Biodrying Process Research Articles

Optimizing aeration rates via bio-methane potential test for enhanced biodrying efficiency of refuse-derived fuel-3

Aeration forms a critical part of the biodrying of refuse-derived fuel-3 (RDF-3) and significantly affects the fuel’s energy potential. Understanding the organic content (OC) of RDF-3 is crucial for determining the optimal aeration strategy. In this study, we conducted a bio-methane potential (BMP) test to estimate the OC by observing the conversion of organic matter into methane (CH₄) and carbon dioxide (CO₂). The observation of BMP was conducted using anaerobic digestion approach where substrate and inoculum are important parameters considered for the success of this test. Various ratios substrate-to-inoculum (S/I) were explored to assess their impact on biogas production, our research involved testing four S/I ratios (0.25, 0.5, 1.0, and 1.5) focusing on identifying the optimal aeration strategy. Based on stoichiometric calculations, the sample’s biogas yield per gram volatile solid indicates RDF-3’s OC is 1.5%. This OC value played a role in establishing the appropriate aeration rate (AR) for the biodrying process, which was determined to be 0.6 m³/kg.day, indicating the action of effective microbial degradation processes. Ensuring the correct AR is vital for maximizing the energy potential of RDF-3. Implementing optimized aeration rates based on the BMP test in waste management practices can significantly improve RDF-3 biodrying efficiency. This approach enhances RDF quality, reduces moisture, increases calorific value, and minimizes greenhouse gas emissions, leading to more sustainable and efficient waste-to-energy conversion.

Thermophilic bacterial agent inoculation enhances biodrying of kitchen waste: Insights into process properties, organic degradation, bacterial communities and metabolic pathways

The high moisture content of kitchen waste (KW) restricts the future treatment and resource utilization. Biodrying is an effective approach to remove the water of KW. However, conventional biodrying only uses the heat generated by the indigenous microorganisms to remove water, which has long treatment cycle and low moisture removal rate. Microbial bioaugmentation is an emerging approach to improve the biodrying efficiency of KW. In this study, a thermophilic bacterial agent (TBA) composed of Bacillus, Geobacillus and Acinetobacter was used to promote water evaporation during the biodrying process. Based on the results, the moisture removal rate of experimental group inoculated with TBA was 82.20 %, which was notably higher than CK group without inoculation. Moreover, TBA significantly increased the amount of organic matter degradation. Microbial community analysis revealed that TBA could promote the proliferation of thermophilic bacteria and make bacterial community more tolerant to high temperature environment. Further analysis of metabolic pathways showed that quorum sensing and glyoxylate and dicarboxylate metabolism were enhanced by TBA inoculation, which can help microorganisms to better adapt to high temperature environment and release more energy to facilitate the water evaporation. This study offers a fresh approach to improve the water removal efficiency in biodrying process.

Simulation and optimization model for mechanical biological treatment biodrying process: validation with experimental results

Simulation and optimization model for mechanical biological treatment biodrying process: validation with experimental results

Synergy of phosphate and hyperthermophilic bio-drying reduces pollution of sludge bio-drying: Reducing ammonia emissions and heavy metal migration risk

Hyperthermophilic bio-drying has stronger organic matter degradation and drying ability than the conventional bio-drying. However, ammonia emissions during the hyperthermophilic bio-drying are significantly higher than those during the conventional bio-drying process due to the higher temperature and pH value. Phosphate has been reported to reduce ammonia emissions during composting. Meanwhile, both the degradation of organic matter and the addition of phosphate buffer can promote the formation of EPS. EPS exhibits strong passivation and adsorption properties for heavy metals and organic pollutants, thus positively impacting the control of pollution in bio-drying products. Furthermore, the formation of EPS and the risk of the migration of heavy metals during hyperthermophilic bio-drying have not been reported. According to the results, compared to conventional bio-drying, the hyperthermophilic bio-drying significantly increased the yield of EPS and generated more active groups, reducing the migration risk of Cu, Zn, Cr, Pb, Cd, As, and Ni. The comprehensive potential ecological risk was reduced by 29.71%, which was higher than the reduction achieved by conventional bio-drying (13.81%). The addition of phosphate significantly reduced the ammonia emissions from the hyperthermophilic bio-drying and retained more nitrogen. Meanwhile, it promoted the formation of EPS and the enrichment of active groups, further reducing the migration risk of heavy metals. Moreover, the addition of phosphate buffer further reduced the comprehensive potential ecological risk of the products obtained from.

Biodrying of municipal solid waste-correlations between moisture content, organic content, and end of the biodrying process time.

Biodrying refers to the decomposition of organic municipal solid waste (MSW) under aerobic conditions. This process usually lasts 14days and requires large amounts of air to be injected into the waste matrix. The efficiency of the biodrying process depends on several geotechnical parameters, including initial moisture content, initial organic content, bulk density, dry density, solid particle density, and porosity. To examine the potential influence of these parameters on the biodrying process, we analyzed 13 biodried MSW samples. The results revealed a strong positive linear relationship between the initial moisture content and the mass loss percentage. In the first three days of the biodrying process, the waste mass rapidly decreased; afterwards, the daily mass loss occurred at a less rapid, more constant rate. The established average mass removal ratio between the volatile solids and water was 1:6.38 with a standard deviation of 1.06. Dry and solid particle densities were preserved in all 13 experiments; thus, the corresponding void ratio remained unchanged. This finding suggests that the settlement and degradation of MSW that occur during the biodrying process did not significantly influence the airflow rate.

Utilization of pineapple peels, rice-washed water, and local microorganisms derived from golden snails in biodrying process of yard waste

Comestoarra.com developed Teknologi Olah Sampah di Sumber (TOSS), an on-site solid waste processing method, which efficiently converted yard waste, specifically leaves and twigs, into biomass pellets through three steps: shredding, biodrying, and pelletization. During biodrying, bioactivators expedited moisture reduction. A comparative study was conducted between Comestoarra’s AR124 bioactivator and an alternative, MOL, derived from pineapple peels, rice-washed water, and golden snails, with the first two being waste materials and the latter a rice field pest. To assess their performance in converting yard waste into refuse-derived fuel (RDF), various parameters were analyzed: moisture content, volatile matter, ash content, fixed carbon content, and calorific value. The Indonesian Standard SNI 8966:2021 for RDF in power plants served as reference criteria. Both bioactivators met these standards. AR124-produced RDF had 8.0±0.0% moisture, 65.0±1.0% volatile matter, 13.7±4.9% ash, 13.3±4.2% fixed carbon, and calorific value of 14.74±1.3MJ/kg (3,523±310.7 kcal/kg). MOL bioactivator resulted in RDF with 5.0±0.0% moisture, 65.0±1.0% volatile matter, 16.7±4.2% ash, 13.3±4.2% fixed carbon, and calorific value of 13.89±1.1MJ/kg (3,320±262.9 kcal/kg). These findings suggest that MOL holds promise as a bioactivator for improving the biodrying process in RDF production.

Refuse-derived fuel (RDF) production and analysis in mechanical-biological treatment (MBT) plant from the municipal solid waste

This study reports on the potential of refuse-derived fuels (RDF), which are produced from Sulaimani Municipal solid waste (MSW) using a biodrying process. Plastic, organic wastes, iron materials, and textiles were used in the formulation of RDF samples. A sample of raw MSW material was collected comprising of 40.6% organic, 29.3% plastic, 6.3% Textiles, 5.1% paper, 3.1% wood, 4.6% glass and stone, 5.2% iron containing materials, and 1.3% others. Physical and chemical properties of the RDF were investigated, including its moisture, ash, total chlorine, and heavy metal content with, calorific value. Based on the experimental results, RDF produced from MSW can be classified into net calorific and total chlorine content values NCV 2 and Cl 4 respectively. In accordance with the European Committee for Standardization (CEN standard), the results of this preliminary investigation of RDF samples made from non-biodegradable and non-recyclable MSW fractions, is necessary to analyze a larger pool of samples in order to project appropriate RDF energy-recovery-enhancing composition.

Application of biodrying with hot air aeration system to process solid waste into rdf

Biodrying is a promising method to process municipal solid waste (MSW) while generating refuse-derived fuel (RDF) output. Recent developments in the process of generating refuse-derived fuel (RDF) have led to a renewed interest in minimal pretreatment processes. Although extensive research has been carried out, one of the most significant current discussions about generating refuse-derived fuel (RDF) using biodrying methods is that it has taken a long time to process. The biodrying method using air from the atmosphere takes 21 days to convert solid waste into RDF. As a result of this, Biodrying processes need to be accelerated by flowing hot air into the biodrying reactor. The aim of this study is to analyze the biodrying process temperature profile with a hot air aeration system. The methodological approach taken in this study is to circulate the hot air that comes from the combustion of wood charcoal. Hot air is discharged into solid waste that is inserted into the biodrying reactor. The temperature and concentration of solid wastewater are analyzed every 15 minutes. The results of this study show that the initial MSW temperature of the front reactor was 40o C and that of the rear reactor was 31o C.In the first 15 minutes until 60 minutes, the temperature shows an increase. The MSW temperature of the front reactor was 47o C, and the rear reactor was 35o C.At the 30th minute of the front reactor, it was 63o C, the rear reactor was 61o C; at the 45th minute of the front reactor, it was 81o C, the rear reactor was 73o C; and at the 60th minute of the front reactor, it was 80o C, the rear reactor was 79oC. These findings have significant implications for the understanding of how circulate the hot air aeration system works well.

Moisture evaporation effect on pore structure and microbial distribution during sludge biodrying

Biodrying of dewatered sludge is an eco-friendly and efficient technology to decrease the sludge moisture content (MC) by metabolic heat generated from sludge organic matter degradation. By analyzing the water states and visualizing the sludge pore structure during the biodrying process, it was found that the bound water accounted for 96.5–97.9% of the sludge water and interstitial water was only 2.0–3.5%. The microscopic and dispersed sludge pores were transformed into larger and linked ones by the transformation of bound water into interstitial water and the subsequent evaporation. As a result, the depth of live bacteria distribution thickened, reaching 0–180 µm, 0–330 µm, and 0–350 µm during the temperature ramp-up to 45.6 °C, the peak temperature of 70.7 °C, and the cool-down to 45.6 °C, respectively. Briefly, as moisture evaporated, the pore structure of the sludge expanded and the microbial distribution deepened. Moreover, the phylum of anaerobic bacteria was drastically decreased.

The effect of aeration rate and feedstock density on biodrying performance for wet refuse-derived fuel quality improvement

This study investigates the effect of aeration rate and feedstock density on the biodrying process to improve the quality of type 2 wet refuse-derived fuel. The aeration rate and feedstock density were varied to investigate these parameters’ effect on the system’s performance. The experiments used 0.3 m3 lysimeters with continuous negative ventilation and five days of operation. In Experiment A, aeration rates of 0.4, 0.5, and 0.6 m3/kg/day were tested with a feedstock bulk density of 232 kg/m3. In Experiment B, the optimum aeration rates determined in Experiment A (0.5 and 0.6 m3/kg/day) were used, and the feedstock density was varied (232 kg/m3, 250 kg/m3, and 270 kg/m3). The results showed that an aeration rate of 0.5 m3/kg/day was the most efficient for a feedstock density of 232 kg/m3; when the aeration rate was increased to 0.6 m3/kg/day, a feedstock density of 250 kg/m3 was the most effective. However, a feedstock density of 270 kg/m3 was not found to be practical for use in the quality improvement system. When the feedstock density is increased, the water in the feedstock and the water resulting from the biodegradation process cannot evaporate due to the feedstock layer’s low porosity, and the system requires an increased aeration rate. Furthermore, the increase in density scaled with increased initial volatile solid content, initial organic content, and initial moisture content, which significantly impacted the final moisture content based on multivariate regression analysis.

Polynomial Regression Model Utilization to Determine Potential Refuse-Derived Fuel (RDF) Calories in Indonesia

Waste-to-energy (WTE) is one of the Indonesian government’s programs aiming to meet the target of achieving a new and renewable energy (NRE) mix, as well as one of the solutions proposed to overcome the problem of waste. One of the products of WTE is energy derived from raw material waste (refuse-derived fuel/RDF). Using the formula y = 0.00003 x5 − 0.0069 x4 + 0.6298 x3 − 24.3245 x2 + 432.8401 x + 55.7448 with R2 = 0.9963, which was obtained by comparing a scatter plot diagram from the RDF calorie test dataset produced through a bio-drying process, the potential RDF calories produced using the waste composition dataset taken from each region in Indonesia can be calculated. The results of the calculations using the determined equations produce a list of provinces with RDF calorie potential, ordered from the largest to the smallest, using which the government can determine which areas are the main priority for processing waste into energy. Thus, through this method, the target of 5.1% renewable energy sourced from waste can be achieved by 2025.

Comparison of economic benefits for the utilization of reclaimed resources from wastewater treatment plants: a case study in Beijing

Abstract The fate of resource recovery is significantly influenced by the standards of water quality and bio-dried excess sludge for various applications. These standards must be practically attainable while ensuring public and environmental health, safety, and economic advantages. The present study investigates a reclaimed wastewater treatment plant (WWTP) in Beijing that incorporates both reclaimed water utilization facility and bio-dried excess sludge treatment. The study elucidates the standards for reclaimed water quality and bio-dried excess sludge for diverse applications. Notably, reclaimed water demonstrates substantial market demand in terms of economic benefits. However, bio-dried excess faces challenges due to higher operational costs and lower TP content. The heat power of the WWTP effluent water source can not only be harnessed for the bio-drying process blowers but also be elevated air temperatures to expedite the bio-drying process.

Carbon Paste Electrodes Obtained from Organic Waste After a Biodrying Process and Validation in an Electro-Fenton System Towards Alternative Valorization

Abstract. The transformation of agricultural waste into activated carbon represents an attractive approach as new and alternative source, but also as a reduction of pollution associated to the degradation of precursors. The organic residues sugarcane (Saccharum officinarum) bagasse-shell, orange (Citrus sinensis) peel-bagasse, and eucalyptus (Eucalyptus globulus) leaves, obtained from a biodrying process were transformed into activated carbons using phosphoric acid as activating agent. The resulting materials were physicochemically characterized and after that, carbonaceous electrodes were prepared to test the feasibility of using them in a discoloration electro-Fenton wastewater treatment process. Orange peel-bagasse biodried precursor transformed into activated carbon showed the highest efficiency when used as the modifier in a carbon paste electrode due to its highest porosity, electroactive area (24.9x10-2 cm2), and roughness (1.21 a.u.), also to its chemical affinity for anionic molecules. These properties, in addition to the capability of electro-sorb iron ions on the surface during the Fenton reaction, allowed a 44 % methyl orange discoloration efficiency. Sugarcane bagasse-peel and eucalyptus leaves biodried residues were also evaluated with efficiencies under 30 %, mainly attributed to intrinsic composition of the precursor materials. Resumen. La transformación de los residuos agrícolas en carbón activado representa un enfoque atractivo y novedoso, además de que representa una alternativa a la reducción de la contaminación asociada a la degradación de residuos orgánicos. Los residuos orgánicos de bagazo de caña de azúcar (Saccharum officinarum), bagazo y cáscara de naranja (Citrus sinensis), y hojas de eucalipto (Eucalyptus globulus), que fueron obtenidos de un proceso de biosecado, se transformaron en carbón activado utilizando ácido fosfórico como agente activante. Los materiales resultantes se caracterizaron fisicoquímicamente y después de eso, se prepararon electrodos de pasta de carbón modificados con estos materiales, para estudiar la viabilidad de utilizarlos en un proceso de tratamiento de aguas residuales mediante electro-Fenton. El precursor biosecado de bagazo y cáscara de naranja transformado en carbón activado mostró la mayor eficiencia cuando se usó como modificador en un electrodo de pasta de carbón, debido a su mayor porosidad, área electroactiva (24.9x10-2 cm2) y rugosidad (1.21), también debido a su mayor afinidad química por moléculas aniónicas. Estas propiedades, aunadas a la capacidad de electro-sorber iones de hierro en la superficie durante la reacción de Fenton, permitieron una eficiencia de decoloración del naranja de metilo del 44 %. También se evaluaron residuos biosecados de bagazo de caña de azúcar y hojas de eucalipto, con eficiencias inferiores al 30 %, atribuidas principalmente a la composición intrínseca de los materiales precursores.

The application of biodrying method for organic waste treatment in Universitas Trisakti, Jakarta

Universitas Trisakti has been attributed with many activities and has not been equipped with a proper solid waste management to recover the waste that may contaminate the environment. Biodrying becomes an approach of drying technique utilizing the heat generated by biological activities to degrade the organic waste and also acknowledged to be the proper technique to provide the raw material for Refuse Derived Fuel (RDF). This study aims to conduct the process of biodrying technique carried out in an acrylic chamber with the capacity of 18000 cm3. The source of municipal solid waste supplied by the transfer waste facility in the area of Universitas Trisakti. Only organic waste was used during the biodrying process. Aeration rate was 3 l/min. The biodrying process was observed for 8 (eight) days which the activities of microorganisms were identified at the third days, shown by the condensation of the evaporated water released on the top and side walls of the biodrying reactor. Due to this condition, the designed reactor needs further innovation to avoid the condensation of evaporated water to raise the reduction rate of moisture content. This pretreatment study showed the absence of leachate which proves that the biodrying method has the potential to reduce the negative impact of unmanaged solid waste generation.

Sludge biodrying coupled with photocatalysis improves the degradation of extracellular polymeric substances

The efficiency of sludge dewatering is limited by extracellular polymeric substances (EPS) during biodrying. This study investigated the effect of photocatalysis-mediated EPS degradation on sludge dewatering performance during the sludge biodrying process. The photocatalysis of municipal sludge was first carried out to choose a cost-efficient catalyst. Then sludge biodrying tests were performed using TiO2-coated amendment (TCA) and uncoated amendment (TUCA) as the control. Municipal sludge photocatalysis results showed that using TiO2 could efficiently degrade carbohydrates and proteins in the EPS within 60 min. After 20-day biodrying, photocatalysis significantly promoted a reduction in the moisture content and EPS by 17.64% and 6.88%, respectively. The surface-enhanced Raman scattering (SERS) intensities of the C–C–O symmetric stretching vibration peak of D-lactose and the C–S stretching vibration peak of cysteine were significantly decreased by approximately 33.19% and 44.76%, respectively, indicating that photocatalysis indeed promoted the reduction of polysaccharides and cysteine in the EPS, especially after the thermophilic phase. The hydrophilic amino acid content decreased by 23.02%, verifying that photocatalysis could improve EPS hydrophobicity. Consequently, municipal sludge biodrying coupled with photocatalysis promotes sludge EPS degradation and enhances sludge dewaterability, improving the efficiency of sludge biodrying.

Effect of biodrying of lignocellulosic biomass on humification and microbial diversity

By optimizing the carbon to nitrogen (C/N) ratio, this study accomplished an improved level of humification and microbial diversity in the biodrying process of lignocellulosic biomass. The results demonstrated that C/N ratio of 20 accelerated the decomposition of refractory lignocellulose, resulting in lower greenhouse gas emissions and the production of highly mature fertilizer with a germination index of 119.0% and a humic index of 3.2. Moreover, C/N ratio of 20 was found to diversify microbial communities, including Pseudogracilibacillus, Sinibacillus, and Georgenia, which contributed to the decomposition of lignocellulosic biomass and the production of humic acid. Hence, it is recommended to regulate the C/N ratio to 20:1 during the biodrying of biogas residue and wood chips to promote the economic feasibility and bioresource recycling.

Modification of the Aeration-Supplied Configuration in the Biodrying Process for Refuse-Derived Fuel (RDF) Production

Biodrying is an essential part of the mechanical–biological treatment process that minimizes moisture content and simultaneously maximizes heating value for refuse-derived fuel (RDF) production. Although the mechanical separation process operates effectively in Thailand’s RDF production, high organic content levels and their degradation cause moisture contamination in RDF, producing wet RDF. Aeration is essential for an effective biodrying process, and can reduce RDF’s moisture content as well as increase its heating value. To maximize the biodrying effect, aeration should be optimized based on the waste conditions. This study proposes a modified aeration-supplied configuration for wet RDF biodrying. The aeration rate was modified based on the period within the biodrying operation; the first period is from the beginning until day 2.5, and the second period is from day 2.5 to day 5. The optimal aeration supply configuration was 0.5 m3/kg/day in the first period and then 0.3 m3/kg/day until the end of the process; this configuration yielded the greatest moisture content decrease of 35% and increased the low heating value of the biodried product by 11%. The final moisture content and low heating value were 24.07% and 4787 kcal/kg, respectively. Therefore, this optimal aeration-supplied configuration could be applied to meet the moisture content and low heating value requirements of the RDF production standard for Thailand’s local cement industry.

Synergistic Effects of Initial Moisture Content and Particle Size on Drying Rate and Heat Production during Bio-Drying of Sludge after Electro-Dewatering

Electro-dewatered sludge (EDS) can be bio-dried alone, instead of adding bulking agents. The initial moisture content (IMC) and particle size of the electro-dewatered sludge affect the efficiency and energy consumption during the bio-drying process. This study aimed to investigate the synergistic effects of sludge IMC and particle size on the drying rate and heat production of bio-drying with EDS. Experiments were conducted with two different IMC sludge and two different sludge particle sizes. Results showed that the highest moisture removal rate was 43.18% in treatment T4, which had materials with a smaller particle size (<3 mm) and lower IMC (38.69%). And bio-drying of T4 had the highest biological heat production (7413.14 kJ, i.e., 741.31 kJ/kg sludge), and the lowest bio-drying index (the ratio of water loss to volatile solid loss) was 7.10 among the four treatments. Five thin-layer drying kinetic models and a nonlinear regression method were analyzed to estimate the bio-drying kinetic parameters. The Midilli et al. model had a better fitting result, and the highest R2 value was 0.9929 during bio-drying of EDS. The new coefficients k (0.1465) and n (1.0898) were obtained. Through the heat balance, the heat used for evaporation was 40–57% of the total energy consumption (5873–9140 kJ). According to the PCA, the particle size had a great influence on the bio-drying process. Also, the particle size positively correlated with temperature, moisture ratio, and drying rate.

Characteristics of Wastewater from Municipal Waste Bio-Drying and Its Impact on Aquatic Environment—Long-Term Research on a Technical Scale

The implementation of appropriate solutions for municipal waste management is still a significant challenge for the operators of technological facilities. Although there are many separate collection procedures and waste neutralisation systems available, it is still necessary to search for new economically and technologically justified solutions. The priority is environmental care and circular economy compliance. An important aspect is recycling and energy recovery from waste as an alternative fuel. Preparation of municipal waste for energy production requires many preliminary unit processes, and one of the most important factors is drying. It should be emphasised that environmental impact assessment is an indispensable aspect of waste management. The aim of long-term research was to determine the effect of bio-drying of municipal waste on the characteristics of technological and precipitation wastewater and its impact on the quality of the aquatic environment. An investigation was carried out between 2015–2021 on a large-scale installation for 200,000 residents. It was proven that during the wastewater treatment plant operation, the concentration of N-NH4 was exceeded. The concentrations of other pollution indicators corresponded to the normative values. The quality of groundwater also deteriorated. A comparative analysis of municipal waste drying methods showed that the bio-drying process has a significantly lower impact on the natural environment than the methods that are lower in the municipal waste management hierarchy.

Improvement of energy recovery potential of wet-refuse-derived fuel through bio-drying process.

This paper proposes novel wet-refuse-derived fuel (Wet-RDF) bio-drying process with the variation of initial organic substrate and moisture content. The bio-drying was carried out using 0.3 m3 lysimeter aerated continuously at different rates. Two conditions of Wet-RDF feedstock tested included: Experiment A ‒ 37% organic substrate and 58% moisture content with an initial heating value of 2,889kcal/kg; and Experiment B ‒ 28% organic substrate and 35% moisture content with an initial heating value of 4,174kcal/kg. The bio-drying was performed in both experiments under negative ventilation mode and non-ventilation mode, the ventilation mode was set at the aeration rates of 0.2 m3/kg/day and 0.4 m3/kg/day. The results suggest that the optimum aeration rate was 0.4 m3/kg/day, achieving a 30% moisture reduction and a 60% heating value increase from their initial values. As a result, the improved wet-RDF qualified for the local cement industry's standard in terms of heating value.