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Topical Collection "Organic Waste Management"

A topical collection in Sustainability (ISSN 2071-1050). This collection belongs to the section "Environmental Sustainability and Applications".

Editor

Dr. Dimitrios Komilis
E-Mail Website
Collection Editor
Department of Environmental Engineering, Democritus University of Thrace, Kimmeria Campus, GR 671 00 Xanthi, Greece
Interests: solid wastes; life cycle analysis; biological treatment; bioplastics; composting
Special Issues and Collections in MDPI journals

Topical Collection Information

Dear Colleagues,

During the past two decades, under the frameworks of sustainability and circular economy, there has been a high legislative focus on the management of organic waste and biowaste to prevent it from landfilling and to promote its valorization. According to two key European directives (1999/31/EC and 2008/98/EC), organic waste needs to be diverted from landfilling at rates higher than 65% and biowaste needs to be separated at the source at levels higher than 10% to up to 50%. The typical hierarchy pyramid on solid waste actions places biological organic waste management techniques on top of the thermal treatment based energy recovery techniques rendering the former (i.e., composting, anaerobic digestion) more attractive to implement. Low technology composting of organic waste at the community or household level (which is highly promoted lately by municipalities) could be considered as a re-use and even a prevention technique, instead of a recycling technique, which would automatically promote it to the highest position of the waste hierarchy. In addition to typical end-of-the pipe treatment methods, much focus has been recently given on valorization techniques that aim to recover useful products during organic waste biological processes (e.g., recovery of enzymes during solid state fermentation, hydrogen production during anaerobiosis, biomass derived bioethanol) in addition to the typical compost and methane recovery. It is, thus, evident that the term “waste” will soon be fully abandoned and be, likely, soon replaced by the term “by-product”.

This Special Issue will focus on biological organic (solid) waste management techniques, as viewed through the prism of circular economy, and will cover the following state-of-the-art topics:

  • Industrial and medium scale MBT facilities
  • MBT technology: Aerobic versus anaerobic processes
  • Compost, CLO, digestate and other MBT outputs: Quality aspects and indices
  • Valorization of organic waste and recovery of useful compounds
  • Organic waste source separation schemes: decentralized vs. centralized schemes
  • Home and community composting
  • Biochar as a soil amendment
  • Waste-based bioethanol generation
  • Hydrogen production via anaerobic digestion
  • Life cycle analysis in organic waste management

Dr. Dimitrios Komilis
Collection Editor

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Keywords

  • anaerobic processes
  • biochar
  • bioethanol
  • compost quality indices
  • home composting
  • hydrogen production
  • life cycle analysis
  • MBT technology
  • organic waste collection
  • organic waste valorization

Published Papers (19 papers)

2020

Jump to: 2019, 2018, 2017

Article
Using Food Waste in Organic Fertilizer: Modelling Biogenic Carbon Sequestration with Associated Nutrient and Micropollutant Loads
Sustainability 2020, 12(18), 7399; https://doi.org/10.3390/su12187399 - 09 Sep 2020
Cited by 1 | Viewed by 900
Abstract
What are the effects, measured as flows of biogenic carbon, plant nutrients, and pollutants, of moving organic waste up the waste hierarchy? We present a case study of Denmark, where most of the organic fraction of household waste (OFHW) is incinerated, with ongoing [...] Read more.
What are the effects, measured as flows of biogenic carbon, plant nutrients, and pollutants, of moving organic waste up the waste hierarchy? We present a case study of Denmark, where most of the organic fraction of household waste (OFHW) is incinerated, with ongoing efforts to increase bio-waste recycling. In this study, one-third of the OFHW produced in North Zealand, Denmark, is diverted away from incineration, according to the Danish Waste Resource Plan 2013–2018. Co-digestion of OFHW, and digestate application on agricultural soil, utilizes biogenic carbon, first for energy conversion, and the remainder for long-term soil sequestration, with additional benefits for plant nutrient composition by increasing the N:P ratio in the digestate. We show a dynamic model of the biogenic carbon flows in a mix of OFHW co-digested with livestock manure and sewage sludge, addressing the contribution of OFHW to long-term carbon sequestration compared to other agricultural residues and bio-wastes over a time span of 100 years. In addition, we trace the associated annual nutrient and cadmium loads to the topsoil. At constant annual input rates and management practices, a diversion of 33% of OFHW would result in an increased organic carbon build-up of approximately 4% over the current amounts applied. The addition of OFHW, moreover, beneficially adjusts the N:P ratio of the digestate mix upwards, albeit without reaching an ideally high ratio by that measure alone. Cd loads from OFHW remain well below regulatory limits. Full article
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Article
In Vitro Study of Butyric Acid Deodorization Potential by Indigenously Constructed Bacterial Consortia and Pure Cultures from Pit Latrine Fecal Sludge
Sustainability 2020, 12(12), 5156; https://doi.org/10.3390/su12125156 - 24 Jun 2020
Viewed by 915
Abstract
The present study aims at developing an efficient bacterial consortium to biodegrade butyric acid, one of the odor-causing compounds that contribute significantly to pit latrine malodors. Six bacterial strains isolated from pit latrine fecal sludge were selected for the study. Nineteen bacterial consortia [...] Read more.
The present study aims at developing an efficient bacterial consortium to biodegrade butyric acid, one of the odor-causing compounds that contribute significantly to pit latrine malodors. Six bacterial strains isolated from pit latrine fecal sludge were selected for the study. Nineteen bacterial consortia of different combinations were artificially constructed. The individual bacterial strains and bacterial consortia were compared by culturing in mineral salt medium supplemented with 1000 mg/L butyric acid as a sole carbon and energy source at pH 7, 30 °C, and 110 rpm under aerobic growth conditions. A co-culture of Serratia marcescens and Bacillus cereus was an effective bacterial consortium compared to individual component bacterial strains and other bacterial consortia, in which 1000 mg/L butyric acid was completely degraded within 16 h of incubation. A temperature of 30 °C and pH 7 were found to be optimum for the maximum degradation for both S. marcescens and B. cereus. The inoculation sizes of 2.0 and 2.5 were optimal for the maximum degradation for B. cereus and S. marcescens, respectively. The study provides insights that will be of substantial help in the development of effective biological treatment technologies for pit latrine odor to change the pit latrine user community’s and would be users’ perception of pit latrines. Full article
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2019

Jump to: 2020, 2018, 2017

Article
Decentralized Valorization of Residual Flows as an Alternative to the Traditional Urban Waste Management System: The Case of Peñalolén in Santiago de Chile
Sustainability 2019, 11(22), 6206; https://doi.org/10.3390/su11226206 - 06 Nov 2019
Cited by 4 | Viewed by 1464
Abstract
Urban residual flows contain significant amounts of valuable nutrients, which, if recovered, could serve as input for the own city needs or those of its immediate surroundings. In this study, the possibilities for decentralized recovery of nutrient rich residual flows in Santiago, Chile, [...] Read more.
Urban residual flows contain significant amounts of valuable nutrients, which, if recovered, could serve as input for the own city needs or those of its immediate surroundings. In this study, the possibilities for decentralized recovery of nutrient rich residual flows in Santiago, Chile, are studied by means of a case study considering technical and socio-economic criteria. In particular, we calculate circularity indicators for organic matter (OM), nitrogen (N), and phosphorus (P) and cost–benefits of household and community on-site technological alternatives. Kitchen waste (KW) and garden residues (GR) as well as urine were considered as system inputs whereas urban agriculture, municipality green, or peri-urban agriculture were the considered destinations for nutrients recovered. The technologies studied were anaerobic digestion, vermicomposting, and composting, while urine storage and struvite precipitation were considered for nutrient recovery from urine. Material flow analysis was used to visualize the inputs and outputs of the baseline situation (the traditional urban waste management system), and of the different household and municipality resource recovery scenarios (the decentralized valorization systems). Our findings show that decentralized valorization of KW and GR are a clear win–win policy, since they can not only produce important environmental benefits for the city in the long run, but also important cost savings considering the landfill fees and residues transportation of the current centralized waste management system. Full article
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Article
Contribution of Microbial Residues Obtained from Lignin and Cellulose on Humus Formation
Sustainability 2019, 11(17), 4777; https://doi.org/10.3390/su11174777 - 02 Sep 2019
Cited by 3 | Viewed by 835
Abstract
The contribution of microbial residues formed on lignin and cellulose to the formation of humus (HS) was investigated. The microbial residues formed by Aspergillus niger (A. niger) in the cultures of cellulose and lignin in a fluid medium were structurally characterized [...] Read more.
The contribution of microbial residues formed on lignin and cellulose to the formation of humus (HS) was investigated. The microbial residues formed by Aspergillus niger (A. niger) in the cultures of cellulose and lignin in a fluid medium were structurally characterized by elemental analysis, differential thermal analysis (DTA), FTIR spectroscopy and CP/MAS 13C NMR spectroscopy. Compared to cellulose itself, the microbial residue from cellulose contains more aromatic compounds and N-containing compounds and fewer carbohydrates and carboxylic compounds. A. niger improved the thermal stability and aromaticity of the cellulose. However, compared with that on lignin, more N-containing compounds, carbohydrates and carboxylic acid derivatives and less aromatic material were found in the microbial residue from lignin. Regardless of whether the carbon source was cellulose or lignin, A. niger utilized the N in the fluid medium to synthesize its own cells, and eventually, they could transfer the N into the microbial residue; in addition, the O-alkyl species dominated over the alkyl and aromatic compounds in the microbial residue. Although the molecular structures of the components of the microbial residue from lignin tended to be simpler, they were more alkylated, more hydrophobic and less aliphatic than those from cellulose. During culture with A. niger, the cellulose underwent degradation and then a polymerization, which led to an increased degree of condensation but a lower degree of oxidation, providing essential precursor substances for HSs formation. However, lignin underwent oxidative degradation. The microbial residue from lignin had a lower degree of condensation and a higher degree of oxidation. Full article
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Article
Role of Nutrient-Enriched Biochar as a Soil Amendment during Maize Growth: Exploring Practical Alternatives to Recycle Agricultural Residuals and to Reduce Chemical Fertilizer Demand
Sustainability 2019, 11(11), 3211; https://doi.org/10.3390/su11113211 - 10 Jun 2019
Cited by 52 | Viewed by 2662
Abstract
Recycling and value-added utilization of agricultural residues through combining technologies such as anaerobic digestion and pyrolysis could double the recoverable energy, close the nutrient recycle loop, and ensure cleaner agricultural production. This study assessed the beneficial application of biochar to soil to recycle [...] Read more.
Recycling and value-added utilization of agricultural residues through combining technologies such as anaerobic digestion and pyrolysis could double the recoverable energy, close the nutrient recycle loop, and ensure cleaner agricultural production. This study assessed the beneficial application of biochar to soil to recycle digestate nutrients, improve soil quality, and reduce conventional chemical fertilizer. The addition of digestate-enriched biochar improved soil quality as it provided higher soil organic matter (232%–514%) and macronutrients (110%–230%) as opposed to the unenriched biochar and control treatments. Maize grown in soil amended with digestate-enriched biochar showed a significantly higher biomass yield compared to the control and non-enriched biochar treatments but was slightly lower than yields from chemical fertilizer treatments. The slightly lower yield (20%–25%) achieved from digestate-enriched biochar was attributed to slower mineralization and release of the adsorbed nutrients in the short term. However, digestate-enriched biochar could in the long term become more beneficial in sustaining soil fertility through maintaining high soil organic matter and the gradual release of micronutrients compared to conventional chemical fertilizer. Positive effects on soil micronutrients, macronutrients, organic matter, and biomass yield indicates that enriched biochar could partly replace chemical fertilizers and promote organic farming in a circular economy concept. Full article
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Article
Organic Matter Composition of Manure and Its Potential Impact on Plant Growth
Sustainability 2019, 11(8), 2346; https://doi.org/10.3390/su11082346 - 19 Apr 2019
Cited by 11 | Viewed by 1721
Abstract
Since the advent of flush toilet systems, the aquatic environment has received a massive contaminant flow. Furthermore, the perception of human feces has changed from a useful nutrient source for agriculture to a harmful contaminant. In this study, we compared the nutritional quality [...] Read more.
Since the advent of flush toilet systems, the aquatic environment has received a massive contaminant flow. Furthermore, the perception of human feces has changed from a useful nutrient source for agriculture to a harmful contaminant. In this study, we compared the nutritional quality of five samples: (1) human manure (HM), (2) human manure from a family mainly eating organic food (HMO), (3) cow manure (CM), (4) poultry manure (PM), and (5) commercial nursery media (CNM). Samples were analyzed in terms of organic and inorganic nutrient contents, molecular composition, seed germination, and chlorophyll concentration. Pyrolysis gas chromatography/mass spectrometry (GC/MS) was used to describe the differences in molecular composition. Three-dimensional excitation and emission matrix fluorescence spectroscopy characterized the organic composition of water extracts. From the results, CNM, PM, and HMO showed humic- and fluvic-like substance peaks, the highest values of potassium and sulfate ions, and of C/N ratios, indicating greater plant growth potential. This was confirmed by their higher chlorophyll concentrations and germination index values. These results contribute knowledge about the positive effects of manure, changing the negative perception of human excreta from waste to resource. This work provides a reference for reducing the wastewater loading rate in society. Full article
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Article
Short-Term Effects of Different Organic Amendments on Soil Fungal Composition
Sustainability 2019, 11(1), 198; https://doi.org/10.3390/su11010198 - 03 Jan 2019
Cited by 23 | Viewed by 2539
Abstract
Fungi play an essential role in recovering the quality and fertility of soil. There is a limited understating of the complex response of fungal diversity to different organic materials in clay loam soil. Here, we report the response of soil fungi toward the [...] Read more.
Fungi play an essential role in recovering the quality and fertility of soil. There is a limited understating of the complex response of fungal diversity to different organic materials in clay loam soil. Here, we report the response of soil fungi toward the short-term application of manure (M), sugarcane straw (S), and sugarcane straw plus manure (MS), including no organic material control (CK) at two different time points (50 and 100 days after application). Illumina sequencing was used to examine the fungal communities. Our results reveal a significant shift among the soil fungal community structure associated with each organic material application. After both time points, amendments—especially M and MS—decreased the fungal richness and stimulated the copiotrophic fungal group (Ascomycota) compared to the control soil (CK) and S-amended soil. On the contrary, as compared to the M and MS-amended soils, the CK and S-amended soils at both time points increased the fungal richness and stimulated the oligotrophic fungal groups. Organic material use, especially M and MS, showed variable results regarding pathogenic fungi enhancing the abundance of Lophodermium and Cercophora and decreasing Fusarium. Concerning the abundance of plant-beneficial fungi, Mortierella was reduced, and Podospora was increased by M and MS input. FUNGuild showed that the amendment of organic materials efficiently declined the abundance of endophytes and plant pathogens, but also enhanced the animal pathogens in terms of abundance with respect to CK at two time points. This study could be useful to provide a novel understanding of the management of soil-borne pathogens by organic amendments for the sustainable production of short-term crops. Full article
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2018

Jump to: 2020, 2019, 2017

Article
The Evaluation of Hazards to Man and the Environment during the Composting of Sewage Sludge
Sustainability 2018, 10(8), 2618; https://doi.org/10.3390/su10082618 - 26 Jul 2018
Cited by 6 | Viewed by 1723
Abstract
Composting is considered an effective treatment option to eliminate or substantially reduce potential hazards relating to the recycling of sewage sludge (SS) on land. The variation of four major types of hazards (heavy metals, instability, pathogenic potential and antibiotic resistance) was studied during [...] Read more.
Composting is considered an effective treatment option to eliminate or substantially reduce potential hazards relating to the recycling of sewage sludge (SS) on land. The variation of four major types of hazards (heavy metals, instability, pathogenic potential and antibiotic resistance) was studied during laboratory-scale composting of two mixtures of sludge and green waste (1:1 and 1:2 v/v). The heavy metal content of the final compost was governed by the initial contamination of SS, with the bulking agent ratio having practically no effect. The composts would meet the heavy metal standards of the United States of America (USA) and the European Union member states, but would fail the most stringent of them. A higher ratio of bulking agent led to a higher stabilisation rate, nitrogen retention and final degree of stability. A good level of sanitisation was achieved for both mixtures, despite the relatively low temperatures attained in the laboratory system. The antibiotic resistance was limited among the E. coli strains examined, but its occurrence was more frequent among the Enterococcus spp. strains. The type of antibiotics against which resistance was mainly detected indicates that this might not be acquired, thus, not posing a serious epidemiological risk through the land application of the SS derived composts. Full article
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Article
Effect of Sugarcane Straw and Goat Manure on Soil Nutrient Transformation and Bacterial Communities
Sustainability 2018, 10(7), 2361; https://doi.org/10.3390/su10072361 - 06 Jul 2018
Cited by 20 | Viewed by 3150
Abstract
Crop residue and animal manure as a soil amendment have been recognized as a feasible agricultural practice owing to its contribution in improving the soil fertility (SF). The primary advantages of this practice are determined by the activities of soil microorganisms. However, goat [...] Read more.
Crop residue and animal manure as a soil amendment have been recognized as a feasible agricultural practice owing to its contribution in improving the soil fertility (SF). The primary advantages of this practice are determined by the activities of soil microorganisms. However, goat manure (M), sugarcane straw (S), and goat manure plus straw (MS) amendments influence soil bacteria, their activities, and SF in clay-loam soil remains undefinable. Therefore, this study distinguished the efficacy of M, MS, and S amendment on soil enzyme activities and the availability of nutrients, including various bacterial populations in clay-loamy soil with respect to two different phases (50 and 100 days). In order to analyze the bacterial structure and their activities, we employed high-throughput sequencing (HTS) and soil enzyme activity (SEA) tests. Soil amended with M and MS not only significantly enhanced nutrient availability, including C, P, and N, soil pH, as well as SEA for C and N cycles in both phases. Additionally, the increase in nutrient availability was greater in M- and MS-amended soils in the second phase (100 days) compared to the M- and S-amended soils in the first phase (50 days). Moreover, plant growth promoting and lignocellulose degrading bacterial genera were enhanced under M- and MS-amended soil compared to S-amended soil in both phases. Distance-based redundancy analysis (dbRDA) showed that soil pH, carbon-nitrogen ratio (C:N), and nitrates (NO3) were inducing the fewest changes, while total nitrogen (TN), total carbon (TC), available nitrogen (AN), available phosphorus (AP), total phosphorus (TP), available potassium (AK), and ammonium (NH4+) were the main operators in terms of change in bacterial populations. In general, we observed that M and MS are better amendment sources as compared to S amendment in order to enhance the SF in the clay-loamy soil in both phases, but greater fertility was exhibited in the second phase. Full article
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Article
Suitability of Different Agricultural and Urban Organic Wastes as Feedstocks for the Production of Biochar—Part 1: Physicochemical Characterisation
Sustainability 2018, 10(7), 2265; https://doi.org/10.3390/su10072265 - 02 Jul 2018
Cited by 12 | Viewed by 1714
Abstract
Biochar is traditionally made from clean lignocellulosic or waste materials that create no competition for land use. In this paper, the suitability of alternative feedstocks of agricultural and urban origins are explored. A range of biochars was produced from holm oak and a [...] Read more.
Biochar is traditionally made from clean lignocellulosic or waste materials that create no competition for land use. In this paper, the suitability of alternative feedstocks of agricultural and urban origins are explored. A range of biochars was produced from holm oak and a selection of organic wastes, such as greenhouse wastes, greenwastes, a cellulosic urban waste, municipal press cake and pig manure. They were characterized and assessed for their potential agricultural use. The physicochemical properties of biochars were mainly driven by the characteristics of feedstocks and the pyrolysis temperature. The use of pre-treated lignocellulosic residues led to biochars with a high concentration of ash, macro and micronutrients, whereas raw lignocellulosic residues produced biochars with characteristics similar to traditional wood biochars. All biochars were found to be suitable for agricultural use according to the international standards for the use of biochars as soil amendments, with the exception of a biochar from urban origin, which presented high levels of Cr and Pb. The use of these biochars as soil amendments requires a thorough agronomical evaluation to assess their impact on soil biogeochemical cycles and plant growth. Full article
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Article
Suitability of Different Agricultural and Urban Organic Wastes as Feedstocks for the Production of Biochar—Part 2: Agronomical Evaluation as Soil Amendment
Sustainability 2018, 10(6), 2077; https://doi.org/10.3390/su10062077 - 19 Jun 2018
Cited by 8 | Viewed by 1641
Abstract
The recycling of organic wastes in agriculture contributes to a circular economy by returning to the soil nutrients and reducing the need of mineral-based fertilisers. An agronomical and environmental evaluation of a series of biochars prepared from a range of urban and agricultural [...] Read more.
The recycling of organic wastes in agriculture contributes to a circular economy by returning to the soil nutrients and reducing the need of mineral-based fertilisers. An agronomical and environmental evaluation of a series of biochars prepared from a range of urban and agricultural wastes was performed by soil incubation experiments and pot trials. The impact of biochar addition (alone, or in combination with either mineral or organic fertiliser) on soil N, P and micronutrients was studied, as well as the potential limitations for their agricultural use (associated to phytotoxicity and presence of potentially toxic metals). The type and origin of feedstock only had a minor impact on the response of biochar in soil and its interaction with the most important nutrient cycles. The presence of ashes in biochars prepared from urban and pre-treated organic wastes caused an increase in the availability of N and P in soil, compared to raw lignocellulosic biochar. All tested biochars exhibited favourable properties as soil amendments and no phytotoxic effects or negative impacts on soil nutrient dynamics were observed during the soil incubation experiments. Their agricultural use is only limited by the presence of potentially toxic metals in biochars prepared from feedstocks of urban origins. Full article
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Article
Liquid-Phase Respiration Activity Assays to Assess Organic Waste Stability: A Comparison of Two Tests
Sustainability 2018, 10(5), 1441; https://doi.org/10.3390/su10051441 - 05 May 2018
Cited by 3 | Viewed by 1324
Abstract
The stability of twenty-seven composts and organic substrates (including raw, less stable and stable materials) was assessed using two different liquid phase tests. One of the tests was introduced in 1998 and was based on the calculation of a Specific Oxygen Uptake Rate [...] Read more.
The stability of twenty-seven composts and organic substrates (including raw, less stable and stable materials) was assessed using two different liquid phase tests. One of the tests was introduced in 1998 and was based on the calculation of a Specific Oxygen Uptake Rate (SOUR). The newly introduced liquid phase test presented here is simpler to set-up and to perform than the older liquid phase test and is more representative of the composting process due to its longer experimental duration. It is based on the quantification of oxygen consumption in the headspace of a BOD bottle that contains the liquid-solid solution. The results indicate that a marginal correlation does exist between the main indices calculated from both tests. The correlation was slightly stronger for the indices calculated from the raw materials than from the processed ones. The correlation calculated from the processed substrates was statistically insignificant. The SOUR ranged from 1520 to 3650 mg O2/kg VS-h for the raw materials and from 110 to 1150 mg O2/kg VS-h for the processed materials, respectively. The corresponding stability rate related index (LSRI24) of the new liquid phase test introduced here ranged from 240 to 1180 mg O2/dry kg-h for the raw materials and from 64 to 792 mg O2/dry kg-h for the processed ones. Full article
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Article
Adsorption Characteristics of Ammonium Nitrogen and Plant Responses to Biochar Pellet
Sustainability 2018, 10(5), 1331; https://doi.org/10.3390/su10051331 - 25 Apr 2018
Cited by 16 | Viewed by 1622
Abstract
For feasibility of carbon sequestration as well as in the mitigation of greenhouse gases for application of biochar pellet, this experiment was conducted, focusing on the adsorption characteristics of NH4-N on biochar pellet mixed with different ratios of pig manure compost. [...] Read more.
For feasibility of carbon sequestration as well as in the mitigation of greenhouse gases for application of biochar pellet, this experiment was conducted, focusing on the adsorption characteristics of NH4-N on biochar pellet mixed with different ratios of pig manure compost. For NH4-N adsorption on biochar pellets, the loading amount of biochar pellet was 211.5 mg in 50 mL of aqueous solution, and the adsorption fitted very well with Langmuir isotherm. The maximum adsorption and removal rates were 2.94 mg g−1 and 92.2%, respectively, in the pellet that contained 90% of biochar. It was also observed, by kinetic models, that NH4-N was adsorbed fast on biochar pellet with a combination ratio of 9:1 of biochar pellet/pig manure. It was further observed that the higher the amount of biochar contained in the biochar pellet, the greater the adsorption of NH4-N. For the plant response observed for lettuce, it was shown that the leaf biomass in plots treated with a 9:1 biochar/pig manure compost increased by approximately 13% compared with the leaf biomass in plots treated with the compost alone. The leaf biomass of the other treatments was higher than that of the control. This implies that the application of biochar pellets, regardless of the biochar contents, might be useful for soil carbon sequestration and greenhouse gas mitigation for agricultural practices. Full article
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Review
Efficacy of the Vermicomposts of Different Organic Wastes as “Clean” Fertilizers: State-of-the-Art
Sustainability 2018, 10(4), 1205; https://doi.org/10.3390/su10041205 - 16 Apr 2018
Cited by 22 | Viewed by 2921
Abstract
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 [...] Read more.
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. Full article
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Article
Effect of Three Types of Exogenous Organic Carbon on Soil Organic Matter and Physical Properties of a Sandy Technosol
Sustainability 2018, 10(4), 1146; https://doi.org/10.3390/su10041146 - 11 Apr 2018
Cited by 4 | Viewed by 1848
Abstract
Technosols made by covering agricultural soils with coastal sediments need additional organic matter (OM) to be suitable for agricultural use. Climate change will likely increase the frequency and intensity of droughts in several areas. The choice of the nature and quantity of OM [...] Read more.
Technosols made by covering agricultural soils with coastal sediments need additional organic matter (OM) to be suitable for agricultural use. Climate change will likely increase the frequency and intensity of droughts in several areas. The choice of the nature and quantity of OM to add depends on dose-response curves for soil quality. This study quantifies the influence of three contrasting organic materials (vermicompost (VF), green waste compost (GWC) and dairy manure (DM)) on four soil properties: soil organic carbon, evaporation rate, bulk density and structural stability. Soil was sampled in April and May 2014 in an artificial crop field of the vegetable production basin of Mont Saint-Michel (France) made with sediments from the bay of Mont Saint-Michel in 2013. Increasing the dose of OM increased soil organic carbon from 10 to 45 g C kg−1 dry soil and increased the porosity and the structural stability, thus decreasing compaction. Increasing the dose of OM also decreased the evaporation rate. VF and DM had similar effects, while those of GWC were weaker. Compared to DM, VF had greater biological stability. Therefore, high OM inputs along with soil decompaction can increase drought resistance by increasing rooting depth and water retention. Full article
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Article
The Effect of Co-Additives (Biochar and FGD Gypsum) on Ammonia Volatilization during the Composting of Livestock Waste
Sustainability 2018, 10(3), 795; https://doi.org/10.3390/su10030795 - 13 Mar 2018
Cited by 17 | Viewed by 2618
Abstract
The effectiveness of co-additives for improving livestock waste composting (reduction of air pollution and conservation of nutrients) was investigated. Biochar and Flue gas desulphurization gypsum (FGD gypsum) were used to supplement the composting of a mixture of slaughter waste, swine slurry, and sawdust. [...] Read more.
The effectiveness of co-additives for improving livestock waste composting (reduction of air pollution and conservation of nutrients) was investigated. Biochar and Flue gas desulphurization gypsum (FGD gypsum) were used to supplement the composting of a mixture of slaughter waste, swine slurry, and sawdust. Different compositions of additives (0% or 5% each, 10% biochar or FGD gypsum) were tested in triplicate on the laboratory scale. In addition, the effects of two different aeration schemes (continuous and intermittent) were also investigated. Ammonia volatilization, physicochemical characteristics, and compost maturity indices were investigated. The results indicated that the use of the co-additive (Biochar and FGD gypsum) during composting of livestock waste led to a reduction of ammonia volatilization by 26–59% and to a 6.7–7.9-fold increase of nitrate accumulation. The total ammonia volatilization of intermittent aeration treatment was lower than that of continuous aeration using co-additives treatment. It was concluded that co-additives (biochar and FGD gypsum) might be utilized in livestock waste composting to reduce ammonia volatilization and improve nutrient conservation. Full article
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Article
Integration of a Communal Henhouse and Community Composter to Increase Motivation in Recycling Programs: Overview of a Three-Year Pilot Experience in Noáin (Spain)
Sustainability 2018, 10(3), 690; https://doi.org/10.3390/su10030690 - 04 Mar 2018
Cited by 2 | Viewed by 1786
Abstract
This paper presents a three-year pilot experience of a new municipal waste management system developed in Navarre, Spain that integrates composting and hens. The aim of this new system is to motivate the general public to participate more in waste prevention programs. The [...] Read more.
This paper presents a three-year pilot experience of a new municipal waste management system developed in Navarre, Spain that integrates composting and hens. The aim of this new system is to motivate the general public to participate more in waste prevention programs. The Composter-Henhouse (CH) is a compact facility comprised of a henhouse and three composters. This is shared by 30 families who provide the organic part of their kitchen waste to feed the hens. Hens help speed up the composting process by depositing their droppings and turning the organic residue into compost. This study assesses the CH in terms of treatment capacity, the technical adequacy of the composting process, the quality and safety of the compost obtained and some social aspects. Over three years, the CH has managed nearly 16.5 tons of organic waste and produced approximately 5600 kg of compost and more than 6000 high-quality fresh eggs. No problems or nuisances have been reported and the level of animal welfare has been very high. The follow up of the composting process (temperature, volume reduction and compost maturity) and a physicochemical and microbiological analysis of the compost have ensured the proper management of the process. The level of involvement and user satisfaction has been outstanding and the project has presented clear social benefits. Full article
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Article
Improved Precision and Efficiency of a Modified ORG0020 Dynamic Respiration Test Setup for Compost Stability Assessment
Sustainability 2017, 9(12), 2358; https://doi.org/10.3390/su9122358 - 18 Dec 2017
Cited by 4 | Viewed by 2689
Abstract
The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in [...] Read more.
The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in flow rate with time and across sample replicate vessels. Here, we demonstrate the use of a multichannel peristaltic pump to deliver a more consistent air flow to individual vessels. Using finished and unfinished industry compost samples from different sites with varying stabilities, we provide evidence of greater precision of the modified setup compared to the original. Furthermore, the reduced need for air flow adjustment resulted in improved running cost efficiency with less labour demand. Analysis of compost sample oxygen demand supports the current test air flow rate of 25–75 mL min−1, although the improved air flow control will enable future narrowing of the acceptable range for better inter-laboratory performance. Full article
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Review
Immobilization of Heavy Metals in Sewage Sludge during Land Application Process in China: A Review
Sustainability 2017, 9(11), 2020; https://doi.org/10.3390/su9112020 - 07 Nov 2017
Cited by 37 | Viewed by 2457
Abstract
The safe disposal of sewage sludge during the process of municipal wastewater treatment has become one of the major concerns of increased production. Land application was thought of as a more economical method for sewage sludge disposal than landfill and incineration. However, the [...] Read more.
The safe disposal of sewage sludge during the process of municipal wastewater treatment has become one of the major concerns of increased production. Land application was thought of as a more economical method for sewage sludge disposal than landfill and incineration. However, the presence of heavy metals in sewage sludge restricted the use of land application. The environmental risk of heavy metals was dependent on their contents, chemical speciations, and soil characteristics. Composting and chemical immobilization were the commonly used methods to immobilize the heavy metals in sewage sludge. The immobilization mechanism and speciation transformation of heavy metals during the composting process were presented. Aluminosilicate, phosphorus-bearing materials, basic compounds, and sulfides were reviewed as the commonly used chemical immobilizing agents. The problems that occur during the immobilization process were also discussed. The combination of different methods and the modification of chemical immobilizing agents both improved the fixation effect on heavy metals. Full article
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