Abstract

Microplastics are a major form of anthropogenic pollution, and over time, the sediment at the bottom of aquatic environments becomes the sink for the denser of these particles. By mapping and analyzing sediment from lake and estuary systems, this study aimed to find spatial relationships between water and sediment dynamics at stream-to-slack-water transitions and resulting microplastic sediment accumulation characteristics. Sediment was collected along transects extending from the stream mouth to open water depositional environments at four unique study sites. After a series of separations from collected sediment, microplastics were weighed to map longitudinal variations in plastic concentration. At all study sites, the highest concentrations of microplastics (up to 14% dry weight) in sediment were found to focus in spatial hotspots peaking 600–700 m down gradient from the transition to a low-energy environment in intertidal freshwater estuary systems, and 150 m downstream in a lake system, all being associated with environments of clay-dominated sediment deposition. The dominant types of plastics identified were cellophane and polydimethylsiloxane. We hypothesize these spatial hotspots of microplastic accumulation may result from the unique diversity of density ranges for microplastic sediment, ranging from just above 1 g/cm³, but below the 2.7 g/cm³ common for natural mineral sediment, thus creating plastic depositional locations that are spatially offset from those of common mineral grains.

Abstract

Sewage treatment plays a crucial role in sustainable urban and industrial development. This study focuses on the generation and treatment of sewage from residential, institutional, commercial, and industrial sources, distinguishing between grey water and black water. While grey water is relatively easier to treat, conventional practices in India merge both streams for processing. This research evaluates the application of advanced Membrane Bio Reactor (MBR) technology in a Sewage Treatment Plant (STP) at an industrial township in Andhra Pradesh, India, to achieve Zero Liquid Discharge (ZLD). The study demonstrates the significant efficiency of MBR technology in removing contaminants, with Biochemical Oxygen Demand (BOD) reduced from 350 mg/L to 20 mg/L, Chemical Oxygen Demand (COD) from 650 mg/L to 50 mg/L, and Total Suspended Solids (TSS) from 150 mg/L to 4 mg/L. Additionally, oil and grease levels decreased from 19 mg/L to 4 mg/L, and total nitrogen dropped from 45 mg/L to 10 mg/L. These results affirm the effectiveness of MBR in producing high-quality treated water suitable for irrigation and toilet flushing. The research involved systematic sampling of influent and effluent wastewater over a set period, employing analytical methods like spectrophotometry and chromatography. Key operational parameters such as flux rate, transmembrane pressure (TMP), sludge retention time (SRT), and hydraulic retention time (HRT) were monitored to optimize efficiency. Comparative analysis with conventional treatment methods highlights MBR’s advantages, including superior pollutant removal, reduced footprint, and lower energy consumption. Real-time sensors and lab-scale MBR setups were used for continuous data collection and statistical analysis, confirming MBR’s effectiveness in sustainable wastewater treatment.

Abstract This study evaluated the optimal dosage and pH for removing turbidity, chloride, alkalinity, total dissolved solids (TDS), and sulfate from Kızılırmak River water using iron sulfate and aluminum sulfate (10–60 mg/L). Maximum turbidity removal efficiencies were 98.84% for iron sulfate and 78.99% for aluminum sulfate at pH 4.5. Chloride removal was 77.12% at pH 7.0 for aluminum sulfate and 74.33% at pH 6.0 for iron sulfate. Aluminum sulfate reduced alkalinity by 90.40% at pH 8.0, while iron sulfate achieved 99.21% removal at pH 4.5. TDS removal efficiencies were 99.58% for aluminum sulfate at pH 8.0 and 95.61% for iron sulfate, although total dissolved solids concentrations increased with dosage. Sulfate removal was 97.85% at pH 6.0 for aluminum sulfate and 85.92% at pH 7.0 for iron sulfate. The statistical analysis was conducted using IBM SPSS Statistics 25 to assess the relationships between coagulant type, pH, and dosage on pollutant removal. Response Surface Methodology (RSM) was applied, and analysis of variance (ANOVA) was used to determine significance. The model explained 70.7% of variance (R² = 0.707, p < 0.001). pH (p = 0.003), pH² (p = 0.002), and dosage² (p = 0.049) were significant. Kernel Ridge Regression was used for TDS removal due to overestimation in RSM. Both coagulants were effective in removing pollutants, with optimal performance depending on pH and dosage. Aluminum sulfate exhibited higher turbidity and alkalinity removal at certain pH levels, while iron sulfate achieved greater sulfate and TDS removal under acidic conditions.

Abstract

Methane, a potent greenhouse gas, has gained prominence due to its significant contribution to global climate change. Beyond its climate impact, this review recognizes methane’s dual role in influencing local and regional air quality, underscoring its growing concern in the context of contemporary environmental issues. The paper aims to provide an overview of methane sources, geographic distribution, long-term health effects, interactions with other pollutants, and the pivotal role of integrated monitoring systems in effective pollution control strategies. The review delves into the primary sources of methane emissions, including anthropogenic and natural processes. Geographically, it identifies high-risk areas, with substantial emissions concentrated in North America, Europe, and Asia. Prolonged exposure to elevated methane levels in urban and industrial settings is associated with respiratory, cardiovascular, and neurological health issues. Furthermore, methane’s interaction with other pollutants leads to the formation of secondary organic aerosols and ground-level ozone, exacerbating air quality challenges. Efficient pollution control hinges on integrating satellite and ground-based data into monitoring systems, ensuring accurate and timely information. Managing methane emissions presents a complex dilemma, impacting both local air quality and global climate. Addressing this dual challenge necessitates a comprehensive approach encompassing legislative reforms, technological advancements, increased public awareness, and international collaboration. A swift response is imperative to mitigate the adverse effects of methane emissions on the environment and human health.

Abstract

The Yamuna River, a lifeline for millions in India, has been severely polluted over the decades. From 2014–2024, substantial research has been conducted to analyze the extent of its degradation, pollution sources, and mitigation efforts. This review synthesizes studies from this decade, focusing on chemical, biological, and physical parameters of pollution, industrial and municipal waste contributions, agricultural runoff, and policy interventions. Despite increased awareness and remedial measures, the river remains critically polluted, demanding urgent and sustainable solutions. Also, incomplete data has been collected over the years. The focus of researchers has been primarily on Delhi-NCR regions, mainly because industrial and agricultural activities are more prominent in these regions, neglecting the entire stretch of the River Yamuna which is very important to understand the overall health of the river and to analyze the areas that are contributing mostly to its polluted water.