Biochemical methane potential (BMP) and specific methanogenic activity (SMA) tests are performed to assess sludges’ ability to degrade substrates anaerobically. Traditionally, the Modified Gompertz model is applied to estimate methane production and to describe methanization kinetics. However, technical literature reports other models that can be used for these purposes and may be equally or much suitable. This work aimed to determine the BMP and SMA of four types of anaerobic sludges, conduct a kinetic study of methane production, apply six mathematical models in BMP assays, and evaluate which one best describes the methanization bioprocess. The tests were carried out in batch reactors (50 mL reaction volume) maintained at mesophilic temperature (35 °C) and under agitation (150 rpm). Glucose and a volatile fatty acids solution were used as substrates. As inoculants, sanitary sludge, brewery sludge, and two sludges from the swine wastewater treatment (SWS) were used, one of which was previously adapted to microaerobic conditions. SWS degraded the substrates more quickly and returned the highest BMP, SMA, and methane concentration values in the biogas. Thus, in studies of methane production and energy recovery, the application of SWS can be advantageous. Mathematical models that describe exponential functions, mainly the Fitzhugh model, were the most adequate to describe methane production kinetics from readily biodegradable substrates.

The extensive release of heavy metals into the natural water bodies has become globally prevalent from past few decades. Heavy metal toxicity is becoming a serious threat to human and the environment. Due to their prolonged half-life, potential accumulation in different parts of body, and non-biodegradability, metal ions are being obvious entities that can cause several hazardous health risks. A number of methods have been developed for the detection of heavy/toxic metals based on sensors. Among the various new technologies, chemical and optical nano sensors are emerging technology to detect toxic heavy metals. Several nano sensors have been developed using nano materials, synthesized from green or chemical methods. The nano sensors are convenient to prepare and provide enhanced limit of detection, limit of quantification, and onsite detection. This review covers the recent work reported from 2013 to 2019 for the detection of heavy metals using sensors based on nano materials synthesized by different routes. Graphical abstract

The importance of studying the atmospheric pollution due to its effects on human health and other ecosystems, the inexistence of national production of equipment for air sample collection, and the high cost of the imported equipment (especially in developing countries) led the authors of the present work to construct a low-cost Gent type sampler. The construction of the sampler was carried out by combining low-cost materials with good mechanical strength (such as nylon 6.0), hydraulic piping PVC, and the use of a 3D printer. The innovation of the present work is the employment of a 3D printer using ABS polymer to create the grids that cannot be machined. In addition to the sampler, the system is composed of a vacuum pump, a gas meter, and a rotameter. The total cost of the sampling system amounted at about 1200 USD, and the cost of the manufactured Gent type sampler did not reach 100 USD. The results obtained while using this set for sampling atmospheric aerosol for a period of 11 months were compared with the mass concentration of PM₁₀ obtained from the official environmental company, CETESB of São Paulo State, Brazil, showing good correlation with those from CETESB — which confirmed its effectiveness and suitability for use. The low cost, easy operation, and versatility of the built Gent type sampler enable its use for scientific and academic purposes. The equipment can be useful in environmental monitoring networks, in low-income regions, and as an instrument for environmental education used in universities.

In the present work, a systematic review and meta-analysis were performed to examine the probable relation between maternal exposure to bisphenol A (BPA), as estrogen-disrupting compounds, and gestational diabetes mellitus (GDM), and impaired glucose tolerance (IGT). We comprehensively searched three electronic databases to retrieve published studies on maternal exposure to BPA and GDM/IGT, through February 2021. Cochran’s Q test and I² statistics were employed for testing heterogeneity across studies. DerSimonian and Liard random-effects model was used to determine the pooled estimates. Otherwise, the fixed-effects model with inverse-variance weights was applied. Sensitivity analysis was performed to determine the robustness of the results by excluding each study from the pooled estimate. The potential publication bias was examined using Begg’s and Egger’s tests. The pooled odds ratio did not show BPA exposure to be a significant risk factor for GDM (OR = 0.90, 95% CI = 0.62–1.33, I²: 50.7%). Also, no significant association was observed between BPA exposure and risk of IGT (OR = 0.93, 95% CI = 0.40–2.18, I²: 11.5%). Based on the findings of this study, no association was found between exposure to BPA during pregnancy and the risk of GDM/IGT. Albeit no heterogeneity was found between studies.

Dissimilatory nitrate reduction processes, including denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA), are important pathways of nitrate transformation in the aquatic environments. In this study, we investigated potential rates of denitrification, anammox, and DNRA in the sediments of two subtropical rivers, Jinshui River and Qi River, with different intensities of human activities in their respective catchment, China. Our objectives were to assess the seasonality of dissimilatory nitrate reduction rates, quantify their respective contributions to nitrate reduction, and reveal the relationship between dissimilatory nitrate reduction rates, functional gene abundances, and physicochemicals in the river ecosystems. Our results showed higher rates of denitrification and anammox in the intensively disturbed areas in autumn and spring, and higher potential DNRA in the slightly disturbed areas in summer. Generally, denitrification, anammox, and DNRA were higher in summer, autumn, and spring, respectively. Relative contributions of nitrate reduction from denitrification, anammox, and DNRA were quite different in different seasons. Dissimilatory nitrate reduction rates and gene abundances correlated significantly with water temperature, dissolved organic carbon (DOC), sediment total organic carbon (SOC), NO₃⁻, NH₄⁺, DOC/NO₃⁻, iron ions, and sulfide. Understanding dissimilatory nitrate reduction is essential for restoring nitrate reduction capacity and improving and sustaining ecohealth of the river ecosystems.

The pool of primordial follicles formed in the ovaries during early development determines the span and quality of fertility in the reproductive life of a woman. As exposure to occupational and environmental toxicants (ETs) has become inevitable, consequences on female fertility need to be established. This review focuses on the ETs, especially well-studied prototypes of the classes endocrine disrupting chemicals (EDCs), heavy metals, agrochemicals, cigarette smoke, certain chemicals used in plastic, cosmetic and sanitary product industries etc that adversely affect the female fertility. Many in vitro, in vivo and epidemiological studies have indicated that these ETs have the potential to affect folliculogenesis and cause reduced fertility in women. Here, we emphasize on four main conditions: polycystic ovary syndrome, primary ovarian insufficiency, multioocytic follicles and meiotic defects including aneuploidies which can be precipitated by ETs. These are considered main causes for reduced female fertility by directly altering the follicular recruitment, development and oocytic meiosis. Although substantial experimental evidence is drawn with respect to the detrimental effects, it is clear that establishing the role of one ET as a risk factor in a single condition is difficult as multiple conditions have common risk factors. Therefore, it is important to consider this as a matter of public and wildlife health.

After years of development, paste backfill technology has become an important part of China’s green safety mine construction and coal green mining technology system in the new era. In this paper, the research status of paste backfill technology in China’s coal mines is expounded from the aspects of paste backfill materials, strata control theory, and paste backfill technological process. Based on the statistics of the distribution number of coal mines adopting paste backfill technology, several typical paste backfill mines are listed, and the parameters of backfill panel, geological conditions, and paste backfill effect are analyzed, the general conditions of applying paste backfill technology in coal mines are summarized. Finally, some problems in the application of paste backfill technology are pointed out, and the future development of backfill mining is prospected from the research and development of backfill materials, deep underground backfill mining, intelligent paste backfill, and other aspects. This paper provides a reference for a comprehensive and in-depth understanding of the current development status of paste backfill technology in China.

Although water occupies 75% of the earth’s surface, only 0.0067% of the total water is available for human activities. These statistics further decline with the population growth and consequent multiplication in the amount of annual waste produced. The demand for clean and safe drinking water has always been a prime concern in the global scenario. Among various types of waste materials, endocrine-disrupting chemicals (EDCs) and pharmaceutical effluents have become a constant threat to the aquatic ecosystem and possess challenges worldwide. Endocrine-disrupting chemicals (EDCs) are a mixed group of emerging concern chemicals with the ability to mimic the mechanisms of biosynthesis, transport, and metabolism of hormones. These chemicals pose various health threats such as early puberty, infertility, obesity, diabetes, reproductive disorders, cancerous tumors, and related disorders (immune cells, hormones’ activity, and various organs). On the other hand, pharmaceutical compounds such as antibiotics also harm the natural environment, human health, and soil microbiology. Their low concentration, ranging from a few ng/L to μg/L, gives rise to a micro-pollution phenomenon, which makes it difficult to detect, analyze, and degrade in wastewater treatment plants. Activated carbons (ACs) and other adsorbents, including naturally occurring materials (wood, keratin) are considered as nanomaterials (NMs) reference for the separation of organic pollutants. It is generally acknowledged that mass-transfer phenomena control sorption kinetics at the liquid/solid interface, with retention controlled by the sorbent/sorbate properties. Therefore, the type of interaction (strong or weak van der Waals forces) and the hydrophilic/hydrophobic properties of the adsorbent are two crucial factors. Besides, EDCs and pharmaceutical compound sorption on such kinds of nanoporous solids depend on both the molecule size and charge density. The applications of nanomaterials on non-conservative methods, like advanced oxidation processes or AOPs (e.g., photocatalysis and Fenton reaction), are contemplated as more apt in comparison to conservative technology like reverse osmosis nanofiltration, and adsorption, etc. One of the reasons is that AOPs generate free radicals (hydroxyls), which are strong oxidants for the demineralization of organic compounds and the extreme case that hydroxyl radicals can attack any kinds of pollutants with the generation of only water and carbon dioxide as final products. AOPs may imply the use of NMs as either catalysts or photocatalysts, which improve the selective removal of the target pollutant. Therefore, various literature reviews have revealed that there is a timely need to upgrade the efficiency of the remediation approaches to protect the environment against EDCs and pharmaceuticals adequately. There is currently a lack of definitive risk assessment tools due to their complicated detection and associated insufficiency in the health risk database. Hence, our present review focuses on applying carbon-based nanomaterials to remove EDCs and pharmaceuticals from aqueous systems. The paper covers the effect of these pollutants and photocatalytic methods for treating these compounds in wastewater, along with their limitations and challenges, plausible solutions, and prospects of such techniques.

Arsenic, cadmium, copper, lead, and zinc concentrations in the edible part of wild and farmed Sparus aurata from Algerian coastal were determined. The highest concentrations of cadmium (0.0078 mg kg⁻¹ wet weight), copper (0.98 mg kg⁻¹ w.w), and zinc (5.1 mg kg⁻¹ w.w) were recorded in farmed sea bream, whereas the highest arsenic (5.02 mg kg⁻¹ w.w) and lead (0.006 mg kg⁻¹ w.w) levels were registered in wild one. The statistical analysis (Friedman test, p < 0.05) indicated that the origin of fish (wild, farmed in a cage, and farmed in raceway) has relevance to the distribution of metal. Estimated weekly intake of inorganic arsenic, cadmium, and lead for a 72.5-kg person consuming Sparus aurata from Algeria does not exceed 1% of the WHO/JECFA recommended rate for all metals, certainly due to the limited consumption of seafood products by the local population. The total target hazard index is far less than “one” 1, and the carcinogenic risk for arsenic exceeds the acceptable value of 10⁻⁵. Based on the result of this study, the potential risk to human health from the consumption of contaminate farmed sea bream (in the cage) should be considered.

The first aim of this study was to synthesize and characterize reed-based-beads (BBR), an enhanced adsorbent from Tunisian reed. The second purpose was to evaluate and optimize the BBR efficiency for the simultaneous removal of oxytetracycline (OTC) and cadmium (Cd(II)), using central composite design under response surface methodology. The third goal was to elucidate the biosorption mechanisms taking place. It was shown that under optimum conditions (4.19 g L⁻¹ of BBR, 165.54 μmol L⁻¹ of OTC, 362.16 μmol L⁻¹ of Cd(II), pH of 6, and 25.14-h contact time) the highest adsorption percentages (63.66% for OTC and 99.99% for Cd(II)) were obtained. It was revealed that OTC adsorption mechanism was better described by Brouers-Sotolongo fractal equation, with regression coefficient (R²) of 0.99876, and a Person’s chi-square (χ²) of 0.01132. The Weibull kinetic equation better explained Cd(II) biosorption (R² = 0.99959 and χ² = 0.00194). FTIR and isotherm studies confirmed that the BBR surface was heterogeneous, and that adsorption mechanisms were better described by the Freundlich/Jovanovich equation (R² = 0.99276 and χ² = 0.04864) for OTC adsorption, and by the Brouers-Sotolongo model (R² = 0.9851 and χ² = 0.77547) for Cd(II) biosorption. Overall results indicate that, at last, the BBR lignocellulosic biocomposite beads could be considered as cost-effective and efficient adsorbent, which could be of socioeconomic and environmental relevance. Graphical abstract