Alternative Disposal Methods Research Articles

Indigenous Knowledge Systems of Solid Waste Management in Bushbuckridge Rural Communities, South Africa

Indigenous knowledge systems related to solid waste management in economically marginalized communities have been largely overlooked in the scientific literature, even though the indigenous communities of developing nations struggling to manage solid waste rely on these practices. It is startling that indigenous solid waste management practices are scarcely documented in the scientific literature despite their position as potential alternative disposal methods. This gap persists amid limited municipal budgets, inadequate waste collection services, and poor infrastructure in economically marginalized indigenous rural communities in developing nations. Subsequently, in the discipline of solid waste management, this obstacle impedes the recognition and inclusion of indigenous waste management practices into integrated waste management plans. As a result, this causes a delay in their progress or elevation to the same level of credibility as mainstream scientific knowledge. In the process, this relegates the waste management practices of indigenous communities to the background. Against this background, the current study sought to investigate the indigenous solid waste management practices of rural communities in Bushbuckridge Local Municipality. As such, ten cases that captured the spatial cultural diversity of indigenous communities’ practices across Bushbuckridge Local Municipality (BLM) were selected for sampling. Data were collected using ethnographic research methods. Data analysis was carried out using the thematic analysis approach. Inductive logic was used in the interpretation of the current study results. The results of the current study indicate that indigenous communities of Bushbuckridge Local Municipality, in the absence of formal waste management services from the local authority, resort to an indigenous knowledge system to manage solid waste. Waste burning (100%), open-air dumping (100%), and backyard pits (90%) are some of the indigenous waste management practices espoused by the rural communities of BLM. The similarity in practices was corroborated by statistical inferences that revealed that between BLM communities, the amount of indigenous waste management practices is not significant (p > 0.05). However, there are concerns that despite the sustainability aspect associated with recycling (<25%) practices, these disposal methods are not common in the rural communities of BLM. This is a setback for an indigenous knowledge system that is supposed to advance environmental sustainability practices.

Evaluating the economic and environmental benefits of deploying a national-scale, thermo-chemical plastic waste upcycling infrastructure in the United States

Emerging chemical technologies can upcycle plastic waste by producing high-value polymers and other products. In this work, we study the economic and environmental benefits of deploying an upcycling infrastructure in the continental United States for producing low-density polyethylene (LDPE) and polypropylene (PP) from post-consumer plastic waste. Our analysis is based on a computational framework that integrates techno-economic analysis, life-cycle assessment, and value chain optimization. Our results demonstrate that the infrastructure could generate a market of nearly 20 billion USD per year and that this market is robust to various externalities. Our analysis also indicates that the infrastructure can achieve a plastic-to-plastic degree of circularity of 34% relative to residential plastic waste production, and leads to significant environmental benefits over alternative waste disposal methods, including 69%–75% lower greenhouse gas emissions than waste-to-energy systems and 38 million tonnes of avoided landfill waste per year.

Evaluating Technical properties of fired clay Brick production with mosaic sludge: A comprehensive study on heavy metal leachability for sustainable environmental and economic benefits

Mosaic sludge, generated from mosaic industrial activities such as cutting, polishing, and grinding, is often disposed of in landfills or discharged into drainage systems without adequate treatment. This study aims to reuse mosaic sludge from the mosaic industry by incorporating it into fired clay bricks. This approach offers an alternative disposal method, improves brick quality, and minimizes heavy metal leachability, contributing to environmental and economic sustainability. X-Ray Fluorescence (XRF) was conducted to determine the heavy metal concentration from two types of mosaic sludge bodymill mosaic sludge (BS) and polishing mosaic sludge (PS). The result indicates that the highest element concentration in mosaic sludge (BS and PS) shows that barium is the highest with 3253 ppm and 3260 ppm. Meanwhile, the lowest element concentration obtained in BS and PS is cesium with 14 ppm and 17 ppm. SPLP and TCLP also conducted in this study and the result show that, even though the element such as ferum (Fe) and cadmium (Cd) was not detected in XRF but in SPLP and TCLP, it shows that these two elements exist in clay, BS and PS with low concentration. In order to evaluate the compressive strength conducted by incorporating with different proportions 0 %, 1 %, 5 %, 10 %, 20 % and 30 % of BS and PS into fired clay brick. The result shows that compressive strength BS brick was stronger than PS brick. The maximum sludge percentage used in BS brick is 5 % with value of compressive strength is 28.10 MPa. Meanwhile, PS brick had the higher value of compressive strength at 30 % sludge percentage with the value 23.46 MPa. Static Leachate Test (SLT) was performed to evaluate heavy metal leachability from bricks containing different proportions of BS and PS sludge. In the SLT results, Fe exhibits the highest concentration of heavy metals at various proportions of BS and PS: 2.11 mg/L and 2.27 mg/L at 1 %, 1.77 mg/L and 1.88 mg/L at 5 %, 2.34 mg/L and 3.29 mg/L at 20 %, and 2.79 mg/L and 3.64 mg/L at 30 % respectively, among other elements. On the other hand, elements including Cr, Ni, Cu, As, Cd, and Pb demonstrated lower concentrations ranging from 0.00 mg/L - 1.0 mg/L. The result for control brick, BS brick and PS brick shows the same pattern. However, overall results show that the concentration still under limit set by USEPA.

Permeable Reactive Barrier Remediation Technique Using Carbonized Food Waste in Ground Contaminated with Combined Cu and Pb

In recent years, with the escalation of food waste generation, stringent legal constraints on landfill usage and incineration have necessitated the exploration of alternative disposal methods, augmenting interest in diverse recycling strategies. Notably, carbonized food waste (CFW), a byproduct of food waste carbonization, has emerged as an efficacious adsorbent for pollutant removal. This study focuses on the application of in situ remediation techniques, specifically electrokinetic (EK) remediation combined with enhancers, to decontaminate soil afflicted with single or multiple heavy metals. The utilization of a permeable reactive barrier (PRB) infused with CFW aims to mitigate secondary environmental repercussions, including the propagation of contaminants in soil and groundwater. Experiments were conducted on clay samples contaminated with copper, lead, or a combination thereof. Observations revealed that the current density peaked during the initial 1–2 days of the experiment, experienced a resurgence post-electrode exchange, and subsequently diminished. The efficacy of metal removal was predominantly pronounced for copper, with remediation rates ranging from 85% to 92% in singly contaminated samples and 75% to 89% in dually contaminated samples after a 10-day treatment period, incorporating an electrode exchange on the eighth day. Conversely, the efficacy of lead removal was markedly lower, with rates of 0.6% to 33% in singly contaminated samples and 14% to 25% in combined contamination scenarios, suggesting the necessity for extended treatment durations. The post-experimental moisture content indicated successful enhancer injection. Additionally, pH measurements affirmed that heavy metals migrated effectively within the sample matrix, facilitated by the EK phenomenon after the electrode exchange. This study highlights the potential of CFW within PRBs for the remediation of heavy metal-contaminated soils, although the removal efficiencies between different metals is variable, emphasizing the need for tailored approaches in the treatment of lead-contaminated environments.

Impact of brewery sludge application on heavy metal build-up, translocation, growth and yield of bread wheat (Triticum aestivum L.) crop in Northern Ethiopia

In a field study, the impact of different levels of brewery sludge (BS) enrichment on Triticum aestivum L. (wheat plants) was examined in terms of growth, yield, heavy metal absorption, and potential health risks linked to plant consumption. Using a randomized complete block design with seven treatments and three blocks, the study showed that applying up to 12 t ha−1 brewery sludge significantly improved all agronomic parameters (except harvest index) compared to control and mineral-fertilized soil. Heavy metal translocation was generally low, except for Cu and Pb. The sequence of heavy metal translocation was Cu > Pb > Cd > Ni > Zn > Mn > Cr from soil to spikes and Cu > Zn > Mn > Pb > Ni > Cd > Cr from soil to grain. Heavy metal loads were mostly higher in roots than in the above-ground crop parts. The target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR) within wheat grain remained within safe limits for all BS treatments. Consequently, consuming this wheat grain is considered safe regarding heavy metals. Thus, utilizing brewery sludge at 12 t ha−1 as a fertilizer for wheat production and as an alternative method for sludge disposal is plausible.

Nitrogen-Rich Sewage Sludge Mineralized Quickly, Improving Lettuce Nutrition and Yield, with Reduced Risk of Heavy Metal Contamination of Soil and Plant Tissues

Sewage sludge should primarily find use in agriculture, reducing the quantity directed towards alternative disposal methods like incineration or deposition in municipal landfills. This study evaluated the agronomic value and the risk of soil and plant tissue contamination with heavy metals in sewage sludge obtained from two wastewater treatment plants (WWTP). The experiment was arranged as a 2 × 5 factorial (two sewage sludges, five sanitation treatments), involving lettuce cultivation in pots over two growing cycles. The two sewage sludges were sourced from the WWTPs of Gelfa and Viana do Castelo and underwent five sanitation and stabilization treatments (40% and 20% calcium oxide, 40% and 20% calcium hydroxide, and untreated sewage sludge). The Gelfa sewage sludge, characterized by a higher initial nitrogen (N) concentration, resulted in greater dry-matter yield (DMY) (12.4 and 8.6 g plant−1 for the first and second growing cycles, respectively) compared to that from Viana do Castelo (11.0 and 8.1 g plant−1), with N release likely being a major factor influencing crop productivity. The high N concentration and the low carbon (C)/N ratio of sewage sludge led to rapid mineralization of the organic substrate, which additionally led to a higher release of other important nutrients, such as phosphorus (P) and boron (B), making them available for plant uptake. Alkalizing treatments further stimulated sewage sludge mineralization, increasing soil pH and exchangeable calcium (Ca), thereby enhancing Ca availability for plants, and indicating a preference for use in acidic soils. Cationic micronutrients were minimally affected by the sewage sludge and their treatments. The concentrations of heavy metals in the sewage sludge, soils, and lettuce tissues were all below internationally established threshold limits. This study highlighted the high fertilizing value of these sewage sludges, supplying N, P, and B to plants, while demonstrating a low risk of environmental contamination with heavy metals. Nevertheless, the safe use of sewage sludge by farmers depends on monitoring other risks, such as toxic organic compounds, which were not evaluated in this study.

Effect of Food Waste on The Growth Performance, Waste Reduction Efficiency and Nutritional Composition of Black Soldier Fly (Hermetia illucens (L.), Diptera: Stratiomyidae) Larvae

The rate of solid waste generation, especially in Malaysia, has become one of the major concerns for environmental and public health issues. Food waste accounts for the highest percentage of solid waste that ends up in landfills. Due to the living nature of humans and their involvement in agricultural, industrial, and municipal activities, the disposal of food waste happens on a regular basis. Due to the absence of an incineration plant, these wastes are commonly sent into landfills which are considered to be the most cost-effective method for disposal. Nevertheless, consideration for an alternative disposal method such as composting shall not be ruled out entirely. One of the established methods for composting food waste is the utilization of the larvae of the Black Soldier Fly. A study was conducted to assess the growth and nutritional composition, waste reduction capacity and nutritional composition of Black Soldier Fly Larvae (BSFL) reared on food waste. We found that the larvae reared with the food waste and effective microorganism (EM), LFWEM (BSFL reared with a mixture of food waste and effective microorganisms), have a slightly better relative growth rate (2.66 ± 0.35 day-1) compared to larvae reared with only food waste (2.44 ± 0.17 day-1). The waste reduction index was higher in the LFWEM group (5.36 ± 0.18 g/day) compared to the control group, LFC (BSFL reared with chicken feed) (4.85 ± 0.03 g/day) and the LFW (BSFL reared with food waste) group (5.13 ± 0.17 g/day). The nutritional composition of the BSFL reared using food waste shows some potential as it surpasses some of the amount of essential amino acids including Arginine, Histidine, Threonine and Valine, found in the commercially available animal feeds. This finding serves as a baseline to propose potential replacements for animal protein by using BSFL reared with food waste.

Mechanistic exploration of polytetrafluoroethylene thermal plasma gasification through multiscale simulation coupled with experimental validation

The ever-growing quantities of persistent Polytetrafluoroethylene (PTFE) wastes, along with consequential ecological and human health concerns, stimulate the need for alternative PTFE disposal method. The central research challenge lies in elucidating the decomposition mechanism of PTFE during high-temperature waste treatment. Here, we propose the PTFE microscopic thermal decomposition pathways by integrating plasma gasification experiments with multi-scale simulations strategies. Molecular dynamic simulations reveal a pyrolysis—oxidation & chain-shortening—deep defluorination (POCD) degradation pathway in an oxygen atmosphere, and an F abstraction—hydrolysis—deep defluorination (FHD) pathway in a steam atmosphere. Density functional theory computations demonstrate the vital roles of 1O2 and ·H radicals in the scission of PTFE carbon skeleton, validating the proposed pathways. Experimental results confirm the simulation results and show that up to 80.12% of gaseous fluorine can be recovered through plasma gasification within 5 min, under the optimized operating conditions determined through response surface methodology.

An identification of optimal waste disposal method for dumpsite remediation using the Fermatean fuzzy multi-criteria decision-making method.

Improperly managed wastes that have been dumped in landfills over the years pose various challenges, but they also offer potential benefits. The feasibility of recycling such waste depends on the type of wastes, the condition of dumpsites, and the technology implemented for disposal. The selection of an alternative waste disposal method from the many available options for dumpsite remediation is a complex decision-making process among experts. The primary aim of this study is to assist in an extended multi-criteria decision-making (MCDM) method to reduce complexity in the proposed dumpsite remediation problem influenced by multiple criteria and to identify the optimal waste disposal method. Data uncertainties are managed with the proposed Fermatean fuzzy preference scale, and the importance of all socio-economic criteria is assessed using the full consistency method (FUCOM). The final ranking results of the weighted aggregated sum product assessment (WASPAS) method identify that the Waste-to-Energy (WtE) process could play a significant role in the disposal of land-filled unprocessed wastes, promoting sustainable waste management. Meanwhile, the methodology explores the idea that financial and logistical constraints may limit the feasibility of large-scale recycling efforts. This combination of environmental science and decision science addresses real-world challenges, helping municipal solid waste management authorities implement sustainable waste management practices.

Identification of Illegal Dumping and Community Views in Informal Settlements, Cape Town: South Africa

Municipalities face the greatest difficulty in implementing an efficient and effective waste collection system, especially in informal settlements with limited spatial planning. Illegal dumping is exacerbated by the proliferation of informal settlements and the lack of adequate waste management services provided by municipalities. A geographic information system (GIS) provides decision makers with a framework for analyzing and simulating a wide variety of spatial problems, including waste management issues. The purpose of this study is to map areas susceptible to illegal dumping and to determine why the community dumps there. The data were collected qualitatively via a questionnaire using a purposeful sampling technique, and SPSS 28.0 was used to analyze the data. The accessibility of streets and the availability of vacant land affected the location and concentration of illegal dumping in the test area. The lands within a buffer zone of 250 to 500 m of populated areas are the most vulnerable. The majority of residents have individual garbage receptacles, while a minority of 43.18% do not. A total of 52 dumpsites were identified inside the red zone of the model, suggesting a strong likelihood of illegal dumping activities. Hence, the community continues to have difficulties in effectively managing garbage disposal, compelling them to resort to alternative methods of waste disposal.

Evaluation of batch mesophilic anaerobic digestion of waste Euro banknotes for methane Production: Preliminary studies and kinetic approach

The European Central Bank is striving to find environmentally friendly alternative methods of waste disposal. In 2020, it decided to end the disposal of Waste Euro Banknotes (W€B) in landfills and planned to use them for recycling and/or energy recovery. Despite being recognized as an effective tool in a circular economy model, there are no reported studies on the use of W€B as a substrate in anaerobic digestion (AD). Thus, the aim of this research was to assess the viability of W€B to be converted into high-value-added energy products (mainly methane) through AD. W€B (€10 and €20 denominations) provided by the Bank of Spain were used. Biochemical methane potential (BMP) tests of pre-treated (grinded) and untreated W€B were assessed at mesophilic temperature. The ultimate methane yield was considerably higher for pre-treated W€B (334 ± 23 NmL CH4 g VS-1added) than for untreated W€B (297 ± 14 NmL CH4 g VS-1added). The Logistic or Sigmoidal kinetic model adequately fit the experimental data and allowed for obtaining the kinetic parameters of each case studied. In this sense, an increase of 22.4 % in the maximum methane production rate (Rmax) was observed for the pre-treated W€B (52.5 ± 0.9 mL CH4 (g VS·d)-1 compared to the untreated W€B (16.2 ± 1.8 mL CH4 (g VS·d)-1). According to the obtained results, AD may be a good alternative for the energetic valorization and recycling of W€B.

Take-back programs: analysis of millennial participation in alternative clothing disposal methods

Purpose: This study aims to better understand the relationship between millennial consumers and brand or retailer clothing take-back programs. By analyzing general awareness and willingness to participate in these initiatives, inputs such as trust and brand loyalty are evaluated to understand its influence on behavior. Basic demographics were collected to better understand sample representation. A 5-point Likert scale was used to evaluate feelings and beliefs millennial consumers had towards take-back programs. To further analyze the data, a top-two box approach was utilized to predict the execution of the behavior evaluated. The results indicated that there was a general lack of awareness in terms of take-back programs from millennial consumers. In addition, there was confusion between take-back programs and other alternative means of clothing disposal. The data also provided the conclusion that trust amongst millennial consumers and sustainability claims from brands and retailers are low. Finally, personal brand loyalty influenced the willingness to participate in brand and retailer take-back programs. This research uses theory of reasoned action and theory of planned behavior to better understand consumer awareness of take-back programs. The paper addresses awareness of brand or retailer clothing take-back programs and the relationship trust and brand loyalty has on consumer participation.

Comparative life cycle assessment of single-use cardiopulmonary bypass devices

The purpose of this study is to evaluate the impacts of the common cardiopulmonary bypass device over its life cycle. This represents the first such assessment of a complex medical device, to the best of the authors’ knowledge. This study was motivated by practitioners’ concerns over cardiopulmonary bypass devices constructed mainly of single-use plastics, such as polyvinyl chloride and polycarbonate. The open-source software OpenLCA was used to perform each life cycle assessment with respect to ten common impact categories: global warming, eutrophication, acidification, smog, human health cancer, human health non-cancer, water intake, human health air pollutants, ecotoxicity, and natural resource depletion. The environmental impact was evaluated using the Building for Environmental and Economic Sustainability impact assessment method. To quantify the uncertainty in the results, Monte Carlo simulation was used using 5000 runs. A comparative assessment was conducted to determine the potential trade-offs in each impact category of using alternative construction materials. Incineration as a common disposal option could contribute up to 33 % of total CO2 equivalent emissions over the life cycle of the device. Another 33% of total CO2 equivalent emissions are attributed to polycarbonate used in the construction of devices. Polycarbonate was also implicated as the top contributor to the other impact categories considered, except for human health cancer, which is almost entirely affected by the use of polyvinyl chloride in the device, primarily in the tubes. The accuracy of these results is corroborated by the uncertainty analysis. Lastly, the results show that replacing polycarbonate with polyethylene terephthalate, polypropylene, or polyethylene would be no worse than polycarbonate and provide a significant decrease in almost every impact category. Cardiopulmonary bypass devices are constructed primarily of single-use plastics that have relatively significant impacts in the 10 common categories considered. Alternative disposal methods and replacement of polycarbonate with alternative plastics could dramatically reduce the effects in most impact categories.

Temperature, microbiological and chemical composition of broiler chickens’ excrement with litter after its composting with different doses of biodestructor

The rapid growth of production volumes of broiler chicken products both in our country and in most countries of the world is combined with an increase in industry waste. A significant percentage of this waste is poultry droppings with litter. In the absence of implemented technologies for rational disposal of broiler chicken droppings, economic and ecological problems arise locally. Considering the above, the search for effective methods of disposal of broiler chicken droppings is of scientific and practical importance. Composting poultry droppings with litter (sawdust of non-coniferous trees) can be an alternative method of rational disposal of this waste. To accelerate the fermentation of broiler litter, there is a practice of using various microbiological preparations. The effectiveness of using a biodestructor containing bacteria: Bacillus spp., Bacillus subtilis, Bacillus megatherium, Bacillus mesentericus, Bacillus mycoides during composting of broiler chicken excrement and its effect on the microbiological, chemical and physical parameters of fermented biomass remains unexplored. To conduct an experiment, 30 kg samples were formed from the excrement with the litter taken from the poultry house after broiler chickens had been reared for 42 days. In the control group, excrement samples were treated with water without a biodestructor. In the 1st, 2nd, and 3rd research groups, broiler chicken droppings were moistened with biodestructor solutions providing its doses of 143, 1430, and 2860 mg/t, respectively. Temperature and microbiological indicators were determined in the litter of broiler chickens during composting. In non-fermented litter of broiler chickens and litter composted for 150 days using a biodestructor, the crude protein content, mass fraction of Calcium, total Nitrogen and Phosphorus were determined. It has been established that the introduction of a biodestructor at a dose of 2860 mg/t of manure with a moisture content of 60.0 % leads to an increase in the activity of biochemical processes, which is confirmed by an increase in the temperature of the compost during the first hundred days of fermentation. The higher the dose of biodestructor was added to the litter of broiler chickens, the higher the KMAFAnM indicator and the numbers of Bacillus spp. bacteria in compost were higher. A regularity has been established that with the increase in the amount of biodestructor in the litter of broiler chickens, the number of Staphylococcus and Clostridium bacteria in the latter decreases. The use of a biodestructor at a dose of 2860 mg/t of broiler chicken droppings contributes to the increase of Nitrogen, crude protein, and Phosphorus in the compost and accelerates its mineralization compared to the control.

Ecosystem services provided by striped hyenas in the human-dominated landscape of Rajasthan, India

In human-dominated landscapes, quantifying ecosystem services in terms of economic benefits could contribute to establishing peaceful coexistence between humans and large carnivores. In this study, we estimated the monetary value of scavenging benefits provided by striped hyenas (Hyaena hyaena) in an anthropogenic landscape in the semi-arid region of Rajasthan, India. We converted the value of domestic livestock carcasses consumed by striped hyenas from opportunity costs to quantify the value of this important ecosystem service to local people. We determined the monetary value of carcass disposals using two methods, including (1) electric cremation, and (2) pyre burning of animal carcasses. To determine the minimum number of striped hyenas, present in the study area, we employed a photo-capture approach, and we used scat analysis to determine the livestock consumed by striped hyenas. We estimated that striped hyenas removed 23.13 tons (4.4 %) of livestock carcass waste from the total of 525.68 tons of waste generated per year in the Intensive Study Area (ISA). The annual monetary value of livestock carcass waste removal by striped hyenas in the ISA was estimated to be ~US$ 7095 for electric cremation and US$ 49,665 for pyre burning. Our study demonstrates the economic benefit of scavenging services provided by striped hyenas in areas where anthropogenic food is abundant. In such areas, as hyenas scavenge anthropogenic food, local communities benefit from waste management. Using alternative carcass disposal methods without striped hyenas would be expensive and likely environmentally damaging.

Construction of Canal Lining Using Nylon Net

Abstract: The nylon fibers are used in manufacture of various products like carpet, rope, clothes, tires and other durable materials. The reason for using nylon fiber is that it has good hardness, resilience and durability; is readily available in different colors, can be dyed, resistant to soil and dirt, good abrasion and wearing characteristic, availability in different cross-section. The Nylon fiberproduction, though, affects the environment and the disposal of these fibers poses more severe threat. In this regard, use of nylon fiber as ingredient in cement concrete is promising as it provided an alternative method of disposal and fibers, owing to their alsoimprove strength and durability of concrete. The addition of nylon fiber has also been reported to improved durability of concrete,the fibers protect concrete cover from spilling due to bonding character. In present study, nylon fibers are added to normal strengthcement concrete in various proportions andits effects onworkability, compressive strength, and tensile strengthisreported. The nylon fiber is used in variety of applications owing to its high strength, resilience and durability but its disposal poses a serious threat in environment. The use of nylon fiber in concrete hence gives good alternative to the disposal and fibers in turnimpart useful characteristics to concrete. In present study, various proportions of nylon fiber are added in concrete and its effect onworkability, compressive strengthand tensile strengthisreported.

The environmental and economic case for valuing water recovery and its relationship with tailings storage conservation

Alternative tailings disposal methods such as dry stack are often neglected as optimal mine waste disposal methods due to perceived high cost. However, the transition from traditional wet tailings disposal to dry stack and alternative tailings disposal is critical for decreasing freshwater consumption and de-risking projects. This research presents an open-source techno-economic model which allows for the comparison of water use and cost between different tailings disposal-related equipment, addressing a major gap in models available for operators and early technology decision-makers. A case study of a Chilean copper mine is evaluated through the model to optimize the dewatering equipment choice. The findings indicate a substantial technical, environmental and economic return on the thickener control system and hydro-cyclone compared to desalinated and pumped water. Early economic modeling can quickly develop a business case for new water and energy-saving technologies while creating shared de-risked technical, ESG, and business team drivers.

Combined Use of Sewage Sludge Ash and Silica Fume in Concrete

The lack of adequate space for sewage sludge disposal has become a significant challenge in many countries. Landfilling and using sewage sludge as fertilizer in agricultural lands are the main methods for disposal. However, these methods can result in soil and groundwater contamination as well as heavy metal and microbial pollution in soil. An alternative disposal method is using sewage sludge ash (SSA) in concrete production. If the sludge ash is reactive, it can replace a portion of cement in concrete; otherwise, it can be used as a filler. In the present study, X-ray fluorescence (XRF) experiments were conducted to determine the elemental composition of sewage sludge. Then, the sewage sludge was incinerated, and XRF and X-ray diffraction (XRD) tests were performed on the resulting sewage sludge ash. The ash was utilized in different proportions in the mortar and concrete specimens, and compressive strength tests were conducted on the resulting specimens. The results indicate that using 20% SSA instead of cement resulted in a 25% reduction in compressive strength in concrete specimens. However, the combination of 10% silica fume and 10% SSA was the optimal combination to compensate for the reduction in compressive strength caused using SSA.

Remediation of grassland subsidence and reduction of land occupation with tailings backfill technology: a case study of lead-zinc mine in Inner Mongolia, China

The mining industry provides essential mineral resources for human society’s development. However, this industry generates a large quantity of waste material while rapidly extracting valuable elements from ore, such as processed tailings. The existence of mined voids will cause surface subsidence, and the surface stockpiling of tailings and waste rocks occupy a large amount of land and the risk of Tailings Storage Facility (TSF) failure. This paper proposes tailings backfill technology to mitigate surface subsidence and provides an alternative disposal method for tailings generated during ore extraction. Tailings backfill technology prepares the slurry by adding a certain amount of cementitious material into the tailings and transporting it to the underground goaf through a pipeline. The backfill slurry could then gradually build up its strength during the hydration of. Cementitious material. A case study of a lead-zinc mine in the Inner Mongolia Autonomous Region of China using tailings backfill technology was introduced in detail to solve the problems of grassland collapse caused by mine excavation and environmental damage due to tailings disposal. Spread test and rheological test were carried out to study the flow characteristics of filling slurry and the uniaxial compressive strength (UCS) of backfill was tested as well. The result illustrates that the spread of the filling slurry with a solid content between 72% and 76% and cement-tailings ratio between 1:4 and 1:8 is greater than 14 cm, and the UCS of backfill is above 1 MPa. The research shows that the tailings backfill technology recycles tailings waste while mitigating surface grassland subsidence and land occupation of waste disposal. Tailings backfill technology can significantly reduce tailings discharge or even achieve no discharge. A leaching test for heavy metal element classification of the backfill sample was carried out. The results show that the heavy metal detection indicators meet the environmental protection standard requirements and will not cause secondary environmental pollution. Therefore, tailings backfill technology can realize green and efficient management of mine waste and has great application and promotion prospects.

Nickel-Catalyzed Exhaustive Hydrodefluorination of Perfluoroalkyl Arenes

Perfluoroalkyl compounds are persistent environmental pollutants due to their strong C(sp3)-F bonds. Hydrodefluorination has emerged as a potential alternative disposal method for perfluoroalkyl compounds. Although the transformation of trifluoromethyl arenes into the corresponding methyl arenes has been studied by several research groups, hydrodefluorination reactions of longer perfluoroalkyl chains remain rare. Herein, we report exhaustive hydrodefluorination reactions of pentafluoroethyl arenes and longer-chain analogues using molecular nickel catalysis. Despite the cleavage of multiple C(sp3)-F bonds, the reaction already proceeds upon gentle heating (60 °C). A mechanistic investigation indicated that the reaction proceeds via benzylic hydrodefluorination reactions followed by homobenzylic ones. We reveal the multiple roles of the Ni catalyst, which include C-F bond cleavage, promotion of HF elimination, and hydrosilylation.