Biodegradable Organic Waste Research Articles

Potential Use of Earthworms to Enhance Decaying of Biodegradable Plastics

Biosolid application, wastewater irrigation, and plastic mulching technologies are major sources of plastic pollution in agroecosystems. Microplastics may interact with soil physicochemical properties and organisms and negatively affect plant growth. To alleviate environmental plastic pollution, synthetic and biobased biodegradable polymers are replacing nonbiodegradable polymers, but their biodegradation rate in the field is frequently lower than that estimated from standardized biodegradation testing. Plastic polymer biodegradation is a multistep process that involves plastic deterioration, microbial colonization, production of polymer-degrading exoenzymes, and mineralization. However, these physicochemical and biological processes are not always efficient because of unfavorable environmental conditions (e.g., temperature, soil moisture). We propose to use earthworms to increase the biodegradable polymer biodegradation rate by creating optimal habitats for microbial proliferation. Earthworm-induced processes that lead to soil alteration (bioturbation) and solid organic wastes decomposition (vermicomposting) are described to understand how earthworms may favor biodegradable plastic mineralization. Therefore, we suggest two practical sustainable bioengineering strategies: (1) enhancing bioturbation by inoculating agricultural soils with soil-dwelling earthworms, which is viable for horticulture where using biodegradable mulching films increases plastic debris in the soil and (2) vermicomposting with blended biodegradable plastic debris and solid organic wastes, which is complementary to industrial or home composting of single-use biodegradable plastics.

Recent Advances in the Utility of Glycerol as a Benign and Biodegradable Medium in Heterocyclic Synthesis

:Glycerol is a non-toxic, recyclable and biodegradable organic waste produced as a byproduct in the production of biodiesel fuel. Currently, glycerol is considered a green solvent and catalyst for a large variety of applications. This work discusses the significance of glycerol for heterocyclic synthesis. All the reported studies consider glycerol as an efficient and sustainable benign medium.

Is hydrothermal treatment coupled with carbon capture and storage an energy-producing negative emissions technology?

This paper evaluates the feasibility of hydrothermal treatment (HTT) with carbon capture and storage (CCS) as an energy producing negative emissions technology (NET) and compares such system with a conventional bioenergy with carbon capture and sequestration (BECCS) system. Machine learning models were developed to predict product yields and characteristics from HTT of various feedstocks. The model results were then integrated into a life cycle assessment (LCA) model to compute two metrics: energy return on investment (EROI) and net global warming potential (GWP). Results showed random forest models had better prediction accuracy than regression tree and multiple linear regression to model HTT of feedstocks (e.g., microalgae, crops/forest residues, energy crops, and biodegradable organic wastes) and predicted the mass yields of multiple products (biocrude, hydrochar, gas, and aqueous co product) as well as the energy and carbon contents of biocrude and hydrochar. LCA results revealed that the proposed HTT-CCS system constituted a net-energy producing NET for some combinations of feedstock characteristics and reaction conditions. Best overall energy and GWP performance was achieved for HTT-CCS of lignocellulosic biomass at low temperature. Compared with the conventional BECCS system, HTT-CCS generally exhibited higher EROI but higher net GWP, depending on processing conditions and the feedstock types.

Experimental Production of Biogas using Co-Digestion of Organic Waste

Environmental pollution is one of the major problems plaguing the modern world today. The environment and the various elements in the environment need energy to meet their need. So there is a need to produce energy from different sources. Solid Waste is one such material that can be used as a source for deriving energy. The studies on conversion of solid waste to energy have resulted several alternatives including the biogas production from biodegradable organic waste. There are several alternatives in the estimation of biogas yield from bio degradable fraction of solid waste. The different types of biodegradable organic waste may comprises of cow dung, pig waste, poultry manure, food waste, vegetable waste, kitchen waste etc[9]. The present study focuses on production of biogas using cow dung with vegetable waste and poultry manure. In this study, by doing experimentation it is observed that the production of biogas from co-digestion of different organic waste is more than individual waste. The highest yield of biogas is obtained from co-digestion of cow dung with poultry manure than co-digestion of cow dung with the vegetable waste. Waste produced after the production of biogas is used as natural fertilizers for the growth of crops and fields and it gives good yield. By experimentations like energy recovery from solid waste, the conservation of non renewable energy resources may be possible and it also helps to protect our environment [16]

Studies on biodegradation of organic waste in uasb reactor

The industrialization in the developing countries causes severe problems in collection,treatment and disposal of organic effluents. The situation leads to public health andenvironmental problem. Therefore, various high rate anaerobic treatments has beenemerged as a variable alternative for the treatment of many industrial and domesticwastewater containing organic wastes. In this study high rate Upflow Anaerobic SludgeBlanket (UASB) reactor has been critically analyzed, discussed and designed as thesolution of above problem. According to that a UASB reactor has been fabricated forlaboratory study. The UASB system appeared to be economically cost effective ascompared to other systems. This paper also focuses on the principle of startup,operational performance, chemical oxygen demand (COD) removal efficiency, methaneproduction rate, and specific methanogenic activity in the UASB reactor. In the presentstudy, reactor was started initially with mixture of molasses and glucose (50% each)solution with organic loading rate (OLR) 0.933 g COD/L day. Thereafter, OLR is beingincreased in steps. After 15 days of startup of reactor, molasses solution was applied. Thetemperature (35e° C), pH (6.8±0.4), and nutrients requirement were maintained. In thisstudy COD: N: P ratio were maintained at 300: IO: l by adding urea for nitrogen andpotassium di-hydrogen phosphate for phosphorus. For a change of OLR up to 13.33gCOD/L day, all above-mentioned parameter were studied. The removal efficiency andgas production rate depend on activity of granules. A typical organic degrading granule iscomposed of micro-colonies of Methanothrix and several syntropic micro -colonies.

AEROBIC COMPOSTING OF MIXING SEWAGE SLUDGE WITH GREEN WASTE FROM LAWN GRASS

Biological decomposition process is an important goal in terms of pollution reduction. By composting, the organic waste can be converted into compost and can be used for agricultural purposes, to improve the soil quality. The present study aimed to evaluate the behavior of materials such as sewage sludge and green waste during composting, their compatibility in mixtures and the quality of the end product. Also, the study highlighted the technical and operational characteristics of a composting system on a laboratory scale. The main advantage of this laboratory scale experiment is the reduced processing time and the fact that it can be fast adapted to different experimental conditions. The pilot scale experiment allowed to investigate the dynamics of main parameters during the composting process and provide the basis for an efficient design process. The elaborated composting process is a convenient, cost-effective and environmentally friendly process for biodegradable organic waste management, being also a feasible and controllable process. The best intervals for physico-chemical parameter values that were obtained at the end of the composting process are: pH in the range of 8.2 8.6; moisture content in the range of 59.9 % 65.8 %; organic matter in the range of 81.9 % 91.6 %; the C/N ratio in the range of 17.5 18.7. The obtained results show that all composting variants lead to the production of a quality compost that can be used in agriculture.

Valorisation of solid waste as key opportunity for green city development in the growing urban areas of the developing world

Lack of integrated solid waste management practice in fast-growing cities of developing countries is posing a threat to sustainable and green cities development. The fast growing Jimma City in Ethiopia requires up-to-date waste quantification and characterization data for the planning and implementation of sound waste management options such as composting and energy recovery that could create new jobs and promote private sector involvement. Therefore, we quantified, characterized and evaluated energy potential and nutrient value of household solid waste from Jimma City. Total daily waste generated from the city’s households was estimated to be 85.8 tons, with an average per capita generation rate of 0.56 ± 0.17 kg/day. The biodegradable organic waste comprises 76% by weight and had optimum moisture content and carbon to nitrogen ratio for composting. The energy content of combustible household waste was estimated to be 17.5 MJ/kg for gross heating value and 9.54 MJ/kg for the net heating value that surpasses the lower limit for thermal treatment process to be economically viable. Waste-to-energy conversion of combustible waste of cities could reduce annually about 25,303 metric tons of carbon dioxide equivalent greenhouse gas emissions. Char briquettes produced through pyrolysis of solid waste could be a potential substitute for firewood to prevent deforestation and indoor air pollution. In conclusion, composting and pyrolysis are sound waste management options for green cities development in developing countries while minimizing public health risks and cost of treatment and disposal.

FUNGAL CITRIC ACID PRODUCTION USING WASTE MATERIALS: A MINI-REVIEW

Citric acid is one of the extensively used organic acids in many industries. There is a worldwide demand for citric acid consumption due to their many industrial applications. It is also considered as a Generally Recognized As Safe (GRAS) compound. In this review, current developments in microbial fermentation processes for citric acid production have been discussed. In food, beverages, milk and sugar processing several biodegradable organic waste materials are generated in large quantities. These include sugarcane bagasse, grape pomace, apple pomace, pineapple pomace, vegetables, tapioca, coconut husk, banana peels, citrus peels, whey and decaying fruits are found to be potential substrates for citric acid production. A significant effect of substrate concentration, inorganic salts, initial sugar concentration, moisture and additives etc on citric acid production have been highlighted for further improvement in fermentation process. Recent developments in upstream and downstream processes for citric acid production are also deeply discussed. This review gives insights for future possibilities of cost effective fermentation process for citric acid production from several cheap raw materials. Formation of citric acid as an industrial byproduct will help to tackle waste disposal issue and also reduce the dependency of industry over other citric acid producers. Thus, the industry would be benefitted ecologically and economically.

Composting of household organic waste and its effects on growth and mineral composition of cherry tomato

Composting is an alternative for recycling biodegradable organic waste, transforming it into organic fertilizer that can be used as agricultural nutrients, avoiding its disposal in landfills. This study evaluated the composting of household organic waste as a substitution for cattle manure, with a view to its application in the fertilization of cherry tomatoes (Solanum lycopersicum Mill., Var. Cesariforme). Thus, compost piles were set up using 30% organic waste (carbon source) and 70% tree-pruning residues (filling material). Two sources of organic waste were tested: household food waste (FW) and cattle manure (CM), at five proportions (15% FW + 15% CM, 10% FW + 20% CM, 20% FW + 10% CM and the controls 30% CM and 30% FW). After 90 days, the mature compost from each pile was mixed with coconut fibre in a 1:1 ratio and used as substrate filled in 15 L plastic pots, where the cherry tomato plants were grown. The experiment was conducted under greenhouse conditions in a randomized block design, with five treatments and five replicates. Assessments of growth and leaf mineral composition were performed for the cherry tomato plants. The results indicate that cattle manure can be replaced by household food waste as the organic material used in compost piles. Fertilization with organic compost from household food waste positively influenced the growth and nutrient assimilation in the leaf tissue of cherry tomato.

Efecto del compost de residuos orgánicos domiciliares, vegetales y estiércol en el crecimiento de lechuga

El compostaje se presenta como una alternativa para reciclar residuos sólidos orgánicos biodegradables, transformarlos en fertilizantes para la agricultura y evitar su deposición inadecuada en rellenos sanitarios. De esta forma, el objetivo del presente estudio fue evaluar la calidad físico-química y microbiológica de un compost producido a partir de residuos orgánicos y su desempeño en el desarrollo y productividad del cultivo de lechuga crespa (Lactuca sativa L.), en condiciones de invernadero. La materia prima del compostaje fueron residuos orgánicos domiciliares (restos de alimentos) y estiércol de bovino en proporción 1:1. Para la construcción de los montículos de compost, los residuos orgánicos fueron mezclados con podas de árboles triturados. Diferentes concentraciones de compost madurado, 20, 40, 60, 80 y 100%, fueron incluidos en el sustrato de lechuga en un diseño de bloques al azar con tres repeticiones. Los resultados mostraron que el compost orgánico producido presentó características físico-químicas y microbiológicas dentro de los rangos de utilización agronómica y su adición en el sustrato de fibra de coco, favoreció la producción de lechuga, promoviendo un incremento de 63% en la altura de plantas y 75% en el número de hojas.

Efficacy of the Vermicomposts of Different Organic Wastes as “Clean” Fertilizers: State-of-the-Art

Vermicomposting is a process in which earthworms are utilized to convert biodegradable organic waste into humus-like vermicast. Past work, mainly on vermicomposting of animal droppings, has shown that vermicompost is an excellent organic fertilizer and is also imbibed with pest-repellent properties. However, there is no clarity whether vermicomposts of organic wastes other than animal droppings are as plant-friendly as the manure-based vermicomposts are believed to be. It is also not clear as to whether the action of a vermicompost as a fertilizer depends on the species of plants being fertilized by it. This raises questions whether vermicomposts are beneficial (or harmful) at all levels of application or if there is a duality in their action which is a function of their rate of application. The present work is an attempt to seek answers to these questions. To that end, all hitherto published reports on the action of vermicomposts of different substrates on different species of plants have been assessed. The study reveals that, in general, vermicomposts of all animal/plant based organic wastes are highly potent fertilizers. They also possess some ability to repel plant pests. The factors that shape these properties have been assessed and the knowledge gaps that need to be bridged have been identified.

LAB-SCALE STUDY ON CO-DIGESTION OF KITCHEN WASTE, SLUDGE AND SEWAGE

Anaerobic digestion is widely used for biodegradable solid organic wastes in order to recover bio-energy in the form of biogas. Some previous studies presented that co-digestion of various substrates can improve biogas yields as well as enhanceperformance of organic wastes digestion, in comparison with digestion of sole solid waste. This study aimed to evaluate the performance of anaerobic mono-digestion and anaerobic co-digestion of the following mixtures: (a) sole kitchen waste (KW), (b) KW and sewage (SW), (c) sole sludge (SL)and (d) KW and SL. This study was conductedby four lab-scale anaerobic complete mixing reactors (numbered MH1 – MH4) in 4,5 liters working volume atorganic loading rate (OLR) 2,0 g(VS).L-1.d-1. The KW was collected from canteen B4 and SW was collected from effluent from septic tank C6 Building in Ho Chi Minh University of Technology (HCMUT). The results show that the reactor of sole KW obtained average total chemical oxygen demand (tCOD), soluble chemical oxygen demand (sCOD), total solid (TS), volatile solid (VS), total phosphorus (TP) and total Kjeldahl nitrogen (TKN) of 62 %, 62 %, 71 %, 72 %, 73 % and 45 %, respectively, whereas reactor of KW and SW co-digestion had were tCOD, sCOD, TS, VS, TP and TKN removal of 73 %, 78 %, 75 %, 79 %, 59 % and 57 %, respectively. Thus co-digestion of KW and SW revealed an efficient enhancement of digestion, instead of sole KW digestion. Similarly, TS (74 %) and VS removals (75 %) of co-digesting mixtures of SL and KW were higher than those of sole SL digestion (67 %). Furthermore, co-digestion of SL and KW obtained better performance in tCOD and sCOD removals (70 % and 76 %, respectively).

Enhanced energy recovery by manganese oxide/reduced graphene oxide nanocomposite as an air-cathode electrode in the single-chambered microbial fuel cell

Microbial fuel cells (MFCs) provide an opportunity to harvest electrical energy from biodegradable organic wastes. In air-cathode MFCs, cathode plays an important role at which oxygen reduction reaction (ORR) occurs. Herein, MnO2 nanorods are demonstrated as a potential air-cathode catalyst in a single-chambered MFC (sMFC). Synthesis of two different MnO2 morphologies (nanoflakes and nanorods) is demonstrated at room temperature using a simple precipitation method. In order to improve the performance of MnO2 as ORR electrocatalyst, graphene oxide (GO) is used as conductive matrix instead of carbon black. Furthermore, MnO2/GO is hydrothermally treated to obtain MnO2/reduced GO (h-MnO2/rGO) nanocomposite. The sMFC comprising air-cathode with an optimum loading of h-MnO2/rGO delivers 2.7 times higher volumetric power density than that of sMFC without a catalyst and comparable to the state-of-art Pt/C. This is ascribed to superior 4-electron ORR pathway by h-MnO2/rGO and improved charge transport behavior of rGO support as confirmed through detailed electrochemical investigation. This work demonstrates a facile room temperature synthesis process of MnO2 nanoflakes and nanorods, and their role as air-cathode electrocatalyst for competent power generation in sMFC.

Valuable biochemical production in mixed culture fermentation: fundamentals and process coupling.

The mixed culture fermentation is an important environmental biotechnology that converts biodegradable organic wastes to valuable chemicals such as hydrogen, methane, acetate, ethanol, propionate, and so on. For the multistep process of hydrolysis, acidogenesis, acetogenesis/homoacetogensis, and methanogenesis, the typical metabolic reactions are firstly summarized. And then, since the final metabolites are always a mixture, the separation and purification processes are necessary to couple with anaerobic fermentation. Therefore, several typical coupling technologies including biogas upgrading, two-stage fermentation, gas stripping, membrane technology of pervaporation, membrane distillation, electrodialysis, bipolar membrane electrodialysis, and microbial fuel cells are summarized to separate the metabolites and recover energy. At last, the novel technologies such as the controlled metabolite production, medium chain carboxylic acid production, and high temperature ethanol recovery in thermophilic mixed culture fermentation are also reviewed. However, the novel concepts are still needed to meet the demands of better overall performances and lower total costs.

Mitigation of Greenhouse Gases Emission Through Food Waste Composting and Replacement of Chemical Fertiliser

A pilot scale composting plant has been established on-campus in Universiti Teknologi Malaysia (UTM) to achieve the goal as a sustainable campus. Portion of organic wastes were diverted from landfilling by converting it into compost (organic fertiliser) for reducing greenhouse gases (GHG) emission at the landfill and the dependency on inorganic fertiliser. Composting has been reported as a sustainable approach to reduce the footprint of GHG as compared to the waste disposal through landfilling. However, the amount of GHG emitted during composting can vary due to localised condition. The aim of this study was to assess the potential of composting in mitigating GHG emission compared to the current waste management employed in UTM (Landfilling). A business as usual (BAU) scenario represents the current organic waste management practice in UTM was established. Composting was proposed as an alternative scenario. The amount of GHG emitted or reduced from different sources including for transportation, waste processing, waste treatment as well as downstream activities such as carbon sequestration and inorganic fertiliser substitution was estimated based on lifecycle inventory analysis. The result indicated that composting scenario offer a GHG reduction of 66.72 % as compared to the BAU scenario. The fugitive emission from biodegradation of organic waste contributed significantly to the GHG emission for both scenarios whereas the GHG emission from the fossil fuel combustion was considered as not significant. The overall result suggested the potential of composting as a viable technology for sustainable organic waste management in UTM.

Biodegradability of Formulated Enzymatic Solution: An Alternative Waste Reduction System

Solid waste and air pollution are never ending environmental problems that can be partially solved by turning waste into useful bio-products. In this study, enzymatic solutions were developed by formulating enzymatic solutions from fish intestines and fruit peels. This aimed to help in biodegradation of organic solid wastes. Organic waste samples were treated with formulated enzymatic solutions for 7 days in aerated set-up for aerobic degradation. Biodegradability and odor of the waste samples were compared with commercial enzymatic solution. Determination of evolved carbon dioxide (CO2) using gravimetric analysis (GA) was used to determine the percent biodegradability, Dt, of organic solid waste and odor-ranking method was used to determine the odor intensity of the organic waste samples. The result showed that the weight loss and percentage biodegradability of organic waste sample treated with formulated enzymatic solution is comparable with that of the commercial enzymatic solution. In terms of odor intensity, waste treated with the product, formulated enzymatic solution (FES) is also comparable to the waste treated with commercial enzymatic solution. Thus, implying that the developed FES is as efficient as that of the commercial enzymatic solution. These significant results will be helpful to future researchers in providing ways on improving the degradation of organic solid waste and mitigating the increasing glitches on our environment. Enzyme kinetics, physical and chemical properties studies of the solution were recommended for future researchers to accurately determine the effectiveness of the formulated enzymatic solution in the degradation of organic solid waste.

Development of High-Throughput Methods for Nano- and Bulk Silver Toxicity Assays Using Bioluminescent Recombinant <i>Pseudomonas</i> Wastewater Isolates

Silver get washed into sewerage systems and eventually to wastewater treatment plant (WWTP) due to its utilization in industries. This poses concerns about the toxicity of these particles to microorganisms which are involved in biodegradation of organic wastes in biological WWTP. Pseudomonas species (Biosensor cell A, B, C, D and E) originally isolated from WWTP and modified by incorporating a stable chromosomal copy of the lux operon (lux CDABE) derived from <i>Escherichia coli</i> S17ƛ pir were sensitive immediately upon addition of silver nanoparticles (AgNPs) and bulk silver in short terms of incubation ranging from 0 to 300minutes. Microtitre plate luminometre was used to generate detailed luminescence reduction data for the silver particles tested against the bacterial cells in various concentrations ranging from 9µg/ml to 2500µg/ml. The EC₅₀ values generated at various time points showed that the highest toxicity was observed at time point, 0 of incubation for both AgNPs and bulk silver (158µg/ml and 618µg/ml EC₅₀ values respectively); these EC₅₀ values also indicate that AgNPs are much more toxic than bulk silver. Two putative biosensors, E and D showed proportional responses of bioluminescence reduction with increasing toxicant concentrations up to 2500µg/ml, hence displaying dose-dependent responses, superior operational range and sensing capabilities; good features for toxicity assay. Therefore, the recombinant isolate can be used to assay the toxicity of silver particles.

Operation of a Domestic Biogas Plant in an Urban Setting in a Developing Country-A Field Experience

The main source of fuel for cooking and other domestic applications in most developing countries (especially in sub-Saharan Africa) is fuel wood. This source of fuel is not only non-renewable but leads to deforestation and its attendant contribution to global warming. Coal and charcoal, which are also used where available, equally contributes to environmental problems. In countries like Nigeria where there is abundance of fossil fuel, cooking gas and kerosene are unfortunately hardly available and/or affordable to majority of the low income families that should rely on this source of fuel. Electricity supply is erratic and unreliable. Biogas therefore appears to be a credible alternative fuel for cooking and other purposes in such countries. Biogas is a major product of anaerobic fermentation of biodegradable organic waste. It has a calorific value of about 22.4 MJ/ m3 and contains about 50-60% methane. 30-45% carbon dioxide and a small percentage of hydrogen sulfide, hydrogen, carbon monoxide, ammonia, water vapour and mercaptans. The gas is useful as a fuel substitute for firewood, dungs and agricultural residues as well as for petrol and diesel for electricity generation.

Immune response in the larvae of the black soldier fly Hermetia illucens

The black soldier fly Hermetia illucens is an ecological decomposer used for biodegradation of organic waste. Its larvae can develop on a wide range of decaying plant and animal matter, including manure and food scraps, i.e., habitats that are extremely rich in various microorganisms. Living in such conditions requires very well-functioning immune mechanisms. However, the immune response processes have not been examined so far in H. illucens larvae. In order to shed light on the immune system in the black soldier fly, in the present study we have examined H. illucens hemocytes and analyzed the effects of immune challenge of H. illucens larvae on the activity of the key components of insect humoral immune response, i.e., phenoloxidase, lysozyme, and antimicrobial peptides.

TASAS DE GENERACIÓN Y CARACTERIZACIÓN DE RESIDUOS SÓLIDOS ORDINARIOS EN CUATRO MUNICIPIOS DEL ÁREA METROPOLITANA COSTA RICA

Se determinó la tasa de generación y caracterización de residuos sólidos ordinarios, en el sector residencial y comercial de 04 municipios ubicados geográficamente dentro del Gran Área Metropolitana de Costa Rica. Para ello, en el período 2014-2015, se realizaron muestreos en un número representativo de viviendas y comercios durante 07 días consecutivos. La tasa de generación promedio ponderada de residuos para el área de estudio resultó ser de 0,59 kg/hab-día. Los residuos sólidos generados presentan como componentes mayoritarios: orgánicos 55,9%, seguidos de materiales con alto potencial para ser reciclados o utilizados como combustibles (plásticos 10,2%, papel y cartón 10,4%). El contenido de humedad promedio en los residuos fue de 58,7% en masa (mínimo 54% en Alajuela y máximo 63% en Barva), de la cual hasta un 67% puede ser atribuible a residuos orgánicos biodegradables. El peso volumétrico promedio de los residuos resultó de 155 kg/m3 (mínimo de 141 en Belén y máximo de 163 en San José). Se evidenció que existen diferencias significativas en la composición de residuos sólidos para los sectores comerciales y residenciales, principalmente en la fracción orgánica, papel, cartón y plástico.