Organic Waste Research Articles

Implementing Biodigester Technology for Sustainable Waste Management in Mojokerto City, Indonesia

Mojokerto City, located in East Java, grapples with a steadily rising waste generation trend accentuated by the COVID-19 pandemic. Drawing data from the National Waste Management Information System (SIPSN) and supplemented with an exhaustive literature review, this study scrutinizes the potential of biodigester technology as a solution to this mounting challenge. Mojokerto's waste, consistent in its composition from 2019 to 2022, is dominated by food waste, making it an ideal candidate for biodigester intervention. The study revealed that existing biodigester facilities in Mojokerto vary in their waste reduction efficiencies yet collectively demonstrate the viability of converting food waste to energy. For instance, the TPS 3R Magersari Berseri facility showcased an impressive waste reduction rate of 85.0%, processing 62.05 tons out of 73 tons of waste received annually. Comparative analyses of other facilities like TPS 3R Pulorejo "Cahaya Berseri" and TPS 3R Muria Berseri were also conducted, revealing varying degrees of efficiency. These facilities underscore the potential of biodigester technology in managing the rising tide of waste and contributing to sustainable energy generation. The findings of this study also call for increased awareness about food conservation, improved waste segregation at the source, and the promotion of composting and other organic waste processing methods, thereby optimizing the overall efficiency of waste management in the city.

Pemberdayaan Masyarakat Desa dalam Pemanfaatan Sampah Organik melalui Pelatihan Pembuatan Pupuk Organik

Soil conditions vary from region to region. Some are fertile, while others are less fertile. Factors such as nutrient imbalance, soil depletion, decreased organic content, and microbial activity affect soil fertility. To maintain the balance of soil nutrients and organic matter, it is necessary to add organic fertilizers to harmonize the nutrient content of the soil. Chemical fertilizers only provide one type of plant nutrient without improving soil properties. Socialization of organic fertilizers is needed so that people are wiser in maintaining soil fertility with organic materials. The community service was carried out to provide training and practice in making organic fertilizer from livestock manure and plant residues in Duku Candi Baru, Genting Village, Cepogo District, Boyolali Regency. This service activity uses two approaches, namely counseling and training. The extension stage is carried out by providing material about processing cow dung into organic fertilizer. Training is carried out by demonstrating how to make organic fertilizer in a simple way. This training begins with the socialization of making organic fertilizer and compost, which aims to make the community understand first about information about organic fertilizer and compost along with its benefits, then continued with the practice of making organic fertilizer and compost. This training educates the community about the use of organic waste for organic fertilizer in sustainable agriculture. Through a mixture of simple materials such as cow dung, vegetable waste, EM4, and molasses, it is hoped that the community will use organic fertilizers rather than chemical fertilizers for more environmentally friendly agricultural products.

Harnessing Abuja's Municipal Solid Waste as a Renewable Energy Source: Scanning Electron Microscopy Analysis

A study of Abuja’s municipal solid waste (MSW) samples using the scanning electron microscopy analysis was undertaken in this work. In the face of the severe energy poverty being experienced in Nigeria which largely depends on diminishing fossil fuel resources coupled with the associated problem of greenhouse gas emission, the energy potential available in municipal solid wastes needs to be investigated. Using MSW as a fuel source for electric energy production will also positively impact on Abuja’s waste management. This present study requires the analysis of the MSW with aim of confirming that products of its incineration will not be hazardous to the environment. ASTM E 1508 procedures for utilizing the scanning electron microscope (SEM) were followed to identify elements that would be contained in the bottom ash of the incineration process of samples of Abuja’s municipal solid wastes obtained from selected districts of the city. Elemental composition of the bottom ash that will be formed from incineration of Abuja’s MSW was obtained by the use of energy dispersive x-ray analysis. The micrographs plotted indicate that silicon and iron are the principal elements present in the samples with values for silicon and iron being highest at 49.5 and 19.55%, respectively, for the sample from Dutse-Alhaji. The tests also show the presence of silver in the organic wastes generated in Abuja, while presence of sulphur is very minimal. The silicon levels present in Abuja’s municipal solid waste compare well with values for Nigerian coals which have percent silicon contents ranging from 39.0 – 49.4% (Enugu coal – 39.0%; Okaba – 44.8%; Maiganga – 49.4%). The test results also show that Abuja’s MSW samples had grain sizes ranging from 3.5 mm 16 mm. The results indicate Abuja’s MSW combustion rate will be lower than for pulverised coal which is known to have much lower grain size in the range of 75 μm to 106 μm and will need shredding before firing since grain size is a very critical determinant factor in solid fuel combustion rate and burn-out time. The tests conclusively show that Abuja’s MSW will be a more environmentally friendly fuel than coal because of its lower sulphur content.

Study of environmental risk levels due to organic solid waste on the Andrés Avelino Cáceres Platform in the District of José Luis Bustamante y Rivero-Arequipa

Study of environmental risk levels due to organic solid waste on the Andrés Avelino Cáceres Platform in the District of José Luis Bustamante y Rivero-Arequipa

Biogas upgrading and membrane anti-fouling mechanisms in electrochemical anaerobic membrane bioreactor (EC-AnMBR): Focusing on spatio-temporal distribution of metabolic functionality of microorganisms

Electrochemical anaerobic membrane bioreactor (EC-AnMBR) by integrating a composite anodic membrane (CAM), represents an effective method for promoting methanogenic performance and mitigating membrane fouling. However, the development and formation of electroactive biofilm on CAM, and the spatio-temporal distribution of key functional microorganisms, especially the degradation mechanism of organic pollutants in metabolic pathways were not well documented. In this work, two AnMBR systems (EC-AnMBR and traditional AnMBR) were constructed and operated to identify the role of CAM in metabolic pathway on biogas upgrading and mitigation of membrane fouling. The methane yield of EC-AnMBR at HRT of 20 days was 217.1 ± 25.6 mL-CH4/g COD, about 32.1 % higher compared to the traditional AnMBR. The 16S rRNA analysis revealed that the EC-AnMBR significantly promoted the growth of hydrolysis bacteria (Lactobacillus and SJA-15) and methanogenic archaea (Methanosaeta and Methanobacterium). Metagenomic analysis revealed that the EC-AnMBR promotes the upregulation of functional genes involved in carbohydrate metabolism (gap and kor) and methane metabolism (mtr, mcr, and hdr), improving the degradation of soluble microbial products (SMPs)/extracellular polymeric substances (EPS) on the CAM and enhancing the methanogens activity on the cathode. Moreover, CAM biofilm exhibits heterogeneity in the degradation of organic pollutants along its vertical depth. The bacteria with high hydrolyzing ability accumulated in the upper part, driving the feedstock degradation for higher starch, sucrose and galactose metabolism. A three-dimensional mesh-like cake structure with larger pores was formed as a biofilter in the middle and lower part of CAM, where the electroactive Geobacter sulfurreducens had high capabilities to directly store and transfer electrons for the degradation of organic pollutants. This outcome will further contribute to the comprehension of the metabolic mechanisms of CAM module on membrane fouling control and organic solid waste treatment and disposal.

Elevated caproic acid production from one-stage anaerobic fermentation of organic waste and its selective recovery by electro-membrane process

A constructed microbial consortia-based strategy to enhance caproic acid production from one-stage mixed-fermentation of glucose was developed, which incubated with acidogens (Clostridium sensu stricto 1, 11 dominated) and chain elongators (including Clostridium sensu stricto 12, Sporanaerobacter, and Caproiciproducens) acclimated from anaerobic sludge. Significant product upgrading toward caproic acid (8.31 g‧L−1) and improved substrate degradation was achieved, which can be greatly attributed to the lactic acid platform. Whereas, a small amount of caproic acid was observed in the control incubating with acidogens, with an average concentration of 2.09 g‧L−1. The strategy accelerated the shape and cooperation of the specific microbial community dominated by Clostridium sensu stricto and Caproiciproducens, which thereby contributed to caproic acid production via the fatty acid biosynthesis pathway. Moreover, the tailored electrodialysis with bipolar membrane enabled progressive up-concentration and acidification, allowing selective separation of caproic acid as an immiscible product with a purity of 82.58 % from the mixture.

Simulation models of microbial community, pH, and volatile fatty acids of anaerobic digestion developed by machine learning

Anaerobic digestion (AD) is a promising method for treating high-content organic waste via the microbiome in an anaerobic environment. However, because AD is a complex process involving microbial community (MC), it is essential to determine the relationship between the MC, pH, and volatile fatty acids (VFAs). This study employed five machine learning models: artificial neural network, convolutional neural network, extra trees, extreme gradient boost, and support vector machine to estimate the relationship between MC, pH, and VFAs. Methanoregulaceae, Methanomicrobiaceae, Spirochaetes, pH, acetic acid, isobutyric acid, and isovaleric acid were estimated with high accuracy, with R2 >0.800. The variable importance of the models with the highest accuracy was calculated based on the shapley additive explanations analysis. As a result, the MC estimation models suggested syntrophic acetate oxidation by Spirochaetes, and VFAs-pH estimation models suggested that the high organic loading rate during the start-up phase can lead to isovaleric acid accumulation. In an in-silico test using the machine learning simulator, the change of MC resulted in the critical effects on the acetate accumulation from 500 to 1500 mg/L. The optimal relative abundance of Mehtanoregulaceae and Methanomicrobiaceae for the stable operation was suggested as 15–37 % and 3–15 %, respectively, resulting in the acetic acid concentration below 1000 mg/L.

Enhancing chain-elongating microbiomes: Sequential fungi-bacteria cooperation for efficient food waste upgrading using endogenous electron donors

The upgrading of organic waste such as food waste (FW) into medium-chain carboxylates (MCC) is within a bio-based circular economy concept. An efficient chain elongation (CE) microbiome is difficult to obtain, which normally requires long-term acclimatization and an exogenous supplement of electron donor (ED, especially ethanol). In this study, the CE microbiome was rapidly shaped within 18 days and an efficient endogenous ethanol-based CE was achieved through the amendment of distiller yeast (DY) during FW fermentation. Multiple FW feeding accumulated the caproate concentration to 5.76 ± 0.33 g COD/L, which also regulated the CE process from ethanol-dependent to lactate-dependent metabolism. During the lactate-based CE process, the caproate production increased linearly (R2 = 0.82) with the rising D-lactate content. Ethanol-producing fungi yeast mainly consisted of Wickerhamomyces (66.54 %), Saccharomycopsis (5.37 %), Issatchenkia (2.21 %), unclassified_f_Metschnikowiaceae (1.73 %), and Saccharomyces (1.33 %). These yeasts were eliminated by FW feeding, which was in line with the alteration of ED preference from ethanol to lactate. Metagenome analysis indicated that the total relative abundance of lactate-based chain elongators including Ruminococcaceae bacterium CPB6, Clostridium luticellarii, Caproiciproducens galactitolivorans, and Megasphaera elsdenii was increased by 28.6 %, while the ethanol-based chain elongator Clostridium kluyveri kept stable after FW feeding. In addition, the functional genes related to the oxidation of lactate to acetyl-CoA were enriched after FW feeding, which further enhanced the subsequent CE pathway of acetyl-CoA-based reverse β oxidation rather than the fatty acids synthesis. This study provides a new insight into upgrading FW into valuable MCC without exogenous ED addition.

Present State of Phosphorus Recovery Technology from Organic Wastes with High Water Content

Present State of Phosphorus Recovery Technology from Organic Wastes with High Water Content

Solid Fuel Reprocessing from High Moisture Content Organic Waste

Solid Fuel Reprocessing from High Moisture Content Organic Waste

Process Waters from Hydrothermal Carbonization of Waste Biomasses like Sewage Sludge: Challenges, Legal Aspects, and Opportunities in EU and Germany

Hydrothermal carbonization (HTC) has developed considerably over the last 15 years and offers a viable alternative for the utilization of municipal and industrial organic waste such as sewage sludge. However, the technology has yet to establish itself as a valorization process for waste biomasses (2024) and is not yet a recognized state of the art. Nevertheless, the HTC technology could gain greater relevance in the future, especially as an alternative valorization pathway for sewage sludge. During HTC, significant amounts of HTC process water (PW) are produced as a byproduct. The process water is inorganically and organically polluted and has to be treated, as it would be a burden on water bodies and thus on the environment if left untreated. In the EU and specifically Germany, industrial wastewater producers like HTC-plant operators are obliged to treat their industrial wastewater before discharging it into the environment. In addition to a large amount of PW and its treatment to the required limits, the organic load and possible persistent and toxic substances pose major challenges for plant operators. Many proven processes from industrial wastewater treatment were transferred for the treatment of PW. Treatment of the PW in a manner that is industrially viable, economically viable, and efficient is crucial for the effective commercialization of HTC technology. In this, the challenges and opportunities of PW composition, management, and treatment, including legal aspects, are mainly discussed. Therefore, the legal framework in the European Union and specifically for Germany will be elaborated. Furthermore, different treatment pathways are also highlighted.

Production, Utilization, and Evaluation of Organic Waste Recycling

Production, Utilization, and Evaluation of Organic Waste Recycling

Physico-Chemical and Microbiological Changes in Degradation of Agri-residue under Pit Compositing

Management of crop residues has remained a major challenge due to lack of easily adaptable and affordable interventions at farmer’s field. Cellulolytic bacteria and fungi have been recommended for recycling lignocellulosic-rich organic matter and to convert it into nutrient rich compost. However, these inoculants need to be generated on commercial scale for handling large volume of biomass. Also, the microbial formulation should also be capable of degrading diverse type of agri-residues. Seven fungal strains, namely Aspergillus awamori (F-18), Aspergillus nidulans, Trichoderma viride, Trichoderma longibrachitum, Drechslerahalodes, Eupenicilliumcrustaceumand Paecilomycesvariotiiwere characterized based on shelf life, functional activity to make consortium for degradation of various agro and horticultural residues using pit method of composting. An experiment was laid in cemented pits using four different substrates-maize cobs and stalks, paddy straw, kinnow fruit waste and flower waste for rapid degradation. The results revealed a maximum increase in spore count with Paecilomycesvariotii followed by Eupenicilliumcrustaceum and Drechslerahalodes. Out of four different additives, glycerol was found to be most suitable additive for incubation of selected fungi. The results on microbial population revealed highest bacterial population in flower waste and highest actinobacterial population in kinnow waste. It was also observed that inoculated organic waste degraded faster than un-inoculated wastes. As the degradation process progressed, total N also increased with time and varied from 1.1 to 1.5 percent. Flower and kinnow waste degradation was completed in 45 days while that of maize and paddy straw in 75 and 90 days, respectively. The pH range was 6.5-8.0 in all the substrates but in inoculated substrates, the range of pH was 7.2-7.6, while electrical conductivity (EC) was 1.4-3.6. The highest humus% was found with paddy straw followed by maize, flower and kinnow. The final product also showed variation in K% and S% which were found to be 0.6% -1.8% and 0.1% -0.20%, respectively.

Utilization of Organic Wastes into Fertilizer

Utilization of Organic Wastes into Fertilizer

Effect of Cucumber Continuous Monocropping on Traditional Chinese Medicine Residue through Analysis of Physicochemical Characteristics and Microbial Diversity

The use of traditional Chinese medicine (TCM) residue as a crop culture substrate has unique advantages in alleviating the obstacles associated with continuous monocropping, such as increasing production, improving quality and alleviating pests and diseases. However, the effect of TCM residue application on substrates in continuous monocropping practices has not been determined. In this study, the cucumber variety “Jinyou No. 10” was used as the material, and fermented TCM residue, vermiculite and perlite were used as organic substrates (3:1:1). The cucumbers were cultivated on substrates for different durations of continuous monocropping, which were the first cropping cycle (A1), second cropping cycle (A2), third cropping cycle (A3) and fourth cropping cycle (A4). The control (A0) was the substrate sample without any crop planted in it. After the cucumbers were harvested, substrate samples (areas around the cucumber roots) were collected. The physiochemical properties of the cultivated substrates were determined, and the microbial community structures were analyzed through 16S rRNA and ITS sequencing. The physiochemical indices of the substrates with different durations of continuous monocropping (A1–A4) were significantly different than those of the control (A0) substrate. Moreover, the continuous cropping of cucumber had greater effects on fungal communities than on bacterial communities. Bacterial community structure analysis revealed a greater proportion of important bacterial taxa (Proteobacteria, Chloroflexi, and Nitrospirae) in the continuous monocropping substrates than in the A0 substrate. For the fungal community, Ascomycota accounted for the largest percentage of the fungal community in all the samples. The diversity of the microbial community was found to be influenced primarily by electrical conductivity, organic matter content, pH and total potassium content according to the correlation analysis of physicochemical properties and relative abundance of the microbial community. Our study would provide a basis for addressing persistent challenges in continuous cropping and for obtaining the utmost benefit from using TCM organic residue waste.

Kinetics analysis of cellulose chemical-looping gasification using Ca–Fe oxygen carrier

Ca–Fe oxygen carrier (OC) is an effective material with high selectivity on H2 and CO to aid to the gasification of solid fuel materials such as organic solid waste or biomass in chemical-looping gasification (CLG). However, the reaction mechanism of raw materials with high volatiles such as cellulose remains unclear. Kinetics analysis is considered as the efficient method to investigate the reaction mode and mechanism. In this study, isothermal method was conducted and the tristate intermedia products were used as substrates to reveal the kinetics characteristic of cellulose conversion process in CLG. The results demonstrated that the reduction process of Ca–Fe OC could be divided into three stages, and the activation energies were 40.40 kJ/mol, 91.28 kJ/mol and 165.33 kJ/mol, respectively; this indicates that the lattice oxygen could be transferred easily in the first stage, but much more difficult in the later two stages. The weak oxidizing molecules such as CO2 could re-oxide the reduced OC quickly and the activation energy was 27.83 kJ/mol. The mechanism model on kinetic of tar cracking was similar to the reaction between H2 and OC, and the activation energy was 82.27 kJ/mol. The decomposition of char was recognized as the stochastic nuclear shrinkage process with an activation energy of 52.22 kJ/mol.

Nitrogen enrichment does not adversely affect exchangeable bases in rainfed urban arable soils of Kumasi, a tropical West African city

Urbanisation induces nitrogen (N) enrichment in tropical soils. This enhances soil acidification, leading in turn to a decrease in effective cation exchange capacity (CECe) and base saturation (BSe). Here, we investigated if and how these effects of urbanisation-induced N inputs affect the soils of tropical urban agroecosystems. Our aim was to quantify the impact of urbanisation intensity (UI) on total N (TN) contents and stocks, and to detect possible adverse N effects on soil pH, CECe, and exchangeable bases in rainfed urban arable soils of Kumasi, a tropical city in Ghana, West Africa. We analysed 618 topsoil samples (0–10 cm) from arable fields within the urban perimeter, categorised into four classes forming a gradient from low to high UI. For baseline comparison, 9 samples each from both rural arable fields and an urban forest were included. Urban arable soils generally had higher TN levels than their rural counterparts. Among the urban arable soils however, TN levels decreased with increasing UI, possibly as crop production and related N export through harvest intensified. Conversely, increasing UI correlated with increased levels of exchangeable Ca2+, K+, and Na+. No adverse N effect on soil pH, CECe, and BSe was detected. This could be explained with the strong TN-SOC relationship (R2 ≥ 0.9), and an increasingly strong relationship between exchangeable bases and TN and SOC (R2 = 0.5–0.8) with increasing UI. These relationships suggested a major common source of TN, SOC, and exchangeable bases. As the soils are neither chemically fertilised nor limed, these findings supported earlier studies that this source is provided by dumped biodegradable household waste, charred matter, ash, and construction materials. We concluded that soil N enrichment through these materials in Kumasi is accompanied by abundant bases in the same materials, which overcompensate any theoretic acidification. Our findings imply that not only can the fertility of tropical urban arable soils in cities like Kumasi be maintained, but also that the crops and ground water may not be at risk from the mobilisation of trace elements and heavy metals due to the hindered soil acidification.

The Effect of Storage Period and Mixing Techniques on the Chemical Content of Environmentally Friendly BIOPOS Organic Compost at SEAMEO BIOTROP

SEAMEO BIOTROP produces daily waste from oyster mushroom baglog (Pleurotus ostreatus), dry organic waste that contains little water, such as dry leaves, grass straw, and citronella distilled waste. Managing oyster mushroom baglog waste, leaf waste, grass straw, and citronella distilled waste independently at SEAMEO BIOTROP as organic compost BIOPOS (BIOTROP Compost) is an environmentally friendly practice and can provide benefits both economically and ecologically. Apart from being carried out to protect biodiversity from decline, this study can also keep the soil system healthy and sustainable. The aim of this research is to: (1) make BIOPOS organic compost through the use of oyster mushroom baglog, leaf waste, leaf straw, and citronella distilled waste; (2) determine the influence of various types of BIOPOS organic compost (KT1, KT2, KT3) on the chemical content of compost. Research stages include: (1) creating BIOPOS organic compost, (2) measuring the chemical content of BIOPOS organic compost, and (3) measuring the effectiveness of BIOPOS. During the storage period of 30 dam up to 180 dam, BIOPOS organic compost which still contains N (0,54%), P (36,8%), K (7,23%) and complies with SNI 19-7030-2004 quality standards is KT3. In measuring C-Organic value, BIOPOS code KT2 with a storage period of 30 dam gained C-Organic amount of 28,36%, satisfying quality standards. The application of BIOPOS KT1, KT2, and KT3 with a pH range of 8,2- 8,3 high pH can be used to correct problems that often occur in acidic soils and is not effective when applied to sub-optimal alkaline soils because it will cause soil pH to increase sharply. Key words: BIOPOS, citronella distilled waste, grass straw, leaf waste, oyster mushroom baglog waste

A novel high-entropy spinel ferrites (CoNiCuZnMg)Fe2O4 catalyst for H2 production via steam reforming of derived volatiles from polypropylene and waste cooking oil

Municipal organic waste conversion to high-value products is a vital carbon–neutral way to simultaneously tackle the energy crisis and environmental contamination. This study aims to develop and evaluate a novel high-entropy spinel ferrites (Co0.2Ni0.2Cu0.2Zn0.2Mg0.2)Fe2O4 catalyst (HEO) toward H2 production from co-pyrolysis volatiles of polypropylene (PP) and waste cooking oil (WCO) in an integrated two-stage reactor system. In the 1st stage of medium temperature reforming, the optimal 3:7 PP/WCO blend mass ratio facilitated H2 production. Under a catalytic reforming at high temperature of 750 °C in the 2nd stage, the HEO catalyst demonstrated remarkable efficiency, yielding 58.43 mmol·g−1 of H2 with a composition of 65.17 %, a notable 22.3 times higher than that without HEO. The catalyst exhibited a prolonged service life of 540 min without compromising H2 selectivity, maintaining a high yield of 510.2 mmol·gcat.−1·s−1. The exceptional performance of HEO arises from the synergistic effects of multiple elements, augments oxygen vacancy, enhances reducibility, and promotes structural stability in the high-entropy system, which causes the strong C–C breaking ability and the excellent C–H breaking abilities of Fe, Ni, Co, Cu, and Zn species. The analysis of tar, gaseous products, and deactivated HEO catalyst characterization results provides a comprehensive understanding of the co-pyrolysis route and volatiles catalytic reforming process. This study developed a high-entropy ferrite catalyst that not only achieves efficient and stable H2 production but also lays the foundation for a new high-entropy catalyst design concept, fostering the development of efficient reforming catalysts for H2 production.

Turning Trash into Treasure: Utilizing Sericultural Wastes in Mushroom Cultivation

Sericulture, an agro- based industry, generates substantial biodegradable waste, which, when repurposed, can significantly enhance mushroom production. This study explores the innovative transformation of sericultural waste into nutrient- rich substrates for mushroom cultivation, addressing global food insecurity and waste management challenges. The study also highlights the versatility of mushrooms, particularly oyster mushrooms (Pleurotus spp.), in utilizing diverse lignocellulosic wastes. It delves into the nutritional superiority of sericultural by-products over conventional substrates and their potential to reduce environmental pollution. The review underscores the economic and ecological benefits of integrating sericultural waste into mushroom cultivation, contributing to sustainable agriculture and a circular economy. Future directions emphasize the need for optimizing substrate composition and further research to maximize the yield and quality of mushrooms cultivation on sericultural waste, paving the way for a sustainable and profitable synergy between sericulture and mushroom farming.