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•109 ARGs were detected in manure and compost from chicken, bovine and pig farms.•Chicken and pig manure had higher ARG diversity and abundance than bovine manure.•Composting was ...better at reducing ARGs in chicken manure than pig and bovine manure.•There was widespread co-occurrence of ARGs and MGEs in animal manure.•MGEs, heavy metal, and total nitrogen may explain differences among various manure.
Aerobic composting is used widely for animal manure recycling, and it may reduce the amount of antibiotic resistance genes (ARGs) that enter the environment. We sampled three types of animal (bovine, chicken, and pig) manure and the corresponding composts from 12 large-scale farms, and tested multiple ARGs and mobile genetic elements (MGEs) by high-throughput qPCR. A total of 109 ARGs were detected in the manure and compost samples, thereby demonstrating that both are important ARG reservoirs. The diversity and abundance of ARGs were significantly higher in chicken and pig manure than bovine manure, but industrial composting was more efficient at reducing the ARGs in chicken manure than pig and bovine manure. Composting universally reduced some ARGs, but inconsistently influenced other ARGs from different types of animal manures. Network analysis detected the widespread co-occurrence of ARGs and MGEs. floR, ermF, catB3, aac(6′)-lb(akaaacA4), and aadA were identified as suitable indicator genes for estimating the total abundance of ARGs. Our results suggest that different animal species had significant effects on the diversity, abundance, and persistence of ARGs, where the abundance of transposons, heavy metal concentration, total nitrogen level, and the dosage and duration of exposure to antibiotics may explain these differences.
•Biochar as a bulking agent possesses constructive features to assist composting.•Effect of biochar on composting depends on biochar and feedstock properties.•Biochar decreases bioavailability and ...uptake of contaminants from compost.•Generally, biochar reduces harmful effect of feedstock on living organisms.
Biochar is characterised by a large specific surface area, porosity, and a large amount of functional groups. All of those features cause that biochar can be a potentially good material in the optimisation of the process of composting and final compost quality. The objective of this study was to compile the current knowledge on the possibility of biochar application in the process of composting and on the effect of biochar on compost properties and on the content of contaminants in compost. The paper presents the effect of biochar on compost maturity indices, composting temperature and moisture, and also on the content and bioavailability of nutrients and of organic and inorganic contaminants. In the paper note is also taken of the effect of biochar added to composted material on plants, microorganisms and soil invertebrates.
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•Recent studies on biochar blended composting are reviewed.•Biochar facilitated organic matter decomposing and accelerated compost maturity.•Biochar addition could reduce NH3 and GHGs ...emissions during composting.•Co-composted biochar compost has higher quality than the traditional compost.•Future investigation is needed to explore uncertainties.
In recent years, considerable studies have been devoted to investigating the effect of biochar application on organic solid waste composting. This review provides an up-to-date overview of biochar amendment on composting processes and compost quality. Biochar production, characteristics, and its application coupled with the basic concepts of composting are briefly introduced before detailing the effects of biochar addition on composting. According to recent studies, biochar has exhibited great potential for enhancing composting. It is evident that biochar addition in composting can: (1) improve compost mixture physicochemical properties, (2) enhance microbial activities and promote organic matter decomposition, (3) reduce ammonia (NH3) and greenhouse gas (GHG) emissions, and (4) upgrade compost quality by increasing the total/available nutrient content, enhancing maturity, and decreasing phytotoxicity. Despite that, further research is needed to explore the mechanism of biochar addition on composting and to evaluate the agricultural and environmental performances of co-composted biochar compost.
Composting of food wastes: Status and challenges Cerda, Alejandra; Artola, Adriana; Font, Xavier ...
Bioresource technology,
January 2018, 2018-Jan, 2018-01-00, 20180101, Volume:
248, Issue:
Pt A
Journal Article
Peer reviewed
Open access
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•Composting of food wastes was analysed in terms of operation and microbiology.•The main challenges are gaseous emissions and non-biodegradable impurities.•Microbiology of food waste ...composting has been studied with novel molecular tools.•Gaseous emissions include greenhouse gases, ammonia and volatile organic compounds.•Quality of food waste compost is related to chemical content, maturity and stability.
This review analyses the main challenges of the process of food waste composting and examines the crucial aspects related to the quality of the produced compost. Although recent advances have been made in crucial aspects of the process, such composting microbiology, improvements are needed in process monitoring. Therefore, specific problems related to food waste composting, such as the presence of impurities, are thoroughly analysed in this study. In addition, environmental impacts related to food waste composting, such as emissions of greenhouse gases and odours, are discussed. Finally, the use of food waste compost in soil bioremediation is discussed in detail.
•Biochar has the potential to improve animal waste composting process.•It can extend the thermophilic phase and lower pH.•It can also reduce NH3, CH4, and N2O emissions.•Feedstock and pyrolysis ...conditions affect the performance of biochar.•More studies that focus on biochar use in animal mortality composting are needed.
The animal production industry in the United States is currently undergoing a phase of growth; however, such growth brings certain challenges. One of the most prominent concerns in this regard is the increasing amounts of animal waste produced as a natural consequence of stock population growth. For decades, composting, including that of manure and animal mortalities, has been utilized to manage animal waste. Recently, in an effort to enhance the composting process, biochar has been proposed for use as a compost amendment, and over the last few years, an increasing number of papers on composting with biochar have been published. However, although there have been a few review papers that have summarized the literature regarding biochar use in composting, none of these has focused on animal waste composting. Accordingly, the purpose of this review is to critically analyze the role of biochar in livestock and poultry waste composting, identify gaps in our current knowledge, and propose future research directions. On the basis of the studies analyzed, biochar has the potential to improve animal waste composting processes at application rates of 5–10%. Biochar can extend the thermophilic phase of the composting process, lower the pH of compost material, prevent leachate formation, and reduce ammonia, methane, and nitrous oxide emissions. Given that the feedstock used to produce biochar and the pyrolysis conditions employed in its production affect the performance of biochar, it is important to report the physicochemical properties of the biochars used to enable comparison of the results of different studies. Moreover, there is a need for further research to gain a better understanding of the impact of biochar regarding the elimination of antibiotic-resistant genes and animal mortality composting.
•The addition of bamboo biochar (BC) and bacterial powder (B) to pig manure compost reduced gaseous emission.•The dominant bacteria phyla were Firmicutes and Proteobacteria in thermophile stage of ...all treatments.•Dissolved organic carbon (DOC) and temperature showed mainly effect on bacterial activity in thermophile stage.•Electrical conductivity (EC) and total kjeldahl nitrogen (TKN) influenced bacterial activity in maturity stage.
Effect of bamboo biochar (BC) combined with two bacterial powders (B) on gaseous emission and variety of bacterial community during pig manure (PM) composting was investigated. The results showed that treatments of BC, BC + B1 and BC + B2 can reduce peak gaseous emission by 54%, 80% and 69% for CH4, respectively, while 37%, 45% and 45% for N2O, respectively, and 13%, 19% and 26% for NH3, respectively. The evolution of the bacterial community quantified with 16S rDNA analysis showed that in the thermophile stage, total relative abundance percentage of bacterial phyla of Firmicutes and Proteobacteria reached 97%, 97%, 93% and 96% for CK, BC, BC + B1 and BC + B2, respectively. Effects of BC on the compost bacterial community variation analysis proved bacterial activity in the thermophile stage was controlled by the content of dissolved organic carbon and temperature of the compost mixture, while electrical conductivity and total kjeldahl nitrogen also influenced compost maturity stage.
•Biochar enhances environmental conditions for microbial growth in composting piles.•Key biochar properties include porosity, surface area and cation exchange capacity.•Biochar application at 10% is ...recommended for optimum composting performance.•Biochar at 10–30% rates succeeded in mitigating NH3, N2O and CH4 emissions.•Biochar decreased bioavailability of Cu and Zn in composts.
The use of biochar in organic waste composting has attracted interest in the last decade due to the environmental and agronomical benefits obtained during the process. Biochar presents favourable physicochemical properties, such as large porosity, surface area and high cation exchange capacity, enabling interaction with major nutrient cycles and favouring microbial growth in the composting pile. The enhanced environmental conditions can promote a change in the microbial communities that can affect important microbially mediated biogeochemical cycles: organic matter degradation and humification, nitrification, denitrification and methanogenesis. The main benefits of the use of biochar in composting are reviewed in this article, with special attention to those related to the process performance, compost microbiology, organic matter degradation and humification, reduction of N losses and greenhouse gas emissions and fate of heavy metals.
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•Amoxicillin (AMX) alters nitrogen transformation and release relative to control.•AMX raised NH4+-N content and lowered NO2−-N and NO3−-N content versus control.•AMX delays compost ...maturation and alters bacterial community makeup and succession.•AMX reduced Firmicutes, Bacteroidetes and improved Proteobacteria relative abundance.•AMX inhibits ammoniated and ammonia-oxidizing bacteria, boosts denitrifying bacteria.
This study systematically analyzed the effects of amoxicillin (AMX) on the nitrogen transformation and its corresponding functional bacterial communities by conducting two aerobic composting experiments, and AMX impact on bacterial community succession was also evaluated. It provides theoretical and methodological support for harmless composting treatment of large quantities of manure containing AMX in China and for the high-quality compost products. The results showed that AMX exerted several effects on basic physicochemical and biological compost parameters. Notably, temperature changes typically accompanying compost maturation were delayed in AMX compost, reflecting altered compost maturation kinetics and bacterial community structure. Moreover, relative to control, AMX inhibited growth and reproduction of dominant bacterial phyla Firmicutes and Bacteroidetes, with respective reductions of 17.8–26.1% and 0–7.76% in relative abundance (RA) and significantly increased Proteobacteria RA by 1.9–24.8%. Thus, AMX altered both compost bacterial community structure and succession. From the perspective of various nitrogen content changes, AMX has a significant effect on nitrogen conversion and release. Simultaneously, AMX may inhibit ammoniated and ammonia-oxidizing bacterial activity, while significantly increasing the RA of denitrifying bacteria. Indeed, during early composting with AMX, the RA of denitrifying bacteria was 1361.9–1435.0% of control, highlighting differences in nitrogen transformation and release between groups.
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•Organic acids and DOM components were identified during the composting process.•The composition and diversity of bacterial community were compared during composting.•Different ...indexes were used to assess composting stability and safety together.•Correlations of bacteria, organic acids, DOM and composting stability were studied.•A mechanism of DOM transformation driven by tartaric acid and bacteria was proposed.
This study was conducted to assess the roles of bacterial community in the dissolved organic matters (DOM) transformation during sludge composting. The relationship among the bacterial community, organic acids, diverse components of DOM as well as the indexes of the phytotoxin level and stability of materials was analyzed by regression and redundancy analysis. The results showed that there were significant correlations between the parameters for evaluating compost phytotoxicity and maturity including GI, C/N, SUVA254, SUVA280, E253/203, and A240-400, which led to a new index (PC1) by principal component analysis. PC1 was significantly affected by four components of DOM, acetic and tartaric acids that were correlated with the bacteria community shift, especially seven key bacteria. Based on structural equation modeling, the key bacteria with the ability to degrade tartaric acid exerted more important roles in regulating the transformation of DOM components, which was helpful for the stability and safety of compost.
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•Degradation of SMX was positively related with activities of enzymes and microbes.•The combined biochar-compost would weaken each other's remediation effects.•HCGs increased the ...bacterial diversity but reducedthe bacterial richness.•LCGs enhanced the bacterial richness but reduced the bacterial diversity.•HCGs raised functional gene RAs of amino metabolism but lowered those of carbohydrate.
Biochar and compost, two common amendments, were rarely conducted to investigate their combined influence on enzymatic activities and microbial communities in organic-polluted wetlands. This article described the effects of biochar/compost on degradation efficiency of sulfamethoxazole (SMX) and ecosystem responses in polluted wetland soil during the whole remediation process. 1% biochar (SB1) increased degradation efficiency of SMX by 0.067% ascribed to the increase of dehydrogenase and urease. 5% biochar (SB5) decreased degradation efficiency by 0.206% due to the decrease of enzymes especially for dehydrogenase. 2% compost (SC2), 1% biochar & 2% compost (SBC3), both 10% compost (SC10) and 5% biochar & 10% compost (SBC15) enhanced degradation efficiency by 0.033%, 0.015% and 0.222%, respectively, due to the increase of enzymes and biomass. The degradation efficiency was positively related to biomass and enzymatic activities. High-throughput sequencing demonstrated that HCGs (SB5, SC10, SBC15) improved the bacterial diversities but reduced richness through introducing more exogenous predominance strains and annihilated several inferior strains, while LCGs (SB1, SC2, SBC3) exhibited lower diversities but higher richness through enhanced the RAs of autochthonal preponderant species and maintained some inferior species. Additionally, HCGs raised the RAs of amino and lipid metabolism gene but lowered those of carbohydrate compared with LCGs.
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