Simultaneous removal of nitrogen, phosphorus, and organic matter from oligotrophic water in a system containing biochar and construction waste iron: Performances and biotic community analysis.

The issue of combined pollution in oligotrophic water has garnered increasing attention in recent years. To enhance the pollutant removal efficiency in oligotrophic water, the system containing Zoogloea sp. FY6 was constructed using polyester fiber wrapped sugarcane biochar and construction waste iron (PWSI), and the denitrification test of simulated water and actual oligotrophic water was carried out for 35 days. The experimental findings from the systems indicated that the removal efficiencies of nitrate (NO3--N), total nitrogen (TN), chemical oxygen demand (COD), and total phosphorus (TP) in simulated water were 88.61%, 85.23%, 94.28%, and 98.90%, respectively. The removal efficiencies of actual oligotrophic water were 83.06%, 81.39%, 81.66%, and 97.82%, respectively. Furthermore, the high-throughput sequencing data demonstrated that strain FY6 was successfully loaded onto the biological carrier. According to functional gene predictions derived from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, the introduction of PWSI enhanced intracellular iron cycling and nitrogen metabolism.

Vision-Based On-Site Construction Waste Localization Using Unmanned Aerial Vehicle.

In the context of construction and demolition waste exacerbating environmental pollution, the lack of recycling technology has hindered the green development of the industry. Previous studies have explored robot-based automated recycling methods, but their efficiency is limited by movement speed and detection range, so there is an urgent need to integrate drones into the recycling field to improve construction waste management efficiency. Preliminary investigations have shown that previous construction waste recognition techniques are ineffective when applied to UAVs and also lack a method to accurately convert waste locations in images to actual coordinates. Therefore, this study proposes a new method for autonomously labeling the location of construction waste using UAVs. Using images captured by UAVs, we compiled an image dataset and proposed a high-precision, long-range construction waste recognition algorithm. In addition, we proposed a method to convert the pixel positions of targets to actual positions. Finally, the study verified the effectiveness of the proposed method through experiments. Experimental results demonstrated that the approach proposed in this study enhanced the discernibility of computer vision algorithms towards small targets and high-frequency details within images. In a construction waste localization task using drones, involving high-resolution image recognition, the accuracy and recall were significantly improved by about 2% at speeds of up to 28 fps. The results of this study can guarantee the efficient application of drones to construction sites.

Decoupling economic growth from construction waste generation: Comparative analysis between the EU and China.

The reduction and management of construction waste is crucial for the sustainable development of the construction industry. This research aims to explore a comparative analysis on decoupling relationship between economic growth and construction waste generation on European Union (EU) and Chi et al., 2020 to 2020 in the construction industry, through an integrated method framework of "Tapio + Kaya + LMDI". The research results indicate that there are significant differences in construction waste generation among different countries. The growth rates of construction waste in the EU and China from 2004 to 2020 were 2.47 % and 10.5 %, respectively, showing an upward trend. The economic growth of the construction industry in most EU countries is in a decoupling and negative decoupling state with significant regional differences in decoupling status. The construction waste generation in China is mainly in a weak decoupling state. Economic and demographic factors are the main factors promoting the increase in construction waste generation, while technological factors are the main factors inhibiting construction waste generation in EU and China. However, the impact of each factor on construction was generation varies from EU countries. The research reveals the decoupling effect mechanism between construction waste generation and economic growth, and improves the theory of construction waste management, promotes sustainable development. These findings have feasible inspiration for construction waste management in developing countries with different economic growth levels.

Preparation and Properties of High Sound-Absorbing Porous Ceramics Reinforced by In Situ Mullite Whisker from Construction Waste.

Porous sound absorption ceramic is one of the most promising materials for effectively eliminating noise pollution. However, its high production cost and low mechanical strength limit its practical applications. In this work, low-cost and in situ mullite whisker-reinforced porous sound-absorbing ceramics were prepared using recyclable construction waste and Al2O3 powder as the main raw materials, and AlF3 and CeO2 as the additives, respectively. The effects of CeO2 content, AlF3 content, and sintering temperature on the microstructure and properties of the porous ceramics were systematically investigated. The results showed that a small amount of CeO2 significantly promoted the growth of elongated mullite crystals in the resultant porous ceramics, decreased the growth temperature of the mullite whiskers, and significantly increased the biaxial flexural strength. When 2 wt.% CeO2 and 12 wt.% AlF3 were added to the system, mullite whiskers were successfully obtained at a sintering temperature of 1300 °C for 1 h, which exhibited excellent properties, including an open porosity of 56.4 ± 0.6%, an average pore size of 1.32-2.54 µm, a biaxial flexural strength of 23.7 ± 0.9 MPa, and a sound absorption coefficient of >0.8 at 800-4000 Hz.

A comprehensive model for quantifying construction waste in high-rise buildings in India.

The construction industry plays a vital role in the economic development of any country. Concurrently, the sector also generates enormous quantities of construction and demolition waste (CDW) that damages the ecology causing environmental pollution and deteriorating human health. Recently, various governments and other organizations realized the importance of implementing construction waste management (CWM) practices to attain sustainability in construction. The current decade can be called a pathway for achieving the 2030 agenda for sustainable development goals in which CWM plays an inevitable role. However, accurately quantifying construction waste is necessary to successfully implement any CDW management plan. A detailed literature review for the current research revealed that limited information on the magnitude of construction waste is available in India. Therefore, the current paper proposes a practically viable model to estimate the waste generation index (construction waste generated per total floor area) of high-rise residential buildings in India. The waste quantification is being done based on the project documents and expert interviews. The methodology is later validated through a high-rise building with G + 18 stories located in Kerala, India. The study indicated that a high-rise concrete framed structure generates 122.3 kg m-2 of waste during construction. It was also noted that, concrete, aggregates and blocks constitute 92% of the total waste generated in the project. The developed model can also be used as a cornerstone for establishing a construction waste database at the regional level.

A review of extant literature and recent trends in residential construction waste reduction.

The residential construction sector in New Zealand and worldwide is experiencing increased criticism for generating substantial waste that poses environmental concerns. Accordingly, researchers have advocated implementing residential construction waste reduction (RCWR) strategies as a sustainable solution to managing construction waste (CW). This article aims to provide a comprehensive overview of RCWR by analysing 87 articles from the Scopus database using bibliometric and critical review methods. The co-occurrence analysis of keywords revealed five clusters, in which five main themes emerged: (i) waste generation and management performance, (ii) prefabrication and life cycle assessment concepts, (iii) design concepts, (iv) circular economy and (v) decision-making concepts. The findings suggest that sustainable practices such as designing for waste reduction, prefabrication, waste quantification, three-dimensional printing and building information modelling can effectively achieve RCWR. The study also highlights the benefits of RCWR, including reducing environmental impacts, and identifies management, economic, legislative, technology and cultural barriers that affect the implementation of RCWR strategies. These results provide valuable insights to support future policy formulation and research direction for RCWR in New Zealand.

Site selection for construction and demolition waste landfill using catastrophe theory: the case of Bonab city, Iran.

Rapid urbanization and physical development have produced a significant quantity of construction and demolition waste in Bonab, a city in northwest Iran. In order to achieve a high level of accuracy and minimize subjective bias, catastrophe theory (CT) principles were combined in the geographic information system (GIS) environment for identifying suitable locations for safe disposal of the waste. Site selection process for construction waste landfill (CWLF) in Bonab city involved preparation and integration of 12 maps representing elevation, slope, geology, soil type, land use, vegetation, distance to population centers, valuable ecosystems, river, groundwater, and access to the main roadways with the CT to reduce uncertainty associated with subjective evaluations. Evaluation of relative importance of the variables showed that elevation, slope, distance to the city, vegetation cover, and distance to communication networks have greater importance in site selection for construction waste landfill. On the contrary, distance to the river, groundwater level, distance to villages, and valuable ecosystems have the least impact. Suitable areas were identified in parts of the north and west of the city. The identified sites have a gentle slope, low agricultural potential, good access to the communication networks, suitable distance to the city, and no limitations regarding the groundwater level, geological formations, and vegetation cover.

Calcium Carbonate in Waste Flooring for Neutralization of Acid Rock Drainage.

Acid rock drainage (ARD) was successfully neutralized in this study using carpet tiles. Most polyolefin-based carpet tiles contain over 65% of finely ground calcium carbonate (CaCO3) powder by weight in the compound-blended and extruded backing structure; therefore, using them for neutralization is an innovative way to reuse a difficult-to-recycle complex and abundant product. The overall neutralization efficiency potential was calculated at 40% based on the density, purity, and surface images that display the domains of CaCO3 on the tiles. The carpet backing increased the mean of proton activity of AMD collected from a single acidic stream point within the Pinkerton Run tributary near Pittsburgh, PA from 3.3 to 6.1 over the span of four hours in batch-method experiments at CaCO3 loading levels of 0.1 g/L and overall surface area exposure of 229 mm2/mL. Hot acidity levels decreased from 90 to less than 10 mg CaCO3/L, and below detection limits after 20 h of neutralization. The treated and neutralized AMD sample contained 80 mg/L more calcium than the untreated, non-neutralized control, demonstrating the dissolution of CaCO3 from the carpet tile.

En este estudio se utilizaron con éxito losetas de moqueta para neutralizar el drenaje ácido de roca (DAR). La mayoría de las losetas de moqueta a base de poliolefina contienen más de un 65% de polvo de carbonato de calcio (CaCO3) finamente molido en peso en la estructura de soporte extruida y mezclada con compuestos; su utilización para la neutralización es una forma innovadora de reutilizar un producto complejo y abundante y que es difícil de reciclar. El potencial de eficiencia de neutralización global es del 40% en base a su densidad, la pureza y las imágenes de superficie que muestran los dominios de CaCO3 en las losetas. El soporte de la moqueta incrementó la media de la actividad protónica del AMD recogido de un único punto de corriente ácida dentro del afluente Pinkerton Run, cerca de Pittsburgh, PA, de 3,3 a 6,1 en el transcurso de cuatro horas en experimentos por lotes con niveles de carga de CaCO3 de 0,1 g/L y una exposición global del área superficial de 229 mm²/mL. Niveles muy elevados de acidez disminuyeron de 90 mg CaCO3/L a menos de 10 mg CaCO3/L, y por debajo de los límites de detección tras 20 horas de neutralización. La muestra de AMD tratada y neutralizada contenía 80 mg/L más de calcio que el control no tratado y no neutralizado, lo que demuestra la disolución del CaCO3 de la loseta de moqueta.

Geotechnical and geophysical characterisations of construction waste-infilled quarry for housing and commercial developments: Case study of Tehran, Iran.

The fast population growth in the metropolitan areas of the province of Tehran has led to the scarcity of land and inevitable expansion of urban construction to non-engineered fills and construction/demolition waste disposal sites. An abandoned aggregate quarry, infilled with construction wastes over 16 years, has been recently selected for a new development project consisting of several multi-storey commercial and residential complexes (up to 7 storeys). This study was aimed at delineation of the waste materials, geophysical and field and laboratory geotechnical characterisations prior to foundation design, and the design of the excavation programme. Geo-electric resistivity test was used to delineate the waste materials from natural ground materials. Surface and downhole P- and S-wave velocity measurements were used for the estimation of dynamic elastic properties of the wastes. In total, 12 boreholes (15-30 m deep) along with 10 test pits (4-8.5 m deep) provided the opportunity for visual observations of the waste materials, necessary sampling for compositional analyses, laboratory shear strength tests and determination of waste deposit thickness in different regions of the site. Manual standard penetration test (SPT) was also used to evaluate in situ stiffness of the fine materials of the waste. Six field plate load tests were performed on the waste materials at their natural water content conditions and at saturated (flooded) ground conditions to determine their compressibility and the ground reaction modulus. Based on the results from extensive characterisation programme, it was concluded that the waste materials are in a metastable state and exhibit heterogeneity across the site. The findings of current case study can provide new insight into construction/demolition waste behaviour, using available geophysical and geotechnical tools and testing procedures for characterisation, and eventually helping in reliable design of foundations for new development projects.

Spatiotemporal evolution law and output prediction of construction waste in the People's Republic of China.

Based on the relevant data of construction waste (CW) in the People's Republic of China (PRC) from 2010 to 2018, this study applied K-means clustering algorithm and grey prediction methods to systematically investigate the spatiotemporal characteristic distribution and provincial clustering of CW in the PRC, and predicted the annual output of CW in the next five years from the scientific perspective. Results showed that the annual output of CW in the PRC displayed an overall trend of "rising first and then falling" and "being high in the middle east and low in the northwest," and the areas with obvious agglomeration gradually spread from the west to the middle and eastern regions. The law of development was consistent with the goals of the Chinese government to promulgate urban agglomeration development policies, prefabricated building encouragement policies, and CW management regulations. In the next five years, the annual output of CW in the PRC will increase by a small margin. Thus, all aspects of CW resource management should be conducted in a planned and step-by-step manner.

Construction waste landfill volume estimation using ground penetrating radar.

Underground landfill, the primary disposal method of construction waste in several areas, negatively affects the surrounding environments. Suitably locating and estimating waste volume in an underground landfill are vital for adequate disposal and recycling of construction wastes. In this study, we investigated the applicability of ground penetrating radar (GPR) technology to estimate waste depth and volume of a construction waste landfill. The results revealed the following. (1) The GPR technology effectively delineated boundaries between underground waste and the surrounding strata; the topographic structure obtained from the analysis of the associated images was consistent with the actual topography. (2) Layer information from GPR images and electromagnetic wave velocity calculated using the complex refractive index model for construction waste burial depth inversion produced highly accurate results. Waste depth in the landfill was estimated using the GPR inversion results and spatial interpolation. Kriging interpolation exhibited the highest accuracy. (3) The trapezoid, Simpson and Simpson 3/8 rules were suitable for estimating construction waste volume. A three-dimensional model created using the spatial interpolation grid precisely depicted the structure of the buried landfill. Our study provides references for the management, recycling and environmental impact assessment of construction waste.

Estimation of construction waste composition based on bulk density: A big data-probability (BD-P) model.

Estimating the composition of construction waste is crucial to the efficient operation of various waste management facilities, such as landfills, public fills, and sorting plants. However, this estimating task is often challenged by the desire of quickness and accuracy in real-life scenarios. By harnessing a valuable data set in Hong Kong, this research develops a big data-probability (BD-P) model to estimate construction waste composition based on bulk density. Using a saturated data set of 4.27 million truckloads of construction waste, the probability distribution of construction waste bulk density is derived, and then, based on the Law of Joint Probability, the BD-P model is developed. A validation experiment using 604 ground truth data entries indicates a model accuracy of 90.2%, Area Under Curve (AUC) of 0.8775, and speed of around 52 s per load in estimating the composition of each incoming construction waste load. The BD-P model also informed a linear model which can perform the estimation with an accuracy of 88.8% but consuming 0.4 s per case. The major novelty of this research is to harmonize big data analytics and traditional probability theories in improving the classic challenge of predictive analyses. In the practical sphere, it satisfactorily solves the construction waste estimation problem faced by many waste management facility operators. In the academic sphere, this research provides a vivid example that big data and theories are not adversaries, but allies.

"Looking beneath the surface": A visual-physical feature hybrid approach for unattended gauging of construction waste composition.

There are various scenarios challenging human experts to judge the interior of something based on limited surface information. Likewise, at waste disposal facilities around the world, human inspectors are often challenged to gauge the composition of waste bulks to determine admissibility and chargeable levy. Manual approaches are laborious, hazardous, and prone to carelessness and fatigue, making unattended gauging of construction waste composition using simple surface information highly desired. This research attempts to contribute to automated waste composition gauging by harnessing a valuable dataset from Hong Kong. Firstly, visual features, called visual inert probability (VIP), characterizing inert and non-inert materials are extracted from 1127 photos of waste bulks using a fine-tuned convolutional neural network (CNN). Then, these visual features together with easy-to-obtain physical features (e.g., weight and depth) are fed to a tailor-made support vector machine (SVM) model to determine waste composition as measured by the proportions of inert and non-inert materials. The visual-physical feature hybrid model achieved a waste composition gauging accuracy of 94% in the experiments. This high performance implies that the model, with proper adaption and integration, could replace human inspectors to smooth the operation of the waste disposal facilities.

A four-quadrant conceptual framework for analyzing extended producer responsibility in offshore prefabrication construction.

Prefabrication has been widely advocated as a green production strategy to minimize the adverse environmental impacts of construction. Amid economic globalization, prefabricated construction materials are commonly sourced offsite and even offshore. As an issue emerging alongside offshore prefabrication, extended producer responsibility (EPR) is yet to be clearly identified, allocated, and implemented. This research develops a conceptual framework using a design thinking process, through which EPR associated with offshore prefabrication can be analyzed, agreed upon, and allocated. By considering the scope and scale of the responsibility and the procurement methods, the framework comprises four quadrants representing four typical scenarios for implementation of the EPR principle. It is applicable for both short-term and lifelong EPR analysis, in both traditional and integrated project delivery contexts. The framework will be particularly useful for devising public policies to achieve an onshore and offshore stakeholder win-win situation.

An empirical study on waste generation rates at different stages of construction projects in China.

Estimation of construction waste generation is critical to construction waste management decisions. However, current construction waste estimation methods have various limitations (e.g. small samples). To address those limitations, this research conducts an empirical study to evaluate the waste generation rate of different types of waste at different construction stages. In this study, construction waste from 148 new-built residential construction sites in China were sorted and weighted on site and their waste generation rates were estimated separately. The results indicated that the amount of inorganic nonmetallic waste with a generation rate of 16.59 kg m-2 was the highest among the five types of waste (i.e. inorganic nonmetallic waste, organic waste, metallic waste, composite waste, hazardous waste), while the waste generation rate for the underground construction stage, which was 27.57 kg m-2, was the highest among the three stages (i.e. underground stage, superstructure stage, finishing stage). Compared with previous data, the new waste generation rate proposed in this research can better estimate the actual waste generation situation in construction sites, which provides reliable information for proper decision-making. Furthermore, based on the result of the empirical study, some recommendations for construction waste reduction are proposed.

An assessment tool for municipal construction waste management in Brazilian municipalities.

Construction waste is generated during construction and remodelling undertakings. Construction waste management (CWM) is a challenge in developing countries such as Brazil. Thus, it is necessary to create tools by which CWM may be evaluated. This article presents the elaboration of a tool to assess CWM in Brazilian cities; moreover, this method facilitates such analyses in regions which lack substantial quantitative data. In doing so, the tool, known as the Assessment Index for Construction Waste Management (ICWM), combines quantitative and qualitative information and is composed of 49 indicators and 19 criteria divided into the following groups: operational; environmental; politico-economic, educational; and social. The analytic hierarchy process was used to assign the weights attributed to the groups and criteria to build the index. The indicators were measured according to a standardized rating scale proposed for each one. These elements were aggregated in a mathematical formula that enables the calculation of the ICWM. The aggregation method used was a weighted linear combination, and the index is rated on a 0 to 1 scale. The ICWM was tested in four municipalities. In all cases, the management was considered inefficient. The proposed tool proved to be effective in evaluating the CWM. In cities where the ICWM was tested, it was possible to identify the significant deficiencies of the CWM and recommend improvement actions to develop more efficient and sustainable management.

An assessment of construction waste management in India: A statistical approach.

Construction waste needs to be managed in order to minimize environmental burden in India and conserve existing natural resources. Despite numerous policies and guidelines there is improper construction waste management. Towards addressing this issue, a novel approach is presented to unraval and investigate waste management in India using four methods: quantification of waste by wastivity; grouping of influence factors (IFs) by factor analysis; ranking of IFs by analogous importance index; and determination of attitude by concordance among construction crew. The outcomes forecast wastivity of concrete (4.14%) and steel (1.62%), respectively. Exploratory factor analysis groups factors into five categories. The top influence factor (CMT6, 0.901) according to contractors and academicians is: workers should be given training in identifying recyclable material. Engineers favor enforcement of strict punishment for illegal disposal of wastes in violation of Environmental Protection Agency regulations (CMT7, 0.895). Computed concordance indicates: moderate agreement (0.68) among variables under the construction method; strong agreement among variables in documentation (0.76) and construction equipment (0.81); and very strong agreement among variables in worker intention (1.00) and materials (1.00). The variation in attitude of the workforce towards waste management and the proclivity of policy developers towards protocols which include training of workers in efficient waste management are quantified.

A mini review of construction and demolition waste management in India.

The growth of the Indian construction sector is expected to result in a significant demand-supply gap with respect to construction materials such as sand, limestone, and aggregates. Additionally, the vast quantity of unprocessed Construction and Demolition (C&D) waste pose serious problems in some places, particularly in residential, institutional, industrial or commercial construction hotspots. While several waste quantification methodologies have been proposed in the literature, the quantification of waste generation in India is inadequate. This inadequacy can be attributed to the lack of appropriate hierarchical control mechanism, absence of a common C&D waste estimation method, and the lack of C&D waste processing knowledge among generators, collectors, operators, regulators, and the general public. The C&D Waste Management Rules 2016 were introduced to ensure organized collection, storage, transportation, treatment/processing, and disposal of C&D waste in India and fix responsibilities of all stakeholders for management of C&D waste. This comprehensive research attempts to analyze the existing legislation and challenges, and proposes an information framework for organized collection, storage, treatment/processing, and disposal of C&D waste. The C&D waste processing mechanism, potential application of recycled C&D waste products, its limitations, and the best practices of C&D waste management in India are important constituents of the proposed framework.

Evaluating treatment pathways for managing packaging materials from construction of a solar photovoltaic power station.

The reuse of end-of-life packaging materials (EOLPM) on site represents, particularly for remote sites, an important contribution to sustainable business practice because it provides a higher value end use when used to develop on-site mulch to enable soil improvement, thereby reducing transport emissions (in relation to the least preferred option of off-site disposal to landfill), lowering costs and offering employment to local contractors. The objective of the study was to demonstrate a local application of the circular economy for EOLPM to a utility-scale solar electricity (USSE) construction site. Although the principles of the circular economy could not be applied fully at the site, it was possible to demonstrate that EOLPM can be reused on site for a higher value than off-site disposal would give. Given the common occurrence of these materials in the rapidly growing renewable energy sector, this represents an important step forward for the sector internationally. The study is the first of its type reported, and the methods used for characterization of the EOLPM included a range of organic and inorganic chemical analyses and phytotoxicity testing, which were followed by an environmental and financial cost-benefit analysis. The selected option of on-site reuse of the materials as a mulch had a global warming potential of 58 t CO2e compared with the business as usual option (transport to landfill) of 3145 t CO2e. The results also demonstrated the broader potential for using EOLPM from USSE sites for soil improvement at remote locations rather than transporting these materials off site for disposal or reuse.

Value stream mapping for identification and assessment of material waste in construction: A case study.

Construction sites are plagued with numerous problems, such as improper planning and management, high amounts of waste generation and low awareness of waste reduction. Construction and demolition waste literature provides several best practises and prescriptive strategies that help minimise waste during construction. However, it lacks in the systematic identification and minimisation approach of all possibilities of waste. Therefore, studies focusing on principles and tools that help systematically analyse the inefficiencies of on-site processes leading to waste generation and philosophies addressing waste minimisation are necessary. As eliminating waste is one of the key lean principles, this article discusses the need and importance of integrating the lean construction with the construction and demolition waste management. This article aims to estimate and assess the causes of waste generation in a high-rise building construction through a case study in Chennai city (India) using value stream mapping, a key lean construction tool. Onsite monitoring and measurement were performed to quantify the amount of waste generated. A waste generation rate of 66.26 kg m-2 was identified, of which concrete, cement mortar and brick waste represented almost 90% of the total construction waste. Direct observation and interviews of site personnel were conducted to understand the causes of waste generation. A strategic framework has been proposed to improve construction and demolition waste minimisation depicting the synergy of combining lean construction principles with construction and demolition waste management strategies. The proposed framework helps in the systematic identification, assessment and minimisation of on-site construction waste generation.