International Journal of Environmental Science and Technology

The extracellular polymer from a well-characterized environmental isolate of Klebsiella terrigena was impregnated with granular activated carbon (GAC) and evaluated for the removal of Bisphenol A (BPA) from plastic waste leachates. Adsorbent, BPA concentration, contact time, temperature and pH were optimized to obtain the maximum removal. Characterization of the adsorbents was carried out by FTIR and BET. The adsorption capacity was determined using Langmuir, Freundlich and Temkin isotherms; the maximum adsorption capacity (qe) of BPA by biopolymer-impregnated granular activated carbon (BIGAC) obtained by Freundlich and Temkin isotherms was 241 mg/g and 257 mg/g, respectively, with a correlation factor (R2) of 0.9391 and 0.8085, respectively, at 30 °C. The kinetics and isotherm data could be well fitted in a pseudo-second-order kinetic model. Notable removal of BPA was observed by BIGAC in plastic waste leachates obtained directly from source. To obtain information on reusability of BIGAC, regeneration was attempted for granular activated carbon; however, significant (p > 0.05) efficiency of adsorption was lowered after the third instance. The results of this study suggest that BIGAC can effectively remove BPA with the possibility of reusing GAC at least twice. The method may prove to be valuable in cleanup processes for BPA from leachates.

System destabilization is a highly desirable phenomenon during colloidal impurity removal from sewages and wastewaters. Therefore, in this study, the stability of chromium(III) oxide suspension in the absence and presence of albumins [bovine serum albumin (BSA), ovalbumin (OVA), human serum albumin (HSA)] was investigated. Based on the analysis of experimental results, i.e., measurements of adsorption amount, electrokinetic potential, and metal oxide surface charge density as well as system stability, the mechanism of the suspension stabilization/destabilization was proposed. The examined system without the albumins is relatively stable at pH 3, 4.6, and 9 (TSI = 34.8, 36.6, 34.22, respectively), which is associated with the electrostatic stabilization phenomenon. In turn, the least stable is the suspension at pH 7.6 (TSI = 55.43). This is the result of the adsorbent zero surface charge. Regardless of solution pH, the BSA, OVA, or HSA adsorption causes an increase in the system stability (17.55 < TSI < 30). Probably, the steric stabilization is involved in this phenomenon, which results from the mutual repulsion of the adsorption layers formed on the solid surface. Thus, it can be concluded that the albumin presence in the industrial wastewaters impedes the chromium(III) oxide removal.

Contamination of soils and plants to metals around the Iranian Aluminum Company (IRALCO) was studied. Ninety-three soil samples and forty-five plant samples were collected and analyzed for different metals. Spatial distribution and health risk of the metals were investigated using geoaccumulation index (Igeo), the enrichment factor (EF), contamination factor (CF), hazard quotient, hazard index (HI) and carcinogenic risk. Principal component and correlation analyses were used to recognize the origin of contamination. The results of the study indicated that the mean concentrations of total Al (37,930.4), Fe (21,222.9), Mn (558.4), Pb (60.3), As (32.2), Cr (49.2), Zn (109.2), Ni (83.9), and Cd (7.6) mg/kg, in the studied soil samples exceeded the background concentrations of the metals (12,798, 7863.7, 278.7, 26.3, 5.4, 17.7, 32.3, 45.6, 0.8 mg/kg, respectively). The concentrations (mg/kg) of Al (264.66), Fe (203.77), Mn (155.94), Pb (2.09), As (1.68), Cr (3.26), Zn (49.10), Ni (9.99) and Cd (2.62) in the plant samples were higher than the control plants. The principal component analyses revealed that anthropogenic activities were the main source of soil pollution to metals such Al, Mn, Cr, Zn and Ni. The results of Igeo, EF and CF indicated that Al, As and Cd were the most critical contaminants (Igeo > 2, EF > 6, EF > 2). The HI values for Ni (3.93) and Cd (3.31) were higher than the safe value (HI = 1), indicating that the IRALCO may increase the risk of non-carcinogenic diseases in humans. Cancer risk due to the arsenic and cadmium was higher than the acceptable range (Risks exceeding1 × 10–4).

Currently, due to the rapid growth of urbanization and industrialization in developing countries, a large volume of wastewater is produced from industries that contain chemicals generating high environmental risks affecting human health and the economy if not treated properly. Consequently, the development of a sustainable low-cost wastewater treatment approach has attracted more attention of policymakers and scientists. The present review highlights the recent applications of biochar in removing organic and inorganic pollutants present in industrial effluents. The recent modes of preparation, physicochemical properties and adsorption mechanisms of biochar in removing organic and inorganic industrial pollutants are also reviewed comprehensively. Biochar showed high adsorption of industrial dyes up to 80%. It also discusses the recent application and mechanism of biochar-supported photocatalytic materials for the degradation of organic contaminants in wastewater. We reviewed also the possible optimizations (such as the pyrolysis temperature, solution pH) allowing the increase of the adsorption capabilities of biochar leading to organic contaminants removal. Besides, increasing the pyrolysis temperature of the biochar was seen to lead to an increase in its surface area, while it decreases their amount of oxygen-containing functional groups, consequently leading to a decrease in the adsorption of metal (loid) ions present in the medium. Finally, the review suggests that more research should be carried out to optimize the main parameters involved in biochar production and its regeneration methods. Future efforts should be also carried out towards process engineering to improve its adsorption capacity to increase the economic benefits of its implementation.

Carbendazim and Chlorpyrifos are some of the most widespread environmental contaminants of major concern to human and animal reproductive health. Acute toxicity test results for pesticides were evaluated by the Probit analysis method and 96 h LC50 values for C. chanos exposed to chlorpyrifos was 3.73 and 11.5 μg l−1 for carbendazim. Chlorpyrifos and carbendazim significantly decreased total protein, catalase, glutathione S-transferase and acetyl choline esterase and induced lipid peroxidation. Maximum effects of protein, catalase, lipid peroxidation, acetyl choline esterase and glutathione s-transferase were obtained in response to 23.68 μg l−1 of chlorpyrifos and 43.68 μg l−1 of carbendazim. Micronuclei assay results have shown increased abnormality with increasing doses of chlorpyrifos and carbendazim. Maximum increasing in micronuclei was observed in chlorpyrifos exposed C. chanos. This study showed that chlorpyrifos and carbendazim induced alterations in the activity of antioxidant enzymes and could induce clastogenicity.

The rainfall-runoff relationship is one of the most complex hydrological phenomena. In recent years, hydrologists have successfully applied backpropagation neural network as a tool to model various nonlinear hydrological processes because of its ability to generalize patterns in imprecise or noisy and ambiguous input and output data sets. However, the backpropagation neural network convergence rate is relatively slow and solutions can be trapped at local minima. Hence, in this study, a new evolutionary algorithm, namely, particle swarm optimization is proposed to train the feedforward neural network. This particle swarm optimization feedforward neural network is applied to model the daily rainfall-runoff relationship in Sungai Bedup Basin, Sarawak, Malaysia. The model performance is measured using the coefficient of correlation and the Nash-Sutcliffe coefficient. The input data to the model are current rainfall, antecedent rainfall and antecedent runoff, while the output is current runoff. Particle swarm optimization feedforward neural network simulated the current runoff accurately with R = 0.872 and E2 = 0.775 for the training data set and R = 0.900 and E2= 0.807 for testing data set. Thus, it can be concluded that the particle swarm optimization feedforward neural network method can be successfully used to model the rainfall-runoff relationship in Bedup Basin and it could be to be applied to other basins.

Discharging excessive pollution into rivers that exceeds their self-purification capacity decreases the quality of water and threatens the aquatic ecosystem. In such water systems, polluters and environmental protection agencies are involved parties that often have opposite interests. This research proposes a method to enhance the water quality of rivers while satisfying the interests of both parties. It allocates waste loads to polluters and requires them to pay the treatment cost in order to remove pollution. The proposed methodology employs a combination of QUAL2Kw and non-dominated sorting genetic algorithm-II to minimize wastewater treatment costs and dissolved oxygen violation from the standard level. The river inflow uncertainty is considered by Latin hypercube sampling to give more real insights to decision makers through a stochastic approach. As a result, the Pareto sets act as strategies that can be used to meet the objectives, but they show the contradiction between parties’ interests. According to the waste load criterion, this methodology reduces waste load from 145.5 to 79, 107.15 and 115 units for dry, normal and wet months. Also, it decreases treatment cost from the range of [160,000–180,000 $] to [100,000–130,000 $] considering the water quality and dischargers’ interest. According to the results, considering river inflow uncertainty can increase the concentration of dissolved oxygen even more than the standard level, and point sources treat their wastewater more than non-point ones. Generally, it is a suitable tool to find solutions for minimizing the treatment cost in favor of dischargers and improving water quality.