Waste Management Bulletin最新文献

Toxic lead (Pb) in end-of-life silicon solar modules must be recovered to keep it out of the environment. Present literature on Pb recovery from solar waste is sparse and uses chemicals like nitric or hydrochloric acid. Previously, the authors reported Pb recovery from silicon modules by leaching and electrowinning in acetic acid. However, the Pb recovered from acetic solution contained a small amount of metallic Pb with the rest being lead oxides/acetates. These Pb compounds require further processing to obtain metallic Pb for reuse in solar panel solder, leading to additional cost and chemical waste. This paper reports recovery of metallic Pb using an electrochemical system with two half cells connected through a salt bridge. The salt bridge enables optimized recovery rates of Pb as high as 99.99 % for synthetic leachates. The first experiment to recover Pb from real silicon module waste shows 80 % recovery without optimization. The new method offers a low-cost, closed-loop, direct pathway to metallic Pb recovery from end-of-life silicon solar modules for reuse in new modules.

In this study, lupine seed (Lu-SP) and pumpkin seed shells (PSSP) biomasses were used to create alternative and effective adsorbents. Methylene blue (MB) dye was removed from wastewater using the as-prepared adsorbents at variables solution pH 2.0 –11.0, contact period (0–180 min), and adsorbent mass (0.2–2.0 g/L). The solution pH had a synergistic effect on the improved removal of MB and the optimal adsorption removal for both adsorbents occurred at pH 8.0 and 120 min. The adsorption isotherm modelling results showed a good fit with the Langmuir model, with a maximum monolayer adsorption capacity of 48.98 and 77.48 mg/g for PSSP and Lu-SP, respectively. Similarly, the pseudo-first-order (PFO) model is regarded as the best-fit kinetic model for both adsorbents and suggests the predominance of physisorption via interfacial diffusion. Mechanistic investigation of the present system suggests that both intraparticle diffusion and surface sorption mechanisms control the adsorption rate. Notably, the Lu-SP with a lower surface area (54.013 m²/g) outperformed the PSSP (235.992 m²/g) in terms of adsorption capacity under varying pH. Therefore, in addition to electrostatic interaction, adsorption into the micropores via volume filling is considered one of the adsorption mechanisms. This study, therefore, revealed that the PSSP and Lu-SP may be very helpful for removing cationic MB dye from contaminated wastewater.

Kitchen waste is a complex biomass waste, whose composition and properties vary with factors such as source, season and region. It is challenging to classify and characterize it. A thermogravimetric and kinetic study was performed to estimate pyrolysis characteristics and gas emissions of starch, peel, nut shell, and vegetables. Samples underwent pyrolysis in the Simultaneous Thermal Analysis from room temperature to 1200 K at different heating rates of 10, 20, 30 and 50 K/min. The starch had the narrowest pyrolysis temperature range, while nut shell exhibited the highest residual rate. The average activation energy for pyrolysis process calculated using Coats–Redfern method was in order of starch > vegetable ≈ nut shell > peel. The gaseous products and typical functional groups of the released volatiles were identified using specific information from Fourier Transform Infrared Spectroscopy (FTIR) and Mass Spectrometry (MS). These primarily included small inorganic molecules, aldehydes, aromatics, ethers, furans, ketones, organic acids, and phenols. Aliphatic hydrocarbons significantly contributed to the total gas yield and were the most abundant for all samples. The characteristic ion fragment with m/z = 60 was only observed in peel and nut shell, while m/z = 58 ion fragments were exclusive to starch and vegetables. The practical research can provide theoretical basis for the resource utilization and environmental management of kitchen waste.

Waste management poses a pressing global challenge, necessitating innovative solutions for resource optimization and sustainability. Traditional practices often prove insufficient in addressing the escalating volume of waste and its environmental impact. However, the advent of Artificial Intelligence (AI) technologies offers promising avenues for tackling the complexities of waste management systems. This review provides a comprehensive examination of AI’s role in waste management, encompassing collection, sorting, recycling, and monitoring. It delineates the potential benefits and challenges associated with each application while emphasizing the imperative for improved data quality, privacy measures, cost-effectiveness, and ethical considerations. Furthermore, future prospects for AI integration with the Internet of Things (IoT), advancements in machine learning, and the importance of collaborative frameworks and policy initiatives were discussed. In conclusion, while AI holds significant promise for enhancing waste management practices, addressing challenges such as data quality, privacy concerns, and cost implications is paramount. Through concerted efforts and ongoing research endeavors, the transformative potential of AI can be fully harnessed to drive sustainable and efficient waste management practices.

Traditional methods for evaluating the bioconversion capacity of organic solid waste are known for time-consuming property and often exhibit low prediction accuracy. However, leveraging fractal dimensions offers a more precise characterization of the complexity, irregularity, and spatial structure of organic solid waste. In this study, a novel and efficient method for evaluating the bio-accessibility of straw's anaerobic transformation, based on fractal dimensions, was introduced. To comprehensively compare the structural differences, this research encompasses the measurement of nine different varieties of straw under ten distinct pretreatment conditions. The regression sum of squares for these correlations consistently exceeds 0.83, highlighting the robustness of our findings. The results unequivocally demonstrate the close relationship between the fractal dimension and the structural characteristics of straw. This relationship underscores the utility of fractal dimension analysis as a reliable tool for evaluating the anaerobic bio-accessibility of organic solid waste.

This review thoroughly assesses the viability and effectiveness of biological and advanced coagulation methods for treating leachate. It offers a comprehensive analysis of landfill leachate, with a specific focus on its composition and the presence of diverse pollutants and contaminants. The study investigates leachate toxicity and evaluates advanced coagulation processes and strategies designed to remove or reduce organic contaminants by employing coagulants. The novelty of this review lies in its emphasis on demonstrating the efficacy of coagulation and flocculation methods utilizing chemicals such as alum, ferric chloride, and aluminum sulfate in leachate treatment. These methods facilitate the removal of recalcitrant pollutants and demonstrate considerable removal efficiency. Noteworthy removal effectiveness is evident in coagulation/flocculation procedures targeting various contaminants, including suspended particles, heavy metals, and xenobiotic organic compounds. Additionally, the study examines the leachate’s toxicity both before and after treatment with the coagulation process.

Bioplastics have garnered substantial interest as alternatives to conventional petroleum-based plastics. However, their management and conversion to biogas continues to be significantly challenging. In this study, we evaluated the suitability of various plastics for hydrolysis at 160 °C for 12 h using different solvents. The biogas yield (BGY) of the monomers constituting these plastics and the obtained plastic hydrolyzates was comprehensively evaluated. When water was used as a solvent, 100 % hydrolysis of polylactic acid (PLA) and polybutylene succinate (PBS) was observed. When polybutylene adipate co-terephthalate (PBAT) and polyhydroxybutyrate (PHB) were hydrolyzed with water, the degradation ratio was approximately 30 %; however, using an aqueous lactic acid solution as a solvent improved the degradation ratio to 78 % and 100 %, respectively. In the BGY test of the plastic hydrolyzates, the biogas volumes derived from the hydrolyzates were 563, 461, 337, and 573 mL/g COD-added for PLA, PBS, PBAT, and PHB, respectively. With 1,160 gCOD/L waste PLA hydrolyzate, continuous co-digestion of sewage sludge and the hydrolyzate was conducted. Organic loading rates of sewage sludge and the hydrolyzate were 2.3 and 2.4 gCOD/L/d, respectively. The operation was stable and the methane production volume from the PLA hydrolyzate was 414 L/kgCOD-added. Using highly concentrated PLA hydrolyzate, the hydraulic retention time was 19.3 days, which was only 0.7 days shorter than that of anaerobic digestion of sewage sludge only (20 days). Therefore, highly concentrated PLA hydrolyzate maintains the retention time of normal sewage sludge digestion. Conclusively, the present study has crucial practical implications for plastic waste management.

The present study investigates Direct Violet-35 (DV-35) remediation using electrocoagulation process. DV-35 which is an industrial azo dye, after release significantly affects the visual appearance of water bodies and hinders the process of photosynthesis affecting plant growth. Perturbing the food chain, it promotes toxicity, mutagenicity, and carcinogenicity. Therefore, dye remediation is essential before discharge into water streams. To determine the effectiveness of the electrocoagulation process for DV-35 dye remediation, and understand the influence of parameters like current density, inter-electrode spacing, concentration of electrolyte, pH, agitation speed, and initial dye concentration, a detailed study was carried out. Maximum removal efficiency (>98 %) was achieved in 16 min at 263.15 A/m² current density and pH 7.2 for DV-35 concentration of 50 to 500 mg/L. Further, optimized parameters were applied to real textile effluent achieving 99.8 % efficiency. EC mechanism was corroborated by Sips isotherm matching adequately with experimental results. The findings also demonstrated a heterogeneous surface of the produced EC flocs. Pseudo-second-order was obtained with a low operating cost of 0.0018 US $/m³. The DV-35 removal and functional groups were confirmed by UV/VIS and Fourier transforms infrared spectroscopy analysis. The sludge was examined by X-ray Diffraction and Scanning Electron Microscope revealing Crystalline aluminum oxides i.e. bayerite (Al(OH)₃) and diaspore (AlO(OH)). The conclusion of the results revealed EC to be an effective and economical technique for DV-35 remediation from textile wastewater.

This study analysed the composition and leaching results for 12 IFA samples from a local incineration plant by XRF and leaching tests based on BS EN12457-1:2002. XRF results show that the main elements are Ca, Cl and S in all IFA samples. Leaching test results shows a high leachability of Na, Cl, Br, Pb, Zn and Cu. The accelerated carbonation with (NH₄)₂CO₃ was attempted to inhibit heavy metals leaching and remove soluble salts. The effect of (NH₄)₂CO₃ concentration on carbonation efficiency and inhibition of heavy metal leaching was systematically investigated. TGA and ICP-MS were used to determine carbonation capacity and heavy metal leaching, respectively. TGA results show the maximum carbonation capacity is achieved in one hour with 10 wt% (NH₄)₂CO₃ and 76% carbonation occurs -in the first 10 min. Leaching test results reveal that Cu and Pb are efficiently immobilised when the concentration of (NH₄)₂CO₃ is as low as 2 wt% with a s/l ratio of 1:5 within 1 hr. Increasing the concentration of (NH₄)₂CO₃ to 4 wt%, the leaching rate of Zn is also below NEA RVs (National Environment Agency of Singapore). Carbonation is also effective to immobilise Cd and Ni, but not for Cr since it exists as CrO₄^2- and cannot be carbonated. XRF results from a larger scale reaction confirm the significant removal of soluble salts, and lower leachability (except SO₄^2-) is substantiated by leaching tests. By integrating the processes of CO₂ capture with ammonia and accelerated carbonation, our work contributes to CO₂ sequestration and IFA detoxification.

Pinus roxburghii commonly known as Chir Pine is a coniferous tree native to the Himalayas. Pine needles shed from pine trees decay very slowly, form a carpet on the forest floor and are a major cause of frequent forest fires. The abundantly available unutilized pine needles are rich source of lignocellulosic biomass, goes waste, and its management through sustainable utilization has been a challenge.

In the present study, pine needles were fibrillated by using laboratory disc refiner without any chemical treatment under different refiner passes from 0.10 to 0.40 mm to prepare pinepeat. The biomasses under different refiner passes were characterized for pH (6.2–6.5), freeness (481–821 ml), water absorbency (350–580 %), drainage time (9.10–16.99 sec), carbon (45.08 %), nitrogen (0.93 %), hydrogen (6.49 %), sulfur (0.13 %) content and C/N ratio (50.86 %). Anatomical characteristics of pine needle and pinepeat were also examined. The study reported significant change in morphology of pine needles after refining treatment wherein tissues turned into flattened, fibrillated and separated in short groups, increasing the surface area of the fragmented biomass. Application of processed pinepeat as amendments in nursery substrates was further assessed. The significantly higher growth parameters in pinepeat in comparison to conventional growing media suggests pinepeat as an additional environmentally sustainable choice for nursery operations in near future. The utility of pinepeat in this way is imperative for environment waste management and would turn into an alternative, renewable, and reliable growing media as amendments in nursery substrates.