In this study, we present the development of a mobile system to measure real-world total respiratory tract deposition of inhaled ambient black carbon (BC). Such information can be used to supplement the existing knowledge on air pollution-related health effects, especially in the regions where the use of standard methods and intricate instrumentation is limited. The study is divided in two parts. Firstly, we present the design of portable system and methodology to evaluate the exhaled air BC content. We demonstrate that under real-world conditions, the proposed system exhibit negligible particle losses, and can additionally be used to determine the minute ventilation. Secondly, exemplary experimental data from the system is presented. A feasibility study was conducted in the city of La Paz, Bolivia. In a pilot experiment, we found that the cumulative total respiratory tract deposition dose over 1-h commuting trip would result in approximately 2.6 μg of BC. This is up to 5 times lower than the values obtained from conjectural approach (e.g. using physical parameters from previously reported worksheets). Measured total respiratory tract deposited BC fraction varied from 39% to 48% during walking and commuting inside a micro-bus, respectively.To the best of our knowledge, no studies focusing on experimental determination of real-world deposition dose of BC have been performed in developing regions. This can be especially important because the BC mass concentration is significant and determines a large fraction of particle mass concentration. In this work, we propose a potential method, recommendations, as well as the limitations in establishing an easy and relatively cheap way to estimate the respiratory tract deposition of BC.

Triolein embedded cellulose acetate membrane (TECAM) was used for passive sampling of the fraction of naphthalene, phenanthrene, pyrene and benzo[a]pyrene in 18 field-contaminated soils. The sampling process of PAHs by TECAM fitted well with a first-order kinetics model and PAHs reached 95% of equilibrium in TECAM within 20 h. Concentrations of PAHs in TECAM (CTECAM) correlated well with the concentrations in soils (r2 = 0.693-0.962, p < 0.001). Furthermore, concentrations of PAHs determined in the soil solution were very close to the values estimated by CTECAM and the partition coefficient between TECAM and water (KTECAM-w). After lipid normalization nearly 1:1 relationships were observed between PAH concentrations in TECAMs and earthworms exposed to the soils (r2 = 0.591–0.824, n = 18, p < 0.01). These results suggest that TECAM can be a useful tool to predict bioavailability of PAHs in field-contaminated soils.

For most trace elements, the technique of phytoextraction needs significant improvements to become practically feasible. Calculations for Cd revealed that the amount of Cd taken up by Thlaspi caerulescens or Salix spp. needs at least to be the double of the present amount to slightly decrease the Cd concentration in the upper 0.5 m of the soil within a period of 10 years. Additionally, metals taken up by the plants might pose an important risk. Alternatives as bioavailable contaminant stripping and phytostabilization might be more appropriate. Phytoextraction efficiency should be improved and associated risks need more attention before phytoextraction can be established as a commercial technology.

Multi-layered engineered landfill consists of the bottom liner layer (mainly bentonite clay (B)) upon which the hazardous wastes are dumped. In current practice, sand (S) is mixed with bentonite to mitigate the adverse effects of using bentonite alone in the liner layer. Incorporation of waste and unutilized fly ash (FA) as an amendment material to B has been explored in terms of its hydro-mechanical properties, but not gauged its adsorption potential. Indian subcontinent primarily relies on the thermal power source, and FA dumps have already reached its full capacity. The objective of this study is to explore the adsorption characteristics of four B-FA composite mixes sourced within India, considering Pb²⁺ as a model contaminant. The effect of fly ash type, fly ash amendment rate and adsorbate concentration was explored in the current study and juxtaposed with B-S mixes, based on 960 batch adsorption tests. Both B-FA and B-S mixes reached equilibrium adsorption capacity within 65 min. At higher adsorbate concentrations (commonly observed in the liner), B-FA mixes exhibited superior adsorption capacity, mainly one mixed with Neyvelli fly ash (NFA). The effect of higher amendment rate had little impact on the adsorption capacity at different concentration, but gradually decreased the percentage removal of Pb²⁺. The B-S mix showed a drastic decrease in percentage removal at higher adsorbate concentration among all tested mixes. Systematic characterization including geotechnical properties, microstructure and chemical analysis was also done to interpret the obtained results. Both Freundlich and Langmuir models fitted the isotherm data well for all B-FA mixes. The maximum adsorption capacity from the isotherm was correlated to easily measurable Atterberg limits by two empirical relationships.

Increased water demand due to population growth and industrialization has led to increased water consumption. Hence, it is required to find an alternative to water in different industries. Concrete represents a remarkable water-consuming industry. The present study investigates whether the treated leachate of municipal landfills can be employed as a substitute for water in the concrete mixing scheme. For this purpose, concrete samples fabricated at different concentrations of treated leachates were compared to the control sample containing distilled water in terms of unconfined compressive strength (UCS) at the ages of 7 and 28 days. The experimental results revealed treated leachate accelerated the cement setting time by nearly 15 min and increased concrete slumping by 16%. The complete replacement of distilled water with treated leachate decreased UCS by 25% (from 50 to 38 MPa). The scanning electron microscope (SEM) and ultrasonic results showed that a rise in the treated leachate content of concrete increased porosity. Increased porosity would reduce UCS. Leaking of heavy metals existing in the leachate should be also investigated for the solidified matrices. The toxicity characteristic leaching procedure (TCLP) revealed that heavy metals leaching in all the samples are in the acceptable range. Results have shown that the use of leachate up to a concentration of 20% can be used in concrete, and the solidified product can also stabilize the pollutants, successfully. It is a valuable finding because using treated leachate as a practical additive in the concrete can prevent environmental contamination.

The proposed Minamata Convention ban on the use of fluorescent lamps at the end of 2020, with a consequent reduction in mercury (Hg) light products, is expected to produce large amounts of discarded fluorescent bulbs. In this context, the most effective recycling options are a thermal mercury recovery system and/or aqueous solution leaching (lixiviation) to recover rare earth elements (REEs). Due to the heterogeneous nature of these wastes, a complete characterization of Hg compounds in addition to a determination of their desorption temperatures is required for their recycling. The objective of this study is to assess the feasibility of a fast cost-effective thermal characterization to ameliorate recycling treatments. A pyrolysis heating system with a heat ramping capability combined with atomic absorption spectrometry makes it possible to obtain residue data with regard to the temperature ranges needed to achieve total Hg desorption. The major drawback of these heat treatments has been the amount of Hg absorbed from the residue by the glass matrices, ranging from 23.4 to 39.1% in the samples studied. Meanwhile, it has been estimated that 70% of Hg is recovered at a temperature of 437 °C.

BaSO₄ waste powder containing radionuclides generated from nuclear facilities must be immobilized into a stable waste form for final disposal. In this study, the immobilization of BaSO₄ waste powder containing simulant radioactive cobalt by low-temperature sintering was evaluated. A simulated decontamination waste was prepared as a BaSO₄ waste powder containing simulant radioactive cobalt, and Bi₂O₃-B₂O₃-ZnO-SiO₂ glass was used as a binding material for the immobilization. The simulated waste was immobilized into a monolithic waste form at 550 °C without the SO₂ gas generation. The glass was converted into crystal structures during the immobilization. The waste form had a high bulk density (5.05 g/cm³), and it showed a good compressive strength (21.92 MPa). It was also confirmed that the waste form had a high chemical durability through a semi-dynamic leaching test. In particular, the average leaching index of Co was 13.18. These results show that the immobilization has a potential application to BaSO₄ waste powder containing radionuclides for final disposal.

This study aims to assess the viability of waste tire chips as sand reinforcement for enhancing the performance of shallow foundations. Detailed experimental investigation is carried out to analyze the behavior of model footing placed on sand reinforced with waste tire chips, and the observed improvement is quantified in terms of a non-dimensional factor, bearing capacity ratio (BCR). The influence of variation of several factors such as the content of tire-chip reinforcement, the extent of tire reinforced sand zone, footing shape, the effect of submergence, and scale effects on BCR has also been studied. Test results indicate significant improvement in BCR validating the effectiveness of tire chips in improving the bearing capacity of sand. The optimum tire content, depth of reinforced zone, and width of the reinforced zone are recommended as 30%, 1B-2B, and 3B-5B, respectively (B is the width of the footing), where BCR increased to more than 5 under both low strain and high strain conditions. It was also established that submergence of the reinforced soil and shape and size of footing did not have a significant influence on the BCR. Moreover, the performance of tire chip–reinforced sand is found to be better than both fiber- and geogrid-reinforced sand. Bearing capacity increase of up to 1.89 times and 2.40 times was observed in tire chip–reinforced sand in comparison to fiber- and geogrid-reinforced sand, respectively. On the whole, the significant improvement in BCR and the better performance of tire chips over other alternatives ascertain that bulk utilization of tire wastes in shallow foundations has immense potential for effective waste management of large stockpiles of tires and can prove to be an economical and sustainable solution for the construction industry.

This paper analyzes the adoption of an off-grid hybrid renewable energy system (HRES) for a high-rise building owned by a public institution in Nigeria. The analysis is based on the comparison between the use of a single criterion and multiple criteria in the selection of the most feasible energy system. The proposed HRES comprises of a wind turbine, diesel generator, photovoltaic (PV), and battery storage system. Hybrid optimization of multiple energy resources (HOMER) software was used to design the HRES for a case study (based on a single criterion-total net present cost), while Evaluation Based on Distance from Average Solution (EDAS) method was used to evaluate the effect of choosing an optimal system based on multiple criteria. Based on the simulations conducted with HOMER, eight feasible HRES (ES1-ES8) were identified. When the feasible HRES were ranked based on total (NPC), the optimal configuration comprises 70 kW PV modules, 20 kW diesel generating set, 40 kW converter, and 70, 3000 Ah batteries. The results obtained from the optimization process were subjected to a multi-criteria analysis based on sustainability principles. The ranking of the first two systems (ES1 and ES2) returned by single criterion (total NPC) remained the same, while changes were observed in the ranks of the remaining systems (ES3–ES8). This modular feasibility study shows that it would be economical to power the entire university using HRES. It is expected that this study would help the university communities and other stakeholders make informed decision during the planning stage of similar projects.

Electrochemical wet absorption composite system has an excellent potential to remove Hg⁰ from flue gas. In this study, ruthenium iridium titanium platinum quaternary composite electrode is used as an anode and titanium electrode is used as the cathode, and KI/I₂ absorption solution is introduced into the electrocatalysis system as an electrolyte to form KI/I₂ electrochemical catalytic oxidation system. The removal rate of Hg⁰ in flue gas can be increased to 92.3%. The effects of electrolytic voltage, current, Pt content, I₂ concentration, and the ratio of KI/I₂ on the removal of Hg⁰ were discussed. The possible free radicals in the electrochemical cathode, anode, and solution were characterized and tested by XRD, SEM, UV-Vis (detection of H₂O₂, ·OH, O₃), and FTIR (detection of IO₃⁻). Combined with experimental data and theoretical derivation, the mechanism of Hg⁰ removal from flue gas by electrochemical catalytic oxidation alloy formation wet absorption combined process was studied. The results show that the combined process, which is a promising technology can not only improve the removal efficiency of Hg⁰, but also realize the resource recovery of Hg⁰ and I₂, and provide a feasibility study for the subsequent regeneration of KI/I₂ absorption solution.