Wide use of dyes in production of fabric becomes the most problematic and generates high amount of liquid effluent pollutants to the surface water. The potential of waste materials, pineapple (Ananas comosus) leaf powder and lime (Citrus aurantifolia) peel powder, to remove Remazol Brilliant Blue R (RBBR) from aqueous solution through adsorption process was investigated. Batch experiments were conducted at initial dye concentration of 500 mg/L. Data analysis showed a removal percentage more than 90 %. The Langmuir, Freundlich, and Temkin isotherm models were also investigated to study the mechanism of dye molecules onto adsorption process. The optimum equilibrium was obtained by the Langmuir isotherm (R ² = 0.9945) for pineapple leaves and (R ² = 0.9994) for lime peel. The maximum monolayer adsorption capacity adsorbents onto RBBR (9.58 mg/g) were achieved. The pseudo-second-order kinetic indicates that the rate constant was 1.00. The specific area of both adsorbents was identified as homogenous structure and was characterized by field emission scanning electron microscopy (FESEM) analysis. The surface functional groups responsible for dye uptake by adsorbents indicate that both adsorbents were defined as carboxyl group which consists of carbonyl and hydroxyl groups and were analyzed by Fourier transform infrared spectrometry (FTIR) analysis. The overall study indicates that adsorbents prepared from pineapple leaves and lime peels are alternative low-cost product in dye removal from aqueous solution.

Mercury contamination in water has been an issue to the environment and human health. In this article, mercury in marine and oceanic waters has been reviewed. In the aquatic environment, mercury occurs in many forms, which depend on the oxidation-reduction conditions. These forms have been briefly described in this article. Mercury concentrations in marine waters in the different parts of the world have been presented. In the relevant literature, two models describing the fate and behavior of mercury in saltwater reservoirs have been presented, a conceptual model which treats all the oceans as one ocean and the “ocean margin” model, providing that the ocean margins manifested themselves as the convergence of continents and oceans, covering such geological features, such as estuaries, inland seas, and the continental shelf. These two conceptual models have been summarized in the text. The mercury content in benthic sediments usually reflects is level in the water reservoir, particularly in reservoirs situated in contaminated areas (mines, metallurgical plants, chemically protected crops). The concentrations of mercury and its compounds determined in the sediments in surface waters in the different parts of the world have been presented. Due to the fact that the pollution caused by mercury is a serious threat for the marine environment, the short paragraph about mercury bioaccumulation in aquatic organisms has been included. The cited data demonstrated a large scatter of mercury contents both between the fish species and the water areas. Mathematical models, valuable tools which provide information about the possible responses of ecosystems, developed to simulate mercury emissions, both at a small scale, for local water reservoirs, and at a global scale, as well as to model mercury bioaccumulation in the chain web of aquatic systems have been described.

This work reported a comparative study on the electrochemical incineration of nitrilotriacetic acid (NTA) in the presence of different supporting electrolytes (Na₂SO₄ and NaCl). Galvanostatic electrolyses were conducted in an undivided electrochemical cell containing boron-doped diamond (BDD) anode and platinum cathode. Initial solution pH, flow rate, applied current density, and supporting electrolyte concentration were selected as variables, besides the mineralization efficiency of NTA that was selected as response. Central composite rotatable design and response surface methodology were employed here to examine the statistical significance of the selected variables, as well as to determine the optimal conditions of the degradation process. Under the same operating conditions, two regression models were thus constructed to illustrate the differing impact of supporting electrolytes in BDD anode cells. The kinetics for NTA degradation followed different reaction orders for the two scenarios (in the absence and presence of NaCl), indicating the complex interaction between hydroxyl radicals and active chlorine. Despite this, the experimental results demonstrated that effective mineralization of NTA might also be achieved in the presence of chlorides (of lower concentrations). Besides, in the case of chlorides, the average mass transfer coefficient of the system was found to be strongly dependent on the initial solution pH. Lastly, a plausible reaction sequence concerning the electrolytic oxidation of NTA in chloride media was also proposed.

Global change and demographic changes increasingly cause water, food, and health problems at many places of the world. In addition, the growth in bioenergy production leads to land-use change and associated environmental impacts. This Special Issue addresses many of the challenges of agri-cultural, water and nonpoint source pollution management at the watershed scale. In this regard, the Soil and Water Assessment Tool (SWAT) model (Arnold et al., 1998; Arnold and Fohrer, 2005) has proven to be an effective mechanism for assessing water resource and nonpoint source pollution problems for a wide range of scales and environmental conditions across the globe (Gassman et al., 2007). The model is a continuation of nearly 30 years of research efforts by the USDA Agricultural Research Service (ARS). SWAT continues to evolve as users determine needed improvements that will enable more accurate simulation of currently supported processes and new functionalities that will expand the SWAT simulation domain, reflecting the above mentioned challenges.

6 pages | International audience | To better understand the Central Africa forests sensitivity toclimate variability, we jointly analyse the mean annual cycles of greenness, rainfall, cloudiness and solarradiation for the target region 0-5°N/12-19°E using high resolution satellite data. Our results demonstrate theimportance of the diurnal scale for understanding the mean annual cycles of rainfall, cloudiness and solarradiation and the way they shape those of forest greenness. They also suggest that whereas the March-Mayrainy season appears optimal for greenness especially because of favorable light conditions, water availabilityis the main controlling factor in December-January the main dry season and in February at the start of the firstvegetative season. Regarding the little dry season and the second rainy season (July-October) light availabilitymight be the main limiting factor to forests photosynthetic activity. | Afin de mieux comprendre la sensibilité de la forêt d'Afrique Centrale à la variabilité climatiqueactuelle, une analyse détaillée des cycles saisonniers moyens d'activité photosynthétique, de précipitations, decouverture nuageuse et de radiation solaire est menée pour la région 0-5°N/12-19°E, en s'appuyant sur desobservations satellites haute résolution spatiale et temporelle. Nos résultats montrent tout d'abord que l'échellediurne est une échelle clé pour comprendre les cycles saisonniers moyens de précipitations, nébulosité etradiation solaire, et comment ils façonnent celui d'activité photosynthétique des forêts. Ensuite, alors que lasaison mars-mai semble optimale pour l'activité photosynthétique des forêts en raison d'une bonne disponibilitéen lumière, la disponibilité en eau est le facteur de contrôle principal durant la grande saison sèche (décembrejanvier)et au démarrage de la 1ère saison végétative (février). De juillet à octobre, la plus faible disponibilitéen lumière pourrait être le principal facteur explicatif à la baisse de l'activité photosynthétique.

Aluminum is ingested through foods, water, air, and even drugs. Its intake is potentiated further through foods and tea prepared in aluminum utensils and Al salt added in the drinking water for removal of suspended impurities and also fluoride in the affected areas. The ameliorating role of a blue green alga Spirulina is well documented to various pollutants in the animal models. We, therefore, examined its protective role (230 mg/kg body weight) on the hematology of male Swiss albino mice treated with aluminum (sub-acute = 78.4 mg/kg body weight for 7 days, sub-chronic = 7.8 mg/kg body weight for 90 days) and aluminum fluoride (sub-acute = 103 mg/kg body weight, sub-chronic = 21 mg/kg body weight), along with their recovery after 90 days of sub-chronic exposure. This study revealed significant reduction in the values of RBC (5–18 %), Hb (15–17 %), PCV (8–14 %), and platelets (26–36 %), and increase in WBC (54–124 %) in the treated mice, particularly after sub-acute exposure. Aluminum fluoride was comparatively more toxic than aluminum. Further, Spirulina supplement not only alleviated toxicity of test chemicals in Swiss albino mice but also led to their better recovery after withdrawal.

The electro-Fenton (EF) process treatment of 0.1-M (rhodamine B) RhB solution was studied with different graphite cathode materials, and graphite felt (GF) was selected as a promising material in further investigation. Then, the degradation performances of gas diffusion electrode (GDE) and graphite felt (GF) were compared, and GDE was confirmed to be more efficient in RhB removal. The operational parameters such as Fe²⁺ dosage and current density were optimized, and comparison among different modified methods—polytetrafluoroethylene-carbon black (PTFE-CB), polytetrafluoroethylene-carbon nanotube (PTFE-CNT), electrodeposition-CB, and electrodeposition-CNT—showed 98.49 % RhB removal by PTFE-CB-modified cathode in 0.05 M Na₂SO₄ at a current density of 50 A/m² and an air flow rate of 1 L/min after 20 min. Meanwhile, after cathode modified by PTFE-CB, the mineralization efficiency and mineralization current efficiency performed absolutely better than the pristine one. Cyclic voltammograms, SEM images, contact angles, and BET surface area were carried out to demonstrate stronger current responses and higher hydrophilicity of GF after modified. The value of biochemical oxygen demand/chemical oxygen demand (BOD₅/COD) increased from 0.049 to 0.331 after 90-min treatment, suggesting the solution was biodegradable, and the modified cathode was confirmed to be stable after ten circle runs. Finally, a proposed degradation pathway of RhB was put forward.

Food waste is the largest constituent of municipal solid waste in Hong Kong, but food waste recycling is still in its infancy. With the imminent saturation of all landfill sites by 2020, multiple technologies are needed to boost up the food waste recycling rate in Hong Kong. Conversion of food waste into animal feeds is prevalent in Japan, South Korea, and Taiwan, treating over 40 % of their recycled food waste. This direction is worth exploring in Hong Kong once concerns over food safety are resolved. Fortunately, while feeding food waste to pigs and chickens poses threats to public health, feeding it to fish is considered low risk. In order to examine the feasibility of converting food waste into fish feed in Hong Kong, this paper investigates the market demand, technical viability, feed quality, regulatory hurdles, and potential contribution. The results show that a significant amount of food waste can be recycled by converting it into fish feed due to the enormous demand from feed factories in mainland China. Two conversion technologies, heat drying and black soldier fly bioconversion, are studied extensively. Black soldier fly bioconversion is preferable because the end-product, insect powder, is anticipated to gain import approval from mainland China. The authors suggest further research efforts to speed up its application for food waste recycling in urban cities.