Organic Solid Waste Research Articles

Bibliometric analysis on the applicability of anaerobic digestion in organic solid waste

Anaerobic biological treatment can comprise a viable route of CH4 production through the energy recovery of organic solid waste (OSW). This work therefore presented a bibliometric analysis of research trends on the theme "Applicability of biological treatment via Anaerobic Digestion in Organic Solid Waste", considering experimental articles published from 2018 to 2022 in the Web of Science database™; the analysis used VoSviewer software to define research trends, and found that the main terms addressed in the mapped scientific articles were anaerobic, waste, sludge, waste food, municipal waste, anaerobic co-digestion, sewage sludge, organic fraction, co-digestion and biogas. As a product of such mapping, an Interaction Network Diagram was constructed comprising the main terms in addition to a theoretical foundation on anaerobic digestion and biochemical and microbiological aspects about the process.
 Keywords: anaerobic co-digestion, clean energy, food waste, microbial intercropping.

Resource recovery potential from source-separated organic municipal solid waste: opportunities for organic fertilizer production and creating sustainable urban agriculture in Ethiopia

Resource recovery potential from source-separated organic municipal solid waste: opportunities for organic fertilizer production and creating sustainable urban agriculture in Ethiopia

A Review on Biofuels and Chemicals Production by Co-pyrolysis of Solid Biomass Feedstocks and Non-degradable Plastics

Modern lives have resulted in a substantial rise in the volume of plastic waste in recent years. Throughout, there is a lot of solid biomass that can be used as energy. By co-pyrolysis, these waste plastic and solid biomass feedstock mixes can be transformed to produce synergistic fuels and value-added products. To promote environmentally appropriate pathways for waste management and sustainability, the manufactured products can be used as chemicals and pollutant sorbents. This review's main focus is on the advancement of this method of waste disposal and energy production. The difficulties and potential benefits of developing combinations of solid organic waste and plastic feedstock for co-pyrolysis are also covered. With the introduction of waste biomass for improved synergistic effects in waste disposal as well as the recovery of energy and value-added products, the objective was to provide attractive practicable pathways for clean and efficient disposal of plastic wastes.

Polyhydroxyalkanoate synthesis from primitive components of organic solid waste: Comparison of dominant strains and improvement of metabolic pathways

The production of polyhydroxyalkanoate (PHA) from organic solid waste is a research hotspot. However, the allocation and conversion mechanism of different carbon resources between precursor routes and PHA metabolism remains unclear. We compared the PHA synthesis of dominant functional bacteria, Cupriavidus necator (C. necator) and Bacillus cereus (B. cereus), and replenished the metabolic pathways of primitive components (glucose, glycerin, lactic acid and propionic acid). The results showed that the PHA accumulation ability of C. necator (11.8%∼36.5%) was better than that of B. cereus (10.1%∼24.5%). C. necator had a faster rate of cell growth and PHA synthesis than B. cereus, which showed advantages in production efficiency. Most of the carbon of glucose flowed to the direct poly-3-hydroxybutyrate synthesis pathway. The carbon competition inhibited the PHA production from glycerin in C. necator, and cysteine metabolism was an effective pathway for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in B. cereus. There were active amino acid pathway and aminobutyric acid pathway in the utilization of lactic acid in C. necator and B. cereus, respectively. The yield of copolymer was limited by acetyl-CoA in propionic acid system. This study laid the foundation for exploring the PHA synthesis from the components of organic solid waste.

Anaerobic digestion of food waste for biogas production in glass bot-tles

The generation and inadequate disposal of urban solid waste have been a major environmental problem worldwide. The management of solid urban waste generated in large urban centers is problematic and concerning globally. Alternatives are being developed for the treatment of organic solid waste. Brazil has great potential for biogas production, more precisely, biomethane, a component of raw biogas that needs to be purified. Considering the large daily volume of municipal solid waste (MSW) generated in urban centers, the main objective of this study is to develop a biodigestion technique for organic food waste from restaurants, specifically the university restaurant (RU) of UFPR. The experiments were conducted with homogenized and non-homogenized waste with quantities of recyclables added such as plastic, paper, and cardboard at proportions of 0%, 1%, and 5% in the waste mass, and the temperature of 35 and 45°C was controlled for the system's biodigestion. The data were presented as means ± standard deviation. To compare response variables, normality and homoscedasticity were checked, and mean values were evaluated by the one-way analysis of variance (ANOVA) tool. The experiments conditioned to a temperature of 35°C showed statistically significant higher cumulative biogas values when compared to 45°C. As for the experiments that varied the percentage of recyclables inside the biodigester, only 12.5% of the experiments conducted with 1% of added recyclables showed higher cumulative biogas volumes in 30 days of production, followed by 37.5% with 5% of recyclables and 50% with 0% of recyclables (control). Compared to the waste treatment experiments (with 2mm treatment ≠ without 2mm treatment), 21% of the experiments that were not treated with 2mm showed statistically significant higher values (p<0.05) for accumulated biogas in 30 days when compared to their respective treated experiments. This study allowed the development of a biodigestion system using glass bottles and demonstrated the behavior of biodigestion when recyclables are added, conditioned to different process routes (wet and dry), in terms of granulometry and temperature (mesophilic and thermophilic).

Applicability of the Life Cycle Assessment Model in Solid Waste Management in Zimbabwe.

Solid waste increase is inevitable globally due to anthropogenic activities. This adds burden to waste management systems in developing countries including Zimbabwe. Currently, life cycle assessment (LCA) model is used to achieve sustainability and circular economy (CE) in solid waste management. Therefore, the main goal of this paper was to unearth LCA model applicability in solid waste management in Zimbabwe. Data sources were retrieved from databases like Scopus, ScienceDirect and Springer, although government documents were also used. In Zimbabwe, organic and inorganic solid waste is generated from various sources, namely industries, institutions and households. Solid waste management in Zimbabwe is based on traditional linear approach where waste is collected and disposed through landfilling, burning, incineration, burying, open pits or illegally. Most disposal approaches occupy base of waste management pyramid, hence posing detrimental impacts to human health, terrestrial, aquatic and atmospheric ecosystems. Management approaches are far from Agenda 21, Sustainable Development Goals (SDGs), Zimbabwe Vision 2030 and National Development Strategy 1 demands. Literature revealed that LCA model can be utilised to achieve sustainable solid waste management in countries like Zimbabwe. LCA model is essential in management of solid waste in Zimbabwe, since it assists decision makers in selecting management approaches with less environmental health impacts. Moreover, LCA enables application of waste material reuse, recycle, repairing and recovery, thus narrowing the gap to achieve CE and economic growth in Zimbabwe. Owing to LCA model implementation of waste management legislation and policies which support energy recovery and circular economy became easier in Zimbabwe.

Occurrence and ecological risks of microplastics and phthalate esters in organic solid wastes: In a landfill located nearby the Persian Gulf

Landfill sites are the main source of plastic waste. Thus, municipal solid waste (MSW) in landfills may act as a reservior of microplastics (MPs) and related pollutants such as phthalate esters (PAEs) into surrounding environment. However, there is limited information on MPs and PAEs in landfill sites. Levels of MPs and PAEs in organic solid waste disposed in a landfill of Bushehr port were investigated for the first time in this study. The mean MPs and PAEs levels in organic MSW samples were 12.3 items/g and 7.99 μg/g, respectively, and the mean PAEs concentration in MPs was 87.5 μg/g. The highest number of MPs was related to the size classes of >1000 μm and <25 μm. The highest dominant type, color, and shape of MPs in organic MSW were nylon, white/transparent, and fragments, respectively. Di (2-ethylhexyl) phthalate (DEHP) and diisobutyl phthalate (DiBP) were the dominant compounds of PAEs in organic MSW. Based on the finding of present study, MPs showed a high hazard index (HI). DEHP, dioctyl phthalate (DOP), and DiBP demonstrated high-level hazards for sensitive organisms in water. This work illustrated considerable MPs and PAEs levels from an uncontrolled landfill without adequate protection, possibly contributing to their release into the environment. The sites of landfill located near marine environments, such as Bushehr port landfill adjacent to the Persian Gulf, may indicate critical threats to marine organisms and the food chain. Continuous landfills control and monitoring, especially the ones near the coastal area, is highly recommended to prevent further environmental pollution.

Conversion of Lignocellulosic Wastes into Biofertilizer using Bacterial Consortium

Lignocellulosic biomass abundantly and ubiquitously occupies the earth. However, their complex molecular structure prevents their use as a source of organic material for fermentable sugars and nutrients to be used as foods, fertilizers and biofuels. For an efficient carbon cycle, microbial enzymes play a key role in slow biodegradation of lignocellulosic wastes in nature. Microbiological applications can enhance the rate of biodegradation to utilize agro-industrial and organic municipal solid wastes, containing up to 50% lignocellulose substrates, as an inexpensive and sustainable source of plant nutrients. With this hypothesis, the current study was carried out to prepare a consortium of lignocellulose degrading bacteria and use it to convert lignocellulosic substrates in garden, sugarcane, rice, cotton and fruit waste into biofertilizer. Overall, 7-14% reduction in cellulose and 3-6% reduction in lignin content, along with decrease in pH was observed on treatment of above wastes with microbial consortium in 42 days. In spite of the low conversion rates observed in our study, better root, shoot as well as leaf development was observed in moong seedlings grown in soil amended with biofertilizer (3:1 ratio) as compared to controls. Another interesting observation was the biofertilizers with low pH prepared from sugarcane wastes (pH 3.1) and fruit wastes (pH 3.6) supported plant growth more efficiently as compared to other biofertilizers (pH 5.0 to 5.7). Thus, in addition to feasible conversion of lignocellulosic wastes into biofertilizer, our study further suggests the use of selective wastes as raw material depending on the preference of plants for slightly acidic to neutral soil pH for growth.

Supercritical water gasification of organic solid waste: H2 yield and cold gas efficiency optimization considering modeling uncertainties

Supercritical water gasification (SCWG) is one of the typical hydrothermal treatment technologies for organic solid waste. However, the current SCWG optimization methods perform deterministic optimization without considering the uncertainty of the model for calculating the objective function, which leads to low reliability of the optimization results. Therefore, an optimization framework that considers the prediction uncertainties of SCWG data-driven models is proposed to optimize the H2 yield and cold gas efficiency of organic solid waste SCWG. An ensemble prediction model integrating random forest, gradient boosting regression, and K-nearest neighbor algorithms by the stacking learning method are built to predict SCWG gas yields. The cold gas efficiency prediction model is constructed based on the gas yield prediction models. The SCWG optimization models are constructed by combining the H2 yield and cold gas efficiency prediction models. The uncertainties in the H2 yield and cold gas efficiency prediction models are analyzed and integrated into the optimization models. The case studies were conducted to test the proposed framework. The optimization results were verified by the results of similar experimental conditions. It demonstrates that the proposed framework can obtain the robust results of the organic solid waste SCWG optimization, which can provide a reference for SCWG optimization.

Environmental impact scenarios of organic fraction municipal solid waste treatment with Black Soldier Fly larvae based on a life cycle assessment

Biowaste treatment with Black Soldier Fly (BSF) larvae is an alternative option for organic waste valorization. Its environmental impacts should be assessed and compared with conventional treatment options. The research aims to evaluate the treatment of organic fraction of municipal solid waste (OFMSW) with BSF larvae through a life cycle assessment (LCA). This study employed data inventories from literature and aimed to provide a wide range of production parameter values to identify the potentialities of BSF treatment in the best-case and worst-case scenarios. The SimaPro9, the database Ecoinvent3.5, and the impact assessment method IMPACT 2002+ have been employed for the analysis. A sensitivity analysis of relevant parameters was conducted, considering the avoided impacts that can be obtained thanks to the exploitation of larvae proteins for bioplastics or fishmeal production. Research findings highlight six main environmental impact indicators: respiratory inorganics (kg PM2.5-eq), ozone layer depletion (kg CFC-11-eq), terrestrial ecotoxicity (kg TEG soil), land occupation (m2 organic arable), global warming (kg CO2-eq), and non-renewable energy (MJ primary). The most relevant process generating impacts is BSF breeding, followed by boiling, storage, and OFMSW treatment. The environmental performance is better when the conventional fishmeal substituted, thanks to BSF larvae production, is made from areas 10,000 km far, implementing a 100% renewable energy scenario, reducing the energy consumption by 50%, increasing the lifespan of the equipment to 15 years, and products are employed locally. The current study represents the first attempt to evaluate the global higher or lower environmental impact scenario related to OFMSW treatment through BSF larvae.Graphical

STUDY OF THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE GROWTH AND DEVELOPMENT OF THE INSECT SPECIES HERMETIA ILLUCENS (BLACK SOLDIER FLY)

Background. The problem of agricultural waste disposal is currently very relevant. In the Russian Federation, the agro-industrial complex annually produces hundreds of millions of tons of waste that must be disposed of and used rationally. Organic waste from agricultural production and farm animal manure can be effectively disposed of using directed microbiological fermentation and larvae of the insect Hermetia illucens (black soldier fly). As a result of the activity of the enzyme system of black lion larvae and specific microflora, agricultural waste turns into zoohumus with a high content of nitrogen, phosphorus, potassium and trace elements, which can be used as an organic fertilizer that improves the quality of the soil, and the biomass of larvae for animal feed and for obtaining protein concentrate and fat.&#x0D; Purpose. To determine the optimal temperature conditions for the cultivation of the insect species Hermetia illucens (black soldier fly) on various types of substrates, to study the effect of the substrate composition on the production of larval biomass, protein concentrate and fat.&#x0D; Materials and Methods. The research work was carried out in the microbiological laboratory of the Center for Technological Excellence “Advanced Chemical and Biotechnology”, laboratories of the Department of Biology and Technologies of Living Systems, Faculty of Natural Sciences of the Tula State Pedagogical University named after L. N. Tolstoy and insectaria LLC “Lvinka”.&#x0D; To study the effect of the feed composition on the growth and development of the larvae of the insect species Hermetia illucens, substrates from various agricultural, food and animal waste were used. To determine the influence of temperature and humidity on the development of larvae, thermostats and insectarium rooms were used.&#x0D; Results. The study of the effect of various solid organic waste on the biomass of live and dried larvae showed that the larvae of the insect H. illucens grew and developed better on food waste consisting of meat and fish waste, as well as plant food waste. Larvae developed worse on plant residues. This is due to the fact that these wastes contain a large amount of cellulose and much less nutrients in their composition, therefore, on a substrate of this composition, the larvae gained biomass worse. The optimal temperature for the cultivation of insect larvae of the species H. illucens is t-22°C. The ratio of protein and fat in the larvae of the insect H. illucens depends on the composition of the feed. In those types of feed where protein predominates, the content of this component in the larvae is high. For example, when using food meat waste, the content of protein concentrate reaches 595 g/kg, fat only 323 g/ kg, and when using vegetable waste containing a large amount of carbohydrates, more fat and less protein are produced.&#x0D; Concisions. As a result of the research work carried out, it was possible to study the influence of environmental factors on the growth and development of the insect species H. illucens (black soldier fly), and to select favorable conditions for the development of larval biomass. Optimal substrates were selected for the cultivation of larvae of the insect species H. illucens. The most suitable substrates for the production of protein concentrate and fat were also determined.

Flue Gas-Enhanced Water Leaching: AAEM Removal from Agricultural Organic Solid Waste and Fouling and Slagging Suppression during Its Combustion.

Alkali and alkaline earth metals (AAEMs) in agricultural organic solid waste (AOSW) contribute to the fouling and slagging during its combustion. In this study, a novel flue gas-enhanced water leaching (FG-WL) method using flue gas as the heat and CO2 source was proposed for effective AAEM removal from AOSW before combustion. The removal rate of AAEMs by FG-WL was significantly superior to that by conventional water leaching (WL) under the same pretreatment conditions. Furthermore, FG-WL also obviously reduced the release of AAEMs, S, and Cl during AOSW combustion. The ash fusion temperatures of the FG-WL-treated AOSW was higher than that of WL. The fouling and slagging tendency of AOSW greatly decreased through FG-WL treatment. Thus, FG-WL is a simple and feasible method for AAEM removal from AOSW and suppressing fouling and slagging during its combustion. Besides, it also provides a new pathway for the resource utilization of power plant flue gas.

Factors affecting the behaviour of domestic solid waste reduction in households:A case study in Dien Chau, Nghe An

This research aims to analyse the factors affecting the behaviour of domestic solid waste reduction in households in Dien Chau town (Nghe An province) by using the Probit regression model. The data was collected from 60 households. The results showed that the domestic solid waste in the study area is mainly from households and organic solid waste. Besides, there were solid wastes, that are paper, scrap, metal, and plastic, could be recycled and reused. Results of the surveyed households showed that there were many activities to reduce solid waste, such as waste classification at source, recycling and reuse, covert organic rubbish into compost or animal feed, etc. From the Probit model, the factors affecting the behaviour of domestic solid waste reduction at households in Dien Chau town included age, gender, and awareness of households on domestic solid waste reduction. These are affecting factors that can be used as a reference to strengthen the behaviour of reducing domestic solid waste in the study area in the coming time.

Dust removal ash coupled with high-temperature exhaust gas to produce energy gas CO and remove the heavy metals synchronously

In order to solve the utilization problem of dry quenching coke dust removal ash (DRA) and high-temperature exhaust gas (HTEG) at the same time, this study proposes a new technology that combines DRA and high-temperature exhaust gas to produce energy gas CO and realize the removal of heavy metals in dust removal ash. The reaction properties of DRA and high-temperature exhaust gases, as well as the migration law of heavy metals, are preliminarily evaluated using thermodynamic simulation software (FactSage) and a combination of thermogravimetric mass spectrometry (TG-MS). The dropper furnace (DF) experiments are used to verify the feasibility of the new technology by simulating the high-temperature flue gas environment. The findings reveal that as pressure rises, the content of gas products namely CO2 and CH4 rises while the content of gas products CO and H2 falls. At the same time, when the temperature rises, the CO and H2 contents rise. Heavy metals such as Cd, Pb, and Zn are also more volatile, whereas heavy metals such as Ni, Cr, and Cu, require higher temperatures to volatilize. As the temperature increases from 800 to 1200 °C, the Pb removal rate climbs from 34.6% to 92.5%, the Cd removal rate increases from 46.5% to 95.6%, and the Zn removal rate increases from 13.4% to 80.5%. The new technology captures CO2 from high-temperature exhaust gases and converts them into CO energy gases, simultaneously realizing the removal of heavy metals. This provides an innovative solution for the treatment of organic solid waste.

Insights into the Occurrence, Fate, Impacts, and Control of Food Additives in Food Waste Anaerobic Digestion: A Review.

The recovery of biomass energy from food waste through anaerobic digestion as an alternative to fossil energy is of great significance for the development of environmental sustainability and the circular economy. However, a substantial number of food additives (e.g., salt, allicin, capsaicin, allyl isothiocyanate, monosodium glutamate, and nonnutritive sweeteners) are present in food waste, and their interactions with anaerobic digestion might affect energy recovery, which is typically overlooked. This work describes the current understanding of the occurrence and fate of food additives in anaerobic digestion of food waste. The biotransformation pathways of food additives during anaerobic digestion are well discussed. In addition, important discoveries in the effects and underlying mechanisms of food additives on anaerobic digestion are reviewed. The results showed that most of the food additives had negative effects on anaerobic digestion by deactivating functional enzymes, thus inhibiting methane production. By reviewing the response of microbial communities to food additives, we can further improve our understanding of the impact of food additives on anaerobic digestion. Intriguingly, the possibility that food additives may promote the spread of antibiotic resistance genes, and thus threaten ecology and public health, is highlighted. Furthermore, strategies for mitigating the effects of food additives on anaerobic digestion are outlined in terms of optimal operation conditions, effectiveness, and reaction mechanisms, among which chemical methods have been widely used and are effective in promoting the degradation of food additives and increasing methane production. This review aims to advance our understanding of the fate and impact of food additives in anaerobic digestion and to spark novel research ideas for optimizing anaerobic digestion of organic solid waste.

CROP GROWTH ENHANCEMENT: INVESTIGATING THE SIGNIFICANCE OF TEA WASTE COMPOST APPLIED AS ORGANIC FERTILIZER ON THE GROWTH RESPONSE OF MAIZE (ZEA MAYS) PLANT

Recycling and reuse can effectively manage the enormous amount of organic solid waste produced in a nation with a dense population, like Bangladesh, especially if the waste has potential value but there haven’t been many strategies employed to deal with these problems. In that light, the goal of this study was to recycle tea waste while using it as organic fertilizer to boost crop productivity. To prepare compost, tea waste (TW) was collected from various locations within the two municipal corporations of Dhaka City. The compost was then applied to Zea mays plants at different treatment levels with a fixed amount of soil (T0 – Control, T1 – basal dose of fertilizers/15 kg soil, T2 – 4.5 kg TW/15 kg soil, T3 – 6.0 kg TW/15 kg soil, and T4 – 7.5 kg TW/15 kg soil), and the plant growth against the doses were observed for six consecutive weeks. The study discovered that, compared to the control (T0) and conventional chemical fertilizers (T1), the plants displayed a promising growth response in the remaining treatments (T2, T3, and T4) where only TW compost was applied, with the highest growth in treatment T4. Treatment T4 even displayed an early bloom of tassels within the sixth week of observation. Significant differences (p values 0.05) between and within each treatment group were found by statistical analysis (one-way ANOVA). Composting and recycling TW may have potential uses in agriculture and could be a feasible means to achieve zero waste emissions, according to the study’s findings.

Beneficial Microorganisms in the Anaerobic Digestion of Cattle and Swine Excreta

The accumulation of solid organic waste is reaching critical levels in almost all regions of the world. It must be managed sustainably to avoid the depletion of natural resources, minimize risks to human health, reduce environmental burdens, and maintain an overall balance in the ecosystem. This research focuses on the anaerobic digestion of bovine and swine excreta with and without applying beneficial microorganisms as a viable option for recycling agricultural solid wastes. Three greenhouse gases (GHGs)—methane, carbon dioxide, and ammonia—produced by cattle and swine excreta that were treated with and without beneficial microorganisms in bioreactors were quantified. A monitoring and gas concentration measurement system was implemented inside the bioreactors. The behavior of the GHGs and the efficiency of the beneficial microorganisms in treating the farm animal waste were analyzed according to the phases of anaerobic digestion. Average reductions in the concentration in units of ppm of CH4 during the composting process of 46.95% and 34.48% were observed for the cattle and swine excreta treatments, respectively. It was concluded that the studied GHGs had different behaviors in the anaerobic digestion of the treatments in cattle and swine excreta with and without beneficial microorganisms due to the different types of feeding. However, it must be emphasized that beneficial microorganisms are an essential tool for reducing GHGs in anaerobic digestion.

A novel approach for the fractionation of organic components and microbial degraders in ADM1 and model validation based on the methanogenic potential

The anaerobic digestion model No 1 (ADM1), with fixed fractions of the substrate components, is currently used to simulate methane production during the anaerobic digestion (AD) of waste activated sludge (WAS). However, the goodness-of-fit for the simulation is not ideal due to the different characteristics of WAS from different regions. In this study, a novel methodology based on a modern instrumental analysis and 16S rRNA gene sequence analysis for the fractionation of organic components and microbial degraders in the WAS is investigated to modify the fractions of the components in the ADM1. The combination of Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance (NMR) analyses were used to achieve a rapid and accurate fractionation of the primary organic matters in the WAS that was verified using both the sequential extraction method and the excitation-emission matrix (EEM). The protein, carbohydrate, and lipid contents in the four different sludge samples measured using the above combined instrumental analyses were 25.0 – 50.0%, 2.0 – 10.0%, and 0.9 – 2.3%. The microbial diversity based on 16S rRNA gene sequence analysis was utilized to re-set the initial fractions of the microbial degraders in the ADM1. A batch experiment was utilized to further calibrate the kinetic parameters in the ADM1. Based on the above optimization of the stoichiometric and kinetic parameters, the ADM1 with full parameter modification for WAS (ADM1-FPM) simulated the methane production of the WAS very well with a Theil's inequality coefficient (TIC) of 0.049, which was increased by 89.8% than that of the default ADM1 fit. The proposed approach, with its rapid and reliable performance, demonstrated a strong application potential for the fractionation of organic solid waste and the modification of ADM1, which contributed to a better simulation of methane production during the AD of organic solid wastes.

Efficient adsorption of ammonia on activated carbon from hydrochar of pomelo peel at room temperature: Role of chemical components in feedstock

Activated carbon derived from the organic solid waste is a promising material for ammonia removal. The components in the feedstock would affect the performance of activated carbon, but the detailed effect mechanism remains unknown. To reveal the correlations between the components of the feedstock and different ammonia adsorption styles of activated carbon, this study used pomelo peel to prepare ZnCl2-loaded activated carbon for ammonia adsorption via hydrothermal carbonization and KOH activation, focusing on the effect of the chemical components (cellulose, xylan, pectin, and lignin) on the physicochemical properties and adsorption performance of activated carbon. For raw activated carbon in moist conditions, ammonia was mainly adsorbed in the form of Lewis/Brønsted acid-base (37.8 mg/g), followed by the ZnCl2 coordination compound and organic amine forms (22.3 mg/g). Lignin-added activated carbon had the highest adsorption capacity, 91.2 mg/g in moist conditions, followed by cellulose-added and xylan-added activated carbon. The presence of lignin was beneficial for the formation of the phenolic group of activated carbon (increased by 111.3%), which promoted ammonia adsorption in the form of Lewis acid-base, especially in dry condition. Cellulose and xylan enhanced the formation of carboxylic (i.e., increased by 53.0% for cellulose) and lactonic groups (i.e., increased by 73.4% for cellulose) of activated carbon, leading to an increase of ammonia adsorption in the form of Brønsted acid-base and organic amines in moist conditions. The results illustrated the detailed effect of the chemical components in the feedstock on the ammonia adsorption styles, which could guide the selection of appropriate materials to prepare activated carbon for highly efficient ammonia adsorption under various situation.

The state of domestic solid waste and prediction of domestic solid waste quantity until 2035 in Cao Bang city, Cao Bang province, Vietnam

The aim of this paper is to assess the current situation of solid waste generation and forecast the amount of domestic solid waste in Cao Bang city, Cao Bang province in Vietnam by 2035. The study used a number of main research methods such as collecting primary and secondary data, actual investigation methods, using mathematical formulas to calculate and process data to get the results. The results show that the source of domestic solid waste in Cao Bang city is very diverse, mainly from urban areas, accounting for 93.09%. Emission coefficient in urban area is 1.13 kg/person/day and in rural area is 0.51 kg/person/day. Domestic solid waste composition is mainly organic solid waste (58.17%) while non-recyclable solid waste accounts for the lowest rate (7.2%). The amount of generated domestic solid waste in the city is forecasted to be 32,225.42 tons/year by 2035. The research results also show that the estimated amount of domestic solid waste generation in 2035 will increase by 1.13 times compared to 2022. This result is a necessary and important scientific basis to propose solutions to improve the efficiency of domestic solid waste management in the coming time.