Urban Waste Streams Research Articles

Design and fabrication of magnetic cross-linked laccase aggregate using superparamagnetic metal-organic frameworks for phenol removal

Phenolic pollutants represent a significant environmental concern due to their widespread presence in industrial effluents, agricultural runoff, and urban waste streams. Enzymatic bioremediation emerges as a promising approach for the efficient removal of phenolic pollutants from contaminated environments. Laccases exhibit remarkable catalytic capabilities in degrading phenolic compounds into less harmful or even inert products. In this study, magnetic cross-linked laccase aggregate was prepared using superparamagnetic metal-organic frameworks and then was applied for phenol removal. The obtained results showed that the magnetic cross-linked laccase aggregate retains its activity across a broad pH range. Interestingly, (NH4)2SO4 exhibited a positive influence on enzyme activity, resulting in a relative activity of 137.7 %. The findings suggest that an optimal concentration range of 0.4–0.8 % can achieve maximum enzyme activity while avoiding potential negative impacts associated with excessive cross-linking. Optimal pH and temperature conditions were identified for enhanced phenol removal efficiency as pH 4.5 and 45℃, respectively. The investigation revealed the remarkable reusability of the cross-linked enzyme over multiple cycles. Harnessing the power of enzymes for phenolic pollutant remediation holds immense promise for mitigating environmental pollution and safeguarding public health.

Spatiotemporal Variability in Municipal Solid Waste Production and the Determinants in Hefei’s Core Urban Districts

Precision in discerning the spatiotemporal dynamics of municipal solid waste (MSW) production and its drivers is pivotal for informing the seasonal management and recycling of urban waste streams. This investigation zeroed in on Hefei’s central urban zone, deploying a nuanced principal component analysis and geographically and temporally weighted regression (PCA-GTWR) to quantify the sway of the environmental, economic, and living standard variables on the MSW generation patterns. The methodology unfolded across four main phases: (1) leveraging nocturnal light data to approximate the MSW output; (2) employing spatial autocorrelation to probe the variable trends and spatial interdependencies of the waste generation; (3) harnessing principal component analysis to pinpoint critical determinants and preprocess these as inputs for the GTWR model; (4) mapping the GTWR outcomes to elucidate the differential impacts of various factors on the waste production patterns. Key findings reveal a distinctively polycentric MSW distribution, with high-density areas anchored in the urban core and diminishing intensities beyond the secondary periphery. The trio of socioeconomic variables, residents’ living standard variables, and natural variables emerge as pivotal, with the PCA-GTWR offering a vivid spatial delineation of their effects. Notably, socioeconomic growth exerts a pronounced positive influence in more affluent quarters, residential standards bear greater relevance in burgeoning urban sections than in the established core, and environmental influences wield the least sway, ebbing and flowing with the seasons. These insights demystify the undercurrents shaping the MSW production in urban China, serving as a strategic compass for waste minimization initiatives and policy formulation.

The Urban-Industrial metabolism: contribution of waste recycling to the circular economy objectives within the construction sector

The construction and buildings sector is facing an urgent need to reduce GHG emissions and ensure efficient resource utilization while minimizing waste in order to comply with climate change policies and circular economy initiatives. Alkali-activated materials, as an alternative binder to CO2-intensive conventional cement, show potential in utilizing waste streams from urban environments in their production technology, thereby reducing CO2 emissions. This study examines two waste streams generated in Switzerland: incineration ashes from municipal solid waste treatment facilities and mineral wool waste from building stock renovation and demolition activities. Geospatial analysis is combined with LCA methods to assess optimal scenarios for waste recycling, utilizing a multi-objective optimization framework based on mixed integer linear programming. The objectives are to minimize the environmental impacts and costs associated with alternative supply chain networks, thereby identifying optimal locations for waste pre-treatment and concrete manufacturing. The proposed scenarios demonstrate reductions of 56% in global warming potential and 29% in costs when compared to the business-as-usual scenario of conventional cement concrete use and waste landfilling. Results show that recycling of urban waste streams in alternative concrete can reduce GHG emissions of industry and heavy transportation sectors by 0.46 mt. CO2 eq. by year 2030, equivalent to 23% and 4% of the Swiss carbon budget reduction targets for these sectors.

Laboratory-adapted and wild-type black soldier flies express differential plasticity in bioconversion and nutrition when reared on urban food waste streams.

The black soldier fly (BSF) offers a potential solution to address shortages of feed and food sources; however, selecting effective rearing substrates remains a major hurdle in BSF farming. In an urban area like Singapore, current practice is based on rearing BSF on homogeneous waste streams (e.g., spent brewery grains or okara) because heterogeneous food wastes (e.g., mixed kitchen/canteen waste or surplus cooked food) present several operational challenges with respect to the standardization of development, nutritional content, and harvesting. In this study, we compared two genetic strains of BSF larvae (wild-type and laboratory-adapted line) in a bioconversion experiment with diverse types of food waste (homogeneous/heterogeneous; plant/meat) and we quantified the phenotypic plasticity. Our results demonstrate different plasticity in bioconversion performance, larval growth and larval nutrition between the two BSF lines. This difference may be attributed to the selective breeding the laboratory-adapted line has experienced. Notably, larval lipid content displayed little to no genetic variation for plasticity compared with larval protein and carbohydrate content. Despite variation in larval development, heterogeneous food wastes can produce better performance in bioconversion, larval growth, and larval nutrient content than homogeneous food waste. All-meat diets result in high larvae mortality but larval survival could be rescued by mixing meat with plant-based food wastes. Overall, we suggest using mixed meals for BSF larvae feeding. Targeted breeding may be a promising strategy for the BSF industry but it is important to consider the selection effects on plasticity in larval nutrition carefully. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Integrating resource oriented sanitation technologies with urban agriculture in developing countries: measuring the governance capacity of Arba Minch City, Ethiopia

This research study aims to assess the capacity of Arba Minch City to adopt resource-oriented sanitation technology and integrate it with urban agriculture. The overarching goal is to promote sustainable urban development by not only using resources efficiently but also recovering resources from urban waste streams. To measure the city's governance capacity, the study employs a Governance Capability Framework (GCF), which identifies nine conditions and three indicators for each condition across three dimensions: knowing, wanting, and enabling. The framework helps assess the city's capacity for governance throughout the integration of urban agriculture with ecological sanitation (ecosan) technology. The research employs a triangle strategy, which consists of desk research, gray and scientific literature review, and a semi-structured interview with 27 indicators. By employing these strategies, the research evaluates Arba Minch's governance capacity to implement ecological sanitation integration with urban agriculture. The findings of the study show that Arba Minch City's governance capacity to integrate ecosan with urban farming is affected by several factors. These factors include a lack of systematic monitoring and evaluation of previous projects, fragmentation of policy tools to govern the integration of the system, and a lack of adequate public sector participation. Additionally, there is no government body responsible for integrating the system, and various non-governmental organizations play a significant role in financing, organizing, and implementing the system. On the user side, the study reveals a behavioral gap in adapting to resource-oriented sanitation technology and recovered organic fertilizer. The findings suggest that long-term system management requires a strong, active, and well-trained community group capable of taking on the role and responsibility of running similar projects. Furthermore, to mitigate the policy fragmentation challenge, policy harmonization and integration among actors to negotiate, deliberate, and agree on measures to be taken are critical. In conclusion, the study suggests that similar project developers should investigate the factors that motivate users of new technology and influence their behavioral changes. Ultimately, the study recommends a more comprehensive approach to resource-oriented sanitation technology and urban agriculture integration that takes into account governance capacity and community engagement.

Simulating the fate of compost-derived nutrients in an urban garden

The application of compost to urban vegetable gardens presents an opportunity to recycle nutrients from the urban waste stream back into the human food system. However, many gardeners apply phosphorus (P) in the form of compost at a rate that far exceeds what crops can take up. The fate of this P—whether stored in soil, taken up by plants, or exported through leachate, depends on the dynamics of water, carbon (C), and nitrogen (N) in this agroecosystem. We developed a model representing these four currencies (C, N, P, water) in urban garden soils, that was parameterized and validated using data from four years of data from an experiment in which high or low amounts of labile manure-based compost, or recalcitrant municipal compost, are added to garden plots annually. We used the model to simulate the effects of longer-term (10-year) additions of labile or recalcitrant compost at low, medium, or high levels (based on previously reported survey data for Minneapolis-Saint Paul, Minnesota), tracking the fate of added N and P, as well as calculating net C sequestration. The fraction of compost nutrients recovered over 10 years ranged from 3 to 47% (N) and 4–67% (P) with higher efficiencies associated with lower input rates and for recalcitrant compost. Approximately half of added C was ultimately respired by soil microbes, while C sequestration from crop growth was much lower than soil respiration. This model provides a tool for understanding how management decisions and climate control nutrient recycling and loss via leachate from compost application in urban agroecosystems.

Natural freeze concentration of wastewater for nutrient recovery

Water and food are vital needs for all humans and animals living on the earth, and intensive crop cultivation that requires plentiful nutrients and water has evolved to meet food production demands. As population grows and the supply of raw material nutrient deposits and clean water begin to run out, effective recycling becomes increasingly important. However, recovering nutrients from urban waste streams is not yet technically or economically feasible. New energy efficient separation technologies are needed to meet the demand. Making use of the colder climates of polar regions is an opportunity to achieve a more efficient and economical transition to a circular economy. Hence, this study focuses on a natural cold-climate freeze concentration technique that enables the recovery of both water and material concurrently in a single process.Experiments were carried out in a winter simulator device using various waste streams originating from landfill and a biogas production plant. Average partition coefficients between 1.5 and 3 for the concentrates and 0.08 and 0.4 for the ice were achieved for different concentrate mass yields with different water quality measures, essential ions, and elements, including harmful metals. These results confirm that freeze concentration is a potential option when developing new technologies that combine water and material reclamation from wastewater towards sustainable circularity.

Circular Economy Design towards Zero Waste: Laying the foundation for constructive stakeholder engagement on improving construction, renovation, and demolition (CRD) waste management

The city of Montréal is one of many cities worldwide who strive to cut the amount of waste they generate and advance towards zero waste in an effort to meet the Paris Agreement goals. Construction, renovation, and demolition (CRD) waste is a major contributor to urban waste streams but also an area where waste diversion and innovative waste management approaches could deliver significant reductions in waste. One such promising approach is that of circular economy which envisions a future where CRD waste is designed-out of the built environment by keeping construction materials in use. This paper presents a series of methods used to collect and organize data towards advancing circular thinking within CRD material management decision-making in Montréal and mobilizing engagement with the relevant data. Methods includes a detailed literature review, semi-structured interviews with stakeholders from across the building sector value chain followed by a thematic analysis. Collected data is mapped to the internationally recognized United Nations Sustainable Development Goals (SDGs) framework in an aim to provide globally significant methodologies which cities worldwide can use to showcase contributions to the UN SDGs. Advancing towards zero CRD waste in Montréal will require the input of multiple stakeholders. The work presented in this paper is part of a larger research effort which works to deliver an initial but vital first step in the collection, integration, and dissemination of data towards a circular, more sustainable, built environment.

Sustainability assessment of increased circularity of urban organic waste streams

The circular economy, from an urban organic waste perspective, is seen as an approach to deal with increasing waste streams, while contributing to meeting the increasing demand for water, energy, food and other resources in urban areas. However, there is need for a systematic assessment of the broader environmental and social benefits and trade-offs of resource recovery from organic waste streams. This paper presents a framework for assessing the societal impacts of increased circularity in terms of resource recovery from organic waste streams at city scale, building on the design of alternative scenarios for future technology systems. The framework was developed based on a literature review of current frameworks in the area, adapting and combining some of their aspects and adding required features to allow for a broad sustainability assessment. It was also informed by stakeholder interviews. The framework was applied to the case of Naivasha, Kenya to illustrate its applicability and usefulness. The outcome of the application in the Naivasha case indicate potential sustainability improvements from increased circularity, where resource recovery could lead to a reduction of greenhouse gas emissions, more efficient natural resource usage and job creation. It indicated also some risks of negative impacts on the health of workers in resource recovery facilities, and, in this specific case, negative impact on smallholder farmers. The framework proved applicable and useful in the case study, and hence could provide input at early stages of planning even with low availability of data. Thereby it could provide policy-relevant insights towards circular economy implementation approaches that harness the benefits while mitigating any identified potential negative impacts.

Energy recovery from brewery spent grains and spent coffee grounds: a circular economy approach to waste valorization

Currently, the circular economy approach is gaining importance, and it is already a concern to different industrial sectors, intending to eliminate the waste produced while trying to create new value chains. In addition to this disruptive process, the net-zero carbon emissions objective can be fulfilled. In this way, the energy recovery of residual biomass forms is assumed to be a high potential alternative for pursuing this objective. The present work deals with the recovery of brewery spent grains (BSG) and spent coffee grounds (SCG) through direct combustion. Samples were collected and characterized to analyze the viability of BSG and SCG combustion recovery options. From the results, it can be concluded that, although this possibility can be viable under certain circumstances, some constraints due to the composition of these materials can jeopardize this recovery option. Further research concerning the life cycle assessment of these materials and eventual environmental impacts caused by such a solution is still missing and must be conducted. It is also essential to proceed with further chemical characterization of these wastes concerning corrosion-related phenomena and to justify diverting both BSG and SCG from urban solid waste streams. After this preliminary approach, the research can also focus on the economic analysis and quantification of resource availability.

Resources for renewable natural gas: A Hawaii case study

AbstractFeedstock resources for renewable natural gas (RNG) production by biological (e.g., anaerobic digestion) and thermochemical (e.g., gasification) conversion methods in Hawaii have been reviewed. Statewide estimates of RNG production potential from urban resources (wastewater, existing landfills, foodwaste, construction and demolition waste (CDW), and municipal solid waste) total 8860 TJ year−1. Honolulu has the largest resource base for these urban waste streams. Underutilized agricultural land resources in the state could support substantial RNG production from dedicated energy crops (260–520 GJ ha−1 year−1), although agronomic suitability of specific candidate energy crops would need to be evaluated and confirmed.

Increased personal protective equipment consumption during the COVID-19 pandemic: An emerging concern on the urban waste management and strategies to reduce the environmental impact

Personal protective equipments (PPEs) are essential protective products for individuals exposed to microorganism, toxic substances, and pathogens. However, the advent of the coronavirus pandemic generated a heavy demand for PPE, which has led to a rapid accumulation of plastic waste related to potentially infectious PPE in the urban waste stream. Mismanagement of these wastes can lead to subsequent environmental problems. This study estimates the daily consumption of facemasks, gloves, and daily medical waste generation during the SARs-CoV-2 pandemic in the selected 33 countries worldwide. The results indicate that China used the highest daily facemasks and gloves among these selected countries, followed by India, the US, Brazil, Indonesia, and Japan. Moreover, India is the first one in medical waste production, followed by the USA, Brazil, the United Kingdom, France, and Spain. The article also provides viable strategies and discusses the pros and cons of strategies to address the unprecedented generation of plastic waste material during the pandemic. This manuscript also encourages scientific communities and policymakers to pay exceptional attention to the pandemic's plastic waste.

Municipal solid waste: A potential source of clean energy for Khartoum State in Sudan

Sudan is a large African country with a land area of 1.882 million km2 and a population of 43 million people. The country has a fast-growing population, consistent migration from rural to urban areas, raised per-capita demand for power and fuels, and falling fossil-fuel production. Additional baseload or on-demand energy sources are needed to supply the Nile Valley system. The increasing silting of the different hydroelectricity dams is a problem for the future availability of hydroelectricity generation. Non-recyclable combustible municipal solid waste and other urban organic waste streams can be used to provide low-emission baseload electricity and a cost-effective supply of heat for industry. These wastes, which have the potential to be used as feedstocks for energy production, have already been gathered together in enormous quantities. The current landfill disposal method is becoming increasingly expensive, and it leads to several negative environmental impacts, such as methane emissions and air and water pollution. This research looks at how the non-recyclable combustible fraction of waste collected in Khartoum State can be used to generate considerable amounts of energy and industrial heat while reducing the greenhouse gas (GHG) emissions. This might be accomplished by employing and adopting efficient technologies that are extensively used elsewhere in the globe, as well as securing the additional benefits of more permanent jobs, fewer fossil fuel imports, and improved national resource security for Sudan.

Planning decentralized urban renewable energy systems using algal cultivation for closed-loop and resilient communities

To tackle climate challenges, communities need to harvest renewable energy and resources on site locally to close the loops for enhancing the resilience of communities facing unpredictable and uncertain future changes. A decentralization planning of urban renewable energy systems is proposed by treating urban waste streams and producing biomass through applying algal biotechnology. When applying algal technology as a renewable and decentralized energy source in urban systems, the overall performance can vary by levels of urban nutrients, solar and CO2 resources, and the transportation cost when considering its application to different urban densities, urban form, and the spatial scale of urban settings. This research explores three potential impacts on the algal system’s energy performance: (1) urban density, (2) urban form in different contexts, and (3) spatial scale. The research examines the impacts by testing urban settings given in actual contexts in Atlanta, Georgia, USA. Four neighborhoods representing the high-density urban, mid-density urban, mixed suburban, and typical suburban areas are investigated. The density-scale–performance relationships are explored through testing different urban forms of neighborhoods in both hypothetical and actual neighborhood settings. A GIS-based model is developed to estimate the overall energy performance of the decentralized renewable energy system in urban environments. Results show that the energy performance is positive mainly for high-density urban neighborhoods with small-to-medium scales, up to 0.36 MJ per ton of municipal solid wastes for actual settings and 0.37 MJ for hypothetical cases. Neighborhoods with higher density have higher energy performance while up scaling has negative effects on the energy performance with a low degree of significance. Optimal scales are found as a 1-km radius in real test beds and 1.3 km in hypothetical settings, in which the results show trade-offs between scaling effects in the system efficiency gain and the transportation cost increase.

Nature-Based Units as Building Blocks for Resource Recovery Systems in Cities

Cities are producers of high quantities of secondary liquid and solid streams that are still poorly utilized within urban systems. In order to tackle this issue, there has been an ever-growing push for more efficient resource management and waste prevention in urban areas, following the concept of a circular economy. This review paper provides a characterization of urban solid and liquid resource flows (including water, nutrients, metals, potential energy, and organics), which pass through selected nature-based solutions (NBS) and supporting units (SU), expanding on that characterization through the study of existing cases. In particular, this paper presents the currently implemented NBS units for resource recovery, the applicable solid and liquid urban waste streams and the SU dedicated to increasing the quality and minimizing hazards of specific streams at the source level (e.g., concentrated fertilizers, disinfected recovered products). The recovery efficiency of systems, where NBS and SU are combined, operated at a micro- or meso-scale and applied at technology readiness levels higher than 5, is reviewed. The importance of collection and transport infrastructure, treatment and recovery technology, and (urban) agricultural or urban green reuse on the quantity and quality of input and output materials are discussed, also regarding the current main circularity and application challenges.

A Molecular Survey of Bacterial Species in the Guts of Black Soldier Fly Larvae (Hermetia illucens) Reared on Two Urban Organic Waste Streams in Kenya.

Globally, the expansion of livestock and fisheries production is severely constrained due to the increasing costs and ecological footprint of feed constituents. The utilization of black soldier fly (BSF) as an alternative protein ingredient to fishmeal and soybean in animal feed has been widely documented. The black soldier fly larvae (BSFL) used are known to voraciously feed and grow in contaminated organic wastes. Thus, several concerns about their safety for inclusion into animal feed remain largely unaddressed. This study evaluated both culture-dependent sequence-based and 16S rDNA amplification analysis to isolate and identify bacterial species associated with BSFL fed on chicken manure (CM) and kitchen waste (KW). The bacteria species from the CM and KW were also isolated and investigated. Results from the culture-dependent isolation strategies revealed that Providencia sp. was the most dominant bacterial species detected from the guts of BSFL reared on CM and KW. Morganella sp. and Brevibacterium sp. were detected in CM, while Staphylococcus sp. and Bordetella sp. were specific to KW. However, metagenomic studies showed that Providencia and Bordetella were the dominant genera observed in BSFL gut and processed waste substrates. Pseudomonas and Comamonas were recorded in the raw waste substrates. The diversity of bacterial genera recorded from the fresh rearing substrates was significantly higher compared to the diversity observed in the gut of the BSFL and BSF frass (leftovers of the rearing substrates). These findings demonstrate that the presence and abundance of microbiota in BSFL and their associated waste vary considerably. However, the presence of clinically pathogenic strains of bacteria in the gut of BSFL fed both substrates highlight the biosafety risk of potential vertical transmission that might occur, if appropriate pre-and-postharvest measures are not enforced.

Closing the mineral construction material cycle – An endogenous perspective on barriers in transition

Construction and demolition waste (CDW) constitutes a highly voluminous urban waste stream with significant potential for circular mineral construction material usage. This paper uses participatory system dynamics modeling with relevant actors from different public policy and industry sectors to a) to identify structural barriers to the uptake of secondary resource utilization; b) design and test policies administrative (spatial planning, ownership), fiscal (extraction levy, disposal fee) and soft (lighthouse projects) policies and c) discuss the feasibility of implementing these with policies in the political and legislative context of Switzerland. We find practice relevant policy insights, such as the role of distributed control of land use policies resulting in a co-evolutionary lock-in to primary resources consumptions. Policy interventions need to establish new forms of collaboration between regional actors, as hinterland are specializing as resource suppliers for urban regions. Without coordinated interventions that address structural imbalances of material flow, arbitrage effects with other regions render policies ineffective. From a methodological perspective we find that simulation and participatory modeling improves the efficacy of transition interventions as we provide a structural problem analysis as a tool for Stakeholder reflexivity.

The role of soil in the contribution of food and feed.

Soils play a critical role in the production of food and feed for a growing global population. Here, we review global patterns in soil characteristics, agricultural production and the fate of embedded soil nutrients. Nitrogen- and organic-rich soils supported the highest crop yields, yet the efficiency of nutrient utilization was concentrated in regions with lower crop productivity and lower rates of chemical fertilizer inputs. Globally, soil resources were concentrated in animal feed, resulting in large inefficiencies in nutrient utilization and losses from the food system. Intercontinental transport of soil-derived nutrients displaced millions of tonnes of nitrogen and phosphorus annually, much of which was ultimately concentrated in urban waste streams. Approximately 40% of the global agricultural land area was in small farms providing over 50% of the world's food and feed needs but yield gaps and economic constraints limit the ability to intensify production on these lands. To better use and protect soil resources in the global food system, policies and actions should encourage shifts to more nutrient-efficient diets, strategic intensification and technological improvement, restoration and maintenance of soil fertility and stability, and enhanced resilience in the face of global change.This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.

The circular economy potential of urban organic waste streams in low- and middle-income countries

There is growing recognition of the potential environmental and socio-economic benefits of applying a circular approach to urban organic waste management through resource recovery. Decisions around planning and implementing circular urban waste systems require estimates of the quantity of resources available in waste streams and their potential market value. However, studies assessing circular economy potential have so-far been conducted mostly in high-income countries, yet cities in low- and middle-income countries have different challenges when developing a circular economy. This paper addresses this gap by estimating the resource recovery potential of organic waste streams in the context of low- and middle-income countries, illustrated with the case of Kampala, Uganda. A simplified material flow analysis approach is used to track the transformation of waste streams, namely faecal sludge, sewage sludge and organic solid waste into the resource recovery products biogas, solid fuel, black soldier fly larvae and compost. Findings indicate that even at current rates of waste collection, the three waste streams combined could annually yield 135,000 tonnes of solid fuel or 39.6 million Nm3 of biogas or 15,000 tonnes of black soldier fly larvae or 108,000 tonnes of compost and revenues from the products could range from 5.1 million USD from compost to 47 million USD from biogas. The results demonstrate how complex information describing urban waste can be presented to facilitate decision making and planning by stakeholders. By highlighting different resource recovery opportunities, application of this approach could provide an incentive for more sustainable urban sanitation and waste management systems.

Catalytic hydrothermal liquefaction of contaminated construction wood waste for biocrude production and investigation of fate of heavy metals

Heavy metals (HMs) are undoubtedly an unavoidable nuisance in today's era, and their appropriate handling and disposal carry the utmost significance. Construction wood (CW), specifically hazardous and non-hazardous wood is contaminated due to a mixture of different materials like paints, coatings, and copper layers, etc. that need proper attention for safe disposal. Wood waste from building and urban waste streams is abundantly available, which essentials to manage appropriately for energy recovery. In that respect, this study focused on the disposal option of contaminated wood waste via hydrothermal liquefaction (HTL) by turning waste into biocrude. CW is categorized into four types named Untreated wood (UNW), Non-hazardous wood (NHZW), Hazardous wood (HZW), and Mixed wood (MXW). Maximum biocrude yield was obtained by the liquefaction of UNW followed by NHZW, HZW, and MXW in the range between 24.86 and 36.35 wt%. Additionally, the fate of selected heavy metals (chromium, copper, nickel, zinc) was investigated in HTL products. It was concluded that, by the liquefaction of CW, the majority of HMs shifted to the solid residue. The negligible amount of HMs merged into the biocrude and aqueous phase. This study suggests HTL as a promising and sustainable route for the disposal of contaminated wood waste by turning into higher added value (or high quality) products especially biocrude with less HMs concentration as a fruitful product at large scale.