Dye Removal from Colored Textile Wastewater by Poly(propylene imine) Dendrimer: Operational Parameters and Isotherm Studies

This paper deals with the removal of textile dyes from aqueous solutions by poly(propylene imine) dendrimer (PPI). Direct red 80 (DR80), Acid Green 25 (AG25), Acid Blue 7 (AB7), and Direct Red 23 (DR23) were used as model dyes. The effects of operational parameters on dye removal such as dendrimer concentration, dye concentration, salt (inorganic anions), and pH have been studied at 25°C. The Langmuir and Freundlich isotherm models were investigated. In addition, dye desorption of dendrimer was studied. The results indicated that acidic pH supported the adsorption of dyes by dendrimer. Furthermore studies of dye concentration and salt effects exhibited that dye removal percentage by dendrimer was decreased. It was found that the isotherm data of DR80, AG25, and DR23 followed Langmuir isotherm and isotherm data of AB7 followed Freundlich isotherm models. Desorption tests showed that maximum dye releasing of 76.5% for DR80, 84.5% for AG25, 87% for AB7, and 93% for DR23 were achieved in aqueous solution at pH 12. Based on the data of present study, one could conclude that the dendrimer being an environmentally friendly adsorbent with relatively large adsorption capacity might be a suitable alternative for elimination of dyes from colored textile wastewater.     

Dye Removal,Energy Consumption and Operating Cost of Electrocoagulation of Textile Wastewater as a Clean Process

In this research, the efficiency of electrocoagulation treatment process using aluminum electrodes to treat synthetic wastewater containing Reactive Red198 (RR198) was studied. The effects of parameters such as voltage, time of reaction, electrode connection mode, initial dye concentration, electrolyte concentration, and inter electrode distance on dye removal efficiency were investigated. In addition, electrical energy consumption, electrode consumption, and operating cost at optimum condition have been investigated. The results showed that dye and chemical oxygen demand removals were 98.6 and 84%, respectively. Electrode consumption, energy consumption and operating cost were 0.052 kg/m³, 1.303 kWh/m³ and 0.256 US$/m³, respectively. Dye removal kinetic followed first order kinetics. It can be concluded that electrocoagulation process by aluminum electrode is very efficient and clean process for reactive dye removal from colored wastewater.     

Mineral Content of Bottled and Desalinated Household Drinking Water in Kuwait

Three hundred and twenty‐two samples of desalinated household water were collected from 99 sampling locations that covered 95% of Kuwaiti's residential areas. Seventy‐one brands of bottled water were collected from Kuwaiti markets. The water quality parameters that were studied included pH, electrical conductivity (EC), total dissolved solids (TDS), F^?, Cl^?, Br^?, , , , , , , , and the major macronutrients Na⁺, K⁺, Ca²⁺, and Mg²⁺. The analysis yielded a large range of results for most of these parameters, with differences in some cases exceeding 10‐fold. With a few exceptions, the results were found to comply with US‐EPA and WHO standards. Only the water in two brands of bottled water was acidic (pH < 6.5). The TDS was found to be higher than the US‐EPA regulated value in 4 and 3% of the household samples and bottled water brands, respectively. The fluoride levels were generally higher in bottled water than in household water. However, the household water that was produced by the Doha desalination plant and some of the European brands of bottled water were the best samples studied in terms of their quantity of Ca²⁺, Mg²⁺, and Na⁺ compared with the DRI values for those substances. EC and TDS were positively correlated with , , Na⁺, K⁺, Ca²⁺, and Mg²⁺ for household water but only with Ca²⁺ and Mg²⁺ for bottled water.     

Modelling the initial shear stiffness of unsaturated soils as a function of the coupled effects of the void ratio and the degree of saturation

Existing models for predicting the small strain behaviour of unsaturated soil are not capable of predicting the initial shear stiffness during suction reduction under normally consolidated conditions. This problem has been addressed in the present study by combining an existing elastoplastic model and recent experimental data to provide a new model for the initial shear stiffness. The model, which is similar to that typically adopted for saturated soils, uses the average skeleton stress and an additional function of the degree of saturation. This new model not only captures the behaviour of the new experimental results, but it also describes a unique relationship between saturated and unsaturated soils.     

Piles in fully liquefied soils with lateral spread

The paper provides a new analysis procedure for the assessment of the lateral response of isolated piles/drilled shafts in saturated sands as liquefaction and lateral soil spread develop in response to dynamic loading such as that generated by the earthquake shaking. The presented method accounts for: (1) the development of full liquefaction in the free-field soil that could trigger the lateral spread of the overlying crust layer; (2) the driving force exerted by the crust layer based on the interaction between the pile and the upper non-liquefied soil (crust) layer; and (3) the variation of the excess pore water pressure (i.e. post-liquefaction soil strength) in the near-field soil with the progressive pile deflection under lateral soil spread driving force. A constitutive model for fully liquefied sands under monotonic loading and undrained conditions is developed in order to predict the zone of post-liquefaction zero-strength of liquefied sand before it rebounds with the increasing soil strain in the near-field. The analytical and empirical concepts employed in the Strain Wedge (SW) model allow the modeling of such a sophisticated phenomenon of lateral soil spread that could accompany or follow the occurrence of seismic events without using modifying parameters or shape corrections to account for soil liquefaction.     

Aerospectrometric and aeromagnetic characteristics associated Nb–Ta–Sn mineralization, G. Nuweibi albite granite Central Eastern Desert, Egypt

A geophysical signature associated with Nb–Ta–Sn mineralization of G. (G. : abbreviation to word Gebel which means mountain in Arabic) Nuweibi area, located the Central Eastern Desert of Egypt is presented. This signature was established by an integration of airborne gamma ray spectrometric and magnetic data. Variations seen in the gamma ray spectrometric data are used as a base to study the three granitic suites: younger-, albite-, and older granites in G. Nuweibi area. Graphical techniques such as frequency histograms and box-plots are used to visualize the shape of the distribution and determine the anomaly thresholds of the three radioelements eU, eTh, and K% data in these granitic suites. The box-plot graphical representations and calculations made on data sets indicate that no samples have eU values above the thresholds, i.e., no outliers representing values of the box-plots. Nuweibi albite granite is associated with a gamma ray response that includes the strongest eU, eTh, K%, and eTh/K ratio anomalies in the study area. K–eTh plot shows that the albite granite has a higher eTh concentration than the older and younger granites. The increase in K concentration and raise in Th/K ratio of Nuweibi albite granite points to unusual geological processes leading to mineralization and reflects the highly fractionated nature of the magma which results in thorium enrichment. This also reflects that K alteration associated with Nb–Ta–Sn mineralization is both poorly focused spatially and very much weaker than observed in any other mineralizing districts. The distribution of magnetic sources and their locations and depths in the study region are determined by Euler deconvolution and analytical signal techniques. Good clustering of Euler solutions were obtained using SI?=?0.5 and SI?=?1.0 for most of the features in the area under consideration. The solutions obtained have shown magnetic sources which can be related to the impact structure whose depths varies between ground surface to 1.66 km. The analytical signal revealed that the metamorphosed basic rocks (mainly olivine metagabbro), serpentinite and dyke bodies are the main sources of high magnetic anomalies, particularly within the area east G. Nuweibi region.     

Temporal and spatial distribution of dissolved Cu, Ni and Zn in the coastal waters of Jeddah, eastern Red Sea

Dissolved Cu, Ni, and Zn were measured in the surface coastal waters of Jeddah, eastern Red Sea during October 2004 and April 2005. High values of trace metals, particularly Zn, were recorded in the Southern Corniche area close to a sewage effluent indicating a significant contribution from the wastewater. Concentrations of trace metals decreased northward and southward under the effect of dilution. Another hot spot was also observed in the vicinity of Jeddah Desalination Plant (JDP) during April 2005 indicating a possible contribution from the JDP to trace metal contents in the study area. Trace metals were correlated to salinity, nutrients and particulate organic carbon (POC). The good association between Zn and reactive silicate and Ni and ammonium is attributed to simultaneous biological utilization and regeneration. The behavior of copper suggested adsorption of Cu onto the POC during October 2004 whereas in April 2005 the most important process seems to be desorption of Cu from the particulate materials.     

Identification of hazardous waste landfill site: a case study from Zanjan province, Iran

The study of landfill sites is one of the most important studies in landfill engineering, and the landfill site selection involves combination of engineering, science, and politics. This paper describes a comprehensive hazardous waste landfill site selection methodology with the combined utilization of geographic information system and multiple criteria analysis methods, as applied to the Zanjan province in Iran. The six main data categories that were used are geological/engineering geological, geomorphological, hydrological/hydrogeological, climatological, pedological, and social/economical criteria, which included 31 input layers in total. A suitability map for hazardous waste landfilling was prepared for study area with five classes from most suitable to completely unsuitable. Finally, out of the three sites, one site was selected which was chosen by the local authorities. Our work offers a comprehensive methodology and provides essential support for decision-makers in the assessment of hazardous waste management problems in Zanjan province in I.R. Iran and other developing cities in other countries.     

Geochemical and isotopic composition of groundwater in the Complex Terminal aquifer in southwestern Tunisia,with emphasis on the mixing by vertical leakage

The Complex Terminal (CT) confined aquifer of the Djerid basin, southwestern Tunisia, was studied using major ion concentrations and stable isotope contents in order to (1) investigate the changes on its hydrodynamic functioning due to the long-term over-pumping and the large-scale flood irrigation practices, (2) determine the principal mineralization processes of its fossil groundwater, and (3) examine the mode of recharge of this aquifer and whether it contains part of modern hydrological regime. The observed geochemical patterns indicated that the main mineralization processes affecting the CT groundwater water/rock interactions and mixing. The native Na > Cl and Cl > SO₄ > Ca > Na waters, resulting from the dissolution of halite and gypsum and from pyrite oxidation, interacted with those of the underlying and the overlying aquifers without changing their chemical facies. Stable isotope data provided evidences about upward and downward leakage into the CT aquifer and their relationships with anthropogenic activities. They demonstrated that the long-term over-pumping of the CT aquifer, which contributed to the loss of its potentiometric pressure, favored the upward leakage of the artesian deep groundwater along parts of the major faults. Moreover, the large-scale flood irrigation practices in the oases domain, which ensured the recharge of the shallow water table by return flow, enhanced the downward leakage toward the CT aquifer.     

Evaluating the efficacy of SVMs,BNs, ANNs and ANFIS in wave height prediction

Wave Height (WH) is one of the most important factors in design and operation of maritime projects. Different methods such as semi-empirical, numerical and soft computing-based approaches have been developed for WH forecasting. The soft computing-based methods have the ability to approximate nonlinear wind–wave and wave–wave interactions without a prior knowledge about them. In the present study, several soft computing-based models, namely Support Vector Machines (SVMs), Bayesian Networks (BNs), Artificial Neural Networks (ANNs) and Adaptive Neuro-Fuzzy Inference System (ANFIS) are used for mapping wind data to wave height. The data set used for training and testing the simulation models comprises the WH and wind data gathered by National Data Buoy Center (NDBC) in Lake Superior, USA. Several statistical indices are used to evaluate the efficacy of the aforementioned methods. The results show that the ANN, ANFIS and SVM can provide acceptable predictions for wave heights, while the BNs results are unreliable.