New Unstructured Mesh Water Quality Model for Cooling Water Biocide Discharges

A new unstructured mesh coastal water and air quality model has been developed that includes species transport, nonlinear decay, by-product formation, and mass-exchange between sea and atmosphere. The model has been programmed with a graphical user interface and is applicable to coastal seawater, lakes, and rivers. Focused on species conversion and interaction with the atmosphere, the water and air quality model follows a modular approach. It is a compatible module which simulates distributions based on fluid dynamic field data of underlying existing hydrodynamic and atmospheric simulations. Nonlinear and spline approximations of decay and growth kinetics, by-product formation, and joint sea–atmosphere simulation have been embedded. The Windows application software includes functions allowing error analysis concerning mesh and finite volume approximation. In this work, a submerged residual chlorine cooling water discharge and halogenated matter by-product formation has been simulated. An error analysis has been carried out by varying vertical meshing, time-steps and comparing results based on explicit and implicit finite volume approximation. The new model has been named 3D Simulation for Marine and Atmospheric Reactive Transport, in short 3D SMART.     

Effect of water and temperature on ammonia volatilization of maize straw returning

ABSTRACT

Ammonia volatilization is an important nitrogen (N) loss pathway in agricultural production and consequent significant atmospheric pollutant. The primary objective of this study was to (1) examine effects of environmental factors such as temperature and soil water capacity, as well as crop residue (CR) addition as fertilizer, on ammonia (NH₃) volatilization, and (2) search for a comprehensive management strategy to reduce accumulative ammonia volatilization (AAV). A bench-scale cultivated experiment was conducted at two environment temperatures (15 or 25 °C), three forms of soil water capacity (30%, 50%, or 70% soil field moisture capacity), and two treatments of fertilizers (conventional fertilizer urea and straw returning – 10% of total N application arising from maize straw and remainder from conventional urea). Results showed that AAV was markedly decreased by adjusting soil water capacity, temperature, and CR addition. Significant quantified exponential correlation between AAV and soil moisture was observed. More than 70% AAV was reduced in intermediate 50% and high 70% soil moisture compared to low 30%. AAV was less sensitive to temperature than soil moisture using black soils. Only in low soil moisture, AAV rose with increasing of temperature. Straw restoration addition decreased significantly the AAV loss.     

Super effective Zn-Fe-doped TiO2 nanofibers as photocatalyst for ammonia borane hydrolysis

In this study, the photocatalytic activity of TiO₂ nanofibers toward ammonia borane hydrolysis has been strongly modified by doping the nanostructure by ZnO and Fe₂O₃ oxides. Due to the differences in the work function and band gap energy among the three semiconductors (TiO₂, ZnO and Fe₂O₃), illumination of TiO₂ leads to accumulate the electrons and holes on the conduction and valance bands of Fe₂O₃ and ZnO, respectively. Accordingly, the experimental results indicated that the surface of the obtained nanofibers is very active which results in an instant hydrolysis of ammonia borane molecules reaching the active zone surrounding the nanofibers. Moreover, negative activation energy was determined as increasing the temperature led to decrease the photocatalytic performance. Furthermore, kinetic studies indicated that the heterogeneous catalytic reaction describing the ammonia borane hydrolysis process is zero order which additionally supports the super activity of the introduced nanofibers. It was also observed that Fe₂O₃ content in the introduced nanofibers has distinct influence as the best performance was obtained at 1 wt%. The modified TiO₂ nanofibers were prepared by calcination of electrospun nanofibers composed of titanium isopropoxide, zinc acetate and iron acetate in air at 700 °C for 1 h. Overall, the present study opens a new avenue to overcome the fast electrons/holes recombination dilemma facing TiO₂-based nanostructures.     

Characterization of Shredder Residues generated and deposited in Denmark

This study presents a detailed characterization of Shredder residues (SR) generated and deposited in Denmark from 1990 to 2010. It represents approximately 85% of total Danish SR. A comprehensive sampling, size fractionation and chemical analysis was carried out on entire samples as well as on each individual size fraction. All significant elemental contents except oxygen were analyzed. The unexplained “balance” was subsequently explained by oxygen content in metal oxides, carbonates, sulphates and in organics, mainly cellulose. Using mass and calorific balance approaches, it was possible to balance the composition and, thereby, estimate the degree of oxidation of elements including metals. This revealed that larger fractions (>10 mm, 10–4 mm, 4–1 mm) contain significant amount of valuable free metals for recovery. The fractionation revealed that the >10 mm coarse fraction was the largest amount of SR being 35–40% (w/w) with a metal content constituting about 4–9% of the total SR by weight and the <1 mm fine fraction constituted 27–37% (w/w) of the total weight. The lower heat value (LHV) of SR samples over different time periods (1990–2010) was between 7 and 17 MJ/kg, declining with decreasing particle size. The SR composition is greatly dependent on the applied shredding and post shredding processes at the shredding plants causing some variations. There are uncertainties related to sampling and preparation of samples for analyses due to its heterogeneous nature and uncertainties in the chemical analyses results (≈15–25%). This exhaustive characterization is believed to constitute hitherto the best data platform for assessing potential value and feasibility of further resource recovery from SR.     

Enhancement of simultaneous nitrogen and phosphorus removal using intermittent aeration mechanism

Biological nutrient removal grows into complicated scenario due to the microbial consortium shift and kinetic competition between phosphorus (P)-accumulating and nitrogen (N)-removing microorganisms. In this study, three sequential batch reactors with constant operational conditions except aeration patterns at 6 h cycle periods were tested. Intermittent aeration was applied to develop a robust nutrient removal system aimed to achieve high energy saving and removal efficiency. The results showed higher correspondence of P-uptake, polymeric substance synthesis and glycogen degradation in intermittent-aeration with longer interval periods compared to continuous-aeration. Increasing the intermittent-aeration duration from 25 to 50 min, resulted in higher process performance where the system exhibited approximately 30% higher nutrient removal. This study indicated that nutrient removal strongly depends on reaction phase configuration representing the importance of aeration pattern. The microbial community examined the variation in abundance of bacterial groups in suspended sludge, where the 50 min intermittent aeration, favored the growth of P-accumulating organisms and nitrogen removal microbial groups, indicating the complications related to nutrient removal systems. Successful intermittently aerated process with high capability of simple implementation to conventional systems by elemental retrofitting, is applicable for upgrading wastewater treatment plants. With aeration as a major operational cost, this process is a promising approach to potentially remove nutrients in high competence, in distinction to optimizing cost-efficacy of the system.     

Lung function decrement with arsenic exposure to drinking groundwater along River Indus: a comparative cross-sectional study

This study was designed to determine the association between chronic arsenic exposure through drinking groundwater and decrement in lung function, particularly among individuals who do not have signs of arsenic lesions, among an adult population. This was a comparative cross-sectional study conducted during the months of January to March 2009. One hundred participants ≥15 years of age in each group, i.e. exposed (≥100 μg/l) and unexposed (≤10 μg/l) to arsenic, determined by testing drinking water samples (using portable kits), were compared for effects on lung function using spirometry. A structured and validated questionnaire was administered. Examination for arsenic skin lesions was also done. There was a decline in the mean adjusted FEV1 of 154.3 ml (95% CI: −324.7, 16.0; p = 0.076), in mean adjusted FVC of 221.9 ml (95% CI: −419.5, −24.3; p = 0.028), and in FEV1/FVC ratio of 2.0 (95% CI: −25.3, 29.4; p = 0.884) among participants who were exposed to arsenic compared to those unexposed. A separate model comprising a total of 160 participants, 60 exposed to arsenic concentrations ≥250 μg/l and 100 unexposed at arsenic concentrations of ≤10 μg/l, showed a decrement in mean adjusted FEV1 of 226.4 ml (95% CI: −430.4, −22.4; p = 0.030), in mean adjusted FVC of 354.8 ml (95% CI: −583.6, −126.0; p = 0.003), and in FEV1/FVC ratio of 9.9 (95% CI: −21.8, 41.6; p = 0.539) among participants who were exposed to arsenic in drinking groundwater. This study demonstrated that decrement in lung function is associated with chronic exposure to arsenic in drinking groundwater, occurring independently, and even before any manifestation, of arsenic skin lesions or respiratory symptoms. The study also demonstrated a dose-response effect of arsenic exposure and lung function decrement.     

A risk-based approach to design warning system for processing facilities

Alarm flooding is a major safety issue in today's processing facilities. Important recommendations are available for alarm management; however, they are often violated in practice, especially in the alarm systems implemented through the distributed control system. An effective process alarm prioritization and management system is desired for a safe and effective operation of a process facility.In present work, authors address two main issues related to an alarm system – the reliability and the prioritization of the alarms. The main objective is to deal with the alarm-flooding problem in process facilities. A multi alert voting system based on sensor redundancy approach is proposed to improve the reliability. A quantitative risk-based alarm management approach is proposed to address the flooding issue. In the risk-based approach, an integrated model consisting of the probability (P), the impact (I) of the potential hazards, and the process safety time is proposed to prioritize these raised alarms.The proposed approach is further explained by a reactor system with pressure and temperature variable monitoring and controls, where the hazards associated with two alerts caused by over high pressure and over high temperature are analyzed and integrated with response time for alarms generation and prioritization.     

Correction: Insight into the Adsorption Properties of Chitosan/Zeolite‑A Hybrid Structure for Effective Decontamination of Toxic Cd (II) and As (V) Ions from the Aqueous Environments

Journal of Polymers and the Environment -     

Protective effects of Persea americana fruit and seed extracts against chemically induced liver cancer in rats by enhancing their antioxidant,anti-inflammatory,and apoptotic activities

Environmental Science and Pollution Research - This study aims to explore the chemopreventive mechanisms of hydroethanolic extracts from avocado (Persea Americana) in diethylnitrosamine...