One of the problems of wastewater disposal is the release of nitrogen and phosphorus in addition to organic and microbial substances into receiving waters, and the removal of nutrients from wastewater has become one of the main global problems because the compounds of nitrogen and phosphorus in natural aquatic environments cause eutrophication. This quantitative, sectional, and analytical research explored the use of thermo-biological methods in the return sludge line to reduce the pollution and address excessive sludge production. The research also investigated the impacts of temperature changes in the anoxic tank and the return sludge line. Results showed that the existing conventional bioreactor, with a temperature change in the return sludge to 40 °C, significantly improved total nitrogen (TN) and total phosphorus (TP) removal efficiency. Although the change in the temperature of the returned sludge increased the TN and TP removal efficiency, the removal rate was not significant, and this is despite the fact that this efficiency also decreased with increasing temperature. The study revealed a reduction in biomass production coefficient at higher return sludge temperatures, it also highlighted the negative impact on effluent quality and sludge settling capability.
Airborne particulate matter was monitored in Rajshahi city, Bangladesh, focusing on five specific locations during 2022 and 2023. Data collection covered both the dry and wet seasons. According to Bangladesh’s Air Pollution Control guidelines, the annual average concentration of PM2.5 should remain below 35 µg/m³, and the daily average should not exceed 65 µg/m³. Additionally, the daily average for PM10 should remain below 50 µg/m³ and 150 µg/m³, respectively. However, during the study period, PM2.5 concentrations were notably higher in all selected areas during the dry season. The peak PM2.5 concentration measured was 97 µg/m³ at Talaimari in November 2023. Likewise, PM10 levels peaked at 246 µg/m³ during the same month. Both PM2.5 and PM10 concentrations exceeded the limits set by the BAPCR 2022, indicating significant air pollution in Rajshahi. The elevated levels of these particulates pose serious risks to public health. The research also noted unregulated construction activities and a reduction in water bodies within the city. Consequently, strict enforcement of BAPCR 2022 and the Environmental Conservation Rules 2023 is crucial to mitigating the issue.
Layered double hydroxides (LDHs), distinguished by their lamellar nanosheet structures, are highly effective materials for hosting and intercalating functional chemicals, making them suitable for water contaminant remediation. Elevated nitrate (NO3−) levels in water and wastewater, attributed to the high solubility of nitrates, pose significant risks to aquatic ecosystems and human health. This study outlined a simple co-precipitation method for synthesizing zinc-aluminum Zn-Al-LDHs and evaluated their performance in efficiently removing nitrate ions under optimal conditions. The characterization of the Zn-Al-LDH nanostructures was conducted through various techniques, including X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA/DTA), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). Key parameters influencing nitrate adsorption, such as NO3− concentration, pH, adsorbent dosage, contact time, and temperature, were thoroughly examined in a systematic manner. Notably, the calcined form of LDH (Zn-Al-LDH-C) exhibited the highest nitrate adsorption capacity of 94%, with optimal adsorption at pH 6.9 and low temperature. Equilibrium was reached in 80 minutes, and the adsorption capacity rose to 16 mg/g. FTIR analysis confirmed the intercalation of nitrate ions into the calcined material. Adsorption isotherm studies revealed that nitrate adsorption onto Zn-Al-LDH followed the Langmuir model (R²=0.99), indicating a uniform surface and monolayer adsorption mechanism, as opposed to the Freundlich model (R²=0.90). This study demonstrates the potential of enhancing Zn-Al-LDH-C nanostructures to improve their efficiency in removing contaminants from water and wastewater, presenting a promising approach for advanced water treatment solutions.
Artificial dyes are regarded as one of the most problematic environmental pollutants. They are widely applied in the textile, print, paper, paint, pharmaceutical, food, cosmetics, and leather industries. The textile industry produces large volumes of colored wastewater, along with other pollutants such as salts, toxic substances (e.g., heavy metals, biocides, and oxidizing agents), high organic load, nutrients, and sulfur. These dyes adversely affect living organisms and ecosystems by inhibiting photosynthesis and causing health disorders such as skin irritations, allergies, cancer, vomiting, and weakened immune reactions. Thus, they should be removed using physical, chemical, and biological methods. Chemical and physical methods need regeneration processes and chemical agents, and they are expensive. In contrast, bio-decolorization by bacteria, fungi, algae, and plants is an environmentally friendly and cost-effective technique. Bacterial strains can adsorb, degrade, and flocculate dyes. Biodecolorization is positively or negatively affected by operational parameters such as agitation, pH, temperature, dye concentration, carbon and nitrogen sources, salinity, electron donors, and redox mediators. As stated, these parameters have positive (optimum concentration) and negative (beyond optimum) impacts on decolorization efficiency.
Petrochemical complexes play a pivotal role in industrial economies but present substantial environmental risks, including pollution of air, water, and soil, as well as ecological disturbances. This study applied fuzzy failure mode and effects analysis (FMEA) to perform an environmental risk assessment (ERA) of petrochemical operations. By incorporating fuzzy logic into the conventional FMEA framework, the approach effectively quantifies key risk dimensions—occurrence, severity, and detectability—using linguistic variables to reduce ambiguity. The data were obtained from operational records, environmental monitoring systems, and expert consultations to assess and prioritize risks. The main findings revealed several high-risk failure modes. It was concluded that major equipment leaks pose significant risks to soil and water, with a fuzzy risk priority number (RPN) of 0.778, necessitating measures such as advanced leak detection systems and regular maintenance. Toxic gas releases, impacting air quality, exhibited an RPN of 0.700, warranting enhanced gas monitoring and emergency response protocols. Based on the results, wastewater discharge non-compliance, with an RPN of 0.620, contributes substantially to water pollution, calling for upgraded treatment systems and stricter monitoring. The results demonstrated that water pollution accounts for the highest environmental impact (36.4%), followed by soil (31.8%) and air pollution (27.3%). Noise pollution was the least significant risk (4.5%). Mitigation strategies include advanced monitoring technologies, improved maintenance schedules, and targeted safety protocols. This study highlights fuzzy FMEA’s ability to enhance risk management in complex industrial systems and recommends its broader implementation to address environmental challenges in petrochemical operations.
Selecting a suitable and sustainable site for landfilling is a complex and multidimensional problem that involves various environmental, social, economic, and technical factors. Several approaches exist for selecting an appropriate sanitary landfill, each with its own challenges. This study addresses the need for a systematic and expert-driven prioritization of landfill site selection criteria. In this study, due to its ease, affordability, and primarily its capacity to assess numerous criteria simultaneously, a modified Delphi approach was employed to systematically prioritize the criteria for sanitary landfill site selection. The study followed a three-round Delphi design with 15 experts from relevant fields. Using a 10-point scale, experts rated 31 criteria derived from the literature that influence landfill siting decisions. The criteria spanned various landfill aspects and were categorized into three importance levels based on their weights, which was assigned by the experts using a 5-point scale. According to the results of the Delphi method, the most significant criteria for selecting landfill sites were groundwater quality, proximity to sanitary water source protection zones, hydrogeological features, and geotectonic characteristics, with respective weighted scores of 45.12, 41.76, 39.84, and 37.44 (weight=4.80). The first-level criteria reflect the possible influence of landfill leachate on the quality and quantity of water resources and the welfare and contentment of nearby communities. This study also proposed a tool to calculate the final score of the potential landfill sites based on the weighted scores of the sub-levels of the criteria. The final score serves as a measure of the overall suitability and sustainability of each site, with a higher score indicating greater desirability when comparing various locations.
Air pollution, which has long been recognized as a tangible problem due to its harmful consequences, causes irreparable damage to human health. This study investigated the relationship between long-term exposure to toxic air pollutants and the increased risk of malignant diabetes. In this study, 800 articles were found in the initial literature review. Databases used for searching included the Web of Science, Google Scholar, PubMed, and Science Direct (Scopus). In the end, 18 papers were selected. Then, all relevant studies published from 1994 to 2021 were identified. The literature showed that exposure to toxic air pollutants and their inhalation can cause complications in various organs. Chronic diabetes, caused by the reduced production of insulin by the pancreas or its failure to use it, may lead to numerous impairments and permanent effects, including amputation, renal failure, and mortality. Inhaling air pollution causes both acute and chronic heart conditions, persistent respiratory conditions, asthma episodes, neuroendocrine and immunological abnormalities, infertility, premature birth, diabetes, pulmonary, prostate, and blood malignancies, as well as mortality. This study indicates that air pollution affects pancreatic function, which can increase the probability of developing diabetes. The research also found that inhaling these substances can raise the prevalence of diabetes and have various adverse effects.
Poor hazardous waste management (HWM) poses a significant impact on the environment and human health. Although Malaysia has established policies and regulations governing the framework and outlining future directions for sustainable WM, implementing and monitoring the regulations are complex and rigorous. The need for continuous enhancement and renewal of regulations arises to keep pace with evolving technologies and changing circumstances associated with HW production. Therefore, this review critically examines HWM in Malaysia by synthesizing current regulations, relevant literature, and case studies, with an emphasis on recent technological and strategic developments. This study also delves into the current state of HWM practices in Malaysia, scrutinizing the existing regulatory framework and outlining future directions for sustainable WM. Moreover, this review aims to explore potential innovations and technologies that can shape the future landscape of HWM in Malaysia, thus ensuring a harmonious coexistence between industrial progress and environmental stewardship. Eventually, this work will provide a holistic overview of Malaysia’s HW landscape and offer forward-looking recommendations for strengthening environmental resilience, governance, and sustainability.
The lack of recycling facilities and low sorting practices at the source pose challenges in developing countries, including Annaba, Algeria. In 2022, a study was conducted to evaluate household solid waste (HSW) management practices in three localities, including El Hadjar, Berrahal, and Ain Berda. This study involved the analysis of waste from 36 bins and a survey aimed at exploring public attitudes and behaviors toward waste disposal. A significant portion of HSW was found to be organic, while certain recyclable materials, such as paper, cardboard, plastics, and metals, have been informally recycled for over two decades. The majority of respondents were male, but women showed greater involvement in waste sorting activities. Active participation in sorting was more common among small households and residents living in terraced houses or single-family homes. Although a strong sense of civic responsibility was observed, revealed by widespread membership or expressed willingness to join an association, the ‘Not in My Backyard’ (NIMBY) effect was still apparent. Although many participants supported financial contributions to waste management, few participants were comfortable with the idea of sorting bins being located near their homes. Principal component analysis (PCA) highlighted differences between urban El Hadjar and peri-urban Berrahal and Ain Berda. Proposed solutions include composting, source sorting, environmental education, and adjustments to waste collection taxes to improve HSW management.
Individuals’ daily diets include a wide variety of vegetable oils worldwide. Our study assessed the concentrations of polycyclic aromatic hydrocarbons (PAHs) in several vegetable oils (corn, sunflower, olive, soybean, sesame, and canola). A search of major international databases was conducted to find published studies on PAHs in vegetable oils between May 12, 1986, and June 20, 2021. Based on the results of 13 research articles, out of 713 retrieved studies, the most common PAHs found in corn, sunflower, olive, sesame, soybean, and canola were fluoranthene (33.6 µg/kg), dibenz[a,h]anthracene (7.13 µg/kg), phenanthrene (22.45 µg/kg), benz[a]anthracene (16.49 µg/kg), naphthalene (3.92 µg/kg), and pyrene (8.01 µg/kg), respectively. However, the lowest concentrations of PAHs in the mentioned oils were associated with benzo[b]fluoranthene (11 µg/kg), benzo[b]fluoranthene (0.28 µg/kg), dibenz[a,h]anthracene (0.13 µg/kg), benzo [b]fluoranthene (0.22 µg/kg), acenaphthene (0.05 µg/kg), and benzo(g,h,i)perylene (0.150 µg/kg), respectively. According to the continent type, PAHs in vegetable oils were detected in countries of the European Region, Eastern Mediterranean Region, and Western Pacific Region. Based on the findings, there is a country-to-country variation in the carcinogenic and mutagenic risks of PAHs. As a result, vegetable oils pose no threat to human health.
The global increase in plastics production and consumption has heightened human exposure to microplastics (MPs), raising widespread concern. Food represents a major route of human exposure. Since milk is a vital component of the human diet throughout life, its contamination warrants close attention. The current study is the first meta-analysis focusing on MP contamination in commercial milk. Three databases (PubMed, Embase, Scholar, and Web of Science) were searched up to June 2023, following the PRISMA guideline. Four relevant studies were included based on specific inclusion and exclusion criteria. The risk of bias (RoB) was assessed using the Office of Health Assessment and Translation (NTP/OHAT) tool. Four low-RoB studies were included in the meta-analysis. The results indicated that MP concentrations in the analyzed studies ranged from 16 to 10040 particles per sample. Given that milk contamination can occur at all stages (from farm to consumer), future studies should investigate how processing and packaging contribute to the presence and diversity of MPs in milk and their potential health effects. Additionally, standardized sampling and detection protocols should be developed to accurately detect and minimize MP contamination in milk. Preventive strategies are needed to limit the release of MPs into the environment and, consequently, the human body.
In the article titled "Prioritization of Sanitary Landfill Criteria Using a Modified Delphi Approach and Development of a Tool for Efficient Site Selection," published in Avicenna J Environ Health Eng. 2025;12(1):29-39 (doi:10.34172/ajehe.5506), there was an error in the Ethical approval section. The ethics approval code was incorrectly reported as: "The protocol and procedures of this study were approved by the Ethics Committee of Urmia University of Medical Sciences (IR.UMSU.REC.1400.07)." The correct ethics approval code is: IR.UMSU.REC.1400.076 The corrected sentence should read: "The protocol and procedures of this study were approved by the Ethics Committee of Urmia University of Medical Sciences ( IR.UMSU.REC.1400.076)." This correction has now been updated in both the PDF and HTML versions of the article.
The main objective of the present research study was the application of magnesium oxide (MgO) nanoparticles implanted in the matrix of biosilica for treating amoxicillin (AMX)-containing synthetic wastewater. Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used for the characterization. Although the efficiency of UV light alone was insignificant to degrade AMX (efficiency of 32%), the efficiency of the adsorption process was 42.6%, which implies the major role of the adsorption of AMX during its decomposition by photocatalysis. Regarding photocatalysis using MgO-implanted biosilica, increasing the initial pH from acidic to neutral conditions resulted in the enhanced removal of AMX (efficiency of 76%). At an optimum reaction time of 60 minutes and a photocatalyst dosage of 2 g/L, the removal efficiency (%) of AMX was found to be 94.9%. In the presence of 1 mM oxalic acid, the removal efficiency of AMX was 54.9%. The intermediate byproducts of AMX decomposition were also identified utilizing gas chromatography-mass spectroscopy (GC-MS) analysis. According to the results obtained, the treatment process of adsorption-photocatalysis using MgO-implanted biosilica can be recommended as an efficient technique for the degradation of pharmaceutical compounds such as AMX in aqueous environments.
The present study aimed to investigate and evaluate the performance of the Bu-Ali Industrial Town wastewater treatment plant (WWTP), Hamadan, Iran. In this study, the physicochemical and microbial characteristics and heavy metal contents of influent and effluent were evaluated. The mean values of total suspended solids (TSS), total dissolved solids (TDS), chemical oxygen demand (COD), dissolved oxygen (DO), biological oxygen demand (BOD5 ), cyanide, total coliform (TC), fecal coliform and pH in influent were 1210 mg/L, 2165.5 mg/L, 2187.5 mg/L, 2.4 mg/L, 967.5 mg/L, 20.8 mg/L, 1.3×1010 (MPN/100 mL), 1.2×109 (MPN/100 mL) and 6.7, respectively. Additionally, the mean values of the mentioned parameters in effluent were 94.5 mg/L, 2370.4 mg/L, 220.7 mg/L, 5.2 mg/L, 113.4 mg/L, 2.0 mg/L, 1.7×106 (MPN/100 mL), 3.5×104 (MPN/100 mL), and 8.7, respectively. The concentrations of metals including V, Cd, Co, Cu, Cr, Hg, Ni, Pb, and Zn at the inlet of the treatment plant were measured to be 3.9, 14.5, 5.6, 77.9, 142.4,<0.3, 104.0, 73.8, and 720.6 ppb and at the treatment plant, the corresponding concentrations were<0.06, 11.8, 2.4, 14.6, 19.1,<0.3, 73.1, 10.8, and 34.5 ppb. Based on the results, the measured values of some parameters, such as BOD5 , COD, coliforms, and cyanide in the effluent, were higher than the standards set by various organizations. Therefore, discharging such effluent into the environment can harm the ecosystem; their high values result from the lack of any pre-treatment units in various industries. Hence, by obliging certain industries to pre-treat their wastewater before discharging it into the combined wastewater collection system, the above-mentioned parameters can be adjusted to some extent. In addition, considering the high microbial load of the effluent, continuous disinfection and improvement of the disinfection unit can play a significant role in reducing the microbial load of the effluent.
Fluoride in high concentrations is hazardous and a threat to human life. This study used response surface methodology (RSM) to remove fluoride using ionic liquid-modified magnetic activated carbon (IL@mAC) nanocomposite and optimized the process parameters. The IL@mAC nanocomposite was synthesized by Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD), and its adsorption efficiency for removal of fluoride was investigated under different operational such as pH (2-8), contact time (15-100 minutes), initial concentration (10-50 mg/L), and IL@mAC composite (0.01-0.1 g) at room temperature. The equilibrium experiment showed that the highest removal efficiency (~88%) was obtained at pH 5, the initial concentration of adsorbent of 0.1 mg/L, the initial concentration of fluoride of 50 mg/L, and the processing time of 15 minutes. The findings indicated high correlation coefficients for the proposed model (adjusted R2=0.9527 and R2=0.8048). Furthermore, the pseudo-second-order kinetic model was ideal (R2=0.998). The current study suggested that the adsorption process optimized by effective operational factors is highly efficient for fluoride removal.
Hair spray products emit large amounts of volatile organic compounds (VOCs), which are harmful to human health and the environment. This study investigated the total volatile organic compound (TVOC) concentrations and associated health risks of popular hair spray products in Nigeria. The TVOC concentration was determined by simulating an indoor environment using a mannequin in an empty room to mimic a real-life scenario. Ten popular hair spray products used in Nigeria were sprayed on the mannequin, and the TVOC concentration was quantified using an Aeroqual Series 200 Monitor (S-200). The chronic daily intake (CDI) from inhalation, ingestion, and dermal sources was estimated. The hazard quotient associated with inhaling VOCs was also calculated using risk assessment models developed by the United States Environmental Protection Agency (USEPA). The mass generation rate of the hair sprays varied from 0.24 to 1.34 g/s. TVOC levels ranged from 67400±15790 to 134900±17420 μg/m3 . The highest TVOC concentration was determined to be 134900±17420 μg/m3 from hair sprays, with the highest mass generation rate observed in an air mousse. The risk assessment results showed that ingestion accounted for 73% and 66% of the total CDI in adults and children, respectively. The average hazard index for all exposure pathways from inhalation was obtained to be 2.19×105 and 1.57×104 for children and adults, respectively, which is unacceptable. These findings enlighten consumers and regulatory bodies on the concentration of VOCs emitted from hair spray products in enclosed spaces, as well as health risks, and help plan mitigation strategies.
The effect of environmental pollution on contamination and the safety of foods for human consumption is a serious global issue, which has been widely addressed. Heavy metals are among the most frequent environmental pollutants that are extremely health-threatening. This cross-sectional study aimed at investigating the heavy metal content in different types of bread used in Zahedan, Southeastern Iran. A total of 36 different bread types, such as Sangak, Lavash, and Taftoon, baked by bakeries in Zahedan, were examined for various heavy metals (cadmium, lead, chromium, arsenic, copper, cobalt, mercury, zinc, and nickel) by inductively coupled plasma-optical emission spectrometry. The hazard quotient (HQ) of Taftoon, Lavash, and Sangak was<1 in males, females, and children. In addition, the total health risk of the nine studied heavy metals had a ranking order of HIchildren>HIfemales>HImales>1, demonstrating an increasing potential. The total carcinogenic risk factor for bread was 9.98×10-5 and 3.26×10-3 in males and females, respectively. Regarding the carcinogenicity of heavy metals in bread samples collected in Zahedan, it is highly recommended that measures, such as implementing a food control system, proper flour storage, and training farmers, should promptly be taken to reduce contamination.
To use biotechnology for environmental decontamination, the current study attempted to isolate bacterial strains capable of assimilating hydrocarbons. To this end, oil-contaminated soil samples were obtained from a gas station in Mascara (Alegria). Two bacterial strains were identified from the tainted soil. The results demonstrated the capacity of these strains to use hydrocarbon substrates as carbon sources, including diesel, benzene, naphthalene, and toluene. The strains’ capacity to break down diesel oil at 1%, 2%, 3%, and 4% (v/v) concentrations was evaluated. According to the biochemical traits identified, the isolated strains S4 and S11 were associated with the gender of Pseudomonas and Staphylococcus, respectively. Based on these findings, both strains grew best when fed a 2% diesel oil substrate. Using oil diesel, benzene, naphthalene, and toluene as substrates, the isolates’ growth measurement characteristics revealed that strain S4 degraded hydrocarbon substrates more effectively than strain S11. In summary, these bacterial strains can reduce petroleum pollution and aid in the bioremediation process.
A highly stable and high-density amino group (6.54 µmol/m2 ) was loaded on super-hydrophobic silica aerogel derived from pumice by the ultrasonic method and used to remove arsenate (As). After ultrasonic amine grafting, the specific surface area did not change, as 832 m2 /g of a specific surface, a hole volume of 3.84 cm3 /g, and an average hole diameter of 12.39 nm were observable. The selected parameters were directly dependent on As adsorption (100% As removal at the pH rate of 6.85, reaction time of 120 minutes, and initial solute concentration of 95.21 µg/L based on multiple non-linear regression analyses). The kinetics of As adsorption was best explained by the pseudo-first-order kinetic, which is proof of the chemical adsorption mechanism. The heterogeneous surface with multilayer adsorption sites for As adsorption was obtained from various isotherm models. The maximum uptake capacity of 42.2 mg/g was observed based on the Khan model. The spent adsorbent was successfully regenerated and reused by HCl, but a substantial reduction in adsorption capacity was detected after five regeneration-reuse cycles. Based on the results, the ultrasonic method was found to be more effective, economical, and environmentally friendly compared to conventional sol-gel methods for the surface amine functionalization of silica aerogel to remove As from the aqueous solution.
Heavy metals from hazardous waste, such as batteries, electronics, cleaning products, and cosmetics, can be transported to soil through landfill leachates. Due to their persistent structure, toxic metals such as chromium (Cr), cobalt (Co), lead (Pb), and cadmium (Cd) accumulate in the soil and can cause various ecological and health risks. Hence, this study aimed to assess the extent of heavy metal pollution in the soil of landfill sites in Iran. The present study reviewed previous research on the assessment of heavy metal contamination such as Pb, arsenic (As), Cr, Cd, zinc (Zn), Co, and nickel (Ni) in soils of landfill sites. For this purpose, "Magiran", "SID", «IranMedex», "Scopus», "PubMed", "ScienceDirect" and "Web of Science" databases were searched for related articles published until 2024. Persian and English keywords including heavy metals, waste disposal sites, soil, and Iran were used for search. Eventually, out of 206 articles, 21 studies met our inclusion criteria and were included in the study. The concentrations of heavy metals, including Pb, As, Cr, Cd, Zn, Co, and Ni, were found to be higher than national and international standards in some soil samples. Therefore, landfill sites, as an anthropogenic resource, have the potential to transmit pollution to the soil. Contamination levels depend on waste composition, hazardous content, leachate production and migration, landfill age and design, soil characteristics, and operating conditions. Health and ecological risks can be mitigated by reducing hazardous waste, recycling heavy metal-containing wastes, installing anti-seepage systems, and maintaining continuous monitoring.
