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• Rosa damascene was an effective biosorbent for heavy metal removal. • Functional groups of the biosorbent were involved in metal adsorption. • Metal adsorption capacities were 97.68 mg/g for Pb(II) and 90.8 mg/g for Cd(II). • Metal adsorption by R. damascene followed the Langmuir and Elovich models. Due to their toxicity to public health, the presence of inorganic pollutants in the aquatic environment have become a global concern. This work investigates the technical feasibility of R. damascena waste as a biosorbent (RWB) in batch studies for the removal of Cd(II) and Pb(II) from synthetic wastewater. The biomass waste is abundantly available from rose oil industries in Lahore (Pakistan). To improve its treatment performance for metals removal, the biomass waste is pretreated with H 2 SO 4 and NaOH, respectively. To understand the roles of functional groups on the RWB during biosorption, Fourier Transform infrared (FT-IR) spectroscopy and scanning electron microscope (SEM) analyses were used to compare its surface area before and after adsorption. At the same initial metal concentration of 25 mg/L, it was found that the chemically modified R. damascena could remove 95% and 91% of Pb(II) and Cd(II), respectively, under the optimum conditions: pH 6.5, reaction time: 2 h, 10 g/L of dose, and 120 rpm of shaking speed. Its metal adsorption capacities were 24.9 and 24.8 mg/g for Pb(II) and Cd(II), respectively. The Langmuir isotherm was applicable to simulate the adsorption of both target metals, while the pseudo-second order fitted well their kinetics. The characterization results implied the roles of certain functional groups of the biosorbent as electron donors. This indicates that H -bonding was involved in the chemisorption of target metals by the biosorbent. In spite of their encouraging findings, treated effluents were still unable to meet the required discharge limits of 0.05 and 0.005 mg/L for Pb(II) and Cd(II), respectively, mandated by local legislation. This reveals that another subsequent treatment using biological process such as activated sludge is required to complement their removal from wastewater samples. Overall, this work reveals the applicability of R. damascena waste as a biosorbent for heavy metal removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Column studies achieved 24.9 and 24.6 mg/g of adsorption capacities for Pb(II) and Cd(II) • The fixed bed mode attained 24 and 24.3 mg/g of adsorption capacity for Red198 and Blue29. • The Thomas model exhibited a strong correlation with the experimental data. • The Adams-Bohart model effectively described the initial phase of the C e /C 0 < 0.1. • After the 1st regeneration, 97% recovery of target pollutants was attained. • An increasing bed depth extended the operational lifespan of the column study. The adsorption behavior of Cd(II) and Pb(II) ions in a coexisting environment, alongside with both dyes (Reactive Red198 and Blue29) was systematically investigated by using a continuous fixed-bed column completely packed with Rosa damascena waste biosorbent (RDWB). Artificial neural network (ANN) model was also utilized to predict the performance of RDWB for various inputs. Their column performance was assessed by optimizing parameters such as bed depth, influent flow rate, and biosorbents' concentration. It was found that an increasing bed depth considerably extended the operational lifespan and decrease in flow rate delays the column adsorption. Its adsorption capacities were 24.9, 24.6, 24.0 and 24.3 mg/g for Pb(II), Cd(II), Red198, and Blue29, respectively. The RDWB also had a higher adsorption capacity, as compared to previously used biosorbents such as chitosan and biochars due to its good thermal stability and high surface area of 421.46 m2/g. The adsorption of target pollutants took place through ion exchange and electrostatic interactions with negatively charged functional groups on the adsorbent's surface. The experimental data were fitted by various column adsorption models such as the Thomas, Yoon-Nelson, and Adams-Bohart. The findings showed that the Thomas model exhibited a strong correlation with the experimental data. In contrast, the Adams-Bohart model was applicable to the initial phase of the breakthrough curve (C e / C 0 ≤ 0.1). For industrial applications, a scale up model was also presented with the cost analysis of the biosorbent. The comparison of predicted values with experimental percentage (%) removal values of target pollutants by the RDWB indicated the excellent performance of the ANN model for this work. [ABSTRACT FROM AUTHOR]

Food waste is a serious global problem. Therefore, it is essential to reduce food waste and adopt recycling strategies to minimize its environmental impacts. However, conventional waste disposal methods emit harmful gases such as dioxin, CH 4 , N 2 O, and NH 3 , which contaminate the air and water resources. This work reviews the environmental consequences of food waste based on lifecycle assessment (LCA) techniques using methods such as anaerobic digestion, composting, and landfilling. It also pays attention to novel techniques like gasification and hydrothermal carbonization. This review critically evaluates and compares the environmental impacts assessed by LCA such as global warming potential (GWP), climate change (CC), marine eutrophication (MEP), human toxicity (HT), terrestrial eco-toxicity (Tecox), terrestrial acidification (TAP), freshwater ecotoxicity (FEW), freshwater eutrophication (FEP), marine ecotoxicity (ME), fossil depletion (FD), ozone layer depletion potential (OLDP), and land occupation (LO) for each method. This study also highlights the importance of technological innovation and the need to improve current food waste valorization practices by focusing on the LCAs of the approaches listed above. With respect to its novelty, this work consolidates a useful comparison among the food waste utilization technologies with respect to environmental impacts based on LCA studies. Furthermore, this work emphasizes the need for in-depth research on the LCA of sustainable techniques such as gasification, fermentation and hydrothermal carbonization to support evidence-based decision-making. • Households are responsible for 61% of the total food waste. • Bio-waste makes up the largest share (34%) of municipal waste in the EU. • Anaerobic digestion is one of the best conventional methods. • Esterification, gasification and HTC are the best among thermochemical methods. • Food waste recycling decreases waste disposal in landfills, from which it emits GHG. [ABSTRACT FROM AUTHOR]

The generation of microplastics (MPs) has increased recently and become an emerging issue globally. Due to their long-term durability and capability of traveling between different habitats in air, water, and soil, MPs presence in freshwater ecosystem threatens the environment with respect to its quality, biotic life, and sustainability. Although many previous works have been undertaken on the MPs pollution in the marine system recently, none of the study has covered the scope of MPs pollution in the freshwater. To consolidate scattered knowledge in the literature body into one place, this work identifies the sources, fate, occurrence, transport pathways, and distribution of MPs pollution in the aquatic system with respect to their impacts on biotic life, degradation, and detection techniques. This article also discusses the environmental implications of MPs pollution in the freshwater ecosystems. Certain techniques for identifying MPs and their limitations in applications are presented. Through a literature survey of over 276 published articles (2000–2023), this study presents an overview of solutions to the MP pollution, while identifying research gaps in the body of knowledge for further work. It is conclusive from this review that the MPs exist in the freshwater due to an improper littering of plastic waste and its degradation into smaller particles. Approximately 15–51 trillion MP particles have accumulated in the oceans with their weight ranging between 93,000 and 236,000 metric ton (Mt), while about 19–23 Mt of plastic waste was released into rivers in 2016, which was projected to increase up to 53 Mt by 2030. A subsequent degradation of MPs in the aquatic environment results in the generation of NPs with size ranging from 1 to 1000 nm. It is expected that this work facilitates stakeholders to understand the multi-aspects of MPs pollution in the freshwater and recommends policy actions to implement sustainable solutions to this environmental problem. [Display omitted] • The annual global production of plastics rose by 3000% to 600 million tons in 2018. • Annually rivers contribute to 1.2–2.4 million tons of MPs. • About 50,000–15 million particles of MPs are released from water treatment plants. • MPs degradation results in the generation of NPs with size ranging from 1 to 1000 nm. [ABSTRACT FROM AUTHOR]