Effluent Toxicity Research Articles

Ozonation combined to BAC filtration for secondary effluent treatment containing moderate concentration of heavy metals

The treatment of industrial and urban effluents is a recognized strategy for environmental preservation, which brings benefits not only to fauna and flora but also to human health. In this paper, the combination effect of ozonation (O3) and biological activated carbon (BAC) filtration treatments on the inorganic contaminants removal, disinfection, and mitigation of toxicity in secondary effluent from wastewater treatment plants (WWTP) were evaluated. Disinfection efficiency was evaluated using total coliforms and Escherichia coli inactivation, and toxicity was investigated by Eruca sativa germination, Artemia salina larvae and Daphnia similis. The O3-BAC system was efficient to remove metals, disinfect the samples and reduce toxicity. The combined treatment reduced 99.9 % of the assessed metal concentration and ≥ 96 % on samples enriched with 2x the concentration allowed by Brazilian legislation. O3-BAC also demonstrated superior bactericidal performance compared to BAC and O3 alone, exhibiting a 5-log reduction within 24 h against total coliforms and 4-log reduction in E. coli, whereas BAC and O3 achieved ≤ 3-log inactivation. Regarding toxicity, the bioassays demonstrated that the combined treatment effect improved the relative germination of E. sativa (∼97 %), and the relative root elongation showed no differences compared to the control group (∼100 %). Similar behavior was also observed in the analysis with wheat and radish seeds, with no differences noted between the treated samples and the positive control. In relation to A. salina, no toxic results were observed even at high metals concentration. Additionally, BAC treatment reduced D. similis immobilization from 97 ± 6 % to a level with no observed effect. The observed synergy suggests that the O3-BAC combination may address a variety of pollutants and improve treatment efficacy.

Assessing the life cycle and economic impact of cement-modified biochar compared to conventional adsorbents for heavy metal removal in stormwater

Modified biochar is used for heavy metal removal from stormwater, but current modifications rely on high-cost chemicals and result in highly toxic effluents. Additionally, there is limited research on these modifications' environmental impact and cost. This study aims to investigate the life cycle analysis (LCA) and economics of the process of absorption of Cu, Pb and Zn from synthetic stormwater utilizing cement-modified biochar adsorbent and compared it with commonly available adsorbents, activated carbon and zeolite. The cradle-to-gate LCA used experimental data and the Ecoinvent 3.0 database. Adding 1.5 % cement to biochar reduced its negative environmental impact by two to three times compared to plain biochar. Cement addition enhances heavy metal removal by raising pH, promoting precipitation, and reducing metal mobility. Combined with biochar, it increases the available surface area for adsorption, further boosting the system's efficiency in contaminant removal. The cement-modified biochar had the lowest global warming potential (kg CO2 eq), about half of Paddy Husk Biochar (PHBC). Approximately 50–90 % of the environmental impact of cement-modified biochar, zeolite, and PHBC was attributed to raw material collection. The Saw Dust Biochar (SDBC) had the highest sensitivity towards transportation distances among the adsorbents considered. Due to its heightened adsorption capacity, the 98.5 % PHBC composite demonstrated the lowest environmental impacts for Cu and Zn removal in multi-metal systems. Transportation of raw materials and labor costs were the primary cost drivers for biochar-based adsorbents. Among the adsorbents, 98.5 % PHBC was the best, being cost-effective and efficient for heavy metal removal. It is suitable for at-source pollutant removal in low-rainfall and high-pollution areas. Overall, this study helped identify performance weaknesses and modification opportunities for cement modification of biochar in heavy metal pollution control.

ESSAI DE TRAITEMENT BIOLOGIQUE DES HUILES LUBRIFIANTES USAGÉES RÉCUPÉRÉES DANS DES GARAGES DE KINSHASA À L’AIDE DES URINES HUMAINES ET KAOLIN EN RÉPUBLIQUE DÉMOCRATIQUE DU CONGO

In the various car garages of Kinshasa (in the Democratic Republic of Congo), the lack of consideration of environmental standards is the basis of the voluntary and/or accidental discharges of used oils directly into the environment without any prior treatment. These used hydrocarbons are pollutants that can cause major environmental problems due to their toxicity. The aim of this study is to treat used lubricating oils from car garages biologically in order to reduce their toxic potential. To this end, an aerobic biological treatment system was set up by mixing 4L of used oils with IL of urine, 2Kg of active Kaolin and 20L of water. The reduction in the toxicity of hydrocarbons was assessed through acute toxicity tests on the species Gambusia Affinis and microbiological analyses before and after biological treatment of these oils. The results obtained on the toxicity before treatment of these oils revealed that the LC50 was around ±3 ml/g of used oils to say that the pollutant is very toxic. After biological treatment, the LC50 rise to around ±66.7 ml/g for the treated oils, which represents a significant reduction in toxicity and ranks these treated oils in the order of less toxic effluents. The microbiological analyses of the used oils before their treatment did not show any bacteria; on the other hand, the analyses after treatment made it possible to highlight the presence of bacterial colonies whose identification revealed the following bacteria: Citrobacter, Enterobacter, Klebsiella and Pseudomonas, which are mostly lipolytic. This study thus allowed to treat used oils thanks to microorganisms and the intrinsic properties of urine and Kaolin.

Integrating azo dye degradation and lipid accumulation by Candida tropicalis and Pichia kudriavzevii along with insights into underlying metabolomics for treatment of textile effluents

Azo compounds, extensively utilized across various industries, contribute to the release of toxic effluents that are detrimental to both the environment and human health. Traditional methods for azo dye removal often result in harmful byproducts or concentrated sludge, complicating disposal efforts. This study explores the potential of two yeast strains, Candida tropicalis and Pichia kudriavzevii, to effectively decolorize azo dyes (TD4, TD5, and TD6) while simultaneously accumulating lipids. The cultures achieved 80–90 % decolorization of the selected dyes during incubation, with Pichia showing higher efficiency across multiple dyes compared to Candida. Lipid profiling identified valuable fatty acids, such as palmitic acid and oleic acid, with potential applications in biofuels and other industries. Total Organic Carbon (TOC) analysis revealed a reduction in TOC, indicating degradation and mineralization of the dyes by the yeasts. Metabolic profiling via LC-MS confirmed the degradation, showing the presence of intermediates such as azoles, azolines, isoquinolines, pyridines, and benzopyrans in dye-supplemented cultures. Additionally, pathways related to energy metabolism, amino acid metabolism, drug metabolism (cytochrome P450), degradation of aromatic compounds, and steroid biosynthesis were enriched in the dye-treated cultures. Lipid output in the presence of dyes ranged from 40 % to 90 %. The study thus demonstrates a proof of concept for economically viable lipid production combined with efficient dye removal, presenting a sustainable solution to environmental and industrial challenges.

Treatment of produced water from the Permian Basin: Chemical and toxicological characterization of the effluent from a pilot-scale low-temperature distillation system

Thermal distillation presents a promising solution to achieve the beneficial reuse of hypersaline-produced water (PW). This study evaluated the performance of a novel pilot-scale low-temperature thermal distillation system treating PW from the Permian Basin and studied the suitability of the effluent for surface discharge applications. The robustness of the system was evaluated by monitoring over 16 key parameters during continuous operation. Water quality was assessed using a targeted chemical scheme and whole effluent toxicity (WET) tests with model organisms from four trophic levels. The system showed a robust performance during the operation and effectively reduced salinity (>99%), major ions (95–99%), heavy metals (60–100%), ammonia (93%), and organics (43–60%) in feed PW. The WET assessment showed adverse effects on the organisms across multiple trophic levels, involving algae, invertebrates, fish, and bacteria. Comprehensive chemical characterization identified 14 constituents listed as priority pollutants in the distillate, including volatile and semi-volatile organic compounds, metals, and nitrogenous compounds. This study identified 5 constituents at potentially toxic levels for the organisms tested, providing insight into additional polishing steps that may be coupled with distillation to achieve non-toxic effluents suitable for discharge. This study serves as a critical resource for future risk-based research, informs risk assessment efforts, and guides the development of treatment strategies for the beneficial reuse of hypersaline PW.

Seawater submersion for cylindrical lithium-ion batteries thermal runaway prevention

Lithium-ion batteries (LIBs) are currently used in various electric vehicles, including electric boats. To assess the risk of fire due to thermal runaway of the LIB during the operation of ferries, seawater can be used as a cooling fluid for the LIB to prevent thermal runaway as it is abundant. However, the seawater could corrode the electrodes of the battery, which would lead to toxic wastewater. Prevention of thermal runaway of lithium-ion batteries by submersion in seawater needs to be investigated to clarify the corrosion that could lead to toxic wastewater. In this study, fully charged, pristine 18650 NMC Li-ion cells were submerged in synthetic seawater (SSW) to investigate the corrosion effect compared to deionized (DI) water. The results showed that SSW induced rapid voltage discharge, leading to corrosion on the electrodes and toxic effluents, while DI water maintained the stability of the cells and did not cause any corrosion effect. In addition, the prevention of thermal runaway was investigated by exposing fully charged LIB to extreme overheating conditions. The liquid submersion system was activated by rapid voltage drop monitoring to evaluate its effectiveness in preventing thermal runaway (TR). The investigation of TR prevention by SSW submersion showed that the TR process can be effectively prevented. In addition, no corrosion effect was observed during submersion in SSW as the battery voltage was not applied. This study shows that seawater can be used to prevent TR in LIB and does not cause environmental problems comparable to water.

Short-Term Chronic Toxicity of Copper to Hyalella azteca: Contrast in Terms of Equilibrating Diet, Diet Type, and Organic Matter Source.

The most up-to-date regulatory guidelines for establishing acute and chronic numeric limits for copper in freshwaters are based on a biotic ligand model for various species, but the model for Cu lacks data on dietary uptake. In addition, some common macroinvertebrate toxicity assay parameters are less representative of the ecosystem. We investigated the effects of diet and its type in the experimental setup and as an exposure pathway to an established amphipod (crustacean) Hyalella azteca (H. azteca) for Cu toxicity assays. We also investigated another overlooked aspect, the organic matter (OM) source. Our experiments compared the toxicity of pre-equilibrated and unequilibrated natural diets and a laboratory-favored diet in effluent and stormwater sources of organic matter adjusted to standard water characteristics. The experiments indicated a more toxic effect of the pre-equilibrated diet and natural dietary sources, and less toxic effects in the presence of effluent OM compared with stormwater OM, shifting LC50 or EC20 values by as much as 67% compared with the controls. The use of a pre-equilibrated natural diet in toxicity assays provides the advantage of producing toxicity data more representative of field conditions. Considering organic matter type, especially in dietary exposures, will better predict toxicity, accounting for copper complexation with OM from different sources and partitioning to the food supply. Adapting these ecologically relevant parameters in whole effluent toxicity testing or other assays will also provide safer regulatory oversite of discharges to surface waters.

Benchmarking produced water treatment strategies for non-toxic effluents: Integrating thermal distillation with granular activated carbon and zeolite post-treatment

The management of produced water (PW) generated during oil and gas operations requires effective treatment and comprehensive chemical and toxicological assessment to reduce the environmental risks associated with reuse or discharge. This study evaluated a treatment train that included a low-temperature thermal distillation pilot system followed by granular activated carbon (GAC) and zeolite post-treatment for processing hypersaline Permian Basin PW. Our study provides a unique and comprehensive assessment of the treatment efficiency considering a targeted chemical scheme together with whole effluent toxicity (WET) tests across four trophic levels regarding aquatic critical receptors of concern (ROC): Raphidocelis subcapitata, Vibrio fischeri, Ceriodaphnia dubia, and Danio rerio. The distillate from the thermal distillation process met various numeric discharge standards for salinity and major ions. However, it did not meet toxicity requirements established by the United States National Pollutant Discharge Elimination System program. Subsequent post-treatment using GAC and zeolite reduced the concentration of potential stressors, including volatile organics, NH3, Cd, Cr, Zn, and Mn in the final effluent to below detection limits. This resulted in a consistent toxicity reduction across all WET tests, with no observable adverse effects for R. subcapitata, C. dubia, and D. rerio (no observed effect concentration >100%), and V. fischeri effects reduced to 19%. This study realizes the feasibility of treating PW to non-toxic levels and meeting reuse and discharge requirements. It underscores the importance of implementing integrated treatment trains to remove the contaminants of concern and provides a systematic decision framework to predict and monitor environmental risks associated with PW reuse.

Acute toxicity of Oreochromis niloticus fingerlings exposed to effluent from Delta State University, Abraka Nigeria boys hostel

Studies on aquatic pollution are crucial for maintaining environmental health. This study assessed the toxicity of effluents from the male hostel site II at Delta State University (DELSU) on Oreochromis niloticus fingerlings. Behavioral responses and mortality rates were observed as toxicity indicators. The physicochemical characteristics of the raw effluent were evaluated and compared with standard methods. In a 96-hour static bioassay, 20 fingerlings were exposed to varying effluent concentrations: 0%, 20%, 40%, 60%, 80%, and 100%, with the experiment triplicated. Analysis showed pH (5.6), temperature (26.1°C), TDS (304 mg/L), dissolved oxygen (5.7 mg/L), chlorine (5.55 mg/L), ammonia (0.21 mg/L), and hardness (0.79 mg/L). Water analysis over 12-96 hours ranged for pH (5.45-5.62), temperature (22.50-26.30°C), TDS (61.50-237.50 mg/L), DO (4.45-6.00 mg/L), chlorine (0.84-3.98 mg/L), ammonia (0.14-0.37 mg/L), and hardness (6.52-31.93 mg/L), with no statistically significant differences (p>0.05). Behavioral responses included air gulping, irregular swimming, and lack of reflex. Mortality depended on effluent concentration, with no deaths at 0%-80% but 80% mortality at 100%. Lethal times for 50% and 95% mortality at 100% concentration were 48.6 and 102.8 hours, respectively. Diluting or treating wastewater before release is necessary to prevent fish mortality in the wild.

Photo-Fenton like catalyst system with CuCOFe2O4@AC nanoparticles for ciprofloxacin removal from aqueous solutions and effluent toxicity assessment by Escherichia coli and Enterococcus faecalis bacteria

In this study, the removal of the antibiotic ciprofloxacin (CIP) from aqueous solutions was investigated using the Photo-Fenton like (PFL) process and CuCOFe2O4@AC (CAC) magnetic nanoparticles as catalysts. First, CAC nanoparticles were synthesized and their characteristics were determined by XRD, VSM and FESEM, EDS, Mapping, FTIR. The removal efficiency of CIP in each of the nanomaterial processes, including UV, H2O2, CAC, UV+H2O2, CAC+H2O2 (Fenton like), and UV+CAC+H2O2 (PFL), were 1.0%, 7.97%, 61.37%, 6.0%, 73%, and 84%, respectively. Therefore, the PFL process was optimized as a suitable process, and the optimal conditions were determined as follows: H2O2 concentration of 2500 mg/L, pH of five, CAC dose of 600 mg/L, CIP concentration of 15 mg/L, and contact time of 50 min. The removal efficiency of CIP was achieved at 95.99%. The kinetic studies on the PFL process for the removal of CIP shown that the first order kinetic model exhibits better compatibility with the obtained results compared to other investigated kinetic models. Furthermore, the synergistic effect of the PFL process was equivalent to 1.8 times the individual processes. The results of microbiological tests in treated wastewater samples and control sample indicate the non-toxicity of residual pharmaceuticals wastewater on E. coli and E. faecalis bacteria. Due to the non-toxicity of the wastewater and the ability to recover nanoparticles using magnetism, as well as the possibility of recycling the nanoparticles, this technique can be effectively used as a suitable process in pharmaceutical industry wastewater treatment.

Impact of Effluent Treatment Plant Sludge on Growth, Physiology, and Biodegradation Potential of Cyanobacteria: Anabaena variabilis, Nostoc muscorum, and Nostoc sp.

Organic compounds and pollutants from industries like oil refineries, such as total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbons (PAHs) are known to pose toxic effects to the environment by degrading the soil and water quality along with the deposition of heavy metals thereby causing a threat to the life forms existing in them. This pose of imbalance in the ecosystem calls for an exigent notice and effort regarding controlling it. Hydrocarbon sludge from Effluent Treatment Plant (ETP) is one such toxic effluent eluted from oil refineries, and that is yet to be reported for a biodegradation study. Among a huge number of physical and chemical techniques, bioremediation has been a much talked about measure but is not in the required scale of practice yet. The reason could be a lack of efficient standardization for environmental applications. Cyanobacteria being well-known for their ability to survive difficult environmental conditions efficiently and to adapt to a mixotrophic nature, makes them ideal for performing bioremediation at a large scale in the open environment. The study aimed to quantify this ability of cyanobacteria by assessing the TPH content of the treatment sample, Effluent Treatment plant (ETP) hydrocarbon sludge pre- and post-treatment using GC-FID. The study was designed to treat the sludge by cyanobacterial strains in a pre-determined lethal dose concentration and monitor the activity of enzymes vital for a basic degradation metabolism, in addition to the growth rates of the cultures. The figures obtained from the enzyme assays and the growth rates appeared to be collateral in the direction of it being a highly promising bioremediation approach that could be efficiently performed by increasing the scale of application. The chromatograms obtained from the GC-FID depicted significant reductions in the TPH content of the treated samples that strongly indicated the potential of the cyanobacterial cultures to bioremediate an oil- contaminated site or treat toxic effluents from oil refineries.

Data driven multiple objective optimization of AAO process towards wastewater effluent biological toxicity reduction

While the anaerobic-anoxic-oxic (AAO) process is the most widely applied biological wastewater treatment process in municipal wastewater treatment plants (WWTPs), it struggles to meet the increasing demands on biological toxicity control of the treated effluent. To tackle this challenge, this study develops machine learning (ML)-based models for optimizing the AAO treatment process towards improving its toxicity reduction efficacy for the effluent. The water quality parameters, treatment process parameters, and biological toxicity information (based on the nematode bioassay) of the effluent collected from 122 WWTPs in China are used to train the models. The validated models accurately predict the effluent’s quality parameters (average R2 = 0.81) and the biological toxicity reduction ratio of treatment process (R2 = 0.86). To further improve the toxicity reduction, we developed a multiple objective optimization framework to optimize the AAO process via unit process recombination. In the short-range unit combination, the toxicity reduction ratio of the four-unit combined processes (up to 79.8% of anaerobic-aerobic-anaerobic-aerobic) is significantly higher than others. After optimization, it helps to improve the average toxicity reduction efficacy of 122 WWTPs from 48.6% to 70.7%, with a maximum of 87.5%. The methodologies and findings derived from this work are expected to provide the foundation for the optimization, expansion, and technical transformation of biological wastewater treatment in WWTPs.

4-Chloro-2-methylphenoxyacetic acid decomposition by production of reduction species in sulfite excitation through photolysis

This study focuses on the MCPA reduction in sulfite excitation under UV irradiation (US process). After 20 min of reaction time, the ideal pH was 11, and the MCPA: sulfite molar ratio was 3:1. in the PFO kinetic model kobs and robs, range, reach 0. 299 to 0. 029 min−1 and 14.95 to 5.80 mgL−1. Additionally, kinetics and IUPAC methods were used to calculate EEO, which demonstrates that EEO increases from 1.54 to 8.02 kWh as MCPA concentration rises from 50 to 200 mg L−1. m− 3. In order to study intermediate products and the decomposition of MCPA, LC-MS was used and intermediates were detected include C5H8O3 and C5H10O and C6H8. These basic substances have a lot of potential to transform into carbon dioxide and water. Before treatment, the inhibition zone was 39 mm; after 30 min of reaction time, it decreased to 11.4 mm. The reduction in bacterial growth inhibition and intermediate production is evidence that the US process causes effluent environmental toxicity. The US process produces effluent toxicity to the environment, as evidenced by the decrease in bacterial growth inhibition and intermediates production. The US process produces decreasing effluent toxicity to the environment, as evidenced by the decrease in bacterial growth inhibition and intermediates production.

Anaerobic treatment removing tetrabromobisphenol A and biota safety: How do tropical aquatic species respond to effluent toxicity over short- and long-term exposures?

Wastewater containing tetrabromobisphenol A (TBBPA), a commonly used flame retardant found in wastewater, can present significant toxic effects on biota, yet its impact on tropical freshwater environments is not well understood. This study explores the effectiveness of two independent anaerobic treatment systems, the acidogenic reactor (AR) and the methanogenic reactor (MR), for the ecotoxicity reduction of TBBPA-rich wastewater in four tropical freshwater species. Despite presenting good physicochemical performance and reduced toxicity of the influent for most species, AR and MR treatments remain acute and chronic toxicity. Overall, MR exhibited greater efficacy in reducing influent toxicity compared with AR. TBBPA bioaccumulation was observed in Chironomus sancticaroli after short-term exposure to 100% MR effluent. Multigenerational exposures highlighted changes in the wing length of C.sancticaroli, showing decreases after influent and AR exposures and increases after MR exposures. These findings underscore the need for ecotoxicological tools in studies of new treatment technologies, combining the removal of emerging contaminants with safeguarding aquatic biota. PRACTITIONER POINTS: Acidogenic and methanogenic reactors reduced the acute and chronic toxicity of wastewater containing tetrabromobisphenol A. Both treatments still exhibit toxicity, inducing short- and long-term toxic effects on four native tropical species. The aquatic species Pristina longiseta was most sensitive to effluents from acidogenic and methanogenic reactors. TBBPA concentrations recovered from Chironomus sancticaroli bioaccumulation analysis ranged from 1.07 to 1.35 μg g-1. Evaluating new treatment technologies with multiple species bioassays is essential for a comprehensive effluent toxicity assessment and ensuring aquatic safety.

Fenton-like Degradation of Methylene Blue on Attapulgite Clay Composite by Loading of Iron-Oxide: Eco-Friendly Preparation and Its Catalytic Activity.

The continuous discharge of organic dyes into freshwater resources poses a long-term hazard to aquatic life. The advanced oxidation Fenton process is a combo of adsorption and degradation of pollutants to detoxify toxic effluents, such as anti-bacterial drugs, antibiotics, and organic dyes. In this work, an activated attapulgite clay-loaded iron-oxide (A-ATP@Fe3O4) was produced using a two-step reaction, in which attapulgite serves as an enrichment matrix and Fe3O4 functions as the active degrading component. The maximum adsorption capacity (qt) was determined by assessing the effect of temperature, pH H2O2, and adsorbent. The results showed that the A-ATP@Fe3O4 achieves the highest removal rate of 99.6% under optimum conditions: 40 °C, pH = 3, H2O2 25 mM, and 0.1 g dosage of the composite. The dye removal procedure achieved adsorption and degradation equilibrium in 120 and 30 min, respectively, by following the same processes as the advanced oxidation approach. Catalytic activity, kinetics, and specified surface characteristics suggest that A-ATP@Fe3O4 is one of the most promising candidates for advanced oxidation-enrooted removal of organic dyes.

A New Synthesis Method and Characterization of Graphene Oxide Nanocomposites for the Leather Tanning Process

Environmental pollution caused by wastes generated from chrome tan is a major concern nowadays. This study aimed to develop an eco-friendly alternative tanning agent using graphene oxide (GO) based nanocomposite materials. GO was synthesized by a new approach with modification of the Hummers method. Two types of GO-based nanocomposites, GO-TiO2 (GT) and GO-TiO2-PEG (GTP) were prepared by adding TiO2 nanoparticles and polyethylene glycol (PEG) as surface modifiers. They were successfully applied to leather tanning processes at different concentrations (2%, 4%, and 6%). Both synthesized GO, GO-nanocomposites, and the resulting tanned leathers were characterized by Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), and Fourier-transform Infrared Spectroscopy (FT-IR). Different physico-mechanical properties of leathers tanned with nanocomposites were evaluated and the results were compared with chrome-tanned leathers. The tensile strength of chrome-tanned leather was 223 (kg/cm) whereas the maximum tensile strength was found at 228 (kg/cm) and 233 (kg/cm) in 6% GO-TiO2 and GO-TiO2-PEG tanned leathers respectively. The environmental pollution impact of the effluents generated by the new tanning process was assessed. The COD of effluents generated from chrome tanning was 4800 ppm which was significantly reduced to 2400-1440 ppm and 2880-1920 ppm when GO-TiO2 (GT) and GO-TiO2-PEG (GTP) were applied in leather tanning respectively. The TDS and BOD were found at 183.8 and 200 ppm in conventional chrome-tanned wastewater which were significantly reduced to the range of 47.5-18.3 and 100-50 ppm respectively in liquid wastes obtained from the GO-composite tanning process. The maximum reduction of COD, BOD, TDS, and TSS in leather waste liquid was found with the application of 2% GO-nanocomposites in tanning. The results revealed that leathers tanned with nanocomposites possess characteristic properties which were very similar to those observed in chrome-tanned leathers whereas the new tanning agents drastically reduced the intensity of pollutants in leather effluents. The application of new nanocomposites in the leather tanning process is an innovative effort. This new nanocomposite-tanning method showed minimal consequences regarding environmental pollution with the generation of less toxic effluents from the respective tanning process.

Review of Mining and Sanitation Waste Water Management and Their Contribution to Water Contamination in Zambia

This research digs into the convoluted topography of water contamination in Zambia's Copperbelt Province, with an emphasis on the important contributions of mining and sewage effluent. This report provides major conclusions about the origins, types, and effects of contaminants in the region's water bodies based on a thorough review of current research and empirical evidence. Mining activities emerge as a major source of water pollution, with effluent contaminated with heavy metals, sulphates, and other compounds that pose serious hazards to aquatic ecosystems and public health. Despite efforts to improve wastewater treatment, shortcomings persist, resulting in the leakage of toxic effluent into neighboring waterways. Similarly, sewage wastewater contributes to contamination by including faecal coliforms, nutrients, oils, and heavy metals. The effects of water contamination are far-reaching, as indicated by increasing pollutant concentrations in stream sediments and downstream bodies. Aquatic life suffers from habitat destruction, diminished biodiversity, and negative health effects, while communities relying on these water supplies face increased health risks. Given these issues, the paper analyses potential solutions and recommendations for effective wastewater management, with a focus on interdisciplinary collaboration, technical innovation, and regulatory enforcement. Initiatives fostering recycling, resource recovery, and the implementation of advanced treatment technology hold promise for minimizing water pollution and maintaining sustainable water management practices in the Copperbelt Province.

Health Effects of Heavy Metal Contamination in Drinking Water

Water is essential for life, be it the life of animals, plants or human beings. It’s our prime duty to protect, manage and preserve the quality of water. Uncontrolled anthropogenic activities have resulted in contamination of fresh water resources thereby affecting the health of living beings. Rampant industrialization is a major environmental problem on the global scale for the pollution of fresh water with toxic effluents containing heavy metals. Contamination of surface water by heavy metals is the greatest quality issues because of their toxic nature, increased release and negative impact on the health of human beings. Water-borne diseases remain one of the major health concerns in the world. Heavy metals are individual metals and metal compounds that can impact human health. Exposure of humans to metals such as antimony, arsenic, barium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, tin, zinc, etc results in chronic and acute toxicities. The toxicity of heavy metals depends on their concentration, period of exposure and route of exposure. Humans are exposed to heavy metals either by inhalation from the atmosphere, intake through drinking water, or by ingestion through the skin by dermal contact. The present review describes the analysis of ‘heavy metal contamination in drinking water’ with reference to definition, sources, health effects on humans and preventive measures. This study suggests that, the best way to get rid of heavy metal contamination in drinking water is to remove toxic heavy metals by using the best water purification system. Also, the ground water resources must be monitored for quality assessment, source identification and bioremediation of heavy metals.

Studies on sulfur liberation characteristics of Pakistani high sulfur low-rank coal using Hardgrove grinding

ABSTRACT Coal remains the backbone of developing countries’ energy needs and economic development. Coal with improved quality standards is in high industrial demand as it emits minimal CO2, NOx, and SOx. This paper investigates the sulfur liberation characteristics of high-sulfur, low-grade Pakistani coal. The research utilizes Hardgrove grinding and takes advantage of the large differences in hardness and grindability to achieve effective liberation and separation of coal from mineral materials. The proposed mechanism achieves the liberation of microsized pyritic sulfur up to 100 µm in coal. In addition to this, the proposed mechanism achieves a good carbon grade of about 34.58% of the concentrated coal when ground below the liberation size by this mechanism. Based on the results, this process improves the carbon grade of coal by 74.60%, the ash removal efficiency by 34.22%, and the desulfurization rate by about 77.01%. This developed methodology has several important features, such as no use of chemicals, no use of water, reduced energy consumption, dual features of liberation and separation, and elimination of toxic effluents from coal.

Removal of polycyclic aromatic hydrocarbons (PAHs) from produced water using the microalgae Chlorella vulgaris cultivated in mixotrophic and heterotrophic conditions

Chlorella vulgaris was cultivated for 15 days in 10 different treatments under mixotrophic and heterotrophic conditions, using wastewater from oil and poultry industries as the culture medium. The blends were made with produced water (PW), sterilized produced water (PWs), sterilized poultry wastewater (PoWs), sterilized seawater (SWs), and the addition of sodium nitrate to evaluate cell growth in treatments and the removal of PAHs. The heterotrophic condition showed more effective removal, having an initial concentration of 3.93 μg L−1 and a final concentration of 0.57 μg L−1 of total PAHs reporting 83%, during phycoremediation of (PW) than the mixotrophic condition, with an initial concentration of 3.93 μg L−1 and a final concentration of 1.96 and 43% removal for the PAHs. In the heterotrophic condition, the blend with (PWs + SWs) with an initial concentration of 0.90 μg L−1 and a final concentration of 0.32 μg L−1 had 64% removal of total PAHs compared to the mixotrophic condition with 37% removal having an initial concentration of 0.90 μg L−1 and a final concentration of 0.56 μg L−1. However, the best result in the mixotrophic condition was obtained using a blend of (PWs + PoWs) that had an initial cell concentration of 1.18 × 105 cells mL−1 and reached a final cell concentration of 4.39 × 105 cells mL−1, an initial concentration of 4.76 μg L−1 and a final concentration of 0.37 μg L−1 having a 92% total removal of PAHs. The biostimulation process increased the percentage of PAHs removal by 45% (PW) in the mixotrophic condition. This study showed that it is possible to allow an environmental remediation strategy that significantly reduces effluent toxicity and generates high value-added biomass in contaminated effluents rich in nutrients and carbon, based on a circular bioeconomy model.