Current synthesis routes of bismuth oxide nanosheets (BiONS) are relatively complicated, requiring the use of halogens or metalloids. Herein, a facile method to synthesize BiONS without the addition of halogens or other metalloids was developed. The synthesized BiONS were identified to have flake-shaped structures (300–1000 nm in width) with the thickness of 6–10 nm, which were predominantly made of β-Bi₂O₃. Such BiONS were applied to modify the surface of screen-printed carbon electrodes (BiONS-SPCEs) for the development of a robust palladium (Pd²⁺) sensor. After optimizing the electrochemical parameters of the sensor, it was found that the linear sensor response range and limit of detection for Pd²⁺ were 40–400 and 1.4 ppb, respectively. The electrocatalytic activity of the Pd²⁺-sensor was validated in the competing environment of other metal and metalloid ions. Real samples collected during a Pd recovery process from pharmaceutical wastewater were used to verify the application of BiONS-SPCEs in control of palladium recovery process. The quantitative results of post recovery palladium concentrations obtained using BiONS-SPCEs in treated pharmaceutical wastewater samples were in good agreement with those obtained by inductively coupled plasma-optical emission spectrometry (ICP-OES). Thus, such Pd²⁺-sensor provided the possibility of on-site process control of complex industrial samples for obtaining near-instant information that would lead to better management of resources used in the process, and same time assure environmental standards for both recovered products and processed discharge.

Sequencing batch reactors (SBRs), due to its operational flexibility and excellent process control possibilities, are being extensively used for the treatment of wastewater which nowadays is fast becoming contaminated with newer and more complex pollutants. It is also possible to include different expanding array of configurations and various operational modifications to meet the effluent limits which are also continuously getting upgraded. This article provides basic description of SBR process along with its functional and physical variants that lead to improved the removal of nutrients and emerging contaminants. The significance of selectors and various recent advancements in the application of SBR has been discussed along with the possibilities held by SBR process in the treatment of wastewater of different origins and composition to produce effluent of reusable quality.

Continuous radon (222Rn) monitoring was conducted at two stations (site A and site B) with different perpendicular distance from the shoreline in Xiangshan Bay, East China Sea. Based on a 222Rn balance model (various sources and sinks of 222Rn in coastal water), the average rate of SGD was estimated to be 0.69cm/day and 0.23cm/day for site A and site B, respectively. The results from a nutrient analysis of the groundwater indicate that the associated nutrients fluxes loading through the SGD pathway were 4.27×106mol/day for DIN, 2.24×104mol/day for DIP and 1.82×106mol/day for DSi, respectively, which were comparable to or even higher than the levels observed in the local streams. Therefore, adequate attention should be paid to the importance of SGD as one source of nutrients during the eutrophication control process in this area.

Increasingly severe environmental issues, especially those in developing countries such as China, drive the evolution of the environmental protection institution (EPI) to its strictest levels. However, the implementation of the strictest EPI still confronts various challenges and barriers, and the multi-stakeholder features of EPI determine these barriers are not independent of one another but rather present complex interactive relationships. This paper identifies the barriers to implementing China’s EPI from four aspects of environmental legal, economic, regulatory, and public participation institutions. A variable precision rough DEMATEL approach is proposed to visualize the causal relationships and intensities among barriers from the similarities and differences in perspectives of stakeholders from the government, company, and public levels. The obtained causal interactive mechanism among barriers highlights the need to prioritize the improvement of environmental policy assessment, and the concrete measures in policies or plans should be integrated into legislation to ensure they are mutually supportive early. The non-substantive contributions achieved by China’s public participation in environmental protection reveal prejudices that the public is often regarded as a supporter or spectator by both government and company groups, which makes the transparent environmental information disclosure, transfer and feedback into an effective mediation among stakeholders. Comprehensive coordination and feedback mechanisms including source prevention, process control, and severe punishment for consequences while enhancing linkages among stakeholders are put forward to overcome barriers and help implement the strictest EPI.

The dynamic behavior of water quality and quantity in the Egyptian drains is often viewed as a disruption to the normal operation and performance of the process of water reuse in irrigation. The control of such behavior has been challenging and often elusive in practice. Therefore, this paper presents a framework to advance the understanding and opportunities for improving the reuse process by developing a multivariate process control model. The model starts with preliminary analysis for water quality data that are collected at the reuse site on the examined drain. This phase comprises investigating data distribution and dependency. Then, univariate control charts are used to investigate the state of control for the independent and normally distributed variables. For dependent variables, principal components analysis is used as a method of synthesizing the variables information. In this case, principal component scores are displayed using multivariate control charts. If in-control case existed, process capability index is used to provide a numerical measure of whether or not the reuse process is capable of producing water that satisfies the irrigation quality standards. Since the model will only detect assignable causes if out-of-control or in-capable case existed, management, operational, and/or engineering action will usually be necessary to sustain the reuse process. In these cases, an action plan in response to the model signals will be vital. The main function of the proposed model is to safely manage the reuse practice using statistical quality control techniques. The model was demonstrated using water quality data collected during the period from January 2006 to July 2011 from Hanut (EH02) and El-Salam 3 (ESL03) pump stations along Hadus drain, Eastern Nile Delta-Egypt. The recommended model is automatic, algorithmic, self-tuning, and computerizable.

In this study, we studied and developed the modification schemes of environmentally friendly substitutes of neonicotinoid insecticides (NNIs) along with the regulatory measures that effectively enhanced the synergistic degradation of NNIs by soil rhizobia and carbon-fixing bacteria. Firstly, the binding ability of NNIs to the two key proteins was characterized by molecular docking; secondly, the mean square deviation decision method, which is a comprehensive evaluation method, was used to investigate the binding ability of NNI molecules with the two Rubisco rate-limiting enzymes. The three-dimensional quantitative structure-activity relationship (3D-QSAR) model was established for the synergistic degradation and single effect of rhizobia and carbon-fixing bacteria. Finally, after combining the 3D-QSAR model with a contour map analysis of the synergistic degradation effect of soil rhizobia and carbon-fixing bacteria, 102 NNI derivatives were designed. Flonicamid-36 and other four NNI derivatives passed the functional and environmentally friendly evaluation. Taguchi orthogonal experiment and factorial experiment-assisted molecular dynamics method were used to simulate the effects of 32 regulation schemes on the synergistic degradation of NNIS and its derivatives by rhizobia and carbon fixing bacteria. The synergistic degradation capacity of soil rhizobia and carbon-fixing bacteria was increased to 33.32% after right nitrogen supplementation. This indicated that supplementing the correct amount of nitrogen in the soil environment was beneficial to the microbial degradation of NNIs and their derivatives.

This paper first time reports the geochemical processes that are controlling fluoride enrichment in the groundwater of western Kumamoto area, Japan. Fifty (50) groundwater samples were collected and analyzed for the study where fluoride (F⁻) concentration ranges from 0.1 to 1.57 mg/L. About 58 % of the shallow groundwater and 26 % of the deep groundwater samples contain fluoride concentration beyond the Japanese drinking water permissible limit (0.8 mg/L). High F⁻ is largely accumulated in the stagnant zone of the Kumamoto Plain area and associated with Na-HCO₃-type groundwater. High pH, high HCO₃, low Ca²⁺, and high Na⁺ are the major characteristics of high-F⁻ groundwater. Hydrolysis of F⁻-bearing minerals and desorption of F⁻ from hydrous metal oxides are considered to be the primary sources of fluoride in groundwater. A positive correlation between F⁻ and Na⁺/Ca²⁺ ratio (r ² = 0.53) indicates that major ion chemistry plays a significant role in fluoride mobilization. Weakly alkaline nature of groundwater with high pH (7.05–9.45) expedites the leaching process of exchangeable F⁻ from F⁻-bearing minerals as well as favors desorption of F⁻ from metal oxide surfaces. High HCO₃ ⁻ and high PO₄ ³⁻ in the groundwater facilitate desorption process as competing anions, while high Na⁺/Ca²⁺ ratio largely control this process by decreasing positive-charge density of the metal-oxide surfaces. High Na⁺/Ca²⁺ ratio is attributed due to the cation-exchange process, while high pH and HCO₃ ⁻ are the result of both silicate hydrolysis and microbial reduction processes. In addition, calcite and fluorite seem to have a control on groundwater fluoride geochemistry.

The present work explores the sorption capacity of an inexpensive and highly available agricultural waste, rice husk, to remove mercury using realistic concentrations of this metal. The efficiency of the process was evaluated for two initial Hg(II) concentrations, one representing the maximum value for Hg discharges from industrial sectors (0.05 mg L-1), and the other ten times higher. A very small amount of rice husk (0.25 and 0.50 g L-1) was able to reduce the Hg(II) levels in more than 80 % for an initial concentration of 0.05 mg L-1 and in more than 90 % for 0.50 mg L-1, corresponding to residual concentrations of Hg(II) of 0.048 and 0.009 mg L-1, respectively. The biosorvent was reused in further cleaning treatments, maintaining the efficiency and high performance. The sorption kinetics of the Hg-rice husk system is well fitted by the Elovich model and the diffusion models suggested that, depending on the initial Hg(II) concentrations, the sorption process can be controlled by intraparticle diffusion or by both film and intraparticle diffusion. The equilibrium data are well described by the linear isotherm and the distribution coefficient found was 36.1 L g-1. © 2013 Springer Science+Business Media Dordrecht.