Applied Water Science (v.8, #6)

In practice, established operation of activated sludge treatment system with high biomass concentration is restricted because of difficulty in settling the sludge in clarifiers. Membrane bioreactor is a modified form of activated sludge, and despite the superior advantages, its widespread application is restricted by the membrane fouling. Therefore, in this research, to improve the sludge sedimentation at high biomass concentration in the activated sludge system, high-frequency ultrasound (1.7 MHz) was exerted in clarifier of activated sludge system and its performance was compared with a bioreactor followed by an antifouling ultrafiltration membrane. The antifouling ability of NH2-functionalized multiwall carbon nanotubes (NH2-MWCNTs)-modified nanocomposite UF membrane during filtration of mixed liquor-activated sludge was investigated. Hydraulic retention time (HRT) (8–44 h) and mixed liquor suspended solids (MLSS) (6000–14,000 mg/L) were chosen as the operating variables to analyze the process. The biological process showed high COD removal efficiency throughout the experiments (> 96%). The membrane and high-frequency ultrasound had no effect on the system performance in terms of COD, TKN, TN, TP removal. However, the HRT and MLSS indicated an increasing impact on flux. The effect of ultrasound on the sludge properties, i.e., sludge volume index, sludge settling velocity and height of sludge at high MLSS concentration (14,000 mg/L), was not considerable. It was concluded at MLSS of below 10,000 mg/L, about 40% water recovery was obtained. As a result, activated sludge equipped with ultrasound showed a promising performance; however, its industrial development needs further examinations to attain the design criteria.
Keywords: Conventional activated sludge; Antifouling UF membrane; High-frequency ultrasound; Milk processing wastewater

Awash River, one of the major rivers in Ethiopia which originate from the central highland area, crosses different extended agricultural farms as well as various industries which receives large effluents from different sources. Nineteen physicochemical parameters, as well as heavy metals (Fe, Zn, Cu, Pb, Cr, Cd and Ni), were quantified using atomic absorption spectroscopy in eight different sampling stations of Awash River. There was a significant spatial variation (p < 0.05) in average NO3-N, NH4-N, TN, BOD and COD values in Awash River. There is a strong and positive correlation between (pH and EC, r = 0.805), (WT and BOD, r = 0.774), (NO3-N and NO2-N, r = 0.901), (NO3-N and TN, r = 0.906), (NO3-N and TP, 0.830), (NH4-N and TN, r = 0.876), (NH4-N and COD, r = 0.848), (TN and TP, r = 0.819), (TN and COD, r = 0.941) during dry season and also between (WT and BOD, r = 0.704), (turbidity and NO3-N, r = 0.749), (turbidity and NO2-N, r = 0.722), (NO3-N and NO2-N, r = 0.921), (TP and COD, r = 0.789) during wet season. The results showed that the mean concentrations of metals ranked (high to low) Fe > Cr > Cu > Zn > Pb > Cd > Ni during dry season, whereas the concentration of heavy metals during wet season was in the following order of decreasing magnitude Fe > Cu > Zn > Pb > Cr > Cd > Ni. Buffer zones should be protected in order to control soil and agricultural nutrients from entering to Awash River. Moreover, industries at the upper stream area should be properly and adequately treat the wastewater before discharging to the Modjo as well as Awash River.
Keywords: Heavy metals; Sampling station; Spatial variation; Dry season; Wet season

Physical and rheological properties of the Chorfa dam mud: dependency on solids concentration by Abderrahmane Messaoudi; Mohamed Bouzit; Nabila Boualla (1-9).
The main purpose of this study is to determine the mud rheological properties of the Chorfa dam (region of Mascara, Algeria) and to propose a rheological model that describes mud flow behavior. This study helps on one hand to give a better understanding of fine sediment transport dynamics in the dam, as well as contributing to reduce the dredging costs, and on other hand to valorize dredged sediments in road construction. Rheological measurements were conducted using an Engler viscometer and a Haake RS 600 rheometer. Mud samples were prepared with purified water at a range of solids concentration varying between 5.0 and 32.5%. Besides, the physical, chemical and mineralogical characteristics of the Chorfa dam’s mud and the rheological tests were presented and the effect of solids concentration on mud viscosity was studied. The results indicate that the Chorfa dam’s mud showed a non-Newtonian behavior for solids concentration higher than the critical solids concentration, and the apparent viscosity increases with increasing solid concentration at different shear rates. In addition, for a fixed concentration, the apparent viscosity decreases with increasing shear rates, which approves the shear thinning behavior of the Chorfa dam’s mud. Fitting results of four rheological models (Bingham Plastic Model, Ostwald–de Waele (power law), Herschel–Bulkley and Casson) to the experimental data were presented. Hence, the Ostwald–de Waele model was the best fitting model for mud samples.
Keywords: Mud; Solids concentration; Apparent viscosity; Rheometer; Rheological model

The marine microalga Nannochloropsis oculata was investigated for its biosorption capacity for the removal of Cd(II) ions from aqueous solution using batch mode experiments. pH (2–5), biomass dosage (0.0191 g/50 mL and 0.392 g/50 mL) and temperature (293–323 K) being the experimental parameters affecting the biosorption process were observed. To describe the experimental equilibrium data, Langmuir and Freundlich isotherms models were applied. The biosorption potential of N. oculata biomass for Cd(II) ions was found to be 232.55 mg/g. The calculated thermodynamic parameters (∆G°, ∆H° and ∆S°) showed that the biosorption of Cd(II) ions onto N. oculata was feasible, spontaneous and exothermic at 298–323 K. Evaluation of experimental data in terms of biosorption kinetics showed that the biosorption of Cd(II) by N. oculata well followed pseudo-second-order kinetics. The FTIR spectra indicated that the functional groups predominantly involved in the biosorption were –OH, COO–, –CH and phosphate groups. The XRD pattern of the biosorbent showed a change in crystallinity of N. oculata biomass after the biosorption. It was concluded that N. oculata can be used as an effective, low-cost and environmentally friendly biosorbent for the removal of Cd(II) from aqueous solution.
Keywords: Biosorption; Cadmium(II); FTIR; Isotherms; Kinetics; Nannochloropsis oculata ; XRD

Single and binary adsorption of sulfonamide antibiotics onto iron-modified clay: linear and nonlinear isotherms, kinetics, thermodynamics, and mechanistic studies by Victor O. Shikuku; Renato Zanella; Chrispin O. Kowenje; Filipe F. Donato; Nelson M. G. Bandeira; Osmar D. Prestes (1-12).
Iron-modified raw kaolinite clay (Fe-MC) was synthesized by co-precipitation method, characterized, and then applied as a low-cost adsorbent to sequester sulfachloropyridazine (SCP) and sulfadimethoxine (SDM), emergent water contaminants, from aqueous media by batch equilibration at circumneutral pH. The adsorption rate was kinetically described by the pseudo-second-order model. Equilibrium monocomponent sorption data were fitted to three two-parameter linear and nonlinear isotherm models. The data were best described by Temkin and Langmuir nonlinear equations. Linearization of adsorption isotherms is demonstrated to be an unsuitable analytical tool for predicting adsorption isotherms. The Langmuir monolayer maximum adsorption capacities were 4.561 and 1.789 mg/g for SCP and SDM, respectively. The binary adsorption study showed an antagonistic adsorption process of SCP (R q, SCP= 0.625) in the presence of SDM (R q, SDM = 1.032). The thermodynamic parameters, namely enthalpy (ΔH), Gibbs free energy (ΔG), entropy (ΔS), Arrhenius activation energy (ΔEa), and sticking probability (S *), indicated that the processes are spontaneous, exothermic, and physical in nature. The adsorption process was attributed to hydrogen bonding and negative charge-assisted H-bonding (CAHB). Using the Langmuir isotherm, the amount of Fe-MC required for a given volume of effluent of known contaminant concentration could be predicted.
Keywords: Iron oxide; Kaolinite; Adsorption; Sulfonamides; CAHB

In this study, adsorption of Acid green 20 (AG20) by modified sepiolite, hexadecyltrimethylammonium-modified sepiolite (HDTMA-Sep), was optimized using response surface methodology based on a central composite design. Characteristics of natural sepiolite and modified sepiolite can be analyzed by FTIR and XRD techniques. In order to achieve a better comprehension of applicability of adsorbent for removing dyes from colored effluents, isotherm and kinetic studies were also carried out. The maximum dye removal of 78% and 72% for synthetic solutions and real wastewater, respectively, was obtained at the initial dye concentration of 77.1 mg/L, contact time of 24.81 min, solution pH of 6.19 and adsorbent dosage of 1.03 g/L. The kinetic studies revealed that the adsorption process followed pseudo-second-order model. The adsorption data were best fitted to Freundlich model. The result indicated that the contact time and dye concentration have more influence on the removal efficiency rather than pH and amount of adsorbent. The experimental data from this study indicated that the modified sepiolite is an efficient adsorbent for dye removal from aqueous solutions.
Keywords: Adsorption; Sepiolite; Response surface methodology; Acid green 20; Central composite design

Prediction of depth-averaged velocity in an open channel flow by Jnana Ranjan Khuntia; Kamalini Devi; Kishanjit Kumar Khatua (1-14).
This paper presents a new methodology to predict the depth-averaged velocity along the lateral direction in an open channel flow. The novelty of this work is to determine the point velocity and estimate the discharge capacity by knowing the geometrical parameters at a section of an open channel flow. Experimental investigations have been undertaken in trapezoidal and rectangular channels to observe the variation of local velocities along both the vertical and transverse directions at testing sections. For different geometry, hydraulic and roughness conditions, the measurements are taken for several flow conditions. Multi-variable regression analysis has been adopted to develop five models to predict the point velocities in terms of non-dimensional geometric and flow parameters at any desired location. The present method is favourably compared with the analytical method of Shiono and Knight with reasonable accuracy. The performance of mathematical model is also validated with two natural river data sets. Further, statistical error analysis is carried out to know the degree of accuracy of the present models.
Keywords: Open channel flow; Velocity profiles; Regression analysis; Depth-averaged velocity; Error analysis

New analytical solution for stream–aquifer interaction under constant replenishment by Amruta Daga Bhandari; V. H. Pradhan; Rajeev K. Bansal (1-8).
In the present paper, approximate analytical solutions for flow in unconfined aquifers with streams are obtained assuming one-dimensional horizontal groundwater flow in homogeneous and isotropic aquifer with recharge effect using variational homotopy perturbation method which is a combination of variational iteration method and homotopy perturbation method. The governing nonlinear Boussinesq equation is obtained by using a basic principle of conservation of mass followed by Dupuit’s assumptions. Sensitivity of the parameters has been analyzed. The obtained approximate analytical solutions are numerically validated. The present analytical method is reliable and can be equally well applied to other nonlinear equations arising in the stream–aquifer interaction problems.
Keywords: Boussinesq equation; Variational homotopy perturbation method (VHPM); Stream–aquifer interaction

Comparison of cubic, quadratic, and quintic splines for soil erosion modeling by Sarita Gajbhiye Meshram; P. L. Powar; Chandrashekhar Meshram (1-7).
Approximate curve is constructed using quadratic, quintic, and cubic splines and examination between these splines. The point of this construction is to predict sediment yield index (SYI) corresponding to curve number. This strategy is outlined with a contextual analysis of Manot watershed of Narmada Basin, India. The relation among calculated SYI and observed SYI esteems is associated with a coefficient of determination (R 2) of 0.36 and 0.48 for the corresponding quadratic and quintic splines, while the cubic spline showed R 2 of 0.87 (Meshram et al. Arab J Geosci 10:155–168, 2017b; Appl Water Sci 7:1773–1779, 2017c). Numerical results seemed to indicate that the cubic spline method is more accurate than the quadratic/quintic spline method.
Keywords: Sediment; Curve number; Quadratic spline; Quintic spline

This study explored the adsorption of lead ion from aqueous solution onto biochars produced from date seed biomass. Initial evaluation of nine date seed-derived biochars showed that biochar prepared at 550 °C and heating time of 3 h (DSB550-3) was the best adsorbent for Pb2+ ion removal. Therefore, it was selected for further investigation in batch and column experiments. The effects of contact time, initial Pb2+ concentration, and solution pH were studied. Solution pH showed strong effect on the adsorption ability of DSB550-3 biochar to the lead ion, and the maximum adsorption capacity was found to occur around pH 6.0. The batch maximum adsorption capacity of DSB550-3 biochar was 0.360 mmol g−1. The equilibrium data were adequately fitted to Freundlich and Langmuir isotherms (R 2 = 0.97). The adsorption kinetics were best described by pseudo-second-order model (R 2 = 0.94). The breakthrough curve obtained from the column experiment was best described by the modified dose–response model (R 2 = 0.95). The desorption efficiencies of Pb2+ were 2.1%, 23%, 12%, and 55% for DI water, 0.1 M HCl, 0.1 M CaCl2, and a combination of 0.1 M HCl + 0.1 M CaCl2 eluents, respectively. FTIR analysis and batch experiments results suggested that Pb2+ adsorption mechanism was dominated by complexation with active surface groups, precipitation, and cation exchange. Experimental and model results suggested that date seed-derived biochar has high adsorption capacity for Pb2+ compared to other plant-based biochars reported in other literature.
Keywords: Adsorption; Biochar; Date seed; Desorption; Isotherms; Lead

Integrated management of urban watersheds and effective productivity of its resources, especially water resources, requires knowledge of its hydrology. In this regard, flood events and urban runoff produced at the time of floods from the point of harvesting and consumption of critical are very important. In this study in order to evaluate the possibility of using the most appropriate rainwater harvesting systems in Arak watershed, by collecting basic information from the watershed overlooking the city, surrounding watersheds were grouped by using the cluster analysis in homogeneous areas. In each region using the soil conservation service model, the rate of base time and return periods was calculated. Also, using an analytic hierarchy process and quantitative and qualitative criteria, different systems of urban water harvesting were determined for each homogeneous region of Arak watershed.
Keywords: Rainwater harvesting systems; Flood; Urbanized watershed; Analytical hierarchy process

Evaluation of the impact of fly ash on infiltration characteristics using different soft computing techniques by Parveen Sihag; Balraj Singh; Saurabh Gautam; Sourav Debnath (1-10).
The aim of this paper was to investigate the impact of the fly ash concentration on the infiltration process and to assess the potential of five soft computing techniques such as artificial neural network, Gaussian process, support vector machine (SVM), random forest, and M5P model tree and compare with two popular conventional models, SCS and Kostiakov mode, to estimate the cumulative infiltration of fly-ash-mixed soils. Laboratory experiment was carried out with the different combinations of the sand, clay, and fly ash by using mini disk infiltrometer. The combination consists of the different concentrations of sand (25–45%), clay (25–45%), and fly ash (10–50%). The total observation consists of the 138 field measurement. The cumulative infiltration increase with an increment in the concentration of the fly ash, but it decreases when fly ash concentration increases 40–50% in the soil. On the other hand, the cumulative infiltration increases with the decrease in the concentration of clay in samples. The predictive modeling technique, SVM with RBF kernel, is the best technique to predict the cumulative infiltration with minimum error. Results suggest that SVM with RBF kernel is the best-fit modeling technique among other soft computing techniques as well as conventional models to find the impact of fly ash on infiltration characteristics for the given combination of the sand, clay and fly ash.
Keywords: Fly ash; Artificial neural network; Gaussian process; Support vector machine; Random forest; M5P model tree

Experimental studies on the transfer of dissolved solutes from soil into surface runoff on loess slopes in China by Wencai Dong; Chengpeng Cao; Xianbing Meng; Quanjiu Wang; Qiang Fu (1-10).
Overland flow and concomitant solute transport were a major source of pollutants in receiving surface water. The objective of this study was to better understand the mechanisms of soil erosion, solute transport from soil to runoff and lost via runoff, especially the effects of cumulative infiltration before the runoff generation. Laboratory experiments were conducted with three initial soil moisture contents, three rainfall intensities and three slope gradients to evaluate the effects of these variables and their interactions on soil erosion and solute losses to the runoff. The results indicated that if infiltration could be facilitated, the loss of solutes could be increased. Rainfall intensity increases the mass of sediment carried away by the runoff, decreases the time required for runoff formation and increases the solute content in the surface layer. Both the masses of solute and sediment in the runoff increase as the slope gets steeper. The rainfall splash and infiltration before runoff generation were found to play important roles in soil erosion and solute lost to the runoff, if ponding time could be prolonged, the loss of solutes could be reduced. The relationship between cumulative infiltration during ponding time and the average solute concentration in the runoff can be well described by the linear equations. The average solute concentration in the runoff was positive linear correlation with solute concentration in the soil surface layer at the time when runoff took place.
Keywords: Initial soil moisture content; Rainfall intensity; Slope gradient; Solute transport; Ponding time

Adsorptive component of coagulation–flocculation of paint wastewater using Brachystegia eurycoma (seed) coagulant was investigated. The bio-sample was analyzed for functional groups, surface morphology and thermal characteristics. The effects of coagulant dosage, effluent pH and settling time on the process were studied. The coagulation data were analyzed in light of adsorption kinetics, isotherm and thermodynamics. Pseudo-second-order and Langmuir models best described the models, and the values recorded for Gibb’s free energy, entropy and enthalpy values were—28.692 kJ/mol, 0.206 kJ/mol and 34.857 kJ/mol, respectively. At the experimental condition, maximum process efficiency (96.50%) was obtained at coagulant dosage of 5 g/L, pH 8 and coagulation temperature of 35 °C. Having satisfactorily correlated coagulation data to adsorption models, it could be inferred that significant component of the process was predominated by adsorption.
Keywords: Brachystegia eurycoma ; Paint wastewater; Flocculation; Coagulation; Adsorption kinetics

Factors affecting adoption of pressurized irrigation technology among olive farmers in Northern Iran by Nima Nejadrezaei; Mohammad Sadegh Allahyari; Mina Sadeghzadeh; Anastasios Michailidis; Hamid El Bilali (1-9).
The main aim of this paper was to investigate factors affecting the adoption of pressurized irrigation technology among Roudbar County olive farmers by path-structural modeling and Unified Theory of Acceptance and Use of Technology. Data were collected through an information technology questionnaire addressing a cross section of 210 managers of olive farms (4.18% of the statistical population) in the Roudbar County, Northern Iran. Validity of the questionnaire was proofed using several tests (content, face, convergent and discriminant). Likewise, reliability of the questionnaire was tested employing principal component analysis, Cronbach’s alpha, Dillon–Goldstein’s ʃ and reagent stability. Descriptive and inferential statistical analysis of the data was accomplished using SPSSV19 and SmartPLSV3 software. For testing hypotheses, structural equation model and partial least squares that focus on reagent variance were used. Results show a significant relationship between: (a) performance expectancy and behavioral intention, (b) social influence and behavioral intention, (c) facilitating conditions and use behavior. A significant relationship was also observed between intention to use and use behavior of pressurized irrigation technology. The employed model explains 72% of behavioral intention variance and 42% of use behavior of pressurized irrigation technology variance among olive farmers. To increase willingness to accept technology among Roudbar County olive farmers, it is suggested to hold extension and education courses by organizations for raising knowledge and awareness of pressurized irrigation technology. Also, olive farmers can be provided with financial resources and knowledge to enable them to adopt this new irrigation technology.
Keywords: Pressurized irrigation; Technology adoption; UTAUT model; PLS

Precise knowledge regarding the quantities of water available in the Wadi Bechar watershed and better management of this resource is necessary to initiate the transformation of rainfall data into hydrometric data (simulated flow); this is the main objective of the hydrological rainfall–runoff modeling. The primary focus of this paper is the rainfall–runoff modeling on an annual and monthly scale in the Wadi Bechar watershed which covers an area of 6858 km2. We employ the rural engineering model (GR) for annual timestep GR1A and for the monthly timestep GR2M. The input parameters are precipitation (P) and evapotranspiration (ETP) calculated by the Turc method; the output parameter is elapsed water slide (Q). The results obtained indicate that the model takes into account the different atmospheric and underground exchanges, as well as the capacities of the production tank and routing tank. With this work, the contribution of precipitation to flows downstream of the watershed can be evaluated and quantified. On an annual scale, the potential evapotranspiration modulator coefficient X is equal to 2.20 > 1. This indicates that the water from the Wadi Bechar watershed seeps into the ground or into the adjacent watersheds of Wadi Zousfana and Wadi Guir. On a monthly scale, we calibrate and cross-validate the model with the selected input data, determining the model parameter sets that best reflect the transformation of rainfall into flow. The calibration was done with several passages in computer. The value of the capacity of the estimated production tank X1 is equal to 4.74 mm, which reflects the production function, and subsequently indicates the rainfall capacity transformed into a water flow available for runoff at the Wadi Bechar watershed scale. The value of the estimated underground exchange coefficient parameter X2 is equal to 0.02; it reflects the transfer function, which indicates the movement of this surface flow toward the watershed outlet.
Keywords: Precipitation; Hydrological modeling (GR1A and GR2M); Arid zone; Wadi Bechar watershed

Climate change is not a myth. There is enough evidence to showcase the impact of climate change. Town planners and authorities are looking for potential models to predict the climatic factors in advance. Being an agricultural area in Saudi Arabia, Tabuk region gets greater interest in developing such a model to predict the atmospheric temperature.Therefore, this paper presents two different studies based on artificial neural networks (ANNs) and gene expression programming (GEP) to predict the atmospheric temperature in Tabuk. Atmospheric pressure, rainfall, relative humidity and wind speed are used as the input variables in the developed models. Multilayer perceptron neural network model (ANN model), which is high in precession in producing results, is selected for this study. The GEP model that is based on evolutionary algorithms also produces highly accurate results in nonlinear models. However, the results show that the GEP model outperforms the ANN model in predicting atmospheric temperature in Tabuk region. The developed GEP-based model can be used by the town and country planers and agricultural personals.
Keywords: Artificial neural network; Atmospheric temperature; Climate change; Gene expression programming; Tabuk

Characterization of new and fouled SWRO membranes by ATR/FTIR spectroscopy by Mohammed Mahmoodur Rahman; Saad Al-Sulaimi; A. M. Farooque (1-11).
Attenuated total reflection (ATR)–Fourier transform infrared (FTIR) spectroscopy was used to characterize the chemical nature of fouling species on different spiral wound membranes operated at Al-Jubail SWRO plant. Three membranes from different companies operated for a period of 1 year were opened for autopsy, and difference spectra were obtained for the fouled membrane from virgin membranes. The spectra of the foulants were easy to distinguish from the spectra of membrane material. The results showed that the membrane surface of the feed end element was more heavily fouled than the brine end of the element. ATR/FTIR indicated a distinct enhancement to the amide I (1650 cm−1) and amide II (1550 cm−1) bands indicative of protein, and the C–O stretching band associated with polysaccharides is visible near 1040 cm−1. The deposits removed from the surface of membranes showed distinctive bands at 3270 and 1080 cm−1 associated with amino group/polysaccharide.
Keywords: ATR/FTIR spectrometry; Fouling; SWRO membrane; Membrane characterization

Comparing the efficiency of UV/ZrO2 and UV/H2O2/ZrO2 photocatalytic processes in furfural removal from aqueous solution by Reza Shokoohi; Yousef Poureshgh; Saeed Parastar; Sattar Ahmadi; Amir Shabanloo; Zahra Rahmani; Farshad Bahrami Asl; Mohammad Vanaei Tabar (1-8).
Furfural is a toxic chemical compound that is widely applied as a solvent in a great many of industries, and it can cause many problems to the human beings and environment. Various methods of removing furfural from the wastewaters have been studied. AOPs methods are utilized for the elimination of a vast majority of the pollutants due to their high efficiency as well as for their lack of creating secondary contamination. Therefore, the present study aims at comparing the efficiency of UV/ZrO2 and UV/H2O2/ZrO2 photocatalytic processes in removing furfural from aqueous solutions. The solution’s initial pH, furfural’s concentration, zirconium catalyst dosage and time were investigated as the parameters influencing the removal efficiency by the two foresaid processes, and the effect of H2O2 addition in various concentrations into UV/H2O2/ZrO2 process was also evaluated. Spectrophotometer device was employed to assay the concentration of the residual furfural. The results indicated that the pH of the environment, the amount of the nanoparticle and H2O2 input concentration largely influence the furfural omission. The optimal condition for the removal of furfural in UV/ZrO2 process in an initial concentration of 20 mg/L, a pH equal to 3, a catalyst dose of 0.25 g/L during a period of 60-min time was 81.6%, and it was 99% for UV/H2O2/ZrO2 process in a pH equal to 7 with the addition of H2O2 for a concentration of 0.75 mL/L under the same conditions. Generally, it can be concluded that UV/H2O2/ZrO2 and UV/ZrO2 photocatalytic processes can effectively be applied to remove furfural from the aqueous solutions, especially in lower concentrations.
Keywords: Furfural; Photocatalytic processes; Zirconium dioxide; Hydrogen peroxidation

Fresh water is needed for the survival of all living organisms to keep them healthy, safe and clean. Major part of this fresh water is obtained from groundwater. It is observed that the groundwater has been polluting due to anthropogenic activities and affecting the human beings, livestock soil nutrients by mass and environment in certain areas. The paper presents hydrogeochemical assessment of groundwater in shallow aquifers of Greater Noida region. Therefore, various physicochemical parameters such as pH, TDS, EC, TH and major ions, i.e. Cl, SO4 2−, NO3 , Na+, K+, Ca2+, Fe2+, Mg2+, CO3 2− and HCO3 , have been analysed in the present study using standard procedures. The results of major constituents were compared with the water quality standards prescribed by WHO. From the analysed samples, different indices such as soluble sodium percentage (SSP), sodium adsorption ratio (SAR), residual sodium carbonate, magnesium adsorption ratio, Kelley’s ratio and permeability index were characterized in the study. Results delineate that the groundwater is suitable for drinking and irrigational use.
Keywords: Water quality; Groundwater pollution; Urban areas; Water indices

In the present study, the adsorptive potential of modified bentonite in a batch system for the removal of aniline and phenol from aqueous solutions was investigated. The effect of various parameters including contact time (10–120 min), pH (2–10), adsorbent dosage (0.4–1.5 g/L) and initial concentration of aniline and phenol (50–200 mg/L) was investigated in this experimental laboratory study. Maximum removal of aniline and phenol was achieved at contact time of 30 and 45 min for aniline and phenol, respectively, and at the lowest studied initial concentration of 50 mg/L. Optimum bentonite dosage of 1 and 0.4 g/L was obtained for phenol and aniline, respectively. The adsorption process was better at the pH of 6 for aniline and pH of 4 for phenol. It was found that the equilibrium data was best followed by the Langmuir and Freundlich isotherms. Also, the pseudo-second-order kinetic model was best applicable for phenol and aniline adsorption. It was defined that bentonite not only was an inexpensive absorbent, but also a quite effective adsorbent for the removal of aniline and phenol from water and wastewater.
Keywords: Adsorption; Aqueous solution; Bentonite; Aniline; Phenol

This review study is dealing with the recent advances and developments in the metal–organic framework (MOF) materials especially in the aspect of environmental remediation of heavy metals. Its application in some area of technological and mechanical advancement was also considered. The process of its synthesis and characterization was also put into consideration. Metal-organic frameworks can be said to be an exciting new class of nanoporous crystalline materials containing a metal as its central ion surrounded by organic ligands. An overwhelming characteristic of MOFs lies in its surface area which is amazingly large, exceeding those of known best activated carbons and zeolites. There is an increasingly high demand in the application of MOFs for a multitude of environmental uses or application to be used for capturing and separating various unwanted or even environmentally harmful chemicals, elements or materials. The advantage of MOFs over other known adsorbent materials, such as zeolites and carbon black, is that it possesses a far greater surface area along with amazingly great pore properties. In this review the synthesis and characterization of MOFs, the fate of heavy metals, the application of MOFs in heavy metals remediation and other means of heavy metals remediation are well discussed.
Keywords: Metal–organic frameworks; Heavy metals; Environmental remediation

Drainage network quantification with respect to the climate, tectonics, lithology and geomorphology provides significant evidence of the drainage development, hydro-geomorphic and denudation characteristics of an area. The present study was carried out by using Shuttle Radar Topographic Mission DEM to study the drainage morphometry and its influence on the hydrological characteristics of Vaitarna and Ulhas basins in Maharashtra, India. Results of the morphometric analysis reveal that the catchment of Vaitarna and Ulhas can be described as of 6th and 7th order drainage basins, encompassing an area of 3795 and 4733 km2, respectively. Additionally, Vaitarna basin is characterised by relatively higher mean bifurcation ratio as compared to the Ulhas basin, indicative of higher structural control and steeper gradient in Vaitarna basin. Lower drainage density and stream frequency affirm availability of permeable sub-surface material and homogeneous lithological characteristics in both basins. The shape parameters show both basins are semicircular with dendritic and sub-dendritic drainage pattern. The relief parameters of Vaitarna and Ulhas suggest both of these basins are characterised by very high relief and steep slope. GIS-based analysis of all these morphometric parameters indicates the drainage development of the study area progressed well beyond maturity stage and lithology have a major impact on the drainage development in Vaitarna and Ulhas basins.
Keywords: Morphometric analysis; Western Ghats; Watershed management; Geospatial technique; Maharashtra; India

This work aimed at the characterization and application of a cavitation field induced in water by an ultrasonic reactor operating at 1700 kHz and 15 W. It was found that the size of active bubbles varied from 0.23 to 3 µm. The number of active bubbles increased from 6.1142 × 108 s−1 L−1 at 25 °C to 4.4684 × 109 s−1 L−1 at 55 °C. The most active bubbles were those achieving temperature of 4000 K and pressure of 1000 atm at the collapse. The characterized cavitation field removed efficiently toluidine blue (TB), an emerging organic contaminant, through reaction with hydroxyl radical. The best TB-removal rate was obtained under argon saturation, but CO2 completely suppressed the process. TB degradation rate sensitively enhanced with increasing initial substrate concentration and solution pH, whereas the liquid temperature did not affect the degradation rate. Formic acid, as an organic competitor, reduced considerably the degradation of the pollutant.
Keywords: Ultrasound; Cavitation field; Bubble population; Cavitational treatment; Toluidine blue (TB); Degradation

Potentiality of fruit peel (banana peel) was evaluated by adsorption of Congo red (CR) dye from aqueous solution. The adsorption study was performed by varying operating variables such as pH, initial concentration of CR, adsorbent dose, contact time and temperature. The dust of banana peel was characterized by different instrumental techniques such as point of zero charge, scanning electron microscopy and Fourier transformed infrared spectroscopy. The results revealed that the dye adsorption is favorable at higher pH (10). The equilibrium of dye adsorption was assessed by Freundlich and Langmuir isotherm models. Similarly, kinetics of CR adsorptions was assessed by pseudo-first-order and pseudo-second-order kinetics. Results revealed that isotherm and kinetics of dye adsorption fit well with Langmuir isotherm and pseudo-second-order kinetics, respectively. The dye adsorption capacity was recorded as 1.727 mg/g. The thermodynamics of the dye adsorption revealed that the adsorption is thermodynamically favorable, spontaneous and exothermic in nature. The regeneration study suggested that 97.3% dye removal can be achieved by regenerating the spent adsorbent with 0.1 N NaOH solution. Finally, it can be concluded that banana peel could be an efficient adsorbent for removal of Congo red from aqueous medium.
Keywords: Adsorption; Banana peel; Congo red; Kinetics; Isotherms; Thermodynamics

Impact of indiscriminate disposal of untreated effluents in Korangi creek, Karachi, Pakistan by Aamir Alamgir; Moazzam Ali Khan; S. Shahid Shaukat; Jamil Hassan Kazmi (1-13).
Korangi creek is one of the major creek of Indus delta which receives both untreated industrial and domestic effluents. It provides an important waterway to approach Port Qasim. A survey of water quality and the sediments along with biodiversity of benthic fauna was conducted. A total of 24 water and 14 sediment samples were collected from February to November 2014. The mean pH of seawater and sediment samples was 7.41 and 7.5, respectively. The mean salinity of seawater was 36‰. The mean BOD5 of seawater and sediments was 288 mg/l and 1645 mg/kg, respectively, while COD was 1231.9 mg/l and 1645.3 mg/kg, respectively. Cyanide content was low in seawater but slightly higher in sediment. Mean phenol level of seawater and sediment was 0.61 mg/l and 8.11 mg/kg. Heavy metals in the seawater was established to be in the order Pb > Cu > Cr > Ni > Zn > As. The trend in sediment was slightly different and followed the following pattern Pb > As > Ni > Cu > Cr > Zn. The distribution pattern of the estimated variables for seawater and sediments was examined using the principal component analysis and cluster analysis. Annelida and Arthropoda were the dominant components of biodiversity. Taxa diversity was measured and Shannon index (H) ranged between 1.364 and 1.969 while equitability (J) ranged between 0.549 and 0.862. Dominance (D) was in the range of 0.156–0.436.
Keywords: Untreated effluents; Creek; Pollution; Industrial effluents; Karachi

Heavy metal pollution has become an issue of serious international concern. One of the heavy metal cadmium (Cd) is known to be a widespread environmental contaminant and a potent toxin that may adversely affect human health. Microbial remediation has been applied as an efficient strategy to remove or detoxify the heavy metals mainly from soil, water and sediments, etc. Pseudomonas aeruginosa is one of the most significant bacterium present in almost all contaminated sites. They are often resistant to antibiotics, heavy metals, detergents and organic solvents. This review concluded that P. aeruginosa is one of the versatile and high-tolerance cadmium-resistant bacteria isolated from different environment regimens. It can be used as suitable biosorbent for the removal of cadmium and other heavy metals from solution, contaminated waste, water and soil. Apart from this characteristic, P. aeruginosa, used as potent bioinoculant, express Plant growth promoting rhizobacteria (PGPR) activity, biofilm and biosurfactant production, and comprise key role in metal phytoextraction process.
Keywords: Bioremediation; Cadmium; Pseudomonas aeruginosa ; Resistance bacteria; Mechanisms

The determination of depth to freshwater aquifers and lack of geophysical borehole log data to help borehole developers in the design of borehole have long been identified as a problem in coastal areas. This necessitates a study of the coastal environment of Lagos, southwestern Nigeria, to determine the depth to freshwater and give recommendation on the borehole design during installation stage that can be projected to areas immediate to where geophysical logs are available. For this study, twenty geophysical log data were utilized which are spread across Ikoyi, Victoria Island and Lekki of Lagos metropolis. The study shows that the saline water extent in Ikoyi, Victoria Island and Lekki occurs to an average depth of 146, 154 and 162 m, respectively. Relative variation in quality of water across the regions is because of the differences in the thickness of clay units serving as protective units separating the polluted zones from the unpolluted zones. It is recommended that water wells in Ikoyi, Victoria Island and Lekki be drilled to an approximate depth of 240 m and the last 18 m be screened. This research work was able to develop a design model for the boreholes located in the Island. The model includes gravel packing thickness of about 50 m from the bottom of the hole and cement grouting to the surface of the borehole to avoid the contamination of the borehole.
Keywords: Freshwater; Grouting; Gravel packing; Lagos; Aquifers; Borehole log

Evaluation of various membrane filtration modules for the treatment of seawater by Hisham A. Maddah; Abdulazez S. Alzhrani; M. Bassyouni; M. H. Abdel-Aziz; Mohamed Zoromba; Ahmed M. Almalki (1-13).
This study was initiated to identify the treatment efficiency of various membrane filtration modules in the treatment of Red Sea water at Rabigh City. Filtration efficiency (membrane performance) was calculated in terms of water conductivities of feed and product. Four commercial membranes were utilized in the experiment work and they were Polyvinylidene difluoride (FP100), Polyethersulphone (ES404), Polyamide low-pressure film (AFC40) and Polyamide high-pressure film (AFC99). Different pressure values were applied on each membrane type to determine the optimal operating pressure for the treatment. pH levels of produced water were analyzed relative to feed water pH to check the effect of different applied pressures on pH variations. A comparison between the four membranes was established to select the ideal membrane for the treatment. Results showed that the optimal operating pressures for the four membranes FP100, ES404, AFC40 and AFC99 were 10, 30, 60 and 64 bar, respectively. In general, applying higher pressures would increase the treatment efficiency. An inverse relationship between water conductivity and applied pressure was noted, and pH levels slightly decreased at high pressures. Among the four selected membranes, AFC40 was the ideal choice for water treatment due to its relatively lower energy demand and higher treatment efficiency of 99.9%.
Keywords: Membrane; Filtration; Conductivity; Water treatment; Desalination; TDS; Seawater

Chronic Kidney Disease of unknown aetiology (CKDu) is a major health concern in North Central Province (NCP) of Sri Lanka. Anuradhapura and Polonnaruwa are the two most affected districts in NCP. This research was designed to identify main suspected CKDu causative agents in drinking water in NCP. Drinking water samples were collected from shallow wells of CKDu patients and non-patients in Anuradhapura and Polonnaruwa districts. They were tested for chemical ions: chloride, fluoride, nitrate, phosphate, calcium, magnesium, sodium, cadmium and arsenic. An analytical framework was developed to analyse water quality data using statistical methods, namely univariate analysis of variance (ANOVA) and Dunnett’s T3 post hoc test, Kruskal–Wallis (KW) and Mann–Whitney’s post hoc test, discriminant analysis, factorial analysis followed by reliability tests. ANOVA, KW and their post hoc tests were applied to show the significant differences at p < 0.05 in mean and median values of chemical constituents between CKDu patient and non-patient samples. Discriminant analysis was applied to show the degree of accuracy in original sampling groups. Factorial analysis was applied to identify the ion combinations in each group. A secondary set of data obtained from drinking water samples of CKDu endemic and non-endemic areas were also analysed independently using the same analytical techniques to compare the results.
Keywords: Chronic Kidney Disease of unknown aetiology; North Central Province in Sri Lanka; ANOVA; Kruskal–Wallis test; Mann–Whitney’s test; Discriminant analysis; Factorial analysis

This work has been carried out at the southern side of the Tabouant anticlinal in El Ouldja valley in the Aures, east of Algeria. The different water tables exploited belong to many lithological entities (evaporitic and carbonated). The combination of geology and statistics has allowed to study the chemistry origin of these waters. This is water of evaporitic and secondarily carbonates origin. The phenomena causing this class are numerous and are essentially linked to the aquifers chemical composition. The chemical analysis of all samples of the area confirms this. Waters salinity is very variable and generally high. Waters electrical conductivity ranges between 1504 and 6150 μS cm− 1. The extreme chemical facies are chloride–sulfate and calcium–sulfate, with a predominance of this latter. Sulfate and chloride contents can locally reach the respective values of 1100 mg/l− 1and 650 mg/l− 1. Thermodynamic analysis indicated the waters saturation with carbonates, calcite and dolomite, because of the degassing and the CO2 dissolution of evolutive formations, gypsum and halite. The crossed binary diagrams suggest that water salination might be attributed to water–rock interaction through the geochemical process of mineral dissolution, precipitation and ions exchange.
Keywords: Chemical facies; Aquifer; Evaporites; Statistics; Precipitation

Automation and reliability are the crucial elements of any advance reverse osmosis plant to meet the environmental and economic demands. Early fault indication, diagnosis and regular maintenance are the key challenges with most of the reverse osmosis plants in the Indian scenario. The present work introduces a modern reverse osmosis (RO) plant status monitoring unit to monitor different plant parameters in real time and early prediction for faults and maintenance. Developed RO plant status monitoring unit consists of a touch screen-based embedded monitoring unit, water quality sensors (pH, TDS), sampling chamber for controlled water flow, flow sensors, pressure and level sensors. The present system has been developed in a modular fashion so that it could be integrated with any capacity of RO plant units. Developed embedded system monitors various parameters of the plant such as input power, efficiency of the plant, level of input and output water tank and also guides operator with instructions for plant operation. Other than this, a dedicated smartphone app interface has been developed for the operator to acquire data from status monitoring unit, storage on smartphone, and transfer it to the cloud. The developed smartphone-based app also provides facility to integrate plant data with Google map with location information for easy understanding and quick action. The system has also a backup facility to transfer data to the server using 2G GSM module during the unavailability of the operator. A dedicated centralized Web server has been developed for real-time visualization of all installed RO plant status monitoring units. Different machine learning techniques have been implemented on acquired sensors data to predict early warnings related to power failure, membrane fouling and scaling, input water shortage, pipe, tank leakage, water quality sensors damage, non-operation or wrong operation of the plant along with different maintenance actions such as membrane water and chemical wash. Developed RO status monitoring unit has been tested with various RO plants having capacity from 500 LPH to 2000 LPH and deployed at various nearby villages of Rajasthan.
Keywords: Water quality sensors; Reverse osmosis; Embedded system; Early warning; Predictive maintenance

Adsorption of Rhodamine 6G and humic acids on composite bentonite–alginate in single and binary systems by Fatima Gomri; Gisèle Finqueneisel; Thierry Zimny; Sophia A. Korili; Antonio Gil; Mokhtar Boutahala (1-10).
In this work, the preparation, characterization, and sorption of rhodamine 6G and humic acids on a composite sodium alginate–bentonite were investigated. Their structure and morphology were analyzed by several techniques, including Fourier transform infrared spectroscopy, X-ray diffraction, and N2 adsorption at − 196 °C. A synergetic sorption mechanism was observed in binary systems; humic acids adsorption was enhanced by the presence of Rh6G in the mixture. The kinetic studies revealed that the sorption follows a pseudo-first-order kinetic model and the sorption capacities of Rh6G increased with the pH value. The Langmuir isothermal model well described the adsorption isotherm data, showing a maximum adsorption capacity for Rh6G up to 429.5 mg/g at 20 °C. On the basis of the data of the present investigation, it is possible to conclude that the composite exhibited excellent affinity for the dye and humic acids, and it can be applied to treat wastewater containing dye and natural organic matter.
Keywords: Adsorption; Alginate; Bentonite; Composite; Humic acids; Rhodamine 6G

In this numerical study, the pattern and the field of the passing flow through circular channels with the side weir in supercritical flow conditions are simulated using the FLOW-3D model. First, the numerical model results are validated with the experimental data and a good agreement between the results is obtained from the numerical simulation and the experimental data. Then, the effects of the slope change of the circular channel bed on the flow free surface, the discharge of the side weir, the Froude number at the end of the side weir upstream, the discharge coefficient of the side weir, the specific energy and the slope of the S3 profile are investigated. In this study, the flow field turbulence and variations of the free surface computational field are simulated using the RNG $$k - varepsilon$$ k-ε turbulence model and the volume of fluid (VOF) method, respectively. In practice, transmission channels used in irrigation networks and urban sewage disposal systems are steep. Therefore, the main purpose of this computational fluid dynamics (CFD) study is investigating the effect of the bed slope change of circular channels with side weir in supercritical flow conditions on the pattern and the structure of these types of flows.
Keywords: Supercritical flow; Circular channel; Side weir; Bed slope of main channel; Numerical simulation

Waste tea as a novel adsorbent: a review by Siam Hussain; K. P. Anjali; Saima Towhida Hassan; Priy Brat Dwivedi (1-16).
This paper surveys the various developments in the usage of tea beverage industry-based wastes for adsorption and the generation of activated carbon while emphasizing the applied methodology, removal efficiencies, characteristics of the material and the production methods. From the review, it can be determined that the tea industry-based wastes offer a promising, low-cost and effective alternative adsorbent for the removal of various effluents from the water. The full review is about the usage of waste tea as an adsorbent has been done while considering two aspects. Firstly, initial emphasis was placed on reviewing the research work on the removal of various heavy metal ions and pollutants such as copper, chromium, lead, reactive dyes and phenols using tea leaves as an adsorbent. Secondly, research work on the various activation methods and conditions, and the usage of physical and chemical activating agents such as steam, carbon dioxide, phosphoric acid, zinc chloride and potassium salts for the activation of tea leave-based activated carbon have been reviewed and presented here.
Keywords: Activated carbon; Adsorption; Bio-adsorbents; Wastewater treatment; Waste tea leaves

Evaluation of groundwater quality and its suitability for drinking and irrigation using GIS and geostatistics techniques in semiarid region of Neyshabur, Iran by Gouri Sankar Bhunia; Ali Keshavarzi; Pravat Kumar Shit; El-Sayed Ewis Omran; Ali Bagherzadeh (1-16).
Groundwater is a vital source for drinking and agricultural purposes in semiarid region of Neyshabur area (Iran). The present study assessed the groundwater quality and mapped the spatial variation of water samples in terms of suitability for drinking and irrigation purposes. A total 402 groundwater samples were collected from the field with global positioning system (GPS) from 2010 to 2013 and analyzed for pH, calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium, bicarbonate, sulfate, chloride, sodium adsorption ratio (SAR), electrical conductivity (EC), total dissolved solids, and total hardness (TH). A GIS-based ordinary kriging method with best fit semivariogram models was used for preparation of thematic maps of groundwater quality parameters. The results were evaluated and compared with WHO (2011) recommended water quality standard. Results showed that 68.40% of SAR, 25% of Mg2+, 32.62% of Na+, and 1.74% of TH of the total groundwater samples are suitable for the irrigation purpose. Consequently, 55.57% of EC, 89.19% of TDS, 0.75% of pH, and 6.25% of K+ of the total groundwater samples are suitable for the drinking purpose as per the WHO standard. The groundwater quality in the study area is very hard and slightly alkaline in nature. The spatial distribution map of groundwater quality showed 80% of the area suitable for drinking purpose; whereas, 90% of the area demarcated for irrigation purpose.
Keywords: Groundwater quality; GIS; Kriging; Semivariogram; Spatial variability; Iran

The management of natural surface water resources needs the understanding of water quality. The present study on the physico-chemical parameters of water quality of sacred lake Nachiketa Tal of Garhwal Himalaya was undertaken. During the period from May 2015 to April 2016 at four sampling stations, seasonal variations in air temperature, water temperature, electrical conductivity, turbidity, salinity, TDS, dissolved oxygen, free CO2, hardness, alkalinity, nitrates, phosphates, chlorides, calcium and magnesium were recorded. The statistical correlation and cluster analysis between the various physico-chemical parameters of Nachiketa Tal were computed. The results of this study revealed that the concentration of the nutrients, turbidity, electrical conductivity, TDS increased with a decreasing trend of dissolved oxygen in all the sampling stations during the monsoon season. Thus, degradation in the water quality of the lake was resulted in the monsoon season.
Keywords: Nachiketa Tal; Seasonal variations; Sacred lake; Garhwal Himalaya; India

The evaluation of wastewaters treated by biological wastewater treatment plant was performed using multivariate analysis. The samples taken during 1 year were characterized by the Mahalanobis distances (MDs) calculated from 11 original parameters and 4 principal components extracted by principal component analysis. The principal components were interpreted using Ward’s hierarchical clustering analysis and factor analysis. Statistical processing of the samples by means of the MDs calculated in the original and PC space was found to be complementary. Since MDs were not normally distributed, the statistical analysis of their log-transformed values (logMDs) was preferred to common Hotelling’s or Chi-squared statistics of MD2 ones. The outliers were confirmed by Ward’s method and by inspection of their chemical composition. In contrast to complexity and different magnitudes of the original wastewater parameters, the logMD charts provided a simple and effective tool for the evaluation of biological wastewater treatment process.
Keywords: Statistical evaluation; Biological wastewater treatment; Mahalanobis distance; Principal component analysis

Removal of carbaryl insecticide from aqueous solution using eggshell powder: a modeling study by Soumya Chattoraj; Naba Kumar Mondal; Kamalesh Sen (1-9).
A batch study was done for exploring the performance of eggshell powder (EGP) for adsorptive removal of carbaryl from aqueous solution. In the experiment, the operating factors were initial carbaryl concentration (5–20 mg L−1), solution pH (2–10), adsorbent dose (0.01–0.1 g/100 ml) and contact time (10–60 min). For optimization, evaluation of the effects and interactions of the operating factors response surface modeling was applied and the influence of the factors was checked through a two-level four factor Box–Behnken design (BBD) model. The predicted data had shown good agreement (R 2 = 0.9985) with experimental data. Furthermore, the adsorption data were best fitted with Freundlich isotherm and pseudo-second-order kinetics. Thermodynamic parameters revealed that the adsorption of process was spontaneous and endothermic. Finally it can be concluded that the EGP can be used as an alternative adsorbent for the removal of carbaryl from aqueous medium.
Keywords: Carbaryl; EGP; Adsorption; Batch; RSM; Optimization

The influx of effluents from industrial area into the Alaro River in Ibadan has made the investigation of the sediment quality of the river an important environmental issue for discussion. The objective of this study was to determine the concentrations of toxic heavy metals in surface sediment of the river in order to evaluate the impact of the effluent and spatial distribution of the metals downstream. pH, total organic carbon and grain-sized particles of the sediment samples were determined according to standard methods of analysis, while heavy metal concentrations were determined by AAS. Linear least square regression (LLSR) model was employed to describe the distribution pattern of heavy metals along the river network. Hierarchical cluster analysis was applied to locate the heavy metals contamination source and interpret the association between the metal concentrations upstream and downstream, which were found to be significantly different (p = 0.05) The concentrations of Ni, Zn, Cr, Co, Cu, Cd and Pb in downstream sediments were 7.74 ± 0.97, 19.5 ± 4.6, 5.78 ± 0.47, 9.6 ± 1.6. 7.36 ± 0.61, 0.47 ± 0.03 and 7.76 ± 0.80 mg/kg, respectively. The enrichment factor (EF > 1.5) and pollution load index (PLI > 1.0.) showed that the sediment was contaminated with these heavy metals. The toxicity estimation carried out suggested that the sediment was slightly toxic. Metal distribution as shown by LLSR was such that the concentration decreased with distance downstream with R 2 ranging from 0.8810 to 0.9990. The LLSR models obtained are useful to predict the metal concentrations based on the known distance of the river.
Keywords: Heavy metal contamination; Sediment quality; Cluster analysis; Alaro River; Toxicity estimation

The foggaras of Bouda (Algeria): from drought to flood by Youcef Boutadara; Boualem Remini; Saida Benmamar (1-11).
Based on investigations and flow gauges that we conducted in all the foggaras of the Bouda Oasis during the period: 2015–2018, this article examines an original hydraulic phenomenon that occurred recently in the oasis of Bouda in the wilaya of Adrar (Algeria). The exploitation of the boreholes made during the 1980s in the export field of foggaras caused a drying of foggaras water. However, in 2015, the remoteness of the well field and the supply of drinking water by the water resources services led to an increase in foggara flows. At first, it was good news for farmers, but over time the phenomenon became worrying for the population, since the flow has not yet stabilized. The phenomenon is starting to grow; sebkhas and palm groves are today flooded by the surplus of waters of foggaras.
Keywords: Foggara; Bouda; Folding; Tablecloth; Flood; Rise of the tablecloth

Carica papaya seeds of a tropical tree comprise water-soluble and positively charged protein known as cystine protease which emerged as a putative coagulant in both water and wastewater treatments. Natural coagulants applications have been posed in many evaluation assays through many years owing to the difficulties raised by usage of chemical coagulants. It is indispensable to optimize process variables such as pH, turbidity, total dissolve solids (TDS), E. coli and coliforms counts accuracy to raise the efficiency of coagulation operation via employing C. papaya. Experimentally, employing jar tests supported by pretreatment, papaya seed protein as a natural coagulant, alum and solar disinfection to remove turbidity and bacteria was accomplished. The results revealed that the removal efficiency for turbidity was culminated up to 100% by incorporation of both alum and C. papaya seeds at lower dosages of coagulant about 0.2–0.6 mg/L at 30 min. A significant difference was found for paired samples correlations around 0.130 by p value = 0, among TDS, C. papaya and alum dosages and turbidity values. Employing a combined process resulted in turbidity and bacteria (most probable numbers of coliforms) removal around 100%. The highest efficiency of solar disinfection system possessed to fell the sunlight exposure period time by up to 2 h with 100% removal of E.coli and coliforms.
Keywords: Carica papaya seed; Coagulant; Disinfection; Microorganism; Turbidity