Modified lignin can achieve mitigation of ammonia and greenhouse gas emissions simultaneously in composting.

The constant ammonia gas (NH3) and greenhouse gases (GHG) emissions were considered as a deep-rooted problem in composting which caused air pollution and global climate change. To achieve the mitigation of NH3 and GHG, a novel additive derived from wasted straw, with modified structure and functional groups, has been developed. Results showed that the adsorption capacity of modified lignin (ML) for both ammonium and nitrate was significantly increased by 132.5-360.8 % and 313.7-454.3 % comparing with biochar (BC) and phosphogypsum (PG) after reconstructing porous structure and grafting R-COOH, R-SO3H functional groups. The application of ML could reduce 36.3 % NH3 emission during composting compared with control. Furthermore, the synergetic mitigation NH3 and GHG in ML treatment resulted in a reduction of global warming potential (GWP) by 31.0-64.6 % compared with BC and PG. These findings provide evidence that ML can be a feasible strategy to effectively alleviate NH3 and GHG emissions in composting.

Micro-positive pressure significantly decreases greenhouse gas emissions by regulating archaeal community during industrial-scale dairy manure composting.

In this study, the effects of micro-positive pressure formed by covering with a semipermeable membrane in the heating phase of dairy manure composting on greenhouse gas emissions and the mechanism of reducing methane emissions by the archaeal community were investigated. A large-scale experiment was conducted with semipermeable membrane-covered composting (SMC), forced aeration composting (FAC), and traditional static composting (TSC) groups. The results showed that the oxygen concentration and methanogen abundance were key factors in regulating methane emissions. In the heating phase of SMC, the micro-positive pressure could enhance the O2 utilization rate and heating rate, resulting in Methanobrevibacter and Methanobacterium greatly decreasing, and the abundance of mcrA decreased by 90.03%, while that of pmoA did not increase. Compared with FAC and TSC, the cumulative methane emissions in SMC decreased by 51.75% and 96.04%, respectively. Therefore, the micro-positive pressure could effectively reduce greenhouse gas emissions by inhibiting the growth of methanogens.

Reduced greenhouse gas emission by reactive oxygen species during composting.

Reactive oxygen species (ROS) is produced in the composting, which effectively promote organic matter transformation and humification process, but the effect of ROS on greenhouse gas emissions in this process has not been understood. This study proposed and validated that ROS can effectively reduce greenhouse gas emissions intheprocessofcomposting. Compared with ordinary thermophilic composting (oTC), thermophilic composting (imTC) that was supplemented by iron mineral increased ROS production by 1.38 times, and significantly reduced greenhouse gas emissions by 45.12%. Microbial community analysis showed no significant difference in the abundance of microbes involved in greenhouse gas production between oTC and imTC. Further correlation analysis proved that ROS played a crucial role in influencing greenhouse gas emissions throughout the composting process, especially in the initial phase. These findings provide new strategies for managing livestock and poultry manure to mitigate climate change.

A critical review on characterization, human health risk assessment and mitigation of malodorous gaseous emission during the composting process.

Composting has emerged as a suitable method to convert or transform organic waste including manure, green waste, and food waste into valuable products with several advantages, such as high efficiency, cost feasibility, and being environmentally friendly. However, volatile organic compounds (VOCs), mainly malodorous gases, are the major concern and challenges to overcome in facilitating composting. Ammonia (NH3) and volatile sulfur compounds (VSCs), including hydrogen sulfide (H2S), and methyl mercaptan (CH4S), primarily contributed to the malodorous gases emission during the entire composting process due to their low olfactory threshold. These compounds are mainly emitted at the thermophilic phase, accounting for over 70% of total gas emissions during the whole process, whereas methane (CH4) and nitrous oxide (N2O) are commonly detected during the mesophilic and cooling phases. Therefore, the human health risk assessment of malodorous gases using various indexes such as ECi (maximum exposure concentration for an individual volatile compound EC), HR (non-carcinogenic risk), and CR (carcinogenic risk) has been evaluated and discussed. Also, several strategies such as maintaining optimal operating conditions, and adding bulking agents and additives (e.g., biochar and zeolite) to reduce malodorous emissions have been pointed out and highlighted. Biochar has specific adsorption properties such as high surface area and high porosity and contains various functional groups that can adsorb up to 60%-70% of malodorous gases emitted from composting. Notably, biofiltration emerged as a resilient and cost-effective technique, achieving up to 90% reduction in malodorous gases at the end-of-pipe. This study offers a comprehensive insight into the characterization of malodorous emissions during composting. Additionally, it emphasizes the need to address these issues on a larger scale and provides a promising outlook for future research.

Plastics in biogenic matrices intended for reuse in agriculture and the potential contribution to soil accumulation.

The spread of biogenic matrices for agricultural purposes can lead to plastic input into soils, raising a question on possible consequences for the environment. Nonetheless, the current knowledge concerning the presence of plastics in biogenic matrices is very poor. Therefore, the objective of the present study was a quali-quantitative characterization of plastics in different matrices reused in agriculture as manures, digestate, compost and sewage sludges. Plastics were quantified and characterized using a Fourier Transform Infrared Spectroscopy coupled with an optical microscope (µFT-IR) in Attenuated Total Reflectance mode. Our study showed the presence of plastics in all the investigated samples, albeit with differences in the content among the matrices. We measured a lower presence in animal matrices (0.06-0.08 plastics/g wet weight w.w.), while 3.14-5.07 plastics/g w.w. were measured in sewage sludges. Fibres were the prevalent shape and plastic debris were mostly in the micrometric size. The most abundant polymers were polyester (PEST), polypropylene (PP) and polyethylene (PE). The worst case was observed in the compost sample, where 986 plastics/g w.w. were detected. The majority of these plastics were compostable and biodegradable, with only 8% consisting of fragments of PEST and PE. Our results highlighted the need to thoroughly evaluate the contribution of reused matrices in agriculture to the plastic accumulation in the soil system.

Effect of different multichannel ventilation methods on aerobic composting and vegetable waste gas emissions.

Aerobic composting, especially semipermeable membrane-covered aerobic fermentation, is known to be an effective method for recycling and reducing vegetable waste. However, this approach has rarely been applied to the aerobic composting of vegetable waste; in addition, the product characteristics and GHG emissions of the composting process have not been studied in-depth. This study investigated the effect of using different structural ventilation systems on composting efficiency and greenhouse gas emissions in a semipermeable membrane-covered vegetable waste compost. The results for the groups (MV1, MV2, and MV3) with bottom ventilation plus multichannel ventilation and the group (BV) with single bottom ventilation were compared here. The MV2 group effectively increased the average temperature by 19.06% whilst also increasing the degradation rate of organic matter by 30.81%. Additionally, the germination index value reached more than 80%, 3 days in advance. Compared to those of the BV group, the CH4, N2O, and NH3 emissions of MV2 were reduced by 32.67%, 21.52%, and 22.57%, respectively, with the total greenhouse gas emissions decreasing by 24.17%. Overall, this study demonstrated a multichannel ventilation system as a new method for improving the composting efficiency of vegetable waste whilst reducing gas emissions.

A global meta-analysis of greenhouse gas emissions and carbon and nitrogen losses during livestock manure composting: Influencing factors and mitigation strategies.

The management of manure composting contributes to alleviate the global greenhouse effect. To improve our understanding of this process, we conducted a meta-analysis of 371 observations from 87 published studies in 11 countries. The results showed that the difference in nitrogen content in feces significantly affected the greenhouse gas (GHG) emissions and nutrient losses of subsequent composting, with NH3-N, CO2-C, and CH4-C losses all increasing with its rise. Windrow pile composting (especially compared to trough composting) had lower GHG emissions and nutrient loss. C/N ratio, aeration rate, and pH value significantly affected NH3 emission, and a decrease in the latter two can reduce it by 31.8 % and 42.5 %, respectively. Decreasing the moisture content or increasing the turning frequency could decrease CH4 by 31.8 % and 62.6 %, respectively. The addition of biochar or superphosphate had a synergistic emission reduction. The emission reduction of N2O and CH4 by biochar was more prominent (44 % and 43.6 %), while superphosphate on NH3 (38.0 %) was better. And the latter was more suitable if added in 10-20 % of dry weight. Dicyandiamide was the only chemical additive (59.4 %) with better N2O emission reduction performance. Microbial agents with different functions had certain effects on NH3-N emission reduction, while the mature compost had a certain effect on N2O-N emissions (67.0 %). In general, N2O had the highest contribution to the greenhouse effect during composting (74.22 %).

Appraising co-composting efficiency of biodegradable plastic bags and food wastes: Assessment microplastics morphology, greenhouse gas emissions, and changes in microbial community.

Biodegradable plastic bags (BPBs) to collect food waste and microplastics (MPs) produced from their biodegradation have received considerable scientific attention recently. Therefore, the current study was carried out to assess the co-composting efficiency of biodegradable plastic bags (polylactic acid (PLA) + polybutylene terephthalate (PBAT) + ST20 and PLA + PBAT+MD25) and food waste. The variations in greenhouse gas (GHG) emissions, microbial community and compost fertility were likewise assessed. Compared with the control, PLA + PBAT+ST20 and PLA + PBAT+MD25 both accelerated organic matter degradation and increased temperature. Moreover, PLA + PBAT+ST20 aggravated CH4 and CO2 emissions by 12.10 % and 11.01 %, respectively. PLA + PBAT+MD25 decreased CH4 and CO2 emissions by 5.50 % and 9.12 %, respectively. Meanwhile, compared with PLA + PBAT+ST20, the combined effect of plasticizer and inorganic additive in PLA + PBAT+MD25, reduced the NO3--N contents, seed germination index (GI) and compost maturity. Furthermore, adding BPBs changed the richness and diversity of the bacterial community (Firmicutes, Proteobacteria and Bacteroidetes). Likewise, redundancy analysis (RDA) showed that the co-compost system of BPBs and food waste accelerated significantly bacterial community succession from Firmicutes and Bacteroidetes at the initial stage to Proteobacteria and Actinobacteria at the mature stage, increased co-compost temperature to over 64 °C and extended thermophilic composting phase, and promoted the degradation of MPs. Additionally, according to structural equation model quantification results, the inorganic additive of PLA + PBAT+MD25 had more serious toxicity to microorganisms and had significantly adverse effects on GI through CO2-C (λ = -0.415, p < 0.05) and NO3--N (λ = -0.558, p < 0.001), thus reduced compost fertility and quality. The results also indicated that the BPBs with ST20 as an additive could be more suitable for industrial composting than the BPBs with MD25 as an additive. This study provided a vital basis for understanding the potential environmental and human health risks of the MPs' generated by the degradation of BPBs in compost.

Obtención y caracterización fisicoquímica de un sustrato nutritivo hecho a partir de cáscaras de cacao para la producción de plántulas de hortalizas / Obtaining and physicochemical characterization of a nutritive substrate made from cacao shells for the production of vegetable seedlings

En el beneficiado del cacao se producen una gran cantidad de residuos, las mazorcas generalmente son desechadas dentro de los mismos cultivos y genera problemáticas como la proliferación de insectos y microorganismos patógenos. De estos desechos las cáscaras son las de mayor relevancia. La Escuela de Ingeniería Química de ITCA-FEPADE evaluó añadirle valor a este subproducto, incorporando desechos de cáscara de cacao en la formulación de un sustrato para el cultivo de plántulas de hortalizas. El objetivo de esta investigación fue obtener un sustrato orgánico que sirva de soporte material y nutritivo a partir de cáscaras de cacao criollo. La biomasa vegetal se caracterizó teniendo en cuenta parámetros como el porcentaje de humedad, pH, porcentaje de cenizas, contenido de potasio, nitrógeno y fósforo. Se ejecutaron pruebas comparativas de formulación del sustrato, siembra, cultivo y crecimiento de las plántulas de hortalizas de tomate y pepino, obteniendo como resultado la fórmula óptima de un sustrato y abono orgánico y el mejor medio de desarrollo. De los resultados obtenidos se concluye que, a partir de un adecuado procesamiento y aprovechamiento de las cáscaras de cacao, se puede transformar este desecho en un producto biomaterial alternativo que genera una opción de bioprospección agroindustrial. Los valores obtenidos en la caracterización fisicoquímica de las cáscaras de las mazorcas, dependen de condiciones como el tipo de suelo, variables agrometeorológicas, calidad de agua, abono y especie de la planta de cacao. El escenario de siembra condiciona el desarrollo óptimo de las plántulas; los factores como requerimiento de agua, distribución de nutrientes y estabilidad de las plántulas, se ven afectados por la relación del espacio de germinación. Como resultado de la caracterización fisicoquímica, se obtuvo: pH de 5.7, cenizas 18.83%, humedad 73.56%, celulosa 21.39%, lignina 39.81%, nitrógeno total 0.02%, fósforo total 0.02% y ausencia de potasio.

In the cacao beneficiation, a large amount of waste is produced, generally, the cacao pods are discarded within the same crops and generate problems such as the proliferation of insects and pathogenic microorganisms. The shell are the most relevant this waste. In Escuela de Ingeniería Química of ITCA-FEPADE the incorporation of cacao shell waste in the formulation of a substrate for growing vegetables was evaluated because the giving benefit to these by-products. The objective of this research was to obtain a substrate that serves as material and nutritional support for vegetable seedlings, from creole cacao shells. The vegetal biomass was characterized taking into account parameters such as moisture percentage, pH, ash percentage, potassium, nitrogen and phosphorus content. Subsequently, comparative tests of formulation, planting and growth of vegetable tomato and cucumber seedlings were carry out, obtaining as result, the optimal formula for the substrate and the best development environment. It concludes that, through an adequate processing and use of the cacao shell, it is possible to transform a waste into an alternative biomaterial product that generates an agro industrial bioprospecting option. The values obtained in the physicochemical characterization of the shells of cacao pods depend on conditions such as soil type, agrometeorological variables, water quality, fertilizer and cacao plant species. The planting environment determines the optimal development of the seedlings, factors such as water requirement, nutrient distribution and seedling stability seems affected because relation of the germination space. The results of the characterization were a pH of 5.7, ashes 18.83%, humidity 73.56%, cellulose 21.39%, lignin 39.81%, total nitrogen 0.02%, total phosphorus 0.02%, and total phosphorus 0.02% and an absence of potassium.

Improved fertilization efficiency of manure compost obtained by using oil shale semicoke as the bulking agent.

Oil shale semicoke is a kind of solid waste produced during the retorting process of oil shale, which could cause environmental pollution without reasonable disposing. In our previous study, the abandoned semicoke was recycled as bulking agent to reduce the nitrogen loss and greenhouse gases emission during composting. But influences of the obtained semicoke-blended compost on soil properties and plant growth remained unclear, which would be discussed in this study. Through leaching experiments, it was found that the N/P/K retention capacity of soil mixed with semicoke-blended compost significantly increased for the good nutrients sorption capacity of oil shale semicoke. Subsequently, germination test showed the germination index of semicoke-blended compost could attain 120%, implying its low phytotoxicity. And pot experiments exhibited the biomass of cress and Brassica rapa significantly increased by 2-4 times when applying semicoke-blended compost as fertilizer, exhibiting its great benefits to plants. For the increase of crop yield, it was closely related to their elevated nutrients uptake efficiency, also might be related to the improved soil microbial community and activity as the microbial analysis indicated. Finally, results of pollutant detection showed the concentration of polycyclic aromatic hydrocarbons, Cr, As, Cd and Pb in the mature semicoke-blended compost obtained through composting was 2.82, 95.30, 5.95, 0.34 and 14.45 mg kg-1 respectively, meeting the standard for soil application. The research suggests composting could be an effective method for the harmless disposing and resource recycling of oil shale semicoke waste.

Effects of dicyandiamide, phosphogypsum and superphosphate on greenhouse gas emissions during pig manure composting.

This study investigated the effects of dicyandiamide, phosphogypsum and superphosphate on greenhouse gas emissions and compost maturity during pig manure composting. The results indicated that the addition of dicyandiamide and phosphorus additives had no negative effect on organic matter degradation, and could improve the compost maturity. Adding dicyandiamide alone reduced the emissions of ammonia (NH3), methane (CH4) and nitrous oxide (N2O) by 9.37 %, 9.60 % and 31.79 %, respectively, which was attributed that dicyandiamide effectively inhibited nitrification to reduce the formation of N2O. Dicyandiamide combined with phosphogypsum or superphosphate could enhance mitigation of the total greenhouse gas (29.55 %-37.46 %) and NH3 emission (18.28 %-21.48 %), which was mainly due to lower pH value and phosphoric acid composition. The combination of dicyandiamide and phosphogypsum exhibited the most pronounced emission reduction effect, simultaneously decreasing the NH3, CH4 and N2O emissions by 18.28 %, 38.58 % and 36.14 %, respectively. The temperature and C/N content of the compost were significantly positively correlated with greenhouse gas emissions.

Obtención y caracterización físico química de un sustrato nutritivo hecho a partir de los desechos del cacao para la producción de plántulas de hortalizas: en asocio con empresa Chukwa Chocolates / Obtaining and physicochemical characterization of a nutritive substrate made from cacao waste for the production of vegetable seedlings: in association with Chukwa Chocolates

En el beneficiado del cacao se producen una gran cantidad de residuos, las mazorcas generalmente son desechadas dentro de los mismos cultivos y genera problemáticas como la proliferación de insectos y microorganismos patógenos. De estos desechos las cáscaras son las de mayor relevancia. La Escuela de Ingeniería Química de ITCA-FEPADE evaluó añadirle valor a este subproducto, incorporando desechos de cáscara de cacao en la formulación de un sustrato para el cultivo de plántulas de hortalizas. El objetivo de esta investigación fue obtener un sustrato orgánico que sirva de soporte material y nutritivo a partir de cáscaras de cacao criollo. La biomasa vegetal se caracterizó teniendo en cuenta parámetros como el porcentaje de humedad, pH, porcentaje de cenizas, contenido de potasio, nitrógeno y fósforo. Se ejecutaron pruebas comparativas de formulación del sustrato, siembra, cultivo y crecimiento de las plántulas de hortalizas de tomate y pepino, obteniendo como resultado la fórmula óptima de un sustrato y abono orgánico y el mejor medio de desarrollo. De los resultados obtenidos se concluye que, a partir de un adecuado procesamiento y aprovechamiento de las cáscaras de cacao, se puede transformar este desecho en un producto biomaterial alternativo que genera una opción de bioprospección agroindustrial.

In the cacao beneficiation, a large amount of waste is produced, generally, the cacao pods are discarded within the same crops and generate problems such as the proliferation of insects and pathogenic microorganisms. The shell are the most relevant this waste. In Escuela de Ingeniería Química of ITCA-FEPADE the incorporation of cacao shell waste in the formulation of a substrate for growing vegetables was evaluated because the giving benefit to these by-products. The objective of this research was to obtain a substrate that serves as material and nutritional support for vegetable seedlings, from creole cacao shells. The vegetal biomass was characterized taking into account parameters such as moisture percentage, pH, ash percentage, potassium, nitrogen and phosphorus content. Subsequently, comparative tests of formulation, planting and growth of vegetable tomato and cucumber seedlings were carry out, obtaining as result, the optimal formula for the substrate and the best development environment. It concludes that, through an adequate processing and use of the cacao shell, it is possible to transform a waste into an alternative biomaterial product that generates an agro industrial bioprospecting option.

Cellulosimicrobium composti sp. nov., a thermophilic bacterium isolated from compost.

A Gram-stain-positive, yellow-pigmented, non-motile actinobacterial strain, designated as BIT-GX5T, was isolated from a sesame husks compost collected in Beijing, PR China. This bacterium was found to be able to grow in the temperature range from 16 to 50 °C and had an optimal growth temperature at 45 °C. Its taxonomic position was analysed using a polyphasic approach. The 16S rRNA gene sequence (1482 bp) of strain BIT-GX5T was most similar to Cellulosimicrobium funkei ATCC BAA-886T (99.45%), Cellulosimicrobium cellulans LMG 16121T (99.17%) and Cellulosimicrobium marinum RS-7-4T (98.75%). The results of phylogenetic analyses, based on the 16S rRNA gene, concatenated sequences of five housekeeping genes (gyrB, rpoB, recA, atpD and trpB) and genome sequences, placed strain BIT-GX5T in a separate lineage among the genus Cellulosimicrobium within the family Promicromonosporaceae. The major polar lipids of strain BIT-GX5T were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, aminophospholipid and aminolipid. The major isoprenoid quinone was MK-9(H4), while the cell-wall sugars were galactose, rhamnose, glucose and mannose. The peptidoglycan type was A4α l-Lys-d-Ser-d-Asp. The major fatty acids were anteiso-C15:0 and iso-C15: 0, which were similar to other members in the genus Cellulosimicrobium. Results of in silico DNA-DNA hybridization and average nucleotide identity calculations plus physiological and biochemical tests exhibited the genotypic and phenotypic differentiation of strain BIT-GX5T from the other members of the genus Cellulosimicrobium. Therefore, strain BIT-GX5T is considered to represent a novel species within the genus Cellulosimicrobium, for which the name Cellulosimicrobium composti sp. nov. is proposed. The type strain is BIT-GX5T (= CGMCC 1.17687T = KCTC 49391T).

Feasibility of vermicomposting for spent drilling fluid from a nature-gas industry employing earthworms Eisenia fetida.

This study investigated the vermicomposting of spent drilling fluid (SDF) from the nature-gas industry mixed with cow dung in 0% (T1), 20% (T2), 30% (T3), 40% (T4), 50% (T5), and 60% (T6) ratio employing Eisenia fetida under a 6 weeks trial. Eisenia. fetida showed better growth and reproduction performances in the first three vermireactors (T1-T3), and the mortality was higher in the vermireactors that contained more spent drilling fluid (≥40%). Vermicomposting results in a decrease in total organic carbon, C/N ratio, and an increase in EC, total nitrogen, total phosphorous, total potassium compared to their initial values. The RadViz and VizRank showed that vermicomposting results in a greater impact on the C/N ratio (15.24-35.48%) and EC (7.29-26.45%) compared to other parameters. Activities of urease and alkaline phosphatase during vermicomposting initially increased and then declined suggesting vermicompost maturity. Also, seed germination, mitotic index and chromosomal abnormality assays using cowpea signified that the vermicomposts T2 is suitable for agricultural use due to the lower phytotoxicity and cytotoxicity. The results indicated that SDF could be converted into good quality manure by vermicomposting if mixed up to 20% with cow dung.

Effects of microbial culture and chicken manure biochar on compost maturity and greenhouse gas emissions during chicken manure composting.

The effects of chicken manure biochar (CMB) and chicken manure integrated microbial consortium (CMMC) as co-amendments were assessed on compost maturity and reduction of greenhouse gases and ammonia (NH3) emissions during chicken manure composting. Composting was conducted using six combinations of CMB and CMCC (0 % CMB + 0 % CMMC, 0 % CMB + 10 % CMMC, 2 % CMB + 10 % CMMC, 4 % CMB + 10 % CMMC, 6 % CMB + 10 % CMMC, 10 % CMB + 10 % CMMC added on a dry weight basis) in six polyvinyl chloride composting reactors for 42 days under an aerobic environment. Co-amendment of CMB and CMMC extended the thermophilic stage and promoted compost maturity. The release of greenhouse gases [nitrous oxide (N2O) and methane (CH4)] and NH3 from treatments co-amended by CMB and CMMC were reduced by 19.0-27.4 %, 9.3-55.9 % and 24.2-56.9 %, respectively, compared with the control. In addition, a redundancy analysis showed that the C/N ratio and temperature had a significant relationship with greenhouse gases and NH3 emissions among all physiochemical characteristics.

Improved nitrogen conservation capacity during composting of dairy manure amended with oil shale semi-coke as the porous bulking agent.

Oil shale semi-coke is the solid waste produced from the retorting process of oil shale, which may cause pollution to the environment without reasonable disposing. In this study, semi-coke was used as the bulking agent during composting to accelerate biodegradation of the organics as well as decrease the nitrogen loss. Results showed that the addition of semi-coke could accelerate biodegradation of the organics, with a raise in the organic matter loss from 44.99 % to 47.05 % compared with the control. Furthermore, the nitrogen loss significantly decreased from 40.00%-14.70 % in the treatment added with semi-coke due to less emission of NH3 and much more transformation of NH4+-N to NO3--N by nitrification, which could be explained by the increasing abundance of ammonia-oxidizing bacteria and archaea at the late composting stage and drastic shift of the microbial community like Chloroflexi, Firmicutes and Actinobacteria. After the composting cycle, the maturity of the produced compost was elevated greatly in the treatments amended with semi-coke. The result of PAHs detection suggested that there were low PAHs content in the raw oil shale semi-coke and they could be removed effectively to within the range for land application by composting especially when the surfactant was added.

Reducing ammonia and greenhouse gas emission with adding high levels of superphosphate fertilizer during composting.

Previous studies revealed that superphosphate fertilizer (SSP) as an additive in compost can reduce the nitrogen loss and improve the effectiveness of phosphorus during composting. However, few studies have explored the influence of adding SSP with high levels on ammonia and greenhouse gas emission and the suitable amount for SSP addition according to a combined assessment of the composting process and product. The present study aimed to evaluate the impact of SSP with high additive amounts on NH3, CO2, CH4, and N2O emission and organic carbon loss. All piles were mixtures of pig manure and cornstalks with different levels of SSP addition including 10%, 14%, 18%, 22%, 26%, and 30% dry weight basis of raw materials. Compared with the control without SSP, the amount of NH3 cumulative emissions was decreased by 23.8-48.1% for the treatments with 10-30% SSP addition, and the emission of greenhouse gas including CO2, CH4, and N2O by 20.9-35.5% (CO2 equivalent) was reduced by 20.9-35.5%. Adding SSP with the amount exceeding 14% to compost could reduce CO2 emissions by 32.0-38.4% and more than 30% carbon loss at the end of composting but exceeding 26% had an adverse impact on maturity of the composts. Therefore, considering the maturity and safety of compost and gas emission reduction, 14-26% SSP was the optimum amount for composting addition, which is an effective and economical way to increase the nutrient level of carbon, nitrogen, and phosphorus in compost and reduce environmental risks.

Effect of iron nanoparticles on passivation of cadmium in the pig manure aerobic composting process.

Cadmium (Cd) is a toxic metal ion in pig manure impacting on the ecosystem, and hence the immobilization of Cd by green synthesis of iron nanoparticles (G-nFe) is a potential approach. In this study, transformation of Cd (II) during the pig manure thermophilic aerobic composting process in the presence of G-nFe was investigated. The results show that the addition of G-nFe promoted the composting process and release of available phosphorus (AP). In all six experiments, obvious passivation of Cd occurred during 15 days' composting. Particularly when 500 mL kg-1 of G-nFe was added and Cd (II) was added at 0.6%(w/w%), residual Cd increased from 0.0016% to 55.70% and exchangeable Cd decreased from 98.54% to 7.21%. Batch experiments revealed that the G-nFe promoted the transformation of Cd into a larger passivation fraction. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), SEM-Mapping and Fourier transform infrared (FTIR) analysis was used to characterize residual samples, where indicated that the passivation of Cd in compost was highly correlated with the increase of P, it can be concluded that fixing with compost resulted in the formation of Cd phosphate precipitation or co-precipitation with other phosphates.

Utilisation/upgrading of orange peel waste from a biological biorefinery perspective.

Orange peel waste (OPW) (peels, pulp and seeds) is an underutilised residue coming from the orange juice industry. Its classical applications are cattle feeding and composting, while they cannot ensure a total use of OPW, so landfilling is also common practice. On the other side, OPW is very rich in sugars, polysaccharides, essential oils and polyphenols, so there is a vast literature focused on the development and optimization of technologies and processes to several products from OPW. In this review, papers on OPW-based bioprocesses are visited, discovering a wide landscape that goes from the composting and biogas processes on detoxified OPW (deoiled) to bioprocesses to bioethanol, chemicals, flavours and polymers. All these processes are prone to integration within the 2nd-generation biorefinery framework.

The application of the vermicomposting process in the bioremediation of diesel contaminated soils.

Polycyclic Aromatic Hydrocarbons (PAHs) are among the environmental pollutants that have very high carcinogenic and mutagenic activity. Among hundreds of different PAHs, 17 are considered priority pollutants and routinely monitored for regulatory purposes. Extended periods of exposure and expensive clean-up costs are typically associated with the vast majority of processes used for the remediation of areas contaminated with PAHs. The results of this study indicate that bioremediation via vermicomposting could be an effective method for remedying soils contaminated with toxic organic compounds, such as PAHs. This study was conducted over 90 days in the presence of various quantities of organic matter (cattle manure) to recover soils contaminated with PAHs. High-performance liquid chromatography (HPLC) was applied to identify PAHs. An evaluation of the toxicity of the final material and the transformation of the organic matter throughout the process was also conducted. The data presented here suggest a relationship between the molar mass of the PAHs and the ability of the vermicomposting process to promote biodegradation. These results suggest that vermicomposting has great potential to be utilized as a tool for the bioremediation of soils impacted by PAHs.