate and chloride rich groundwater. The correlation matrix has been created and analysed to observe their significant impetus on the assessment of groundwater quality. The current study suggests that the groundwater of the area under deteriorated water quality needs treatment before consumption and also to be protected from the perils of geogenic/anthropogenic contamination.

Eco-hydrologic stability zonation of dams and power plants using the combined models of SMCE and CEQUALW2

Abstract: Construction of dams has a significant impact on hydrological conditions of rivers. Eco-hydrology, as a sub-discipline of hydrology, focusses on ecological processes occurring within the hydrological cycle and strives to utilize them for enhancing the environmental sustainability. The aim of this study was to determine the stable and instable eco-hydrologic regions in the study area. First, the factors affecting the eco-hydrologic stability were selected according to field surveys. Afterwards, the layers related to each factor were prepared in geographic information system (GIS) and ArcGIS 10 software. These factors were also weighted using the analytic hierarchy process and pairwise comparisons. Ultimately, the final map was prepared by integrating and determining the homogenous units. The CEQUALW2 software, as a water quality and hydrodynamic model, was used to confirm the accuracy of the quality data and to perform the water quality simulation in the studied dam. According to the results, pollutant source and water quality were found to be the most important factors. The final map indicated that most of the areas had not a suitable condition in terms of stability at the downstream reaches.

Treatment of industrial oily wastewater by advanced technologies: a review

Abstract: Oily wastewater consists of fats, oils and greases together with a broad spectrum of dissolved organic and/or inorganic substances in suspension. It is regarded as one of the most hazardous wastewaters, causing serious environmental and health threats to the ecosystems, flora and fauna. The global increase in the discharge of oily wastewater coupled with stringent regulations for effluent discharge and incessant drive for re-use of treated wastewater necessitate the need for treatment of the wastewater. Conventional approaches employed in the past are inept for oily wastewater treatment due to low treatment efficiency and high operational costs, among others, hence the need for adoption of advanced technologies as promising alternatives to existing treatment systems for oily wastewater. Furthermore, the use of combined treatment processes is effective for the removal of hazardous pollutants present in high-strength oily wastewater. This review provides insights into advanced and emerging state-of-the-art technologies for safe and efficient treatment of industrial oily wastewater.

Impact of landfill leachate contamination on surface and groundwater of Bangladesh: a systematic review and possible public health risks assessment

Abstract: Dumping of solid waste in the non-engineered landfill is very common in the developing countries. Among the different disadvantages of this kind of landfilling, leachate is the major concern to public health, which is a toxic byproduct generated from the landfill; and can percolate to the ground water and consequently migrate in surface water. Using systematic review on published data, the present study endeavors to compare the leachate contamination potential of four major landfills of Bangladesh, named Amin Bazar, Matuail, Mogla Bazar and Rowfabad; which are situated in 3 of the 6 big mega cities of Bangladesh and assessed the effects of leachate leakage on surrounding water body as well as on human health. This study, for the first time calculated the leachate pollution index (LPI) for the landfill sites of Bangladesh and found that the LPI of Matuail landfill site (19.81) is much higher which is comparable to some polluted landfill sites of India and Malaysia. The concentrations of several potentially toxic metals found in the surface and ground water in the vicinity of the landfill sites were above the maximum permissible limit values of department of Environment, Bangladesh and World Health Organization (WHO). The human health risk index for toxic heavy metals in different vegetables and rice grain showed high health risk potential for Pb, Cd, Ni, and Mn. The total carcinogenic risk for Ni and Pb are found very high in the edible plants near those landfill sites, suggesting the risk of Ni and Pb induced carcinogenesis by the consumption of those plants. The present conditions of surface, ground water and agriculture products near the landfill sites of Bangladesh are much frightening to the biota and local inhabitants.

Computation of subsurface drain spacing in the unsteady conditions using Artificial Neural Networks (ANN)

Abstract: Artificial neural networks are a tool for modeling of nonlinear systems in various engineering fields. These networks are effective tools for modeling the nonlinear systems. Each artificial neural network includes an input layer, an output layer between which there are one or some hidden layers. In each layer, there are one or several processing elements or neurons. The neurons of the input layer are independent variables of the understudy issue, and the neurons of the output layer are its dependent variables. Artificial neural system, through exerting weight on inputs and by suing an activation function attempts to achieve a desirable output. In this research, in order to calculate the drain spacing in an unsteady state in a region situated in the north east of Ahwaz, Iran with different soil properties and drain spacing, the artificial neural networks have been used. The neurons in the input layer were: Specific yield, hydraulic conductivity, depth of the impermeable layer, height of the water table in the middle of the interval between the drains in two-time steps. The neurons in output layer were drain spacing. The network designed in this research was included a hidden layer with four neurons. The distance of drains computed via this method had a good agreement with real values and had a high precision in compare with other methods.

Delineation of groundwater potential zones for sustainable development and planning using analytical hierarchy process (AHP), and MIF techniques

Abstract: Groundwater plays a vital role in the sustainable development of agriculture, society and economy, and it's demand is increasing due to low rainfall, especially in arid and semiarid regions. In this context, delineation of groundwater potential zones is essential for meeting the demand of different sectors. In this research, the integrated approach consisting of analytical hierarchy process (AHP), multiple influence factors (MIF) and receiver operating characteristics (ROC) was applied. The demarcation of groundwater potential zones is based on thematic maps, namely Land Use/Land Cover (LULC), Digital Elevation Model (DEM), hillshade, soil texture, slope, groundwater depth, geomorphology, Normalized Difference Vegetation Index (NDVI), and flow direction and accumulation. The pairwise comparison matrix has been created, and weights are assigned to each thematic layer. The comparative score to every factor was calculated from the overall weight of two major and minor influences. Groundwater potential zones were classified into five classes, namely very poor, poor, moderate, good and very good, which cover an area as follows: 3.33 km2, 785.84 km2, 1147.47 km2, 595.82 km2 and 302.65 km2, respectively, based on AHP method. However, the MIF groundwater potential zones map was classified into five classes: very poor, poor, moderate, good and very good areas covered 3.049 km2, 567.42 km2, 1124.50 km2 868.86 km2 and 266.67 km2, respectively. The results of MIF and AHP techniques were validated using receiver operating characteristics (ROC). The result of this research would be helpful to prepare the sustainable groundwater planning map and policy. The proposed framework has admitted to test and could be implemented in different in various regions around the world to maintain the sustainable practices.

Adsorption of tartrazine and sunset yellow anionic dyes onto activated carbon derived from cassava sievate biomass

Abstract: The toxic effects of anionic dyes such as tartrazine and sunset yellow on humans and the aquatic environment are of serious concern. The need for the removal of these dyes from wastewaters led to the use of adsorption techniques as a cheap and efficient treatment method. Thus, this research was based on the preparation of a low-cost activated carbon derived from cassava sievate designated as CS, which was utilized in the adsorption of sunset yellow and tartrazine from simulated wastewater. The sorption process was carried out under varying process factors in a batch mode. Adsorbent characterization displayed the presence of surface functional groups by the FT-IR and a porous structure as revealed by scanning electron microscopy. Optimum dye uptake was recorded at pH (1.0–2.0), temperature (30–40 °C), CS dosage (0.1 g), and dye concentration (150 mg/L). A maximum CS monolayer uptake of 20.83 and 0.091 mg/g was recorded for tartrazine and sunset yellow dyes, respectively. The pseudo-second-order (R2 > 0.99) and Freundlich (R2 > 0.92) models were most fitted to the kinetics and isotherm data of the uptake of the dyes on CS. The adsorption equilibrium attainment was reached was within 90 min of dye sequestration. The experimental results revealed that both sunset yellow and tartrazine dyes were considerably adsorbed onto the environmentally compatible and low-cost activated carbon derived from cassava sievate.

Adsorption isotherm modeling for methylene blue removal onto magnetic kaolinite clay: a comparison of two-parameter isotherms

Abstract: In this work, kaolinite clay was modified with magnetic magnetite nanoparticles (Fe3O4@MC) by co-precipitation with ferrous and ferric ions as iron precursors to ameliorate its textural and adsorption capacity for methylene blue (MB) dye uptake from synthetic wastewater at low concentrations. The adsorbents were characterized using XRD, BET surface area analysis, VSM, SEM and HRTEM. The BET surface area after chemical treatment increased from 14.616 to 26.913 m2 g−1. The saturation magnetization of Fe3O4@MC was 6.22 emu g−1 and the exhausted adsorbent recoverable by a simple magnet. Adsorption data were modeled using six nonlinear two-parameter isotherm equations, namely Freundlich, Temkin, Fowler–Guggenheim, Elovich, Flory–Huggins and Langmuir model, and the best-fitting model arrived at using three mathematical error functions. MB adsorption onto unmodified clay was best described by the Fowler–Guggenheim isotherm, whereas MB adsorption onto Fe3O4@MC was best described by the Freundlich model. Increase in BET surface area increased the theoretical and experimental maximum adsorption capacity

Monitoring and investigating dust phenomenon on using remote sensing science, geographical information system and statistical methods

Abstract: Dust is a phenomenon occurring in most parts of the world causing financial loss and adverse environmental effects and impacts. Many parameters are involved in dust phenomenon occurrence, some of which are natural and some of them are due to human processes and their influence on the environment. Monitoring the environmental changes can be worthwhile and efficient procrastination the occurrence of this phenomenon. In this research, we scrutinized the Persian and English database in a structured way using dust keywords, heavy metals, remote sensing, geographical information systems and statistical methods. Articles taking into consideration these three fields were retrieved, analyzed descriptively and reported. In accordance with this methodology, the study was conducted in a period from 1992 to 2016. Findings: Among the methods used, the method of interpolation, zoning of dust and their distribution with GIS is more applicable, and among satellite images, MODIS images are the most applicable ones. The results obtained from this study indicated that statistical methods, remote sensing and geographical information system are among effective tools in studying germane researches done on dust monitoring and detection.

Assessment of land-use and land-cover changes in Pangari watershed area (MS), India, based on the remote sensing and GIS techniques

Abstract: In this paper, we focus on the assessment of land-use and land-cover change detection mapping to the effective planning and management policies of environment, land-use policy and hydrological system in the study area. In this study the soil and water conservation project has been applied during the five years and after five years what changes have been found in the land-use and land-cover classes and vegetation. In this view, this land-use and land-cover mapping is a more important role to decide the policy for watershed planning and management project in the semiarid region. In an emerging countries, fast industrialization and urbanization impose a significant threat to the natural atmosphere. The remote sensing and GIS techniques are crucial roles in the study of land-use and land-cover mapping during the years of 2007, 2014, and 2017. The main objective of this is to prepare the land-use and NDVI maps in the years of 2008, 2014 and 2017; these maps have prepared from satellite data using the supervised classification method. A normalized difference vegetation index map (NDVI) was done by using Landsat 8 and LISS-III satellite data. NDVI values play a major role in monitoring the vegetation and variation in land-use and land-cover classes. In these maps, four types of land are divided into four classes as agriculture, built-up, wasteland, and water body. The results of study show that agriculture land of 18.71% (158.24 Ha), built-up land of 0.62% (5.31 Ha), wasteland of 40.33% (341.02 Ha), and water body land of 17.39% (147 Ha) are increased. Land-use and land-cover maps and NDVI values show that agriculture land of 22.97% (194.29 Ha), 5.46% (14.59 Ha), and 0.08% (0.22 Ha) decreases during the years of 2008, 2014, and 2017. The results directly indicate that the supervised classification method has been the accurate identified feature in the land-use map classes. This classification method has been given the better accuracy (95%) from spatiotemporal satellite data. The accuracy was also tally with ground-truth and Google earth information. These results can be a very useful for the land-use policy, watershed planning, and management with natural resources, animals, and ecological systems.

Meteorological and hydrological drought monitoring using several drought indices

Abstract: With respect to the necessity of comprehensive studies on drought and also high damages that caused by drought, this research studied the meteorological and hydrological droughts. In this study, Lighvan, Navroud and Seqez basins with different climates were selected. We used monthly data of stream flow, precipitation and evaporation from 1992 to 2016 for the study of drought phenomena. The aim at this study is to analyze the SPI and SPEI for determination of dry and wet meteorological periods and use of the SSI for the exploration of hydrological drought. The analysis of drought characteristics such as intensity and duration in three areas with different climates shows that the climate change has a major impact on the characteristics of the droughts. The relations between the duration and severity of drought have been more accurate in the period of 9 months in the Navroud watershed basin. The most significant events are SPI-9 with the duration of 57 months and the severity of 34.7, SPEI-9 with the duration of 34 months and the severity of 28.09 and SSI-9 with the duration of 41 months and the severity of 30.2. According to the obtained equations in different time periods, it was resulted that the highest accuracy was observed in the relationship between the meteorological and hydrological drought characteristics in the watershed basin of Seqez for a period of 6 months. The results show that in all three basins, the correlation between the meteorological and hydrological drought is significant at the level of 99%. Results show that hydrological and meteorological droughts in Navroud and Lighvan basins have a significant correlation with 48-month periods and in the Seqez basin with 12- and 24-month periods, and the relations between hydrological droughts and meteorological droughts were obtained using the nonlinear linear models (polynomial, exponential and logarithmic). The good R2 between the duration and severity of SPI-9 and SSI-9 is 0.8 and 0.92, respectively, for polynomial equations. The maximum determination coefficient of duration and severity of SPEI-9 and SSI-9 is 0.72 and 0.82, respectively, using polynomial equation. The application of several indices indicating different components of the hydrological cycle integrates many factors that affect and trigger droughts, and thus can help in providing a wider realization of the characteristics of droughts on various water sections.

Preparation and characterization of powdered and granular activated carbon from Palmae biomass for mercury removal

Abstract: Two forms of activated carbon (i.e., granular and powdered forms) used to test mercury removal in solution. These activated carbons were obtained from the shells of a palmae biomass and used in mercury ion removal in aquatic systems. The African palmae shell taken out from a broadly and simply full-fledged palm tree. This biomass serves as a precursor in the formulation of activated carbons not documented. The powdered and granular fractions of activated carbons described for chemical composition, isoelectric point, and surface area. The mechanism of reactions and the kinetics involved were studied using the results of protonation and rate limitations. The parameters used in the batch mode study included pH, contact time, initial concentration of the adsorbate and the dose of the activated carbons. A comparison of performances, contact time demonstrated the highest adsorption efficiency of 93% for the powdered activated carbon and 92% for the granular activated carbon. The dosage recorded the lowest adsorption efficiency of 84% using granular activated carbon. Comparatively, this study brought to the fore that activated carbon derived from the Plamae biomass remains a novel bio-sorbent

Temporal assessment of heavy metal concentration and surface water quality representing the public health evaluation from the Meghna River estuary, Bangladesh

Abstract: The Meghna River, the largest and the widest river in Bangladesh, is important for navigation, irrigation, fish spawning and shelter, industrial usages, and drinking water sources for millions of people living in nearby areas. The present study illustrated the seasonal variation of some physicochemical parameters and the four heavy metals (Cr, As, Cd, and Pb) distribution in the surface water of Meghna River estuary. It also evaluated the human health risk for adult and children due to directly contact with the surface water through ingestion and dermal pathways. The ranges of metal concentration in the study area were found in the descending order as: Cr (0.036–0.054; mean 0.045 ± 0.005) > As (0.012–0.036; mean 0.024 ± 0.007) > Cd (0.009–0.050; mean 0.018 ± 0.012) > Pb (0.007–0.014; mean 0.009 ± 0.007). In most cases, the concentrations of As, Cr, Pb, and Cd surpassed the guideline limits of human consumption. However, the one-way ANOVA study revealed that the average concentrations of the selected metals in the ten sampling sites were not significantly different at a 95% confidence level. Therefore, it is assumed that the metal contamination in the study area might have been caused due to the anthropogenic sources along with the natural phenomenon. The distribution of the metal contents and the physicochemical parameters in the surface water greatly were significantly different concerning both winter and summer seasons at a 95% confidence level. The evaluated hazard quotient (HQ) and the hazard index (HI) for the investigated metal compounds were in the acceptable limit (< 1). In addition, the attribution of metal contents did not overweigh the carcinogenic risk (CR) range (10–6 to 10–4), and the adults are more susceptible than the children. Although the risk is within the acceptable level, but adequate monitoring aspects should be implemented to control surface water pollution especially for the metal discharge to the river estuary.

Evaluation of alkaline-based activated carbon from Leucaena Leucocephala produced at different activation temperatures for cadmium adsorption

Abstract: Heavy metal contamination in water is happening worldwide. Adsorption using activated carbon is a common choice for cleaning the wastewater. The drawback of activated carbon is the higher cost of production due to the need for high heat in the process. This work investigated on activated carbon produced from the abundantly available Leucaena leucocephala biomass in order to reduce the cost of raw material. The biomass was chemically activated at different activation temperatures. The produced activated carbon was characterized using SEM, FT-IR, surface analyzer, and TGA. Isothermic and thermodynamic studies were done to evaluate the adsorption properties of the activated carbon. It was found out that higher surface area can be obtained using the higher activation temperature. Higher NaOH to carbonized sample ratios also resulted in higher surface area for all activation temperatures, which are 662 m2g-1 for 700 °C activation temperature, 735 m2g-1 for 750 °C, and 776 m2g−1 for 800 °C. Isothermic studies showed that all of the activated carbon that is produced from Leucaena leucocephala biomass are fit to the Langmuir isotherm, regardless of any activation temperature. Lastly, the thermodynamic study found out the adsorption process is endothermic, reflected by the positive value of ΔHo. It can be concluded that Leucaena leucocephala is a promising alternative material for producing activated carbon.

Synthesis and characterization of ZnO nanoparticles using aqueous extract of Becium grandiflorum for antimicrobial activity and adsorption of methylene blue

Abstract: Nanotechnology is a recent field of modern research dealing with synthesis, strategy and manipulation of particle’s structure in size range of 1–100 nm. This study introduces one of the methods of synthesis of nanoparticles, i.e., green synthesis of ZnO NPs using aqueous leaf extract of Becium grandiflorum (AM: ‘Yedegamentisie’). The biomolecules of the plant extract (such as phenols, flavonoids, saponins, glycosides, steroids, tannins and alkaloids) were used as capping and reducing agent during synthesis of ZnO NPs. Response surface methodology coupled with Box-Behnken design (RSM-BBD) was used to optimize the synthesis of ZnO NPs and adsorption studies of the as-synthesized ZnO NPs. Then, ZnO NPs was characterized using different spectroscopic and microscopic instruments such as UV–Vis spectroscopy, FTIR, XRD and SEM–EDS to consider its purity, shape and crystallinity. UV–Vis analysis showed peaks in the range 305–312 nm due to synthesis of ZnO NPs. FTIR analysis showed the availability of different phytochemicals in the plant extract and synthesis of ZnO NPs at 490 cm−1. Powder XRD patterns confirmed formation of phase pure wurtzite structures of ZnO NPs. The synthesized ZnO NPs were used to remove MB dye from aqueous solution by acting as a photocatalyst and adsorbent as well as, it also showed antimicrobial activity against two gram positive (Staphylococcus epidermidis, Staphylococcus aureus) and three gram negative (Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa) bacteria.

Morphometric analysis of a drainage basin using geographical information system in Gilgel Abay watershed, Lake Tana Basin, upper Blue Nile Basin, Ethiopia

Abstract: GIS and remote sensing approach is an effective tool to determine the morphological characteristics of the basin. Gilgel Abay watershed is stretched between latitude 10.56° to 11.22° N and longitude 36.44° to 37.03° E which is one major contributing river of Lake Tana which is the source of Blue Nile. The present study addressed linear and areal morphometric aspect of the watershed. The study deals with emphasis on the evolution of morphometric parameters such as stream order, stream length, bifurcation ratio, drainage density, stream frequency, texture ratio, elongation ratio, circularity ratio, and form factor ratio. The morphometric analysis of the basin revealed that Gilgel Abay is firth-order drainage basin with total of 662 drainage network, of which 511 are first order, 111 are second order, 30 are third order, 9 are fourth order, and 1 is fifth-order stream. The total length of stream is longer for first order and decrease with increasing stream order. The mean bifurcation ratio is 5.16 which is greater than the standard range, and it indicates that basin is mountainous and susceptible to flooding. Low drainage density is observed which is 0.6 km−2. It indicates that basin is highly permeable and thick vegetation cover. Areal aspect of the morphometric analysis of the basin revealed that the basin is slightly potential to flooding and soil erosion, indicating that runoff generated from the upland area of the watershed is significantly infiltrated at the gentle downstream part and contributing to groundwater potential. Further studies with the help of GIS and remote sensing with high-resolution remote sensing data integrating with ground control data in the field are more effective to formulate appropriate type of natural resource management system.

Exploration of groundwater potential zones using analytical hierarchical process (AHP) approach in the Godavari river basin of Maharashtra in India

Abstract: Total natural and groundwater resources play the most crucial role in developing ecological, biological and socioeconomic doings. Various parameters like land use, geology, elevation, slope, lineament, lineament density, drainage density and geomorphology affect the groundwater development of recharge and its accessibility. In this research, geographical information system (GIS), remote sensing, weighted overlay analysis and analytical hierarchy process (AHP) methods have been used for groundwater prospects mapping, and identifying suitable solutions site for soil and water conservation structures. To calculate the weights were assigned to every layers component in the determination of affecting factors. The weighted overlay analysis (WOA) tool is applied to give the sub-parameter ratings based on the scientific literature. The final map of potential groundwater zone map has prepared using Arc GIS 10.1 software and AHP methods. About 49.71% of the areas fall under the 'good potential zone, 41.05% falls under the 'moderate potential zone', and 9.22% falls under the 'poor zone by using AHP technique. Groundwater potential zone map is depend on the weighted overlay analysis and analytical hierarchy process (AHP) methods. The highest GWP is located in the lower part of the basin due to the best surface runoff gathering, infiltration situations and subsurface storage volume. The present study procedure, methods and outcomes can be valuable to estimate the suitable groundwater zones parallel to improve the dry land area in the semi-arid and arid regions of India.

Feldspar-banana peel composite adsorbent for efficient crude oil removal from solution

Abstract: The problem of oil spill pollution associated with the transport of crude oil and its products across the globe is of serious concern. The sorption technique has proved to be promising for oil spill treatment but is limited by the hydrophilic nature of most natural organic sorbents. The combo of natural organic and inorganic sorbents have been found to enhance the hydrophobicity for oil sorption. Therefore this study was aimed at the preparation of a novel feldspar-banana peel biochar composite (FBPC) with enhanced hydrophobicity for the sorption of crude oil. The prepared sorbent was characterised by the scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, while the crude oil was characterised using standard methods. Batch sorption was used to determine the effect of contact time (30–150 min), temperature (25–100 °C), pH (2.0–10.0), oil concentration (4.0–12.0 g/L) and sorbent dosage (0.1–0.5 g) on sorption. SEM analysis of FBPC revealed a porous structure, while XRD confirmed the crystalline phases of feldspar. The crude oil samples had pH (6.40–6.60), density (0.960 0 0.962 g/cm3), kinematic viscosity (24.0–27.6 cSt) and API gravity (24.25–24.51°). The Langmuir model with R2 > 0.7781 presented the best fit than the Temkin and Freundlich model in the isotherm analysis, while the pseudo-second-order model with R2 > 0.9711 was applicable in the kinetics of sorption. The thermodynamic analysis revealed a decrease in randomness at the crude oil-FBPC interface. The prepared FBPC was found to be an efficient inorganic–organic composite sorbent with enhanced hydrophobicity for the sorption of crude oil.

Investigation on operating parameters and cost using an electrocoagulation process for wastewater treatment

Abstract: Wastewater generated from different sources affects the health of living organisms and the natural environment due to the availability of different pollutants. Electrocoagulation (EC) is a good technology implemented for wastewater treatment before discharging to an environment as effluents. The electrocoagulation process is an effective method to the remove the color, chemical oxygen demand (COD), turbidity, and consumption of less energy from wastewater by considering different operating parameters. In this study, the major operating parameters for the electrocoagulation process such as pH (3–7.50), electric current (0.03–0.09 A), electrolytic concentration (1–3 g/L), the distance between electrodes (1–2 cm), electrolysis time (20–60 min) and combination of electrodes (Fe–Fe and Al–Al) were studied. The maximum removal of color–94.40%, COD–97.02%, and turbidity–90.91% with required energy consumption –36kWhr/m3 was obtained at the electric current–0.09 A, electrolyte concentration–3 g/L, pH–7, electrode combination–Fe–Fe, and distance between electrodes–3 cm, respectively. The studied parameters were affected the removal % color, % COD, % turbidity, and also the consumption of energy depending on the desired setup of fixed values of the parameter. Consumption of energy and electrode dissolution is related to the cost of operating in electrocoagulation in addition to the cost of labor and the small amount of sludge produced for disposal.

Estimation of heavy metal contamination in the Hindon River, India: an environmetric approach

Abstract: The Hindon River is a major freshwater resource predominantly for the rural population of the western region in Uttar Pradesh, India. The river receives industrial wastewaters having heavy metals concentration at potentially toxic levels. The focus of this study is to estimate the heavy metals (such as Fe, Cu, Zn and Cr) contamination in the Hindon River using Nemerow pollution index followed by environmetrics to identify their pollution source. The water samples are collected from 28 industrial discharge sites in the river to analyze metals concentration during pre- and post-monsoon months. The estimated Nemerow pollution index value is more than 3 indicating severely contaminated river water. Principal component analysis results confirm that Fe and Cu are the major contaminants in the river, which indicates the direct input of wastewater from electroplating industries. Therefore, it is suggested that a strategic eco-conservation plan should be formulated and implemented in advance to prevent the deterioration of the water quality and aquatic life.

Kinetic studies of Congo red dye adsorption by immobilized Aspergillus niger on alginate

Abstract: Releasing of dye-containing wastewater by the textile industry into general water bodies can adversely affect aquatic ecosystems and human health. The objective of this study is to assess the Congo red dye biodegradation and detoxification by immobilized Aspergillus niger obtained from textile dye wastewater. The effects of process parameters like pH, temperature, reaction time and initial concentration on Congo red degradation were studied. Equilibrium adsorption isotherms, kinetics and thermodynamics were also investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data fitted well to Langmuir isotherm and the kinetic data fitted well to the pseudo-second-order model. The degraded metabolites of Congo red were characterized by using UV–Vis spectrophotometer, Fourier transform infrared spectroscopy and high-performance liquid chromatography, further confirmed that biodegradation of Congo red was due to reduction of the azo bond. Phytotoxicity test confirmed that degradation metabolites were a less toxic than original dye. The reusability of the immobilized Aspergillus niger was repeated with six cycles and removal efficiency ranged from 98 to 72%. The results in this study substantiate that immobilized Aspergillus niger could be employed as a good adsorbent for the removal of Congo red dye from wastewater.

Simulation of the impact of climate change on runoff and drought in an arid and semiarid basin (the Hablehroud, Iran)

Abstract: This study evaluates the impact of climate change (CC) on runoff and hydrological drought trends in the Hablehroud river basin in central Iran. We used a daily time series of minimum temperature (Tmin), maximum temperature (Tmax), and precipitation (PCP) for the baseline period (1982–2005) analysis. For future projections, we used the output of 23 CMIP5 GCMs and two scenarios, RCP 4.5 and RCP 8.5; then, PCP, Tmin, and Tmax were projected in the future period (2025–2048). The GCMs were weighed based on the K-nearest neighbors algorithm. The results indicated a rising temperature in all months and increasing PCP in most months throughout the Hablehroud river basin's areas for the future period. The highest increase in the Tmin and Tmax in the south of the river basin under the RCP 8.5 scenario, respectively, was 1.87 °C and 1.80 °C. Furthermore, the highest reduction in the PCP was 54.88% in August under the RCP 4.5 scenario. The river flow was simulated by the IHACRES rainfall-runoff model. The annual runoff under the scenarios RCP 4.5 and RCP 8.5 declined by 11.44% and 13.13%, respectively. The basin runoff had a downward trend at the baseline period; however, it will have a downward trend in the RCP 4.5 scenario and an upward trend in the RCP 8.5 scenario for the future period. This study also analyzed drought by calculating the streamflow drought index for different time scales. Overall, the Hablehroud river basin will face short-term and medium-term hydrological drought in the future period.

Morphometric analysis and watershed prioritization in relation to soil erosion in Dudhnai Watershed

Abstract: Morphologic parameters of a watershed could help in segregating critical sub-watersheds for taking up conservation practices and mitigation interventions. Determination of critical watersheds or prioritization of sub-watersheds is inevitable for efficient and sustainable watershed management programs and allocation of its natural resources. The traditional methods of determination of morphologic parameters are time consuming, expensive and requires huge labor. However, the process becomes easier, cheaper and faster with the advent of Geographical Information System (GIS) and remote sensing technologies. In the present study, a combined approach of using toposheet, remotely sensed digital elevation model and morphometric ArcGIS toolbox has been adopted to determine morphometric parameters in Dudhnai river basin, a sub-basin of river Brahmaputra which is prone to both erosion and sedimentation. Seven sub-watersheds of Dudhnai have been prioritized by using the morphometric parameters and ranked them according to its vulnerability to soil erosion. The results of bifurcation ratio, drainage density, drainage intensity and constant of channel maintenance showed that Dudhnai watershed is a well-dissected watershed with less risk to flooding and soil erosion. However, significantly high values of infiltration number and ruggedness number obtained are indicative of very low infiltration which may result in high surface runoff and soil erosion. The study also revealed that channel erosion is stronger than sheet erosion in the basin. The prioritization of the sub-watersheds implied that Chil sub-watershed is the most susceptible sub-watershed that needs greater attention for soil and water conservation measures. The results of the present study could aid various stakeholders who are involved in the watershed development and management programs.

Evaluating the groundwater quality of Damodar Fan Delta (India) using fuzzy-AHP MCDM technique

Abstract: In recent years, groundwater pollution has become increasingly a serious environmental problem throughout the world due to increasing dependency on it for various purposes. The Damodar Fan Delta is one of the agriculture-dominated areas in West Bengal especially for rice cultivation and it has a serious constraint regarding groundwater quantity and quality. The present study aims to evaluate the groundwater quality parameters and spatial variation of groundwater quality index (GWQI) for 2019 using the fuzzy analytic hierarchy process (FAHP) method. The 12 water quality parameters such as pH, TDS, iron (Fe−) and fluoride (F−), major anions (SO42−, Cl−, NO3−, and HCO3−), and cations (Na+, Ca2+, Mg2+, and K+) for the 29 sample wells of the study area were used for constructing the GWQI. This study used the FAHP method to define the weights of the different parameters for the GWQI. The results reveal that the bicarbonate content of 51% of sample wells exceeds the acceptable limit of drinking water, which is maximum in the study area. Furthermore, higher concentrations of TDS, pH, fluoride, chloride, calcium, magnesium, and sodium are found in few locations while nitrate and sulfate contents of all sample wells fall under the acceptable limits. The result shows that 13.79% of the samples are excellent, 68.97% of the samples are very good, 13.79% of the samples are poor, and 3.45% of the samples are very poor for drinking purposes. Moreover, it is observed that very poor quality water samples are located in the eastern part and the poor water wells are located in the northwestern and eastern part while excellent water quality wells are located in the western and central part of the study area. The understanding of the groundwater quality can help the policymakers for the proper management of water resources in the study area.

Spatiotemporal analysis of vegetation cover changes around surface water based on NDVI: a case study in Korama basin, Southern Zinder, Niger

Abstract: In the modern era, vegetation dynamics is an important aspect of climate change studies. The present study examined spatiotemporal changes of (NDVI) normalized difference vegetation index in the Korama basin (Southern Zinder of Niger) from 2000 to 2018, and their correlation with climatic factors was predicted. To analyze the change of vegetation cover, geographical information system, MODIS_NDVI, remote sensing, and climate variables (e.g., temperature and precipitation) datasets were used. Further, the correlation was performed for different years of vegetation types during the growing season (June–October). Our results show an increasing trend in average maximum annual NDVI across the Korama River Basin in the years 2000 and 2018. Conversely, significantly increasing trends in most of the areas were reported. Moreover, in downstream the vegetation cover is increased in Matameye and Magaria, but with a smaller increase in the upstream rate in Mirriah. Furthermore, a decrease in the surface water was observed in the Tessaoua, Matameye, and Magaria sections of the study region in 2000 and 2018, while a rise in water surface area was observed in Matameye and Magaria in the years 2006 and 2012. During rainy and dry seasons, NDVI correlated differently with temperature and precipitation with strong seasonal variations, while the mean vegetation period of NDVI does not show any significant change. In addition, moderate increase was observed in years 2000 and 2012 (r: 0.22; P: 0.50; R2: 0.05; r: 0.31; P: 0.34, R2: 0.10, respectively), and weak decrease in 2006 and 2018 (r: 0.61; P: 0.04; R2: 0.37; r: 0.58; P: 0.06, R2:0.33, respectively). The analysis indicates that climatic parameters such as precipitation and temperature are the main limiting factors affecting the vegetation growth. Indeed, the trends calculated by the correlation analysis showed that as climate factors increased (July, August, and September), the NDVI value increased at a rate of 0.16, reflecting the best growth in vegetation and rise in water bodies, although significantly decreased during years. This study would be highly useful in choice-making for sustainable water resource management in the Korama watershed in Southern Zinder, Niger.

Evaluation of groundwater quality for drinking and irrigation purposes using GIS-based water quality index in urban area of Abaya-Chemo sub-basin of Great Rift Valley, Ethiopia

Abstract: Groundwater is the major resource for drinking and irrigation purposes in urban areas of Abaya-Chemo sub-basin of Great Rift Valley, Ethiopia. There is an incredible increase in demand in the sub-basin for good-quality groundwater resources. However, the exhaustive irrigation and rapid urbanization has posed a serious threat to groundwater quality in the urban districts of sub-basin like Arba Minch town. The aim of the study was to evaluate the groundwater quality status and to map their spatial distribution with respect to the suitability for drinking and irrigation purposes in Arba Minch town, Ethiopia. Fourteen bore well samples were examined for geochemical variations and groundwater qualities. The spatial distribution maps of quality parameters were prepared using the kriging method in ArcGIS 10.3. Drinking water quality index, sodium adsorption ratio (SAR), percentage sodium (Na%), residual sodium carbonate (RSC), and permeability index (PI) were considered for drinking and irrigation suitability assessment. Comparison of the hydrochemical results with the World Health Organization (WHO) and Ethiopian drinking water standards (ES) and various classifications revealed that the current status of the groundwaters is suitable for drinking and irrigation purposes except for a few sites at the northwestern part of the study area. The WQI results revealed that 7% and 64% of samples fall from excellent to good classes for drinking categories. Irrigation indices also demonstrated that 80% of samples fall in good classes for irrigation purposes. About 75 percent of samples belong to Ca–Mg-HCO3 facies, and the reaming samples belong to Ca–Mg–Cl facies. The results of the study concluded that the proposed approach is reliable and efficient for the groundwater pollution status evaluation and can also be applied in decision making for effective groundwater resources monitoring in the study area.

Preparation of ZnO/Nylon 6/6 nanocomposites, their characterization and application in dye decolorization

Abstract: Nylon 6/6 and ZnO/nylon 6/6 nanocomposite films were prepared by solvent casting method. Morphological study displayed that ZnO NPs are better dispersed in nylon 6/6. However, some agglomerations were found by the incorporation of high quantities of fillers. The thermal stabilities of neat nylon 6/6 films decreased by addition of nanoparticles (NPs). DSC study shows that the NPs slow down the crystallization rate of neat polymer matrix. POM of Nylon 6/6 upon crystallization showed distinct sized spherulites, which decreased by the incorporation of NPs because of nucleation effect of NPs. The mechanical properties of neat polymer are decreased by addition of ZnO NPs, which might be due to agglomeration of fillers. The neat nylon 6/6 and ZnO/nylon 6/6 nanocomposite were used for the photodegradation of alizarin red (AR) dye, which shows that pure nylon 6/6 degraded about 28% dye while 30% ZnO/Nylon 6/6 degraded about 58.3% dye within 5 h irradiation.

Assessment of heavy metal and physico-chemical pollution loadings of River Benue water at Makurdi using water quality index (WQI) and multivariate statistics

Abstract: In this work, the quality of River Benue water at Makurdi was assessed for its heavy metal load alongside seven other physico-chemical parameters using water quality index (WQI) and multivariate statistical tools. A total of 45 samples from three (3) different points along the River course were collected for five months (October 2018–May, 2019) spanning the dry and wet seasons. Samples were analysed in accordance with standard methods. Most of the parameters evaluated were found to fall in the allowable limits of the World Health Organization (WHO) among others, except for colour, turbidity, total suspended solids, nickel, lead and cadmium. WQI analysis using the BISWQI, OWQI and CCMEWQI indicated that all indexing methods were suitable for estimating the WQI of River Benue as they all showed that the water corresponded to the classification as “poor water”. Heavy metal index of the river ranged from13.40–6080.00 and from 47.07–7240.00 for the dry and wet seasons, respectively, and was majorly influenced by high cadmium and lead pollution levels. Principal component analysis (PCA) revealed three rotated factor with respective communality levels for both the dry and wet seasons. Factor 1 was positively loaded with nine parameters which accounted for 32.3% of the total variance during the dry season, while it was positively loaded with 10 parameters in the wet season accounting for 25.9% of total variance. Hierarchical cluster analysis (HCA) revealed that the river was zoned into four clusters each for both dry and wet seasons. Sampling points 2 and 3 were the most polluted during the dry season, while sampling point 1 was found to be the most polluted in the wet season. It was concluded that the increasing and diverse nature of anthropogenic activities on the river course was responsible for the deteriorating quality of the water. The study recommended continuous pollution monitoring and local regulations to reduce the entrance of both diffuse and point source pollution into the river.

Evaluation of water quality and eutrophication status of Hawassa Lake based on different water quality indices

Abstract: Lake Hawassa is one of the major Ethiopian Rift Valley Lakes having an endorheic basin system. The surrounding community makes use of the lake water for the multiple purposes of irrigation, domestic water supply, recreation and fish harvesting. The aim of the present study was to ascertain the water quality of the lake in terms of water quality indices (WQI) and its health over a period of three months covering both dry and wet seasons. Overall, the water quality of Lake was unfit and bad as per the weighted arithmetic method (120.06–228.29) and modified Bascaron water quality index (MBWQI) methods (26.81–33.89), respectively. However, the quality was indicated as marginal, as per the Canadian Council of Ministers of the Environment (CCME) water quality index method (44.2–51.1). On average, the lake was under the hypertrophic stage as per the standard based on the results of Secchi depth and nutrient concentration. The current study showed the lake being unfit for all-purposes as per WAWQI range (> 100). According to the physicochemical and biological parameters, of the lake, it requires mitigation measures to control Eutrophication and pollutants inflow.