Underground carbon dioxide sequestration for climate change mitigation – A scientometric study

Biochar integrated reactive filtration of wastewater for P removal and recovery, micropollutant catalytic oxidation, and negative CO2 e: Process operation and mechanism

Biochar (BC) use in water treatment is a promising approach that can simultaneously help address societal needs of clean water, food security, and climate change mitigation. However, novel BC water treatment technology approaches require operational testing in field pilot-scale scenarios to advance their technology readiness assessment. Therefore, the objective of this study is to evaluate the system performance of BC integrated into hydrous ferric oxide reactive filtration (Fe-BC-RF) with and without catalytic ozonation (CatOx) process in laboratory and field pilot-scale scenarios. For this investigation, Fe-BC-RF and Fe-CatOx-BC-RF pilot-scale trials were conducted on synthetic lake water variants and at three municipal water resource recovery facilities (WRRFs) at process flows of 0.05 and 0.6 L/s, respectively. Three native and two iron-modified BCs were used in these studies. The commercially available reactive filtration process (Fe-RF without BC) had 96%-98% total phosphorus (TP) removal from 0.075- and 0.22-mg/L TP, as orthophosphate process influent in these trials. With BC integration, phosphorus removal yielded 94%-98% with the same process-influent conditions. In WRRF field pilot-scale studies, the Fe-CatOx-BC-RF process removed 84%-99% of influent total phosphorus concentrations that varied from 0.12 to 8.1 mg/L. Nutrient analysis on BC showed that the recovered BC used in the pilot-scale studies had an increase in TP from its native concentration, with the Fe-amended BC showing better P recovery at 110% than its unmodified state, which was 16%. Lastly, the field WRRF Fe-CatOx-BC-RF process studies showed successful destructive removals at >90% for more than 20 detected micropollutants, thus addressing a critical human health and environmental water quality concern. The research demonstrated that integration of BC into Fe-CatOx-RF for micropollutant removal, disinfection, and nutrient recovery is an encouraging tertiary water treatment technology that can address sustainable phosphorus recycling needs and the potential for carbon-negative operation. PRACTITIONER POINTS: A pilot-scale hydrous ferric oxide reactive sand filtration process integrating biochar injection typically yields >90% total phosphorus removal to ultralow levels. Biochar, modified with iron, recovers phosphorus from wastewater, creating a P/N nutrient upcycled soil amendment. Addition of ozone to the process stream enables biochar-iron-ozone catalytic oxidation demonstrating typically excellent (>90%) micropollutant destructive removals for the compounds tested. A companion paper to this work explores life cycle assessment (LCA) and techno-economic analysis (TEA) to explore biochar water treatment integrated reactive filtration impacts, costs, and readiness. Biochar use can aid in long-term carbon sequestration by reducing the carbon footprint of advanced water treatment in a dose-dependent manner, including enabling an overall carbon-negative process.

Effective removal of methylene blue with zero-valent iron/tea residual biochar composite: Performance and mechanism

Zero-valent iron (Fe⁰)-modified biochar (BFN) was prepared via low-temperature pyrolysis of tea residue (TR) and ferric nitrate hexahydrate (FN) coupled with NaOH activation for the removal of methylene blue (MB). BFN exhibited a specific surface area of 382.66 m²·g^-1, an average pore diameter of 4.97 nm and an equilibrium adsorption capacity as high as 452.5 mg·g^-1 of 0.33 g·L^-1 toward 150 mg·L^-1 MB within 60 min at 30 °C and pH 7.0. The recovered MB is far below of the removal rate in each of adsorption-desorption cycle because the removal mechanism is that MB molecular was firstly chemically adsorbed, then it was reduced and mineralized by BFN with the formation of nitrate, sulfate, CO₂ and H₂O.

Environmental management of industrial decarbonization with focus on chemical sectors: A review

A considerable portion of fossil CO₂ emissions comes from the energy sector for production of heat and electricity. The industrial sector has the second order in emission in which the main parts are released from energy-intensive industries, namely metallurgy, building materials, chemicals, and manufacturing. The decarbonization of industrial wastes contemplates the classic decarbonization through optimization of conventional processes as well as utilization of renewable energy and resources. The upgrading of existing processes and integration of the methodologies with a focus on efficiency improvement and reduction of energy consumption and the environment is the main focus of this review. The implementation of renewable energy and feedstocks, green electrification, energy conversion methodologies, carbon capture, and utilization, and storage are also covered. The main objectives of this review are towards chemical industries by introducing the potential technology enhancement at different subsectors. For this purpose, state-of-the-art roadmaps and pathways from the literature findings are presented. Both common and innovative renewable attempts are needed to reach out both short- and long-term deep decarbonization targets. Even though all of the innovative solutions are not economically viable at the industrial scale, they play a crucial role during and after the energy transition interval.

Nanostructured materials via green sonochemical routes - Sustainability aspects

The production of environmentally friendly nanostructured materials with well-defined properties is a major challenge. Characteristics of the nanomaterials such as dimensionality, size and morphology strongly affect their performance in various applications. Additionally, sustainability considerations require an acceptable level of efficiency while being economically feasible and environmentally benign. The use of ultrasonic irradiation (UI) is a green and powerful technology, which can be applied for the synthesis of a variety of nanostructured materials. This review critically discusses the progress made in the fabrication of environmentally benign engineered nanomaterials with various dimensionalities (i.e., zero, one, two, or three dimensions) assisted by UI. The evolution and current status in this area are further illustrated using a scientometric approach. Application of UI for the synthesis of nanostructured materials has been also assessed according to the main sustainability pillars including the performance and environmental compatibility, as well as the relevant economic and social considerations. The outlook as well as recommendations for future research has been also provided and discussed towards the promotion of sustainable nanomaterials synthesis and application in various fields.

A Scientometric Study on Industrial Effluent and Sludge Toxicity

The growth of industrialization has led to an increase in the production of highly contaminated wastewater. Industrial wastewater contains highly complex compounds varying in characteristics and required to be treated before its discharge into a water medium from various industries. However, the efficiency of the treated wastewater from the toxicity reduction perspective is unclear. In order to overcome this barrier, toxicity assessment of the industrial wastewater before and after treatment is crucial. Thus, in this study, a scientometric analysis has been performed on the toxicity assessment of industrial wastewater and sludges, which have been reported in the literature. Web of Science (WoS) core collection database has been considered the main database to execute this analysis. Via the search of pre-researched keywords, a total number of 1038 documents were collected, which have been published from 1951 to 2020. Via CiteSpace software and WoS analyser, these documents went under analysis regarding some of the scientometry criteria, and the detailed results obtained are provided in this study. The total number of published documents on this topic is relatively low during such a long period of time. In conclusion, the need for more detailed contributions among the scientific and industrial communities has been felt.

Engineered nanomaterials for (waste)water treatment - A scientometric assessment and sustainability aspects

Application of nanomaterials for the treatment of effluents originated from various industrial and non-industrial sources, has been rapidly developed in recent decades. In this situation, there is a need for conclusive studies to identify the current status of the knowledge in this field and to promote the commercialization of such technologies by providing recommendations for future studies. In the present manuscript, a scientometric assessment on the progress made in this field has been performed and the results have been organized and discussed in terms of science statistics, research hotspots and trends, as well as the relevant sustainability aspects. Based on a set of keywords, identified through a pre-literature analysis, a total of 6539 documents were retrieved from the Web of Science (WoS) database and analyzed to achieve the main goals of this study. The results demonstrate that the studies in this field have been initiated since the beginning of the 2000s but were mainly performed in lab and pilot scales. Also, China and Iran were identified as the most contributing countries in this scientific area in terms of the number of publications. Among various types of engineered nanomaterials (ENMs), there has been especial attention for the application of iron-based nanomaterials as well as carbonaceous structures (such as graphene oxide and biochar). Besides, there are not still strong collaborations formed among researchers in this area worldwide. Regarding the research hotspots, the synthesis of green and sustainable nanomaterials (e.g., biosynthesis approaches) has received attention in recent years. The results can also demonstrate that the most widely studied pathway for the removal of pollutants from (waste)waters involves the adsorption of the pollutants using ENMs. Treatment of contaminants of emerging concern (CECs) as well as exploring the mechanisms involved in the treatment of contaminated (waste)waters using ENMs and the possible by-products are considered the current trends in the literature. Regarding the sustainability aspects of ENMs for (waste)water treatment, the results achieved in this study calls for in-depth sustainability studies, which consider parameters such as economic, environmental, and social aspects of nanomaterials utilization for (waste)water treatment purposes, besides the technical parameters, to push transferring such technologies from lab and pilot scales to large and real-scale applications.

Treatment technologies for pharmaceutical effluents-A scientometric study

Treatment of highly polluted pharmaceutical effluents is a major challenge all over the world for technical and economic considerations. In this study, scientometric study is performed on the application of various methods for the treatment of pharmaceutical effluents to explore further developments. In this regard, a total of 1964 documents were retrieved from the Web of Science (WoS) database using a set of relevant keywords to cover all published documents. The extracted documents were subjected to scientometric study including the contributed authors, publications, citations received, contributing countries and institutions as well as the subject categories. From the data retrieved, the status of scientific knowledge on the subject history and current trends were identified and scientific gaps were critically discussed. Publications in this area started to appear since the sixties and were considerably promoted around the beginning of 2000s. Scientific publications of years 1960-2018 followed sigmoidal trend. It was found that leading countries are China and the United States in terms of scientific output on treatment technologies for pharmaceutical effluents. Among the active journals published, "Water Research" has received the most citations. A detailed discussion on the science and developments in this field is provided including the potential applications of scientometry.