The over-use of antibiotics in animal husbandry in China and the concomitant enhanced selection of antibiotic resistance genes (ARGs) in animal manures are of serious concern. Thermophilic composting is an effective way of reducing hazards in organic wastes. However, its effectiveness in antibiotic degradation and ARG reduction in commercial operations remains unclear. In the present study, we determined the concentrations of 15 common veterinary antibiotics and the abundances of 213 ARGs and 10 marker genes for mobile genetic elements (MGEs) in commercial composts made from cattle, poultry and swine manures in Eastern China. High concentrations of fluoroquinolones were found in the poultry and swine composts, suggesting insufficient removal of these antibiotics by commercial thermophilic composting. Total ARGs in the cattle and poultry manures were as high as 1.9 and 5.5 copies per bacterial cell, respectively. After thermophilic composting, the ARG abundance in the mature compost decreased to 9.6% and 31.7% of that in the cattle and poultry manure, respectively. However, some ARGs (e.g. aadA, aadA2, qacEΔ1, tetL) and MGE marker genes (e.g. cintI-1, intI-1 and tnpA-04) were persistent with high abundance in the composts. The antibiotics that were detected at high levels in the composts (e.g. norfloxacin and ofloxacin) might have posed a selection pressure on ARGs. MGE marker genes were found to correlate closely with ARGs at the levels of individual gene, resistance class and total abundance, suggesting that MGEs and ARGs are closely associated in their persistence in the composts under antibiotic selection. Our research shows potential disseminations of antibiotics and ARGs via compost utilization.

The presence of antibiotics in animal manure represents a significant concern with respect to the introduction of antibiotic residues to the environment and the development of antibiotic-resistant pathogens. In this review, we have (1) compiled reported detections of antibiotics in poultry litter, swine manure, and cattle manure; and (2) discussed the treatment of antibiotics during conventional agricultural waste management practices. The most reported antibiotics in animal manure were fluoroquinolones, sulfonamides, and tetracyclines, all of which the World Health Organization has listed as critically important for human health. Relatively high treatment efficiencies were observed for antibiotics in composting, anaerobic digestion, and aerobic/anaerobic lagooning. Interestingly, active management of compost piles did not demonstrate a significant increase in antibiotic degradation; however, low- and high-intensity compost systems exhibited high treatment efficiencies for most antibiotics. Anaerobic digestion was not effective for some key antibiotics, including lincosamides and select sulfonamides and fluoroquinolones. Given the potential for energy recovery during anaerobic digestion of agricultural waste, efforts to optimize antibiotic degradation represent an important area for future research. Lagoons also exhibited fairly high levels of antibiotic treatment, especially for aerobic systems; however, the operational costs/complexity of these systems inhibit utilization at the full-scale. No overall trends in antibiotic treatment efficiency during these three agricultural waste management practices were observed. Finally, we posit that increased efforts to include analysis of antibiotic residues in animal manure in national surveillance programs will provide important information to address concerns over the continued use of antimicrobials in animal feeding operations.

In this study, two composting strategies (not turned and turned windrows) of pig slurry solid fraction (SF) were evaluated and compared in terms of their suitability to obtain a composted manure appropriate for further pelletizing (i.e., moisture content <40%). The effect of the two composting strategies on carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ammonia (NH3) emissions were also investigated.Six identical SF windrows of approximately 4 m3 and 1800 kg were set up outside, on a concrete pad in an open-sided, roofed facility, and composted for a period of 72 days. During the experimental period, three SF windrows were composted unturned (NTW), while the others three SF windrows were turned (TW) six times: at day 7, 16, 28, 35, 50 and 57. Carbon dioxide, methane, nitrous oxide and ammonia emissions were measured three times a week for the first 3 weeks and twice per week thereafter for the 72 days of composting. In correspondence of each turning operation, gases emissions rates from TW, were evaluated two times: before and immediately after turning. Due to the production of heat generated during the composting process, high losses of water occurred from both NTW and TW. However, at the end of the trial the average moisture content in composted manure from NTW and from TW resulted, respectively, 46.7% and 34.6%. Therefore, under the specific conditions adopted in this study, composting of pig slurry SF in NTW did not give a suitable product for further pelletizing. In addition, composted manure from NTW resulted in significantly (p < 0.05) lower total nitrogen (2.9% vs 3.4%) and NO3–N (714 mg kg−1 vs 1358 mg kg−1) content. However, in terms of CO2-eq, total gaseous emissions recorded over 72 days of trial from TW (120.4 kg CO2-eq. t−1) were approximately 95% higher as compared to those (64.7 kg CO2-eq. t−1) obtained from NTW.

This study aims to evaluate a new biosorbent derived from co-composting eggshell with other organic materials (potato peels, grass clipping, and rice husk) for uptaking Pb(II) from an aqueous medium. This biosorbent contains a high amount of eggshell (30 % w/w; CES) and its performance was compared to mature compost without eggshell (CWES) and natural eggshell (ES). Sorption kinetics and equilibrium data were fitted to pseudo-second-order and Langmuir models, respectively. From a kinetic point of view, lead sorption into CES was fast, attaining equilibrium within less than 180 min. Batch experiments indicated that maximum sorption capacity of Pb into CES is 23 mg g⁻¹. The sorption capacity of CES was not significantly dependent on pH within the range of 2–5.5. In comparison to ES, organic matter of CES provided supplementary sites for lead sorption and an increase of 43 % in the sorption capacity was observed. Nevertheless, CWES was the biosorbent with higher sorption capacity. Still, this study points out the potential of new use of CES as an effective biosorbent to lead removal from aqueous matrices.

In this work, different analytical techniques (thermal analysis, ¹³C cross-polarization magic angle spinning (CPMAS) NMR and Fourier transform infrared (FT-IR) spectroscopy) have been used to study the organic matter changes during the co-composting of pig slurry with cotton gin waste. To ensure the validity of the findings, the composting process was developed in different scenarios: under experimental pilot plant conditions, using the static pile system, and under real conditions on a pig farm, using the turning pile system. Also, the thermal stability index (R1) was determined before and after an extraction with water, to evaluate the effect of eliminating water-soluble inorganic salts on the thermal analysis. The results of the thermal methods showed the degradation of the most labile organic matter during composting; R1 increased during composting in all piles, without any influence of the presence of water-soluble inorganic ions in the sample. The NMR showed a decrease in the abundance of the carbohydrate molecules and an increase in the aliphatic materials during composting, due to a concentration effect. Also, FT-IR spectroscopy was a useful technique to study the trends of polysaccharides and nitrate, as indicators of organic matter transformations during composting.

Compost or composting has been widely investigated under the background of heavy metal pollution of agricultural soils and rapid growth of organic wastes. Compost is rich in nutrients, humic matter, and microorganisms; it may be added to agricultural soil as a fertilizer to improve soil fertility and promote the growth of crops and microorganisms, and as a soil amendment to relieve heavy metal pollution. However, the effectiveness and security of compost application in agricultural soil continue to generate concern. In this review, the efficacy and mechanisms of compost remediation technologies for heavy metal-contaminated agricultural soil are presented. Poor quality, unsuitability for multiple heavy metal-contaminated soils, and potential long-term risks are the main limitations of the effectiveness and security of compost application to soils. Therefore, improving the quality of the compost, adding amendments, or combining with phytoremediation may be considered when adopting compost to remediate polluted agricultural soil. In addition, we propose several approaches to optimize these strategies and render the remediation of heavy metal-contaminated agricultural soil using compost safer and more effective. The findings of this review will help support the large-scale application of compost in agriculture in the future.

This study proposes a factorial inexact stochastic fuzzy chance constraint programming framework for dealing with uncertainties in municipal solid waste management under consideration of greenhouse gas (GHG) emission trading. It can reflect uncertainties expressed as fuzzy, interval, and random variables and generate desired management strategies for minimizing the integrated cost for solid waste disposal and purchasing GHG emission credit. Moreover, multilevel factorial analysis is conducted to reveal the main and interactive effects of uncertain parameters. The results show that effective waste allocation schemes can be obtained to meet the waste disposal demands and GHG emission requirements under different α-cut levels. The changes in the fuzzy confidence level have impacts on the waste allocation schemes, especially for the waste flow to the incinerator. The disposal cost differs across the three levels of 0.3, 0.5, and 0.7 for incinerator capacity constraint when the fuzzy confidence level of composting capacity constraint is equal to 0.5, implying the existence of the interaction between uncertainties in the incinerator and composting facility. Comparison between the waste management practices with and without considering GHG emission requirements indicates that the purchase of GHG emission credits would contribute about 10 % to the total cost, which would not be influenced significantly by the α-cut level.

The behavior of aliphatic hydrocarbons during co-composting of sewage sludge activated with palm tree waste was studied for 6 months using Py-GC/MS. The main aliphatic compounds represented as doublet alkenes/alkanes can be classified into three groups. The first group consists of 11 alkenes (undecene, tridecene, pentadecene, hexadecene, heptadecene, octadecene, nonadecene, eicosene, uncosene, docosene, tricosene) and 15 alkanes (heptane, octane, nonane, decane, undecane, dodecane, tetradecane, pentadecane, heptadecane, octadecane, nonadecane, eicosane, uncosane, docosane, and tricosane), which remain stable during the co-composting process. The stability of these compounds is related to their recalcitrance behavior. The second group consists of five alkenes (heptene, octene, nonene, decene, dodecene) and tridecane as a single alkane that decreases during co-composting. The decrease in these compounds is the combined result of their metabolism and their conversion into other compounds. The third group is constituted with tetradecene and hexadecane that increase during composting, which could be explained by accumulation of these compounds, which are released by the partial breakdown of the substrate. As a result, these molecules are incorporated or adsorbed in the structure of humic substances.

Biofiltration of NH₃ and H₂S with different packing media, biodehydration stage compost (BSC), and curing stage compost (CSC) was studied. Meanwhile, fluorescence excitation–emission matrix (EEM) spectroscopy was used to characterize the conversion mechanisms of organic matter during these biofiltration processes. Both biofilters were effective for the simultaneous removal of NH₃ and H₂S when inlet concentrations of NH₃ and H₂S were 0–50 and 50–250 mg/m³, respectively. An abrupt increase in the inlet gas concentrations of NH₃ and H₂S to 100–150 and 200–250 mg/m³, respectively, caused the decrease in the removal efficiencies (REs) of NH₃ and H₂S in the BSC biofilter, followed by a slow upturn. By contrast, relatively steady REs of both NH₃ and H₂S were observed in the CSC biofilter. After 60 days of operation, the average REs of NH₃ and H₂S were more than 95 % in the CSC biofilter. During the operation of CSC, nitrate and nitrite peaked around the 30th day, whereas sulfate showed a steady increase. The excitation–emission matrix fluorescence and parallel factor analysis (EEM-PARAFAC) indicated that the simultaneous inlet of NH₃ and H₂S facilitated the degradation of protein-like substances, whereas humic-like substances played an important role in the packing filters for the treatment of the two odorous pollutants.

The objective of this study was to assess the degree of long-term waste maturation at a closed landfill (Etueffont, France) over a period of 21 years (1989–2010) through analysis of the physicochemical characteristics of leachates as well as biochemical oxygen demand (BOD), chemical oxygen demand (COD), and metal content in waste. The results show that the leachates, generated in two different sections (older and newer) of the landfill, have low organic, mineral, and metallic loads, as the wastes were mainly of household origin from a rural area where sorting and composting were required. Based on pH and BOD/COD assessments, leachate monitoring in the landfill’s newer section showed a rapid decrease in the pollution load over time and an early onset of methanogenic conditions. The closing of the older of the two sections contributed to a significant decline for the majority of parameters, attributable to degradation and leaching. A gradual decreasing trend was observed after waste placement had ceased in the older section, indicating that degradation continued and the waste mass had not yet fully stabilized. At the end of monitoring, leachates from the two landfill linings contained typical old leachates in the maturation period, with a pH ≥ 7 and a low BOD/COD ratio indicating a low level of waste biodegradability. Age actually contributes to a gradual removal of organic, inorganic, and metallic wastes, but it is not the only driving factor behind advanced degradation. The lack of compaction and cover immediately after deposit extended the aerobic degradation phase, significantly reducing the amount of organic matter. In addition, waste shredding improved water infiltration into the waste mass, hastening removal of polluting components through percolation.