Wet Waste Research Articles

Automatic Waste Segregation System

The Automatic Waste Segregation System aims to enhance waste management practices by efficiently sorting waste into three categories: wet waste, dry waste, and metallic waste. Utilizing advanced sensor technologies, this system leverages an LM393 IC moisture sensor to detect the moisture content in waste, effectively identifying wet organic materials such as food scraps. Additionally, an infrared (IR) sensor is employed to distinguish dry waste, including paper, plastics, and textiles, based on the reflective properties of the materials. To further enhance the sorting process, a metal detector is integrated to identify and segregate metallic waste, ensuring that recyclables are collected accurately. The automation of waste segregation not only reduces the manual labor involved in traditional waste sorting methods but also increases the accuracy and efficiency of the process. This system is designed to operate autonomously, with real-time monitoring and feedback mechanisms that allow for seamless integration into existing waste management infrastructures. The collected data on waste types can be utilized for further analysis, enabling municipalities and organizations to develop more effective waste disposal and recycling strategies. By implementing this Automatic Waste Segregation System, we aim to address the growing challenges of waste management, reduce landfill dependency, and promote recycling and resource recovery. This innovative approach aligns with global sustainability goals, contributing to cleaner environments and enhanced waste resource management. The project has the potential to significantly improve waste processing efficiency, reduce environmental impact, and foster community awareness regarding the importance of proper waste segregation. Key Words: Arduino Mega, IR Sensor, DC Motor, Rotary Indexer, Container, etc.

Preparation of Sampling Plan For the Gravimetric Characterization of Solid Waste From the Municipality of Itaquaquecetuba

Objective: the objective of this study is to utilize a sampling design for the collection of USW samples for gravimetric characterization, with the aim of proposing and standardizing a methodology that allows for the collection of statistically representative samples of this biomass Theoretical Framework: It was based on national and international technical standards that deal with the collection, preparation and sampling of waste. In addition, statistical sampling concepts were used, as well as the National Solid Waste Policy. Method: The methods used in this research include analysis of technical standards (national and international) for municipal solid waste combined with statistical methods of probabilistic sampling. Results and Discussion: As a result, a statistically valid sampling methodology was developed and applied to the waste from the municipality of Itaquaquecetuba, leading to the collection of MSW samples from 35 trucks, which represented the characteristics of the types of wet waste generated in the municipality. This provides essential data for the integrated management of waste in the region. Research Implications: The research proposes a statistically valid sampling plan for the collection and analysis of urban solid waste that can be adapted and used in any region of the country or internationally. Originality/Value: The work contributes to the literature by proposing a statistically valid sampling plan for the collection and sampling of waste, using as a basis the characteristics of urban solid waste generated in Brazil.

A Review on EcoBinSense: Smart Waste Management System for Urban Area Using IOT and Android

Continuous urbanization and industrialization has to led to increase in volume and type of waste generated. It is estimated that in 2006 the total amount of municipal solid waste generated globally reached 2.02 billion tones, representing a 7% annual increase since 2003 (Global Waste Management Market Report 2007). This poses a problem for local and national governments to ensure sustainable and effective waste management. Technology always helps mankind in making life easier. In public places, proper disposal of waste is not being followed which causes overflow of waste in dustbins that has become a threat to the environment. Segregation, management, transport and disposal of waste plays an important role to minimize the risk to the public and environment. The economic value of waste is best realized when it is segregated. Currently there is no such system of segregation of dry, wet and metallic wastes at a household level. This paper is an innovative way to revolutionize the waste management system using sensors. Segregation is achieved using respective automated sensors and the level of dustbins are monitored simultaneously. Presently there's no such system for segregation of dry and wet wastes at domestic level or social unit level. This paper proposes an automated sensor based waste management and segregation system. It is designed to sort the refuse into 2 categories: wet and dry (metal).

Influence of moisture content and inlet temperature on the incineration characteristics of municipal solid waste (MSW)

Incineration is an effective method for the treatment of municipal solid waste, pre-treatment reduces the waste moisture content to increase the incineration performance. However, the inlet temperature variation influenced by the environment is often ignored at this stage, and the coupling of moisture content and inlet temperature directly affects the incineration performance. To investigate the optimal inlet conditions for the incineration, the numerical model of a 600 t/d incinerator was established according to a reference case. Detailed analyses of the combustion characteristics of the bed and furnace is conducted under various moisture contents and inlet temperatures. The incineration efficiency under multiple factors is analyzed using response surface methodology, with sensitivity to these factors derived from the surface derivative. The results indicate that at an inlet temperature of 30 °C, the rates of volatile release and fixed carbon combustion are negatively correlated with the moisture content, and maximum incineration efficiency of 39.02 % is reached at a moisture content of 28.12 %. At a moisture content of 33.26 %, The rates of moisture evaporation, volatile release, and fixed carbon combustion are positively correlated with inlet temperature, and the maximum incineration efficiency of 38.76 % is achieved at an inlet temperature of 40 °C. The incineration efficiency exhibits a negative sensitivity to moisture content, whereas its sensitivity to inlet temperature is contingent upon the specific temperature range. The combination of 26.53 % moisture content and 40.86 °C inlet temperature yields the highest incineration efficiency of 40.69 %. The findings of this study provide useful information for the pre-treatment of municipal solid waste, contributing to the enhancement of operational efficiency in waste-to-energy plants.

Pilot microbial electrolysis cell closes the hydrogen loop for hydrothermal wet waste conversion to jet fuel

The global shift toward net-zero emissions necessitates resource recovery from wet waste. In this study, we demonstrate the first feasibility of combining pilot-scale microbial electrolytic cells (MECs) with hydrothermal liquefaction (HTL) for simultaneous post-hydrothermal liquefaction wastewater (PHW) treatment and efficient hydrogen (H₂) production to meet biocrude upgrading requirements. Long-term single reactor operation revealed that fixed anode potential enabled rapid startup, and low catholyte pH and high salinity were effective in suppression of cathodic methanogenesis and acetogenesis – resulting in high current density of 16.6 A m−2 and 9.3 A m−2 when feeding synthetic wastewater and PHW respectively. Additionally, the anode biofilm exhibited spatial variations in response to local environmental conditions. Onsite parallel or serial operations of multiple MECs showed good performance using actual PHW with a record-high H2 production rate of 0.5 L LR day−1 for MEC over 10 liters scale, and the optimal chemical oxygen demand (COD)-to-H2 yield reached 0.127 kg-H2 per kg-COD, supporting a self-sufficient, closed-loop upgrade to jet fuel.

Hydrothermal carbonization of woody waste: Changes in the physicochemical properties and the structural evolution mechanisms of hydrochar during this process

The Chinese medicine residue (CMR) is composed of wet woody waste, including licorice and ephedra, so using hydrothermal carbonization (HTC) to recover renewable energy from the CMR is a suitable treatment method. An in-depth analysis of the physicochemical properties and structural evolution mechanism of hydrochars is helpful in fundamentally promoting the energy utilization of traditional Chinese medicine waste residue. Therefore, this study analyzed the physicochemical properties and morphological structure of hydrochar produced under varying HTC conditions using multiple testing methods. The evolution of the hydrochar's structural characteristics can be categorized into three stages: component decomposition, structural rearrangement, and carbonization. During the component decomposition and carbonization stages, numerous nanoscale micropores form within the hydrochar. These micropores' specific surface area and pore volume can reach up to 113.420 m2/g and 0.01913 cm3/g, respectively. The highest fractal dimension values for D1 and D2 are 2.6354 and 2.5565, while the maximum values for the microcrystalline stacking height (Lc) and the average number of crystalline layers (Nave) are 0.3354 and 1.9968, respectively. Consequently, the hydrochar produced during these stages exhibits a rougher pore surface and a more complex structure, making it more suitable for adsorbing heavy metals from soil and sequestering CO2. During the structural rearrangement stage, the hydrochar exhibits higher contents of fixed carbon (FC), MgO, P2O5, and a higher C/N atomic ratio, with maximum values of 38.51%, 0.99%, 1.12%, and 28.49, respectively. Thus, the hydrochar produced during this stage is more suitable for soil remediation and nutrient recovery.

Effectiveness of NGOs in mountainous solid waste management: A case study from Healing Himalayas in Rakchham, Himachal Pradesh, India.

Non-governmental organizations (NGOs) play a critical role in addressing solid waste management (SWM) challenges in remote mountain communities, including the ecologically fragile Himalayan region. This study evaluates the impact of Healing Himalayas, an NGO, in Rakchham village, Himachal Pradesh, India. The objectives were to evaluate the effectiveness of Healing Himalayas' decentralized SWM model in promoting stakeholder engagement and resource recovery, assess the role of collaborations between local authorities and the NGO in financing waste management practices, investigate the influence of tourism and seasonal variations on solid waste generation patterns and waste management practices in Rakchham, and material recovery facilities, followed by glass (36.7%), paper/cardboard (18.4%) and metal (4.1%). A fee-based system involving the local village council funded waste operations. Waste generation exhibited significant seasonal fluctuations, with tourism influxes driving increased volumes. Healing Himalayas' initiatives promoted community participation, with over 15 awareness workshops conducted. Key challenges included limited financial resources, inadequate infrastructure, lack of advanced treatment facilities and need for context-specific solutions like efficient wet waste management in cold climates. The study highlights Healing Himalayas' decentralized model's success in fostering stakeholder engagement, behavioural change and resource recovery. The findings inform effective strategies for NGO-led waste management initiatives tailored to remote Himalayan communities.

Co-hydrothermal carbonization of lignocellulosic biomass and swine manure: Optimal parameters for enhanced nutrient reclamation, carbon sequestration, and heavy metals passivation

Hydrochar, the primary product of hydrothermal carbonization (HTC) of wet organic waste, is recognized as a versatile, carbon-abundant material with diverse applications. However, optimizing its performance for specific uses remains challenging. Therefore, this study introduced a co-HTC process involving carbon-rich lignocellulosic materials and ash-rich livestock manure [i.e., Zanthoxylum bungeanum branch residue (ZB) and swine manure (SM), respectively]. The impacts of HTC temperature (i.e., 180 °C, 220 °C, and 240 °C) and mass ratios (i.e., 1:0, 7:3, 5:5, 3:7, and 0:1) on hydrochar properties (e.g., pH, EC, nutrient contents, heavy metal content and availability, chemical stability, etc) and the characteristics of process water were evaluated. Results reveal that co-HTC dramatically improved the quality of hydrochars compared with that derived from a single feedstock. Notably, the ZB:SM ratio had a more substantial impact on total nutrient content, carbon stability, and heavy metal accumulation and mobility. Additionally, the synergistic effects of ZB and SM were greatly dependent on the HTC temperature. By adjusting the feedstock mass ratio and HTC temperature, a highly-functionalized hydrochar can be produced. For example, hydrochars produced at 240 °C with a 7:3 ZB to SM ratio (HC240-7) is optimal for degraded soil amendment, enhancing carbon sequestration and nutrient supplementation. Results from this study could provide valuable insights for improving waste management through HTC and expanding the environmental and agricultural application of hydrochar.

Whisky decarbonisation potential using bio-waste

The objective was to investigate the potential of the Scottish Whisky industry to employ the circular economy to decarbonise and reduce costs, using its own bio-waste as a source of energy to power distilleries. The analysis uses a literature review of the fossil fuel energy for heat used in modern distilleries in terms of MJ/Lalcohol. It then determines the energy content of the whisky distillery bio-wastes: draff, pot ale, spent lees and wash (SLW). Outside the distillery there are bio-wastes in the barley straw on farms and from the malt-house, barley husks, rootlets and dark grains and the maturation barrel preparation area with a wood char waste. The energy in the wastes is also expressed as MJ/Lalcohol which then enables the determination of the proportion of the energy to operate the distillery that can be provided from the bio-waste. The distillery wastes all have a high water content, the amount of which is reviewed. The energy to evaporate this water is determined to give the net energy from the bio-wastes. The findings are that in the distillery, including the energy to evaporate water, requires 60 MJ/Lalcohol, with half of this used to evaporate water. Most of the energy in wet wastes is used to evaporate the water and there is only 8.7 MJ/Lalcohol to contribute to the distillery energy requirements. For dry draff and PAS the energy is sufficient to operate the distillery, but the energy to dry the draff has to be provided at some stage in the process. However, there is enough energy in barley straw and malthouse wastes to provide the rest of the heat required in a distillery and to completely decarbonise the whisky industry. This is the first time that all the bio-wastes have been assessed in whisky manufacture, from the farm to the maturation barrel stores. It is proposed that the best way to use these diverse bio-wastes is gasification of the solid wet waste to produce a biomass gasification gas (BGG) with direct burning of the BGG to generate the heat to burn the PA and SLW and evaporate the water.

Low-energy thermo-chemical conversion processes of municipal wet waste

Hydrothermal carbonization (HTC) is a low-energy thermochemical process that converts wet biomass into a carbon-rich solid, commonly called hydrochar, for use in a variety of areas, such as soil amendment, biofuels or to produce carbon-based materials. The purpose of this paper is to increase knowledge for the economic valorization of municipal wet waste, considered as a raw material to obtain high value-added products through an HTC process and an additional chemical activation procedure. In the first part of the work, a 4.5-liter batch reactor was designed, built, and used in the HTC experimental campaign by varying the main process parameters, namely reaction time, amount and type of organic waste (e.g. vegetables, fruits, bread, pasta), water concentration, temperature and pressure. In addition, some experiments were conducted by applying the steam explosion technique at the end of the HTC process. The HTC results showed that in biomass with high water content, increasing residence time decreases the hydrochar yield. Considering a dry heterogeneous waste with high carbon content, the yields at the end of the process are much higher. In the second part of this work, the hydrochar samples were treated with a high-temperature activation process based on the use of KOH, obtaining activated carbon. Particularly, the best results were achieved by using high KOH: hydrochar ratios, resulting in high-quality activated carbons with good porosity and a high surface area of 2890 m2/g. Finally, an energy analysis was carried out to evaluate how to make the whole process cost-effective.

PRODUÇÃO DE SILAGEM COM RESIDUO UMIDO DE CERVEJARIA PARA ALIMENTAÇÃO DE VACAS LEITEIRAS.

Dairy farming in the State of Amazonas only exists on an industrial scale because of the high cost and lack of availability of cattle feed imported into the State. There is a concrete difficulty in establishing quality forage plantations due to the inadequate climate and soils, causing livestock farming to cause environmental degradation and being considered an activity with a high negative impact due to fires to obtain new pasture areas. At the same time, waste from the local brewery industry is discarded when it could be used to feed dairy cows. The aim was to develop a simple way to use waste from a brewery located in the city of Manaus as an alternative to the high-cost feed used in industrial dairy farming and, possibly, to make family farming (Carvalho et al., 2021) viable through a methodology that defines the specific conditions for sun drying and proper storing of the wet waste, ensuring an increase in the product’s shelf life and enabling its river distribution to the inland of the state (Salman, 2020).

Mono-and bi-metal catalytic hydrothermal liquefaction of food waste: Screening the process parameter on product yield and characterizations

Biofuels and chemicals derived from wet food waste (FW) can serve as a strategy to significantly reduce emissions and mitigate environmental pollution while preventing the loss of valuable resources. Hydrothermal liquefaction (HTL) is one of the most promising thermochemical techniques for converting wet waste into crude oil-like products (biocrude). In this study, catalytic HTL of FW was carried out using cobalt (Co), magnesium (Mg), and cobalt-magnesium (Co–Mg) supported on ZSM-5 to produce high-quality biocrude. The impact of key operating parameters, such as reaction solvent, temperature, reaction holding time, and catalyst amount, was investigated. In comparison to non-catalytic liquefaction, catalytic liquefaction significantly improved the biocrude yield. The maximum biocrude yield (60.89 wt%) was achieved with bimetallic Co–Mg/ZSM-5 catalysts at 280 °C with 10 wt% of catalyst at a reaction time of 15 min. Various analytical methods, including GC-MS, FT-IR, CHNS, TGA, and NMR, were employed to identify the composition and quality of the biocrudes. Catalytic liquefaction with Co–Mg/ZSM-5 in an ethanol solvent resulted in a higher percentage of ester compounds (74.15%, area percentage). The biocrude obtained through the catalytic process had lower oxygen and nitrogen content, which led to a higher heating value (HHV). Biocrude quantification revealed the presence of 12.16 wt% of linoleic ester compounds. The concentration of total nitrogen (TN) in the catalytic aqueous phase was as high as 2.44 g/L, significantly greater than the 0.32 g/L found in the non-catalytic aqueous phase. Furthermore, the optimum Co–Mg/ZSM-5 catalyst demonstrated excellent reusability and stability in FW liquefaction.

SMART GARBAGE BIN

ABSTRACT: The smart trash can utilizes an ultrasonic sensor (like SONAR) to detect garbage proximity, prompting the servo motor to open the lid when garbage is nearby and closing it otherwise. By this our smart trashcan features sensor-based opening, enabling touchless operation for convenient disposal, ideal for hands-free access when busy or avoiding contact. Additionally, a moisture detector segregates wet and dry waste as per government protocols. An odour detector alerts users to foul smells, prompting timely disposal. A red LED indicates fullness, aiding efficient waste management. This innovative solution enhances public sanitation, suitable for street installation. An accompanying app locates nearby available bins, promoting convenient disposal. Keyword – garbage, smart trash can

Economic and sustainability prospects for wet waste valorization: The case for sustainable aviation fuel from arrested anaerobic digestion

Valorizing wet wastes to sustainable aviation fuel (SAF) can be achieved through sequential arrested anaerobic digestion (AAD) to volatile fatty acids (VFAs) and thermochemical catalytic upgrading. Alternatively, conventional anaerobic digestion (AD) can use wet waste to produce biogas (for electricity generation), biomethane, or green hydrogen. To assess the VFA-SAF pathway, we conducted a comprehensive techno-economic analysis (TEA) of each approach using Aspen Plus and discounted cash flow models, coupled with life cycle assessment (LCA) to estimate fuel carbon intensity (CI) and evaluate the implications of policy incentives for carbon emissions reduction.First, we calculated the minimum fuel selling price (MFSP) required to meet a 10 % internal rate of return (IRR) for each product without policy incentives. In this scenario, all pathways faced challenges in meeting the market values of equivalent fossil-based products. Next, we examined projected costs for alternative sustainable technologies and found that SAF and biomethane from wet waste were competitive, while electricity and hydrogen costs were significantly higher. Finally, we incorporated current policy incentives; with incentives, all pathways exceeded a 10 % IRR using fossil-equivalent selling prices. Among all the options considered, VFA-SAF produced the most profitable carbon-negative fuel that was economically competitive with alternative sustainable technologies.

ANALISIS EFEKTIVITAS PENANGANAN LIMBAH B3 RUMAH SAKIT BHAYANGKARA KOTA KENDARI

The fundamental problem regarding waste is its management and the impacts that will occur if the waste is not managed well or even not managed at all. Effectiveness of sustainable waste management at Bhayangkara Hospital, Kendari City. The aim of this study is to analyze the effectiveness of managing hazardous and toxic waste, organic wet waste and inorganic dry waste at the Bhayangkara hospital. The study method used was descriptive qualitative by conducting observations and in-depth interviews. Based on the data collected, Bhayangkara Kendari Hospital is strategically located in the eastern part of the city, so it can be accessed by public transportation from anywhere in Kendari. As a result of its operations, hospitals cause four main types of pollution: 1. Liquid waste management; 2. Management of air pollution; 3. Management of Hazardous and Toxic Materials; 4. Management of hazardous and toxic waste. The Bhayangkara hospital management has carried out intensive routine activities including management aspects of potential pollutants, especially hazardous and toxic waste, organic wet waste and inorganic dry waste.

Pengembangan Modul Cetak Pengolahan Sampah Basah Berbantuan Maggot BSF dan Efektivitasnya dalam Meningkatkan Pengetahuan Lingkungan Siswa

The environment is defined as a set of aspects in the form of physical, chemical and biological as well as social factors that have a direct or indirect relationship to living things and human activities in the short and long term. However, the environment can experience various problems, one example is environmental damage by causing waste in the environment. One of the reasons for the waste generated by the community is their lack of knowledge about the environment. It was proven in preliminary research at SMA Negeri 11 Pinrang, the results of the initial analysis using students' environmental knowledge questions were still low with an overall result of 43.73. These results indicate that there are still many students who do not know environmental topics and problems, especially waste and its processing, so they are lazy about disposing of waste according to the server and processing the waste, especially wet waste. This research is development research referring to Plomp and Nieven's development design and conducting a quasi-experiment using the PjBL model in class X at SMA Negeri 11 Pinrang. The research results show that the printed module has a practicality value of 91.1% in the very practical category so it is suitable for use in the learning process. The average pretest result for the experimental class was 50.8 in the low category after learning using printed modules and the PjBL model and the posttest was 88 in the very high category and experienced an increase of 37.2%. The average pretest result for the control class was 44.26 in the low category after learning only using the PjBL model and the posttest was 79.6 in the high category and experienced an increase of 35.34%. Therefore, it can be concluded that the printed module is practical and effective in the experimental class with an N-Gain value of 0.75.

Analytical Study of Generation, Composition, And Potential For Waste Recycling

Background: Waste is still a serious problem globally. Accumulated and poorly managed waste becomes a reservoir for disease vector animals in the environment. Sources of waste include home activities, offices, schools, campuses, industry, and other public places Methods: This research was conducted using a survey, which took samples from several research locations and used observation sheets as a data collection tool. In this research, measurements and recording were carried out to calculate the generation and composition of waste in the campus environment. Results: The research results describe the generation and composition of waste at one of the survey locations, Unja Sports Hall. The survey, conducted for five days, yielded results that included the average waste generation per day being 2.5 L and most food waste. The average dry waste generation is 5.3827 L consisting of 6.84% paper, 73.44% plastic, 2.15% badminton cocks and 17.58% styrofoam. The waste with the most significant recycling potential is dry, namely 76%, including 8.87% paper, 66.27% plastic, and 0.41% cans. Apart from that, wet waste also has the potential to be recycled as compost, namely 24.58%, consisting of 17.08% food waste and 7.77% yard waste. Based on organic and inorganic waste, organic waste has a recycling potential of 24.58%, and inorganic waste has a recycling potential of 66.27%. Conclusion: Organic waste that can be recycled consists of food and yard waste, and inorganic waste consists of plastic, paper, and cans. This waste recycling process will produce a craft that has selling value. Before carrying out the recycling process, a waste sorting process is carried out according to specific criteria.

Design and Development of Dry Waste Management System for Electricity Generation

The rise of the waste will be the bigger issue of all over the world. The majority of the waste will normally dump to fill the lands, this will become the major issue and creates the environmental issues in surroundings. To overcome this, we placed an idea in this project initially to segregate dry waste and wet waste automatically in view of minimizing the man power. In this project microcontroller will acts as a central unit of the system. The sensors are used to identify dry waste and wet waste. In our work, we consider dry waste like paper, wood, plastic etc., and send to the heat chamber and then after burning, heat energy is converted into electrical energy using thermos electric generator. The investigations are carried out by different finite elements to analyze the electricity generation w.r.t temperature variation in the system. The best part of this prototype system is not only reducing the waste but also generates electricity. Keywords— Composting, incineration, Microcontroller, Dry Waste, Wet Waste, thermoelectric generator

Effect of Wet Grinding Concrete Slurry Waste on Hydration and Hardening Properties of Cement: Micro-Nano-Scale Modification.

The concrete slurry waste (CSW) produced by concrete mixing plants is a type of hazardous waste that is difficult to handle. To better recycle the CSW separated from the aggregates, this study uses a variety of wet-grinding processes to refine the solid in it, replaces some of the cement with the solid particles in wet grinding concrete slurry waste (WCSW), and investigates the properties of WCSW and its effect on the hydration and hardening properties of cement. The results show that a suitable wet-grinding process can ensure that the particle size in WCSW is less than 10 μm, the particle morphology is more flat, and the degree of hydration is higher. The WCSW particles can promote early cement hydration; after adding WCSW, the heat release peak of cement hydration appears earlier and more early hydration products are produced, and with the increase in the substitution amount, the promoting effect on early cement hydration will be more significant. The WCSW particles have a great effect on improving the strength of mortar, especially in the early stage. At 1 d, when the substitution amount is 7.5 wt.%, the compressive and flexural strength is increased by 43.67% and 45.04%; this is related to the filling of matrix pores and the improvement of the interface transition zone by micro- and nanoparticles. After the wet grinding of CSW, fine WCSW particles are obtained, which can improve the performance of cement-based materials by replacing cement.

Detection of volatile hydroperfluoroalkanes during hydrothermal liquefaction of perfluoroalkyl carboxylic acids at circumneutral pH

Hydrothermal liquefaction (HTL) is a promising technology for converting wet organic waste such as sewage sludge into biocrude oil while simultaneously destroying per- and polyfluoroalkyl substances (PFAS). This study tracked the fate and degradation of six representative PFAS in water to address the effect of perfluoroalkyl chain length on degradation rates and the formation of volatile transformation products at 300–350 °C. While perfluorosulfonic acids were recalcitrant, perfluoroalkyl carboxylic acids (PFCAs) were rapidly and completely decarboxylated to hydroperfluoroalkanes (1 H-perfluoroheptane in the case of perfluorooctanoic acid). The volatile hydroperfluoroalkane was subsequently defluorinated without detectable fluorocarbon intermediates yielding 30–60 % defluorination for ammonium perfluoro(2-methyl-3-oxahexanoate), perfluorobutanoic acid and perfluorooctanoic acid after 2 h at 350 °C. Increasing temperature (especially at 350 °C) and longer perfluoroalkyl chains substantially enhanced the defluorination. This is the first study to report volatile hydroperfluoroalkanes from PFCAs in HTL, raising concern about the potential emission of long-lived greenhouse gasses into the atmosphere, but also opening new avenues for PFAS destruction through HTL.