Global Conference on Waste Management and Recycling

Sludge palm oil, a low-cost byproduct of the crude palm oil milling process, can potentially be converted from waste into high purity of biofuel using a rotor-stator hydrodynamic cavitation reactor. To obtain high purity of methyl ester, five independent variables, namely methanol, potassium hydroxide, diameter of hole, depth of hole, and speed of rotor, were optimized using a response surface methodology. Production of biodiesel from pretreated sludge palm oil via continuous transesterification process resulted in a methyl ester purity of 96.54 wt.% and a biodiesel yield of 92.2 vol.% under a recommended condition of 3.5 vol.% of methanol, 1.4 g/L of potassium hydroxide, 5.0 mm of hole diameter, 6.0 mm of hole depth, and 3000 rpm rotor speed, This recommended condition had the potential to reduce chemical consumption of both methanol and potassium hydroxide by 27.1% and 39.1%, respectively. As a result, the rotor-stator type hydrodynamic cavitation reactor provided high purity of methyl ester and a high yield of biodiesel within a short reaction time inside the reactor of 30 s. Therefore, this cost-effective 3D printed reactor also provides more efficient mixing, faster reaction rate, greater product yields, simple operating principle, and less operation energy, than conventional mixing methods. Moreover, this process allows the conversion of waste sludge palm oil to bioenergy. This makes biodiesel production more sustainable than those edible oils, as they are not subject to resource depletion, pricing fluctuations, and food demand.

An ultrasonic probe reactor with a power of 1000 W and frequency of 18 kHz was applied to produce biodiesel from pretreated sludge palm oil (PSPO), and calcium oxide (CaO) was proposed as a solid catalyst for the transesterification of PSPO to biodiesel with methanol. Three independent variables of methanol, CaO loading, and sonication time were optimized to determine the highest purity of methyl ester using the response surface methodology. The results showed that under the recommended conditions of 49.9 wt.% methanol, 20.0 wt.% CaO content, and 3.0 min sonication duration, a high purity of methyl ester of 96.57 wt.% was achieved, while the yield of biodiesel was 81.6 wt.% after washing. Furthermore, the CaO reusability investigation was performed. The reusability research results show that CaO can be reused for at least five cycles using high intensity ultrasound. This study demonstrated the interesting potential of using PSPO as a raw material for biodiesel production with a heterogeneous base catalyst for an environmentally friendly process. This renewable resource of sludge palm oil is not only cost-effective but also sustainable, making it a promising option for producing biodiesel. Furthermore, it helps to minimize the negative impact of waste disposal on the environment as well as boost the bio-gas ecosystem by converting it into renewable biofuel.

Researching new, more sustainable ways of recycling plastics is critically important and immediate goal for both industry and academia. There are too many techniques for recycling plastics, however chemical recycling, which involves recovering the original monomers or intermediate oligomers by depolymerizing polymer chains, is gaining popularity. Additionally, the chemical recycling process provides an alternative method for the utilization of PET waste derived precursors to produce valuable products for industrial applications. Alcoholysis is a method of chemical recycling that can be used to recycle polyethylene terephthalate (PET), one of the most widely used thermoplastic polymers. This method is one of the most preferred since diverse products with varying molecular weights and physical properties can be obtained by changing the process conditions like reaction temperature, reaction pressure, quantity of alcohol, polymer content, and catalyst loading. Isooctanol alcoholysis can be used to recycle PET and produce dioctyl terephthalate (DOTP), which is known as the most environmentally friendly plasticizer. Additionally, many different kinds of catalysts, including deep eutectic solvents, ionic liquids (ILs), metal salts, nanomaterials, organometals, polyoxometalates, etc., have been successfully used and catalysts play a significant role in PET chemical recycling. In this study, isooctanol alcoholysis and different kinds of catalysts are investigated. The results show that higher temperature (180 °C) was beneficial to the conversion of PET and the yield of DOTP, which can reach about 97% and 95% after 60 min, respectively. /p>

This study investigated the nutritional content and development characteristics of Black soldier fly larvae (BSFL) raised on a variety of alternative industrial waste sources. The substrates consisted of brewers spent grain (BSG), pig manure (PIM), poultry manure (PM), and rice bran/groundnut skin (RBGS) and were replicated 8 times in a small insectary. Proximate nutrient and mineral composition of the larvae were analyzed. RBGS recorded an improved (p < 0.0001) total weight of larvae, number of larvae, efficiency of conversion and substrate reduction index than the other substrates. Crude protein, fat and energy (%) contents of the BSFL were higher (p < 0.000) in the RBGS and BSG groups. Crude protein fat and dry matter yield (g) of the BSFL was better (p < 0.0001) in the RBGS group compared to the other substrate groups. RBGS recorded the lowest (p < 0.0001) mineral content compared to the other substrates. As a result, the crude protein level of the BSFL of the substrates is sufficient to substitute conventional feed protein sources in the fish and livestock feed industry.

The active participation of the public in waste sorting plays a vital role in minimising environmental contamination by ensuring efficient waste management practices. Even though people desire to engage in waste sorting and recycling, they often experience confusion in picking the right bins because it requires cognitive effort. Consequently, they ignore the waste sorting system or dispose of waste in incorrect bins. This experimental study investigated the role of symbols as nudging cues in improving waste sorting accuracy. Specifically, the idea of incorporating symbols lets the individuals involved in waste sorting accurately, irrespective of their knowledge about whether the waste is recyclable or not. Therefore, they will be very accurate in disposing of the waste in the right bin by simply matching the symbols with less cognitive effort. We employed two bin conditions: 1) standard waste items to be sorted in standard bins (Colour-Only bin condition) and 2) symbol-labelled waste items to be sorted in symbol-labelled bins (Symbol & Colour bin condition). In this experiment, participants sorted five items from each recyclable and general waste into the appropriate bins. We found higher waste sorting accuracy in the Symbol & Colour bin condition compared to the Colour-Only bin condition. The current study presents empirical evidence that the inclusion of symbols on packaging and bins as nudging cues enhances the accuracy of waste sorting while reducing cognitive effort. Additionally, this approach mitigates the likelihood of confusion when choosing the correct bin./p>

Understanding the variations in the geochemical behavior of phosphogypsum designed to storage or valorization is crucial for assessing the safety and operational efficacy of this waste management. The aims of the present study are i) to investigate the leaching behavior of phosphogypsum using different leaching tests, and ii) to module its geochemical behavior using PHREEQC. The studied PG samples were collected from a Moroccan phosphate treatment plant. The samples were characterized for their i) chemical composition; ii) mineralogical composition), iii) chemical species release rate using static and kinetic leaching tests. Chemically, the PG samples were mainly composed of Ca (23.03-23.35 wt.%), S (17.65-17.71 wt.%), and Si (0.75-0.82 wt.%), and non-negligible amounts of trace elements: REE (344-349 ppm), Cd (3.5-7.4 ppm), U (9.3-27.4 ppm)). Mineralogically, the PGs are mainly formed by gypsum (94.2-95.9 wt.%), and quartz (1.67-1.76 wt.%). The overall findings of the leaching assessment tests showed that PG could be considered as non-hazardous material except for sulfates, with a high leachability in L/S of 2 under high acidic conditions. In addition, the PGs showed a higher reactivity at 60°C compared to room temperature with a higher release rate at the beginning of the leaching tests. By using PHREEQC for geochemical modeling, the speciation of Ca, S, P and F was done to determine their distinct chemical forms under varying pH conditions. The study pinpointed the controlling phases that governed the dissolution of the examined elements by calculating their SI. These phases are gypsum, anhydrite and bassanite.

Informal settlements encounter significant challenges regarding sanitation and illegal landfills, which contribute to environmental pollution and population health issues. Waste management in these settlements has not received enough attention from Romanian local and national public authorities, resulting in a lack of comprehensive studies on the subject. With the recent official formal acknowledgement of informal settlements in the Romanian legal framework (2019), this paper builds on an ongoing research project developed at the Technical University of Civil Engineering in Bucharest, whose objective is to explore the issues regarding waste management in informal settlements. Considering that access to public utilities (such as drinkable water, wastewater management and proper waste disposal) is a vital component of sustainable development and a global objective for all types of dwellings (EU’s policies) and, simultaneously, waste management is a top action line regarding environmental protection, the study aims to identify challenges of waste management and illegal landfills and how they relate to blue-green infrastructure in informal settlements, with a case study on Resita city. Since the project will be completed in mid-2024, the present article illustrates the results of the sociological research based on a survey applied to approximately 150 inhabitants of informal settlements and a detailed analysis of population needs, reflecting a communitarian perspective on waste management and the blue–green infrastructure. The findings show the level of community involvement and willingness to contribute to waste prevention, collection, recycling, and composting activities and the relationship with different natural environment components.

Walnut palm fiber is the fibrous support of the dietary seed of the walnut diet; it is recovered after destemming, compacting, and extraction of the red edible liquid, it represents approximately 25 to 30 % of the weight of the seed entering the oil mill. The fibers thus separated from the seed represent a significant quantity of waste. Although PNF (palm nut fiber) is biodegradable and bio compactable, its rapid properties of forming agglomerates limit its recycling applications: this is why the daily management of these constitutes a headache for many agricultural communities. What is the best approach to getting rid of waste without seriously harming our biodiversity? Many of these farmers hastily adopted solutions: such as incineration, dehydration, spreading on plantations as fertilizer. But these different solutions have consequences that are not. Revealed to the naked eye, these practices are in reality monstrous for the preservation of biodiversity. This calls into question these multiple techniques adopted. However, various chemical processes in depth on the PNF(palm nut fiber),allowed us to discover the exceptional and very interesting properties that the cellulose of palm nut fiber abounds as resources used in the manufacture of brake pads for rolling machines.

Food banks play a crucial role in reducing food waste and addressing food vulnerability. This involves an efficient supply chain that collects food waste, processes it, and distributes it to those in need, aligning with the goals of a circular economy to minimize the risk of food crises. The research aims to understand the supply chain of the Food Bank Bandung and analyze the implementation of a circular economy in its supply chain. The study used qualitative methods, the information was gathered through interviews with the Food Bank located in Bandung City. The obtained information was processed into a supply chain design, and each process was analyzed. The analysis concludes that the Food Bank in Bandung implements a circular economy by transforming surplus food, which would otherwise be wasted, into consumable foods. Donors provide food to the food bank, where surplus items are processed into ready-to-eat meals. The food bank then distributes these meals to various agencies, including social welfare institutions, informal schools, and integrated healthcare centers. Additionally, the food bank applies circular economy concepts by providing inedible food to BSF cultivation for maggot consumption. By analyzing the circular economy in the food bank of Bandung city, this research contributes to future studies by providing a more extensive dataset.

Waste management in Ukraine is facing today a new challenge – hostilities. The purpose of this article is to analyze changes in waste management in Ukraine caused by war, and to review challenges and opportunities appeared due to the changes in waste structure and manufacturing patterns. Statistical data on waste generation in the pre-war period and after 2022 were processed. An analysis of the hostilities impact on the implementation of legislative and strategic documents and international obligations of Ukraine was also carried out. After constant increase during 2018–2021, 2.5 times less waste was totally generated in 2022. Almost all waste categories have decreased, except spent solvents, paper and cardboard, plastic and textile waste. In 2022, more than 7 million tons of household waste was generated, which is almost twice less than the last 5 years. There is a significant increase in the amount of construction waste, medical waste, metals, old cars. Over 670,000 tons of demolition waste have already been generated in Ukraine since 2022. Main challenges currently include military waste collection due to safety reasons, waste management is not provided in or near war zones, necessity to check the waste for the presence of explosive and other dangerous substances, shortage of equipment and personnel, no developed infrastructure and advanced technologies for collection, sorting, transportation, storage, and processing complex flows of demolition waste, influence on international agreements and obligations. Despite the challenges associated with hostilities, this opens a unique window of opportunities to “reboot” approaches to waste management and deploy a large-scale circular economy in Ukraine. This will provide the conditions for the development of recycled construction waste market. Solving the problem of effective waste management is a key to solving the issues of energy and resource independence of any country, saving natural and energy resources, and is an urgent strategic task of state policy.

The sustainability of the environment and the protection of public health depend on effective solid waste management and resource recovery optimization. Unreliable information regarding the detected solid waste and its physical composition has been mentioned in several studies in the literature. Every strategy, from the process to the result, has the potential to misrepresent the issue. In this work, a well-organized sampling and structured waste sorting approach were implemented, using a statistically reliable solid waste characterization method to verify the prediction model created in the Python language. The data were sampled and analyzed using the ASTM D5231-92 method. The methodology was based on Household Solid Waste (HSW) from 48 households divided into three levels (high, medium, and low) in eight of the twelve districts and thirty-three Collection Centers (CC). The collection of solid waste from three industrial enterprises enabled us to complete our methodology. A total of 205.63 kilograms of waste (an average of 25.70 kg per day) were sorted into thirteen categories at level I: Food waste (FW), Paper (Pap), Cardboard (Car), Textiles (Text), Waste Bags (WB), Plastic (Pla), Metals (Met), Waste Classified Combustible (WCC), Waste nonclassified combustibles (WNCC), Aluminum (Al),Glass (Gl), Special Waste (SW), and Other Waste (Oth). At level II, thirty categories were identified, and at level III, fifty-three waste fractions were organized according to a three-level approach (multi-level approach). The results showed that FW (51%), which occupies the most dominant position, and GL (2.06%), which has the lowest rate among Household and Industrial Waste (HIW). The production rate of HSW in the study areas was 0.66 kg per person per day. Statistical analyses revealed that the composition of HIW was independent of variations in the Waste Generation Rate (WGR). Waste composition and WGR were statistically similar for the three standing groups. Model 1 shows that the presence of family members in every household leads to an increase in Household Waste Generation Rate (HWGR). Thus, socioeconomic parameters significantly influence HWGR. This suggests that a critical stratification parameter depends on standing type. As a result, the prediction of the WGR, model 2, was presented using linear models with seven exogenous variables (FW, Pap, WB, Text, Met, WNCC, and Oth). The research revealed a weak correlation between the variables and a link between them exists. Furthermore, the individual percentage composition of FW, WNCC, GL, SW, and Oth is not significant in WGR, indicating that manual sorting of these waste types is not necessary. The valorization project in the case study is still under discussion.

Plant nutrient leaching is one of the biggest limitations in agricultural crop production, chiefly on sandy soils. The utilization of coal clinker ash (CA) remains subdued in cropping systems, yet its characterization reveals that it has the capability to improve poor agricultural soils. This study was done to assess the potential of CA to improve nitrogen and potassium retention as well as its influence on the C/N ratio in sandy soils. Leaching experiments were conducted in a greenhouse with an uncontrolled environment at Tottori University in Japan. Using cylindrical PVC pipes, 50 cm in length and a diameter of 10.5 cm, one end was closed with a water-porous material to allow for drainage. The treatments included control (sandy only), CA1 10 %, CA1 20 %, CA2 10 %, CA2 20 %, and rice biochar (positive control) at 5 % w/w, replicated three times. The concentration of total NO3 – -N leached was significantly affected by the application of clinker ash, with CA at 10 % for both types leaching at par with biochar. Solution K was leached highest in CA1 at 20 % and for NH4+ -N retention, CA2 treatments retained the highest amount. C: N ratio of sandy soil was equally affected and improved by the application of clinker ash. After the leaching period, pH and EC tested were significantly affected by the application of clinker ash. Clinker ash is embedded with characteristics that are critical in improving the nutrient and chemical properties of sandy soil.

Aquaculture is the fastest growing food sector worldwide. Mussels which are the group of shellfish are becoming a more and more popular food within current society. Mussels are mostly cultivated in large aquaculture farms, including various processing activities that are contributing to climate change and global warming. Carbon Footprint (CF) is the total amount of greenhouse gas emissions associated with a product along the supply chain, including use and end-of-life recovery and disposal and Life Cycle Assessment (LCA) is an environmental method that can reveal many environmental impacts, including carbon footprint. The aim of applying this life cycle strategy to the mussel industry is to produce and consume this seafood sustainability. The studies to determine the environmental footprint, in particular the carbon footprint resulting from aquaculture production, using the LCA approach are very necessary. The study aims to investigate the life cycle analysis of mussel farms. As a result of LCA studies, the hotspots of mussel farming carbon emission are identified as large amounts of non-recyclable plastic raw materials, socks and fossil fuel consumption from logistics. LCA studies are crucial to assess the carbon emissions of aquaculture in the light of sustainable development goals and to improve environmentally friendly, sustainable production.

Fly ash is the main industrial byproduct from coal combustion processes and it offers untapped potential as a source material. The proper processing and fractionating of those by-products can allow to obtaining of individual components with distinct properties. This research focuses on the thermal treatment behavior of fly ashes fractions sourced from lignite and bituminous coals from Polish coal-fired power plants. Fractions were obtained using dry aerodynamic classification. Controlled heating up to 1200*C experiments (TG, DSC analysis) combined with evolved gas analyses (CO2, H2O, SO2) and advanced mineralogical studies reveal key transformations, decomposition patterns, phase stabilities, and melting transitions in the obtained high-Ca and high-Si ash fractions. Main transformation processes and phenomena are described and discussed. The results reveal important information about the variations among grain sizes of coal fly ash fractions, which is relevant for their suitability for specialty applications in various industries where thermal processing is essential, such as cement production and ceramics manufacturing. Furthermore, the results assist in appropriate planning for processing and specific use of coal combustion byproducts and discovering new possible directions across industries that use thermal treatments in the production cycle.

Coal fly ash, a byproduct of combustion processes, is emerging as a valuable resource for diverse material and industrial applications. This study explores the variety of fly ash fraction properties and its influence on clay-cement suspension properties. Fractions ranging from coarse (100+um) to ultrafine (0…10um) are obtained by employing dry aerodynamic separation methods, each possessing unique characteristics. The investigation delves into the individual properties of these fractions, showcasing their potential as subproducts for tailored building materials. The study contributes to a comprehensive understanding of fly ash processing and highlights the prospect of obtaining specific fractions to optimize the properties and performance of various materials with fly ash additives. The results show that applying of dry separation methods to coal fly ash processing allows for the extraction of several subproducts, each characterized by a unique combination such properties as particle sizes, and mineralogical and chemical composition. This process facilitates the customization of building materials, enabling the production of tailored products with specific attributes and performance characteristics.