Khaled S. Balkhair

Field accumulation risks of heavy metals in soil and vegetable crop irrigated with sewage water in western region of Saudi Arabia

Wastewater irrigated fields can cause potential contamination with heavy metals to soil and groundwater, thus pose a threat to human beings . The current study was designed to investigate the potential human health risks associated with the consumption of okra vegetable crop contaminated with toxic heavy metals. The crop was grown on a soil irrigated with treated wastewater in the western region of Saudi Arabia during 2010 and 2011. The monitored heavy metals included Cd, Cr, Cu, Pb and Zn for their bioaccumulation factors to provide baseline data regarding environmental safety and the suitability of sewage irrigation in the future. The pollution load index (PLI), enrichment factor (EF) and contamination factor (CF) of these metals were calculated. The pollution load index of the studied soils indicated their level of metal contamination. The concentrations of Ni, Pb, Cd and Cr in the edible portions were above the safe limit in 90%, 28%, 83% and 63% of the samples, respectively. The heavy metals in the edible portions were as follows: Cr > Zn > Ni > Cd > Mn > Pb > Cu > Fe. The Health Risk Index (HRI) was >1 indicating a potential health risk. The EF values designated an enhanced bio-contamination compared to other reports from Saudi Arabia and other countries around the world. The results indicated a potential pathway of human exposure to slow poisoning by heavy metals due to the indirect utilization of vegetables grown on heavy metal-contaminated soil that was irrigated by contaminated water sources. The okra tested was not safe for human use, especially for direct consumption by human beings. The irrigation source was identified as the source of the soil pollution in this study.

Aquifer parameters determination for large diameter wells using neural network approach

Abstract Use of artificial neural networks (ANNs) is becoming increasingly common in the analysis of groundwater hydrology and water resources problems. In this research, an ANN was developed and used to estimate aquifer parameter values, namely transmissivity and storage coefficient, from pumping test data for a large diameter well. The ANN was trained to map time–drawdown and well diameter data (input vector) to its corresponding transmissivity and storage coefficient values (output vector). Based upon a pre-specified range of aquifer parameters, the input vectors were generated from the analytical solution of Papadopulos and Copper for large diameter well in a homogeneous, isotropic, non-leaky confined aquifer. The ANN was trained with a fixed number of drawdown data points corresponding to a varying pre-specified range of aquifer parameters and time-series values. Once the network is trained to an acceptable level of accuracy, it produces an output of aquifer parameter values for any input vector. The results obtained with the ANN are in good agreement with published values. A significant advantage of the ANN approach is that it overcomes the problem of determining the storage coefficient, which when determined by traditional type curve matching method is of questionable reliability.

Green biocides, a promising technology: current and future applications to industry and industrial processes

The study of biofilms has skyrocketed in recent years due to increased awareness of the pervasiveness and impact of biofilms. It costs the USA literally billions of dollars every year in energy losses, equipment damage, product contamination and medical infections. But biofilms also offer huge potential for cleaning up hazardous waste sites, filtering municipal and industrial water and wastewater, and forming biobarriers to protect soil and groundwater from contamination. The complexity of biofilm activity and behavior requires research contributions from many disciplines such as biochemistry, engineering, mathematics and microbiology. The aim of this review is to provide a comprehensive analysis of emerging novel antimicrobial techniques, including those using myriad organic and inorganic products as well as genetic engineering techniques, the use of coordination complex molecules, composite materials and antimicrobial peptides and the use of lasers as such or their modified use in combination treatments. This review also addresses advanced and recent modifications, including methodological changes, and biocide efficacy enhancing strategies. This review will provide future planners of biofilm control technologies with a broad understanding and perspective on the use of biocides in the field of green developments for a sustainable future.

Chemodynamics of Methyl Parathion and Ethyl Parathion: Adsorption Models for Sustainable Agriculture

The toxicity of organophosphate insecticides for nontarget organism has been the subject of extensive research for sustainable agriculture. Pakistan has banned the use of methyl/ethyl parathions, but they are still illegally used. The present study is an attempt to estimate the residual concentration and to suggest remedial solution of adsorption by different types of soils collected and characterized for physicochemical parameters. Sorption of pesticides in soil or other porous media is an important process regulating pesticide transport and degradation. The percentage removal of methyl parathion and ethyl parathion was determined through UV-Visible spectrophotometer at 276 nm and 277 nm, respectively. The results indicate that agricultural soil as compared to barren soil is more efficient adsorbent for both insecticides, at optimum batch condition of pH 7. The equilibrium between adsorbate and adsorbent was attained in 12 hours. Methyl parathion is removed more efficiently (by seven orders of magnitude) than ethyl parathion. It may be attributed to more available binding sites and less steric hindrance of methyl parathion. Adsorption kinetics indicates that a good correlation exists between distribution coefficient (Kd) and soil organic carbon. A general increase in Kd is noted with increase in induced concentration due to the formation of bound or aged residue.

Effect of azo dye on ammonium oxidation process and ammonia-oxidizing bacteria (AOB) in soil

Ammonia-oxidizing bacteria (AOB) play a key role in the production of nitrate-N (NO3−-N) in terrestrial ecosystems. A study was planned with the aim of assessing the effect of azo dyes released by textile and dyestuff industries on the NH4+-N oxidation process in soil. The data was analyzed statistically using a two factorial completely randomized design (CRD). The results of the study demonstrated that higher doses of reactive black 5 (RB5) significantly suppressed the NH4+-N oxidation process throughout incubation. Average percent inhibition rates (%) were in the following order: coarse > fine > medium soil. Overall average percent inhibition rates (%) of nitrification in soils exposed to 30 mg-N kg−1 soil ammonium sulfate [(NH4)2SO4] were 46–53% higher than those from 90 mg-N kg−1 soil. This may be attributed to (NH4)2SO4 that acts as a substrate for the proliferation of AOB. NO3−-N concentration was strongly negatively correlated (r = −0.86) with various amounts of RB5, whereas a strong positive response was observed for the inhibition rate (r = 0.92). A considerable decrease in AOB population (up to 92.58%) was detected for >200 mg kg−1 soil plus N fertilizer, which differed with soil type. This study could be helpful to investigate the effect of contaminants on biochemical processes occurring in soil. Furthermore, the inhibitory effect of azo dye on the NH4+-N oxidation process suggests that critical concentrations of organic dyes may be used as an inhibitor to release NO3−-N in soil at a slow rate in order to further reduce NO3−-N contamination in terrestrial and aquatic ecosystems and to allow less frequent application of ammonium fertilizer in soil as well.

Study of modern nano enhanced techniques for removal of dyes and metals

Industrial effluent often contains the significant amount of hexavalent chromium and synthetic dyes. The discharge of wastewater without proper treatment into water streams consequently enters the soil and disturbs the aquatic and terrestrial life. A range of wastewater treatment technologies have been proposed which can efficiently reduce both Cr(VI) and azo dyes simultaneously to less toxic form such as biodegradation, biosorption, adsorption, bioaccumulation, and nanotechnology. Rate of simultaneous reduction of Cr(VI) and azo dyes can be enhanced by combining different treatment techniques. Utilization of synergistic treatment is receiving much attention due to its enhanced efficiency to remove Cr(VI) and azo dye simultaneously. This review evaluates the removal methods for simultaneous removal of Cr(VI) and azo dyes by nanomicrobiology, surface engineered nanoparticles, and nanophotocatalyst. Sorption mechanism of biochar for heavy metals and organic contaminants is also discussed. Potential microbial strains capable of simultaneous removal of Cr(VI) and azo dyes have been summarized in some details as well.

Cesium-137: Radio-Chemistry, Fate, and Transport, Remediation, and Future Concerns

In recent years, considerable interest has arisen with regard to the fate and transport of radionuclides such as iodine-131 (131I), cesium-134 (134Cs), and cesium-137 (137Cs) in aquatic environments. 137Cs is an important indicator of radioactive pollution in aquatic environments. The transport and fate of anthropogenic 137Cs is related to the chemical properties of ionic Cs (Cs+), which generally dictates a high degree of mobility and bioavailability of this radionuclide. The transport of 137Cs and its partitioning between abiotic and biotic components of aquatic ecosystems are complex processes that are considerably affected by a number of factors such as mineralogical composition of suspended and bottom sediments and the characteristic geochemistry of water. These factors influence sorption and desorption kinetics of 137Cs and the transport of particulate 137Cs. Nevertheless, substantial evidence suggests that direct biological 137Cs accumulation from the aquatic environment occurs readily in micro-organisms and aquatic plants. The evidence discussed in this work indicates that 137Cs is continuously re-circulated in biological systems for many years following a pulse of contamination. Possible remediation methods for the contaminated aquatic systems are also discussed. This review provides guidelines for future work plans for the study of the fate and transport of 137Cs in the aquatic environment in the wake of Fukushima Nuclear Power Plant disaster in 2011 and to provide answers to the urgent questions with respect to strategies for mitigating contamination and reducing radiation exposure for people living in the most affected regions of the world.

Case study evaluation of the geomorphologic instantaneous unit hydrograph

Several issues related to the probabilistic and hydraulic structure of the geomorphologic instantaneous unit hydrograph (GIUH) are addressed. These issues are: (1) accuracy of the geomorphologic expressions of the probabilities of surface runoff movement in a watershed, (2) identifying, for a given storm, a representative time-average velocity for surface runoff, (3) estimation of this velocity for the ungauged watersheds and effect of velocity estimation errors on the GIUH predictability, and (4) suitability of incorporating a linear expression for infiltration in the GIUH as well as the estimation problem of the infiltration coefficient and its effect on the reliability of predicted hydrographs. These issues are analyzed through application of the GIUH for two gauged watersheds in the southwestern region of Saudi Arabia. Twelve storm events are used in the analysis and the results are presented.

Removal of metallic elements from industrial waste water through biomass and clay

This study reports the removal of nickel(II) and copper(II) ions (Ni2+ and Cu2+) from aqueous solution using pure and chemically pretreated biomass from Arachis hypogea (peanut shells), Prunus amygdalus (almond shells), Arundo donax (giant cane) and two clay materials, clay G and clay B. These materials are indigenous, easily available, surpulus by-products for biosorption studies. Batch experiments were carried out to determine the effect of various adsorbent factors such as initial pH, temperature, particle size and contact time on the adsorption process. For adsorption application, up to 99% removal of both metal ions was achieved by biomass and clay materials. Furthermore, chemically modified adsorbents significantly increased the uptake capacity of biomass, suggesting that the affinity between metal and sorbent can be increased after pretreatment. Equilibrium isotherms were analyzed using Langmuir and Freundlich isotherm models, and both models fitted to explain the adsorption behavior of metal ions on to biomass and clay. This shows that the adsorption of metal ions on the adsorbent is a physical adsorption mechanism. In conclusion, owing to its outstanding nickel(II) and copper(II) uptake capacity, the utilized biomass proved to be an excellent biosorbent.

Synthesis of zeolite from marble powder waste: a greener approach and its application for the removal of inorganic metals from wastewater

AbstractThe wastewater containing heavy metals, produced at various stages of operation in textile, printing, plastic, and paper-making industries, pose major hazards to the environment and the public health. Therefore, it is necessary that the pollutants should be treated before discharge by using highly efficient adsorbents. Zeolite is a potential material and can conveniently be processed as adsorbents for the removal of environmental pollutants. A wide range of commercial zeolite has been marketed but due to high cost it is of limited use. The present research offers a green approach for the application of zeolite synthesized by using marble powder waste as a precursor. The significance rests on the conversion of waste into a useful adsorbent marble zeolite (MZ). Zeolite is an environmental friendly, novel, and cost-effective adsorbent. In the current study, remediation of heavy metals in industrial wastewater is done using zeolite. The marble waste contains metals like Zn, Ni, Pb, Cr, Cd, and Cu in i...