Improved sewage sludge dewaterability saves costs in biosolids transport and disposal, making reliable dewaterability assessment essential for both research and full-scale process evaluation. However, laboratory-based indexes commonly used to predict dewatering performance often show limited correspondence with full-scale results. Nonetheless, indexes such as capillary suction time (CST), sedimentation and centrifugation methods, specific resistance to filtration (SRF), and mixed dead-end techniques show biases when trying to resemble full-scale results. In our present article, we pose that lack of predictability originates from overlooking all the phenomena involved in the dewatering process. Four critical phenomena are identified to occur during dewaterability: (1) mixing of sludge and conditioner; (2) suspension destabilisation; (3) flocs formation, and (4) compression and expression. By systematically evaluating widely used laboratory indexes this review shows that these methods capture only part of the dewatering process and generally fail to represent the compression and expression stages that ultimately determine the ultimate achievable solids concentration. The analysis highlights sludge compressibility as a critical factor limiting the predictive capacity of conventional indexes. Based on this synthesis, centrifugation, dead-end filtration, and combined centrifugation–filtration approaches are identified as more suitable methods for laboratory-scale assessment because they better represent the compression behaviour of sludge. The review provides a conceptual framework linking dewatering phenomena with experimental assessment methods, supporting the development of improved evaluation strategies and facilitating the testing of emerging, environmentally friendly conditioning technologies.
Worldwide, 40% population consumes wheat (Triticum aestivum L.) as a staple food that is low in zinc (Zn) content. Zn deficiency is a major micronutrient disorder in crop plants and humans worldwide, adversely impacting agricultural productivity, human health and socio-economic concern. Globally, the entire cycle of increasing the Zn concentration in wheat grains and its ultimate effect on grain yield, quality, human health & nutrition and socio-economic status of livelihood is less compared. So the present studies were planned to compare the worldwide studies for the alleviation of Zn malnutrition. Zn intake is affected by numerous factors from soil to crop, crop to food and food to humans. The post-harvest fortification, diversification in dietary habits, mineral supplementation and biofortification are various possible approaches to enhance the Zn concentration in food. The wheat grains Zn is influenced by the Zn application technique and time concerning crop developmental stages. The use of soil microorganisms mobilize unavailable Zn, and improve Zn assimilation, plant growth, yield and Zn content in wheat. Climate change can have an inverse impact on the efficiency of agronomic biofortification methods due to a reduction in grain-filling stages. Agronomic biofortification can improve Zn content, crop yield as well as quality and ultimately, have a positive impact on human nutrition, health and socioeconomic status of livelihood. Though bio-fortification research has progressed, some crucial areas are still needed to be addressed or improved to achieve the fundamental purpose of agronomic biofortification.
Poor indoor air quality has become of particular concern within the built environment due to the time people spend indoors, and the associated health burden. Volatile organic compounds (VOCs) off-gassing from synthetic materials, nitrogen dioxide and harmful outdoor VOCs such benzene, toluene, ethyl-benzene and xylene penetrate into the indoor environment through ventilation and are the main contributors to poor indoor air quality with health effects. A considerable body of literature over the last four decades has demonstrate the removal of gaseous contaminants through phytoremediation, a technology that relies on plant material and technologies to remediate contaminated air streams. In this review we present a state-of-the-art on indoor phytoremediation over the last decade. Here we present a review of 38 research articles on both active and passive phytoremediation, and describe the specific chemical removal efficiency of different systems. The literature clearly indicates the efficacy of these systems for the removal of gaseous contaminants in the indoor environment, however it is evident that the application of phytoremediation technologies for research purposes in-situ is currently significantly under studied. In addition, it is common for research studies to assess the removal of single chemical species under controlled conditions, with little relevancy to real-world settings easily concluded. The authors therefore recommend that future phytoremediation research be conducted both in-situ and on chemical sources of a mixed nature, such as those experienced in the urban environment like petroleum vapour, vehicle emissions, and mixed synthetic furnishings off-gassing. The assessment of these systems both in static chambers for their theoretical performance, and in-situ for these mixed chemical sources is essential for the progression of this research field and the widespread adoption of this technology.
Progressively and projected integration of rare earth metals (REMs) in modern technologies, especially in the clean energy, consumer electronics, aerospace, automotive, and defense sectors, place REMs as critical raw materials in the supply chain and strategic metal from the fourth industrial revolution perspective. Current REM production from the primary mineral resources in the supply chain versus industrial demand is at a bottleneck. Alternatively, REM-bearing anthropogenic wastes are pertinent and potent to addressing the critical supply chain bottleneck. Although secondary REM resources are prudent to address the critical supply chain bottleneck, the absence of effective and efficient technologies to recover these REMs from anthropogenic waste imposes challenges and provides opportunities. Hence, this review analyses and discusses the significance of anthropogenic wastes for REM recovery, the status of recycling technologies for sustainable valorization of REMs, challenges, and opportunities. The current review covers the potential quantitative REM wealth locked in various anthropogenic waste like (i) spent rare earth permanent magnets, (ii) spent batteries, (iii) spent tri-band REM phosphors, (iv) bauxite industry residue red mud, (v) blast furnace slag and (v) coal mines, and coal byproducts and status of valorization technologies for circularizing the REMs. In industrial waste like red mud, steelmaking slag, blast furnace slag, and coal fly ash typically 109,000, 2000, 39,000, and 354,000 tons of REM get scrapped, respectively, in a conservative estimation. In the years 2020 and 2021, respectively, 240,000 and 280,000 tons of REM were produced by mine production in contrast to 504,000 tons of REM that were scrapped with REM-bearing industrial waste. This review revealed that total REM currently getting scrapped with anthropogenic waste versus projected REM demand for the years 2022, 2023, 2024, and 2025 could be standing at 2.66, 2.51, 2.37, and 2.23, respectively. Our investigation revealed that efficient recovery of REMs from anthropogenic waste is significant and promising but associated with challenges like lack of industrial-scale valorization process, lack of a clear strategy, road map, policy, effort, funding, and diversified research.
Water quality index (WQI) is one of the most used tools to describe water quality. It is based on physical, chemical, and biological factors that are combined into a single value that ranges from 0 to 100 and involves 4 processes: (1) parameter selection, (2) transformation of the raw data into common scale, (3) providing weights and (4) aggregation of sub-index values. The background of WQI is presented in this review study. the stages of development, the progression of the field of study, the various WQIs, the benefits and drawbacks of each approach, and the most recent attempts at WQI studies. In order to grow and elaborate the index in several ways, WQIs should be linked to scientific breakthroughs (example: ecologically). Consequently, a sophisticated WQI that takes into account statistical methods, interactions between parameters, and scientific and technological improvement should be created in order to be used in future investigations.
