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Objective: To compare the carbon footprint of caesarean and vaginal birth., Design: Life cycle assessment (LCA)., Setting: Tertiary maternity units and home births in the UK and the Netherlands., Population: Birthing women., Methods: A cradle-to-grave LCA using openLCA software to model the carbon footprint of different modes of delivery in the UK and the Netherlands., Main Outcome Measures: 'Carbon footprint' (in kgCO 2 equivalents [kgCO 2 e])., Results: Excluding analgesia, the carbon footprint of a caesarean birth in the UK was 31.21 kgCO 2 e, compared with 12.47 kgCO 2 e for vaginal birth in hospital and 7.63 kgCO 2 e at home. In the Netherlands the carbon footprint of a caesarean was higher (32.96 kgCO 2 e), but lower for vaginal birth in hospital and home (10.74 and 6.27 kgCO 2 e, respectively). Emissions associated with analgesia for vaginal birth ranged from 0.08 kgCO 2 e (with opioid analgesia) to 237.33 kgCO 2 e (nitrous oxide with oxygen). Differences in analgesia use resulted in a lower average carbon footprint for vaginal birth in the Netherlands than the UK (11.64 versus 193.26 kgCO 2 e)., Conclusion: The carbon footprint of a caesarean is higher than for a vaginal birth if analgesia is excluded, but this is very sensitive to the analgesia used; use of nitrous oxide with oxygen multiplies the carbon footprint of vaginal birth 25-fold. Alternative methods of pain relief or nitrous oxide destruction systems would lead to a substantial improvement in carbon footprint. Although clinical need and maternal choice are paramount, protocols should consider the environmental impact of different choices., (© 2024 The Authors. BJOG: An International Journal of Obstetrics and Gynaecology published by John Wiley & Sons Ltd.)

The objective of this study was to estimate the carbon footprint (CF) of milk production (in kg of CO 2 equivalents (CO 2 e) per kg of fat and protein corrected milk (FPCM)) in dairy farms of the San Martín region, in the Peruvian Amazon. A cradle-to-farm gate characterization and analysis were carried out on eight representative dairy farms. Greenhouse gas (GHG) emissions were estimated using equations, following the 2019 refinement of the 2006 IPCC Guidelines. The results showed an average milk production of 9.7 ± 0.82 L milk/cow/day, Gyr x Holstein crosses as the predominant breed, use of cultivated grasses such as Brachiaria brizantha, living fences (Guazuma ulmifolia Lam) as the predominant silvopastoral arrangement, and low level of external inputs such as feed or grain additives. In relation to CF, an average value of 2.26 ± 0.49 kg CO 2 e/kg FPCM was obtained, with enteric fermentation being the most important source (1.81 ± 0.51 kg CO 2 e/kg FPCM), followed by manure management, land use, and energy/transport (0.26 ± 0.06, 0.14 ± 0.04, and 0.05 ± 0.04 kg CO 2 e/kg FPCM, respectively). Differences were found between farmers, obtaining lower CF values (1.76 vs 3.09 kg CO 2 e/kg FPCM) on farms with better feed quality, higher production levels, and a higher percentage of lactating animals compared to dry cows. It is concluded that dairy farms in the Peruvian Amazon region can reduce their emissions if they improve their current feeding practices., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Crop productivity maximization while minimizing carbon emissions is of critical importance for achieving sustainable agriculture. Socio-economic and ecological benefits should be taken together under the circumstance of stagnant farming profitability and climatic variability. The effectiveness of various mulching strategies in rain-fed semiarid areas has been confirmed, but scarce the comprehensive evaluations of the conventional and new mulching strategies in terms of yield, economic benefit, and carbon footprint based on life cycle assessment (LCA) have been conducted. Hence, a two-year field experiment was conducted on maize (Zea mays L.) crop to explore the effects of four mulching strategies (PM: plastic-film mulching, SM: maize straw mulching, BM: biodegradable-film mulching, and NM: no mulching) on the yield, net return, greenhouse gas (GHG) emissions, and carbon footprint (CF). The results revealed that PM and BM significantly increased maize yield by 11.3-13.3% and 9.4-10.6%. PM marginally raised the net return by 2.0-2.4% whereas BM slightly reduced it by 4.6-8.8% relative to NM. Unexpectedly, the yield and net return were the lowest under SM, and intensified N 2 O emissions, GWP direct , and yield-scaled GWP direct were observed. When the GHGs using LCA concept and SOC sequestration rate were considered, the lowest net GWP (1804.1-1836.4 kg CO 2 -eq ha -1 ) and CF (148.9-119.9kg CO 2 -eq t -1 ) were observed in the SM treatment due to the boost of soil organic carbon (SOC) sequestration. Conversely, PM and BM significantly increased the net GWP and CF compared to NM. When the tradeoffs between the high production, high net return and low net GWP were assessed by an integrated evaluation framework, the NM was recommended as an efficient low-carbon agricultural practice in the rain-fed semiarid areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A three-season field experiment was established and repeated twice with spring barley used as cover crop for different perennial grass-legume intercrops followed by a full year pasture cropping and winter wheat after sward incorporation. Two fertilization regimes were applied with plots fertilized with either a high or a low rate of mineral nitrogen (N) fertilizer. Life cycle assessment (LCA) was used to evaluate the carbon footprint (global warming potential) of the grassland management including measured nitrous oxide (N2O) emissions after sward incorporation. Without applying any mineral N fertilizer, the forage legume pure stand, especially red clover, was able to produce about 15 t above ground dry matter ha(-1) year(-1) saving around 325 kg mineral Nfertilizer ha(-1) compared to the cocksfoot and tall fescue grass treatments. The pure stand ryegrass yielded around 3t DM more than red clover in the high fertilizer treatment. Nitrous oxide emissions were highest in the treatments containing legumes. The LCA showed that the low input N systems had markedly lower carbon footprint values than crops from the high N input system with the pure stand legumes without N fertilization having the lowest carbon footprint. Thus, a reduction in N fertilizer application rates in the low input systems offsets increased N2O emissions after forage legume treatments compared to grass plots due to the N fertilizer production-related emissions. When including the subsequent wheat yield in the total aboveground production across the three-season rotation, the pure stand red clover without N application and pure stand ryegrass treatments with the highest N input equalled. The present study illustrate how leguminous biological nitrogen fixation (BNF) represents an important low impact renewable N source without reducing crop yields and thereby farmers earnings., (Copyright © 2015. Published by Elsevier B.V.)

A benchmark simulation model, which includes a wastewater treatment plant (WWTP)-wide model and a rising main sewer model, is proposed for testing mitigation strategies to reduce the system's greenhouse gas (GHG) emissions. The sewer model was run to predict methane emissions, and its output was used as the WWTP model input. An activated sludge model for GHG (ASMG) was used to describe nitrous oxide (N(2)O) generation and release in activated sludge process. N(2)O production through both heterotrophic and autotrophic pathways was included. Other GHG emissions were estimated using empirical relationships. Different scenarios were evaluated comparing GHG emissions, effluent quality and energy consumption. Aeration control played a clear role in N(2)O emissions, through concentrations and distributions of dissolved oxygen (DO) along the length of the bioreactor. The average value of N(2)O emission under dynamic influent cannot be simulated by a steady-state model subjected to a similar influent quality, stressing the importance of dynamic simulation and control. As the GHG models have yet to be validated, these results carry a degree of uncertainty; however, they fulfilled the objective of this study, i.e. to demonstrate the potential of a dynamic system-wide modelling and benchmarking approach for balancing water quality, operational costs and GHG emissions.

A multiple cropping system is beneficial for utilizing natural resources, while increasing the grain production and economic outputs. However, its impact on greenhouse gas emissions is unclear. The objective of this study was to evaluate the influence of rice-based cropping systems on methane (CH4) and nitrous oxide (N2O) emissions, the carbon footprint (CF), grain yields, and net economic returns in eastern China. Four treatments were applied: rice–fallow (as a control), rice–milk vetch, rice–wheat, and rice–rapeseed. Methane and N2O emissions were measured every 7 days via static chamber and gas chromatography methods from the 2019 rice season to the 2021 non-rice season. The CF was calculated based on the life cycle assessment. The results showed that multiple cropping systems significantly increased the annual grain yield by 1.2–6.4 t ha−1 and the annual CH4 and N2O emissions by 38–101 kg CH4-C ha−1 and 0.58–1.06 kg N2O-N ha−1, respectively. The average annual net returns for rice–wheat and rice–rapeseed were 131–150% greater than those for rice–milk vetch and rice–fallow. The annual CFs increased in the following order: rice–wheat (19.2 t CO2-eq ha−1) > rice–rapeseed (16.6 t CO2-eq ha−1) > rice–milk vetch (13.9 t CO2-eq ha−1) > rice–fallow (11.5 t CO2-eq ha−1). The CH4 emissions contributed to the largest share of the CF (60.4–68.8%), followed by agricultural inputs (27.2–33.7%) and N2O emissions (2.9–5.9%). Moreover, nitrogen fertilizer accounted for 65.6–72.4% of the indirect greenhouse gas emissions from agricultural inputs. No significant difference in the CF per unit grain yield was observed between the four rice-based cropping systems. The CF per net return of rice–wheat and rice–rapeseed significantly decreased by 37–50% relative to that of rice–fallow and rice–milk vetch. These findings suggest the potential to optimize rice-based cropping systems for environmental sustainability and grain security. [ABSTRACT FROM AUTHOR]

Abstract Background Health care has the intrinsic obligation to preserve health. This concept is also applicable to planetary health. Nitrous oxide (N2O) lacks clinical indications in modern anaesthesia, while it is a high-potential greenhouse gas. Its seemingly low cost contrasts with the consequential externalised socio-economic costs due to its contribution to the climate crisis, which is approximately €698 per emitted ton of CO2 equivalent. This difference can be internalised through emission taxation. In this study, we aim to evaluate how much N2O – total amount and converted to CO2 equivalent – is used at a German university hospital and compare this amount to that used at European hospitals. Furthermore, how the cost of N2O usage changes under different emission taxation scenarios is calculated. Methods This trial was a retrospective observational study at a German university hospital with approximately 1,250 beds between 2016 and 2020. Additionally, five European hospitals from the Health Care Without Harm Network were used for comparison from a European perspective. The main outcome parameters were the amount of N2O used, in total and converted to CO2 equivalent, and the total cost at emission taxation of €0, €25, €55 and €698 per ton CO2 equivalent. Results At the peak, 2,104 tCO2 equivalent in N2O was emitted in 2019. The actual cost was €14,040 in this year, while the corresponding socio-economic damage due to the climate crisis was almost €1.5 million. Other European hospitals showed comparable amounts of emissions. Conclusions The annual peak amount of emitted N2O corresponded to the total annual greenhouse gas emission of 188 people in Germany. To achieve a drastic reduction in use, the abandonment of recommendations by anaesthesiologic societies appears necessary, in addition to an internalisation of future costs via emission taxation, which will cause inadequate cost for a medication without relevant benefit or indication. To that end, the inclusion of health sector emissions within national or international greenhouse gas taxation, for example, the European Union Emissions Trading System, appears necessary and expedient in view of the urgent need to address the ecological transformation. Trial registration The trial was registered with the German Clinical Trials Register, identifier DRKS00024973 on 12/04/2021.

Background: Health care has the intrinsic obligation to preserve health. This concept is also applicable to planetary health. Nitrous oxide (N2O) lacks clinical indications in modern anaesthesia, while it is a high-potential greenhouse gas. Its seemingly low cost contrasts with the consequential externalised socio-economic costs due to its contribution to the climate crisis, which is approximately €698 per emitted ton of CO2 equivalent. This difference can be internalised through emission taxation. In this study, we aim to evaluate how much N2O – total amount and converted to CO2 equivalent – is used at a German university hospital and compare this amount to that used at European hospitals. Furthermore, how the cost of N2O usage changes under different emission taxation scenarios is calculated. Methods: This trial was a retrospective observational study at a German university hospital with approximately 1,250 beds between 2016 and 2020. Additionally, five European hospitals from the Health Care Without Harm Network were used for comparison from a European perspective. The main outcome parameters were the amount of N2O used, in total and converted to CO2 equivalent, and the total cost at emission taxation of €0, €25, €55 and €698 per ton CO2 equivalent. Results: At the peak, 2,104 tCO2 equivalent in N2O was emitted in 2019. The actual cost was €14,040 in this year, while the corresponding socio-economic damage due to the climate crisis was almost €1.5 million. Other European hospitals showed comparable amounts of emissions. Conclusions: The annual peak amount of emitted N2O corresponded to the total annual greenhouse gas emission of 188 people in Germany. To achieve a drastic reduction in use, the abandonment of recommendations by anaesthesiologic societies appears necessary, in addition to an internalisation of future costs via emission taxation, which will cause inadequate cost for a medication without relevant benefit or indication. To that end, the inclusion of health sector emissions within national or international greenhouse gas taxation, for example, the European Union Emissions Trading System, appears necessary and expedient in view of the urgent need to address the ecological transformation. Trial registration: The trial was registered with the German Clinical Trials Register, identifier DRKS00024973 on 12/04/2021. [ABSTRACT FROM AUTHOR]

Copyright of Anaesthesiologie & Intensivmedizin is the property of DGAI e.V. - Deutsche Gesellschaft fur Anasthesiologie und Intensivmedizin e.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The locally manufactured small-scale agricultural machinery in Egypt has recently acquired high importance in order to localize technology and innovation at the farm level. This study aims to design a cost-effective multi-seed planting raisedbed machine to rationalize water use and enhance land productivity in the Nile Delta of Egypt. The small farmers will adopt this technique to enable water, energy, seeds, and effort saving. The design of the machine went through a systematic process of tests to ensure that the design fit for purpose considering a set of design criteria such as soil type, crop type, and varieties as well as seeds size, planting rates, roads networks, farm sizes, cost-effectiveness, and available existing traction forces. The analyses using SolidWorks, a solid modelling computer-aided design and engineering application program, and Ansys simulation software were carried out to the loads and stresses subjected to different parts of the machine in order to identify the proper thickness and materials to manufacture the machine. Based on the stress and strain analysis, the machine structure and its components were designed. The main components of the machine include the main skeleton, seed drill box, planter seed box, feeding chambers, and cells as well as a feeding tube, gearbox, ditchers, ground-driving wheel and transmission mechanism, and mounting triangle. After building the machine components, various investigations were performed by subjecting the used materials to ascending loads to analyze shearing force, normal stress, shear stress, strain, and strength analysis in a micro meshes scale in all machine components. These tests enabled the identification of deformations, equivalent elastic strain, and Safety factor on different machine parts. The simulated values of the machine's parts in thicknesses and dimensions were in good correspondence and consistency with the actual design values. The model showed that the boundary conditions were accurate and rational, and it would provide a scientific basis for the optimum design of the raisedbed machine under multiple and interlinked loads. [ABSTRACT FROM AUTHOR]

The study investigates the relationship between carbon footprint and economic growth in Nigeria and Ghana over the period between 1990 and 2020 (31 years). The carbon footprint related variables used in the study include greenhouse gas emissions, renewable energy consumption, electricity consumption and trade openness. These variables have been regressed against gross domestic product per capita (a proxy for economic growth). The fully modified least square and panel dynamic least square have been employed for the main analysis of the study. The findings have revealed that greenhouse gas emissions and renewable energy consumption have a significant negative effect on economic growth in Nigeria and Ghana, while electricity consumption and trade openness have insignificant positive and negative relationships with economic growth respectively. The study recommends, among others, that the governments should initiate a carbon pricing law which should be implemented through tax policy specifically on the emissions from burning of biomass which consist of methane (CH4) and nitrous oxide (N2O) from the combustion of biomass in forest areas as well as carbon dioxide gas from the combustion of organic soils. High taxes will deter indiscriminate bush burning among others, resulting in lower environmental pollution and degradation. This measure will help reduce adverse greenhouse gas emissions and positively impact economic growth. [ABSTRACT FROM AUTHOR]

A multiple cropping system is beneficial for utilizing natural resources, while increasing the grain production and economic outputs. However, its impact on greenhouse gas emissions is unclear. The objective of this study was to evaluate the influence of rice-based cropping systems on methane (CH4) and nitrous oxide (N2O) emissions, the carbon footprint (CF), grain yields, and net economic returns in eastern China. Four treatments were applied: rice–fallow (as a control), rice–milk vetch, rice–wheat, and rice–rapeseed. Methane and N2O emissions were measured every 7 days via static chamber and gas chromatography methods from the 2019 rice season to the 2021 non-rice season. The CF was calculated based on the life cycle assessment. The results showed that multiple cropping systems significantly increased the annual grain yield by 1.2–6.4 t ha−1 and the annual CH4 and N2O emissions by 38–101 kg CH4-C ha−1 and 0.58–1.06 kg N2O-N ha−1, respectively. The average annual net returns for rice–wheat and rice–rapeseed were 131–150% greater than those for rice–milk vetch and rice–fallow. The annual CFs increased in the following order: rice–wheat (19.2 t CO2-eq ha−1) > rice–rapeseed (16.6 t CO2-eq ha−1) > rice–milk vetch (13.9 t CO2-eq ha−1) > rice–fallow (11.5 t CO2-eq ha−1). The CH4 emissions contributed to the largest share of the CF (60.4–68.8%), followed by agricultural inputs (27.2–33.7%) and N2O emissions (2.9–5.9%). Moreover, nitrogen fertilizer accounted for 65.6–72.4% of the indirect greenhouse gas emissions from agricultural inputs. No significant difference in the CF per unit grain yield was observed between the four rice-based cropping systems. The CF per net return of rice–wheat and rice–rapeseed significantly decreased by 37–50% relative to that of rice–fallow and rice–milk vetch. These findings suggest the potential to optimize rice-based cropping systems for environmental sustainability and grain security.

Copyright of Österreichische Wasser- und Abfallwirtschaft is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study was conducted to determine the carbon footprint of poultry farms. Breeder farms were included in the study. The fuel and electricity bills from farm, house size and age, flock size and number of flocks per year, and manure management were all collected. The methane, nitrous oxide, and carbon dioxide equivalent emissions were calculated, as well as the effect of these gases on breeder farms productivity, as well as determining the carbon footprint of breeder farms to reduce the negative effects of greenhouse gas emissions. In addition to providing necessary information on breeder's chicken performance and advising poultry farmers on the relative merits of different climatic conditions to help set standards for different production traits. The experiments were conducted of closed farms in the city of Mansoura during the period from May 2019 to December 2021 and the capacity of the farm was 43,300 breeders' chickens. The results showed that the amount of methane gas produced from the farm was 1.76 ton ch4 yr-1 and nitrous oxide gas was 0.13 ton n2o yr-1 for manure management. Thus, the total emissions of manure management are estimated at 81.65 tons of co2-eq. The amount of greenhouse gas emissions for diesel is 5.23 tons of co2-eq. The amount of greenhouse gas emissions (GHG) for the electricity used in the farm is 0.15 tons of co2-eq. In the end, the total amount of emissions produced from the farm is 87.04 tons of co2-eq. In the end, the total amount of carbon dioxide equivalent emissions generated from Egypt's farms is 271.8 (kiloton co2-eq). [ABSTRACT FROM AUTHOR]

An assessment was performed for elucidating the possible impact of different aeration strategies on the carbon footprint of a full-scale wastewater treatment plant. Using a calibrated model, the impact of different aeration strategies was simulated. The ammonia controller tested showed its ability in ensuring effluent ammonia concentrations compliant with regulation along with significant savings on aeration energy, compared to fixed oxygen set point (DOsp) control strategies. At the same time, nitrous oxide emissions increased due to accumulation of nitrification intermediates. Nevertheless, when coupled with the carbon dioxide emissions due to electrical energy consumption for aeration, the overall carbon footprint was only marginally affected. Using the local average CO2 emission factor, ammonia control slightly reduced the carbon footprint with respect to the scenario where DOsp was fixed at 2 mg·L−1. Conversely, no significant change could be detected when compared against the scenarios where the DOsp was fixed. Overall, the actual impact of ammonia control on the carbon footprint compared to other aeration strategies was found to be strictly connected to the sources of energy employed, where the larger amount of low CO2-emitting energy is, the higher the relative increase in the carbon footprint will be. HIGHLIGHTS Oxygen and ammonia control are compared using a calibrated full-scale wastewater model.; Ammonia control is found to enable savings on aeration energy (7–23%) while increasing N2O emissions.; Overall WWTP carbon footprint is affected by assumed CO2 emission factors for electrical energy.; Assuming the average local CO2 emission factor, ammonia and oxygen control show a similar carbon footprint.;

[Display omitted] • A pilot-scale MABR was operated after a demonstration-scale AnMBR. • The MABR achieved > 99 % removal of both sulfide and dissolved methane. • Energy requirement for the MABR operation was negligible (<0.05 kWh/m3). • > 99 % of produced N 2 O was recovered in off-gas from the gas permeable membranes. Anaerobic secondary treatment can enable energy-efficient removal of organic matter but may produce effluent containing dissolved methane and sulfide that must be managed before discharge or reuse. In this study, we operated a Membrane-aerated Biofilm Reactor (MABR) to achieve reliable removal of dissolved sulfide and methane from anaerobic secondary effluent at pilot-scale. The pilot-scale MABR was equipped with gas permeable polymethyl pentene (PMP) membranes, promoting surface growth of aerobic biofilm via diffusion-based aeration (lumen-to-surface diffusion). The system treated anaerobic secondary effluent from a demonstration-scale anaerobic membrane bioreactor (AnMBR) processing 90 m3/d primary effluent. MABR influent flow rate was increased from 8.2 to 32.7 m3/d to elevate substrate loading rates to the biofilm. The MABR consistently achieved >99 % removal of sulfide and dissolved methane, even at the maximum substrate loading rate: 2.3 g-S/m2/d for sulfide and 2.5 g-CH 4 /m2/d for dissolved methane. Despite effective sulfide and methane removal, incomplete nitrification (<25 % ammonia removal) occurred, with a portion of ammonia converted into nitrous oxide (N 2 O), a greenhouse gas 298 times more potent than CO 2. Operating the MABR incurred low energy costs: 0.01 to 0.05 kWh/m3 for the compressor supplying air to the membrane lumen and 0.01 kWh/m3 for the influent pump. An in-depth mass balance of N 2 O emissions from the MABR revealed that N 2 O was subject to counter-diffusion (surface-to-lumen diffusion) in which >99 % of the N 2 O produced within the biofilm was recovered in off-gas from the gas permeable membranes (hollow fibers). [ABSTRACT FROM AUTHOR]

The aim of the experiments was determine the amount of greenhouse gases emitted (nitrous oxide,ethane and carbon dioxide equivalent) resulting from poultry farms and the effect of these gases on energy productivity of poultry, as well as determining carbon footprint of laying hens production farms to reduce the negative effects of greenhouse gases emissions. In addition to providing necessary information on the performance of laying hens and providing guidance to poultry farmers on the relative merits of different climatic conditions to help set standards for different production traits. The experiments were conducted in one of the farms in the city of Mansoura during the period from June to October 2021 and the capacity of the farm was 40,000 laying hens. The results showed that the amount of methane gas produced from the farm was 0.4 ton CH4 yr-1 and nitrous oxide gas was 0.677 ton N2O yr-1 for manure management. Thus, the total emissions of manure management are estimated at 50.365 tons of CO2-eq. The amount of greenhouse gas emissions for diesel is 434.59 tons of CO2-eq. The amount of greenhouse gas emissions (GHG) for the electricity used in the farm is 8 tons of CO2-eq. In the end, the total amount of emissions produced from the farm is 492.96 tons of CO2-eq. [ABSTRACT FROM AUTHOR]

[Display omitted] • Testing a municipal wastewater treatment using bioelectrochemical techniques. • Improved treatment of wastewater from bioelectrochemical systems over control. • Bioelectrochemical systems displayed half Nitrous Oxide emissions over control. • Potential bioelectrochemical designs for future wastewater treatment identified. Reducing carbon footprint and greenhouse gas emissions are prime global goals. Wastewater treatment contributes significantly, and this study developed a technology with a focus on utilisation in small-decentralised plants. Bioelectrochemical systems (BES) utilise bacteria to remove pollutants while generating power and a range of experiments were performed to investigate their suitability compared to conventional trickling filters. A lab-based trickling filter was inferior to one adapted with electrodes both in terms of organic matter (COD) and phosphate reduction, but the BES did not generate electrical output due to inferior cathode configuration. An enhanced, novel, dual-BES system was developed with improved cathode positioning and operated as a cascade. This demonstrated improved COD (79 %) and total nitrogen (102 %) removal over the trickling filter. Concomitantly it emitted 47 % less N 2 O and generated an electrical output of 0.62 mA at 311 mV. Further work is needed to optimise BES but these results are encouraging in the development of sustainable biotechnologies. [ABSTRACT FROM AUTHOR]

Integrated farm system model (IFSM) is a cost effective and efficient method of estimating greenhouse gas (GHG) emissions from dairy farms and analyzing how management strategies affect these emissions. An IFSM (DairyGHG model) was employed in this study to predict the GHG emission and assess the carbon footprints of four dairy farms in Southeast Queensland, Australia. Four representative commercial farms were selected: Farm 1 (220 cows; Jersey), Farm 2 (460 cows; Holstein Friesian), Farm 3 (850 cows; Holstein Friesian) and Farm 4 (434 cows; Holstein Friesian). The animal emission contribution to carbon footprints for Farm 1, 2, 3 and 4 were 54.2, 60.0, 59.6 and 38.6 % respectively for total output. Likewise the manure emission contribution to carbon footprints for Farm 1, 2, 3 and 4 were 30.6, 29.0, 29.0 and 58.3 % respectively. On the basis of per kg of energy corrected milk the amount of GHG produced for Farm 1, 2, 3 and 4 are 0.39 kg CO2Eq, 0.64 kg CO2Eq, 0.54 kg CO2Eq and 1.35 kg CO2Eq respectively. The method and database developed for these dairy farm GHG assessments may be considered an important step towards a harmonized methodology for the quantification of emissions in dairy farms.

Nitrous oxide (N 2 O) emitted from biological nutrient removal activated sludge systems contributes significantly to the total carbon footprint of modern wastewater treatment plants. In the present study, N 2 O production and emissions were experimentally determined in a large-scale plant (220,000 PE) employing combined nitrogen (N) and phosphorus (P) removal. As a modelling tool, the Activated Sludge Model 2d (ASM2d) was extended with modules describing multiple N 2 O production pathways and N 2 O liquid-gas transfers. The new model was calibrated and validated using the results of laboratory experiments and full-scale measurements. Different operational strategies were evaluated following the proposed model-based procedure. Heterotrophic denitrification was found to be the predominant pathway of N 2 O production under both anoxic and aerobic conditions. This behaviour could primarily be attributed to the predominant abundance of heterotrophic denitrifiers over nitrifiers. Simulations revealed that the optimal solution for minimizing liquid N 2 O production is to set the dissolved oxygen concentration in the aerobic zone from 1 to 2 mg O 2 /L and to enhance the mixed liquor recirculation rate (MLR) (>500% of the influent flowrate) while not compromising effluent standards. Regarding the actual conditions, the potential reduction in the carbon footprint was estimated to be 10% by applying the proposed operational strategy. The results suggest that considerable improvements can be achieved without substantial upgrades and increased costs. Image 1 • An ASM2d-N 2 O model predicts liquid and gaseous N 2 O in the full-scale bioreactors. • Heterotrophic denitrification as predominant N 2 O production pathway. • N 2 O production mitigation via adjusting oxygen concentration and recirculation rate. • Potential 10% reduction in the total carbon footprint after optimization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reduce DO levels can effectively decrease N 2 O emissions. • NOB adaptation to low DO levels gradually appeared after 200 days of operation. • FA treatment combined with low DO suppressed NOB but increased N 2 O emissions. • FNA treatment combined with low DO suppressed NOB and did not affect N 2 O emissions. In mainstream partial nitritation/anammox (PN/A), suppression of nitrite oxidizing bacteria (NOB) and mitigation of N 2 O emissions are two essential operational goals. The N 2 O emissions linked to three typical NOB suppression strategies were tested in a covered rotating biological contactor (RBC) biofilm system at 21 °C: (i) low dissolved oxygen (DO) concentrations, and treatments with (ii) free ammonia (FA), and (iii) free nitrous acids (FNA). Low emerged DO levels effectively minimized NOB activity and decreased N 2 O emissions, but NOB adaptation appeared after 200 days of operation. Further NOB suppression was successfully achieved by periodic (3 h per week) treatments with FA (29.3 ± 2.6 mg NH 3 -N L−1) or FNA (3.1 ± 0.3 mg HNO 2 -N L−1). FA treatment, however, promoted N 2 O emissions, while FNA did not affect these. Hence, biofilm PN/A should be operated at relatively low DO levels with periodic FNA treatment to maximize nitrogen removal efficiency while avoiding high greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

The wastewater sector accounts for up to 7 and 10% of anthropogenic CH 4 and N 2 O emissions, respectively. Nowadays wastewater treatment plants are going through a paradigm shift to approach a net-zero carbon condition. Numerous ongoing measures have taken place to identify the sources of greenhouse gases and minimize the carbon footprint. This paper systematically reviews all known practices leading towards net-zero carbon wastewater treatment. The greenhouse gas emissions from the wastewater sector are identified and carbon footprint quantification tools, such as reliable models and emission factors are compared. The direct process emissions can contribute to over 60% of the carbon footprint in wastewater treatment plants, while around 30% of the carbon footprint is due to energy-related indirect emissions. Therefore, greenhouse gas mitigation via process optimization and energy usage in wastewater treatment plants are comprehensively described. The implantation of novel nitrogen removal processes can reduce both greenhouse gas emissions and energy consumption. Other techniques such as source separation systems can potentially allow mitigation of N 2 O emissions by 60% while avoiding energy-intensive nitrogen fertilizer production. Nutrient recovery methods are another approach which offer negative value for the net carbon footprint. Recovering N 2 O for energy production is a promising method which can lead to both direct and indirect carbon footprint reductions. Ultimately, to achieve full decarbonization any remaining emissions need to be offset, including carbon footprint of chemicals usage and transportation. [Display omitted] • Wastewater sector is going through a paradigm shift towards decarbonization • GHG emission hotspots are identified and emission factors are reviewed • WWTPs may be responsible for approximately 5% of total GHG emissions • Direct emissions can contribute to >60% of the carbon footprint in WWTPs • Process modifications and energy optimization play key roles towards net-zero WWTPs [ABSTRACT FROM AUTHOR]

Excessive application of synthetic nitrogen fertilizer and discharge of organic wastes were the primary sources of greenhouse gas (GHG) emissions in agricultural system. Synthetic nitrogen fertilizer substitution (NSS) practice by organic amendments was considered as a possible strategy to decrease the on-field N 2 O emission and simultaneously increase the soil organic carbon (SOC) and yield in cropping system. The effects of NSS practice on the trade-offs between crop yield and net greenhouse (NGHG) emissions have been still uncertain at a global level at present. This study carried out a joint use of meta-analysis, NGHG balance assessment and carbon footprint (CF) to quantitatively assess the effects of the NSS practices from multi-points. Results showed the NSS practice improved crop yield by 2.00 %, showing a positive effect at a global level, especially in rice and maize production systems. Meanwhile, the NSS practice significantly increased SOC storage by 23.97 %. For the on-field N 2 O and CH 4 emissions, the effect sizes varied large under different factors, without significant difference. The general trends were that the NSS practice decreased the average effect sizes of N 2 O emission and increased the average effect sizes of CH 4 emission. Standing at a farmland and system levels, the NSS practice increased the NGHGs and CFs both at the area and yield scales for paddy system. For upland cropping system, both of the yield-based and area-based CFs were reduced under the NSS practice due to the improved yields of wheat and maize. In conclusion, the NSS practice showed positive effects on improving crop yield and SOC storage at the global level but negative effect on decreasing the on-field GHG emissions. Crop type was the primary influencing factor. According to the current results, we assumed that the NSS would be an effective practice for upland cropping systems because it would generate the less NGHG emission and CF when producing unit mass of grain products. However, the NSS would not be a good practice for the rice production system. The results provided valuable information for the development of sustainable agricultural production in the world. • Effect of substituting synthetic N fertilizer by organic wastes (NSS) was analyzed. • A global meta-analysis, NGHG balance and carbon footprint were jointly used. • NSS practice showed positive effects on improving crop yield and SOC stock. • NSS practice showed negative effect on decreasing the on-field GHG emissions. • NSS was an effective practice for upland cropping system but not for rice system. [ABSTRACT FROM AUTHOR]

The livestock activity is linked to processes with environmental repercussions. Methane (CH4) and nitrous oxide (N2O) are two important greenhouse gases (GHG) emitted into the atmosphere by livestock during the processes of enteric fermentation and excreta management, which contribute to global warming. The objective of this paper was to review the amount of GHG emitted (kg CO2e) per kg of product generated from the main ruminant species (sheep, goats, buffaloes and bovines) used in tropical areas, under grazing conditions. For small ruminants, according to previous researches, emission intensities (EI) for meat was between 25 - 49.5 kg CO2e and for milk was within 5.5 and 11.2 kg CO2e; for buffaloes, EI was among 2.5 – 5.8 kg CO2e / kg FPCM and 21 – 70 kg CO2e / kg CW; for meat cattle, EI was amid 21- 76 kg CO2e; and for dairy cattle, EI was betwixt 2 – 9 kg CO2e. The differences found between the regional averages and the data for the same area of a country, can be due to different factors such as the quality of the pastures, level of intensification of the systems and climatic conditions.

Metal salts are widely used for the precipitation of phosphorus during wastewater treatment transforming soluble orthophosphate to an insoluble salt. In practice, more complex reactions are taking place including a reduction of the chemical solubility of dissolved greenhouse gases, such as nitrous oxide, present in the wastewater stream. In this respect, it was postulated that phosphorous precipitation will lead to artificial N2O stripping and hence to an increased carbon footprint of wastewater treatment plants. From lab-scale experiments utilizing N2O-saturated synthetic sewage solutions, it was evidenced that metal salt addition leads to N2O stripping with 20.8 g N2O per liter for a FeCl2-based precipitant to 26.4 g N2O per liter for a Aln(OH)mCl3n-m-based precipitant. Taking this maximum potential stripping effect into account for a carbon footprint analysis, a potential contribution of 16.11 kg CO2,eq·PE−1·a−1 was calculated in a case study, where FeCl3 was considered. With respect to the defined system boundary conditions, the overall on-site and off-site CO2 emissions were raised by 34% from 46.87 kg CO2,eq·PE−1·a−1 to 62.97 kg CO2,eq·PE−1·a−1 through CO2,eq coming from phosphorous precipitation. [ABSTRACT FROM AUTHOR]

Abstract Fugitive greenhouse gas (GHG) emissions in the form of nitrous oxide (N 2 O) and methane (CH 4) have been reported from many different wastewater treatment plants. However, the majority of the current literature only reports emissions during short periods of time and only focuses on one of the two GHGs. In this study, N 2 O and CH 4 emissions from the aerated parts of a plug-flow full-scale bioreactor treating municipal wastewater were studied over five months from November through March. A multiple gas hood collection system was used to simultaneously monitor the first three aerated compartments of the plug-flow bioreactor. Results show temporal variations in N 2 O emissions with N 2 O detected during November, no emissions during December and January, and a recovery of emissions from February onwards. In addition, different spatial emissions were found across the three aerated zones, with the highest N 2 O emissions detected in the second aerated zone. A daily N 2 O emission pattern was characterised by an N 2 O peak correlated with the ammonium that arrived in the monitored zone. However, CH 4 emissions occurred during the whole monitored period and showed a spatial variability inside the plug-flow bioreactor, presenting the highest emissions in the first aerated zone and then decreasing in the two subsequent zones. In addition, the dynamic carbon footprint (C-footprint) of the bioreactor is presented in which the contribution of the direct and indirect emissions (related to electricity consumption) is assessed. Results show that CH 4 emissions account for the majority of the direct emissions. Moreover, CH 4 and N 2 O emissions represent approximately 60% of the total emissions (direct and indirect) originating from the bioreactors. Graphical abstract Image 1 Highlights • Temporal and spatial GHG emissions monitored in a plug-flow full-scale bioreactor. • N 2 O emissions present temporal and spatial variability with periods of no emission. • N 2 O emissions were linked to the arrival of ammonium in the monitored zone. • Constant temporal CH 4 emissions were detected, showing only spatial variability. • CH 4 was the main contributor to the C-footprint, overcoming indirect emissions. [ABSTRACT FROM AUTHOR]

Abstract Water resource recovery facilities (WRRFs) contribute to climate change and air pollution, as they are anthropogenic potential sources of direct and indirect emission of greenhouse gases (GHGs). Studies concerning the monitoring and accounting for GHG emissions from WRRFs are of increasing interest. In this study, the floating hood technique for gas collection was coupled with the off-gas method to monitor and apportion nitrous oxide (N 2 O) and carbon dioxide (CO 2) emissions from both aerated and non-aerated tanks in a municipal water resource recovery facility, in order to investigate its carbon footprint (CFP). To our knowledge, this is the first time that the chamber technique was applied to evaluate gas fluxes from the settler, where an emission factor (EF) of 4.71 ∗ 10−5 kg CO2,eq kg bCOD −1 was found. Interesting results were found in the disinfection unit, which was the major contributor to direct N 2 O emissions (with a specific emission factor of 0.008 kg CO2,eq kg bCOD −1), due to the chemical interaction between hydroxylamine and the disinfectant agent (hypochlorite). The specific emission factor of the biological aerated tank was 0.00112 kg CO2,eq kg bCOD −1. The average direct CO 2 emission was equal to 0.068 kg CO2 kg bCOD −1 from the activated sludge tank and to 0.00017 kg CO2 kg bCOD −1 from the secondary clarifier. Therefore, taking into account the contribution of both direct N 2 O and CO 2 emissions, values of 0.069 kg CO2,eq kg bCOD −1, 0.008 kg CO2,eq kg bCOD −1 and 0.00022 kg CO2,eq kg bCOD −1 , were found for the net CFP of the aerated compartment, the disinfection unit and the clarifier, respectively. The plant energy Footprint (eFP) was also evaluated, confirming that the aeration system is the major contributor to energy consumption, as well as to indirect CO 2 emission, with a specific eFP of 1.49 kWh kg bCOD −1. Graphical abstract Unlabelled Image Highlights • CO 2 and N 2 O emitted during wastewater treatment in water resource recovery facilities • Floating hood technique utilised for gas collection • CO 2 and N 2 O emissions from aerated and non-aerated tanks • Comparison of two methods for the measurement of gas fluxes from non-aerated tanks • Contribution of disinfection process to N 2 O emissions from WRRFs [ABSTRACT FROM AUTHOR]

The livestock activity is linked to processes with environmental repercussions. Methane (CH4) and nitrous oxide (N2O) are two important greenhouse gases (GHG) emitted into the atmosphere by livestock during the processes of enteric fermentation and excreta management, which contribute to global warming. The objective of this paper was to review the amount of GHG emitted (kg CO2e) per kg of product generated from the main ruminant species (sheep, goats, buffaloes and bovines) used in tropical areas, under grazing conditions. For small ruminants, according to previous researches, emission intensities (EI) for meat was between 25 - 49.5 kg CO2e and for milk was within 5.5 and 11.2 kg CO2e; for buffaloes, EI was among 2.5 – 5.8 kg CO2e / kg FPCM and 21 – 70 kg CO2e/ kg CW; for meat cattle, EI was amid 21- 76 kg CO2e; and for dairy cattle, EI was betwixt 2 – 9 kg CO2e. The differences found between the regional averages and the data for the same area of a country, can be due to different factors such as the quality of the pastures, level of intensification of the systems and climatic conditions. [ABSTRACT FROM AUTHOR]

To comprehensively understand the effects of different fertilization regimes on carbon sequestration and greenhouse gas (GHG) emissions in apple orchard production systems, we assessed the carbon (C) emissions and nitrogen (N) losses along with the life cycle assessment (LCA) to quantify the carbon footprint (CF) and nitrogen footprint (NF) under different fertilization regimes in the Loess Plateau, China. The field experiment was comprising four N fertilizer regimes such as i) single inorganic fertilizer with 800 kg N ha−1 (N800); ii) single inorganic fertilizer with 400 kg N ha−1 (N400); iii) inorganic and organic fertilizers each with 200 kg N ha−1 (N200+O200) as well as without N fertilizer treatment as control (CK). Data regarding the soil organic carbon (SOC), nitrate N (NO 3 −–N), ammonium N (NH 4 +–N) and emissions of carbon oxide (CO 2) and nitrous oxide (N 2 O) were measured. Organic fertilizer substitution (OFS) boosted SOC while decreased NO 3 −–N and NH 4 +–N concentrations. The cumulative CO 2 emissions and emission factors (EFs) of N 2 O did not change significantly amongst fertilization strategies; however, as compared to N800, N400 and N200+O200 significantly reduced N 2 O emissions by 41.8%–45.7% and 43.5%–46.6% respectively. The NF was dominated by N residues (73.0%–97.4%) and organic fertilizer (24.37%), with a significant difference detected between N400 and N200+N200 treatments. Meanwhile, compared to inorganic plots, OFS significantly reduced CF (345.9%–368.0%), which was influenced by SOC sequestration. The CF from N plots in apple orchard was dominated by fertilizer (21.7%–39.6%), pesticides (4.3%–6.2%) and N 2 O (5.6%–11.8%). In addition, our results were further supported by a meta-analysis with 22 published studies, which showed that organic fertilizer and chemical fertilizer + organic fertilizer significantly reduced regional CF by 388.8% and 78.2%, respectively. However, regional NF ranged from 441.4 kg N-eq ha−1 to 453.9 kg N-eq ha−1, with no significant difference between fertilizer strategies. Therefore, reducing the amount of N fertilizer and partial OFS is a viable long-term strategy for mitigating climate change through C sequestration, reduction of N residues, and GHG mitigation, which could be beneficial to low C apple production in the Loess Plateau, China. [ABSTRACT FROM AUTHOR]

With rapid urbanization and infrastructure investment, wastewater treatment plants (WWTPs) in Chinese cities are putting increased pressure on energy consumption and exacerbating greenhouse gas (GHG) emissions. A carbon footprint is provided as a tool to quantify the life cycle GHG emissions and identify opportunities to reduce climate change impacts. This study examined three mainstream wastewater treatment technologies: Anaerobic–Anoxic–Oxic (A–A–O), Sequencing Batch Reactor (SBR) and Oxygen Ditch, considering four different sludge treatment alternatives for small-to-medium-sized WWTPs. Following the life cycle approach, process design data and emission factors were used by the model to calculate the carbon footprint. Results found that direct emissions of CO2 and N2O, and indirect emissions of electricity use, are significant contributors to the carbon footprint. Although sludge anaerobic digestion and biogas recovery could significantly contribute to emission reduction, it was less beneficial for Oxygen Ditch than the other two treatment technologies due to its low sludge production. The influence of choosing “high risk” or “low risk” N2O emission factors on the carbon footprint was also investigated in this study. Oxygen Ditch was assessed as “low risk” of N2O emissions while SBR was “high risk”. The carbon footprint of A–A–O with sludge anaerobic digestion and energy recovery was more resilient to changes of N2O emission factors and control of N2O emissions, though process design parameters (i.e., effluent total nitrogen (TN) concentration, mixed-liquor recycle (MLR) rates and solids retention time (SRT)) and operation conditions (i.e., nitrite concentration) are critical for reducing carbon footprint of SBR. Analyses of carbon footprints suggested that aerobic treatment of sludge not only favors the generation of large amounts of CO2, but also the emissions of N2O, so the rationale of reducing aerobic treatment and maximizing anaerobic treatment applies to both wastewater and sludge treatment for reducing the carbon footprint, i.e., the annamox process for wastewater nutrient removal and the anaerobic digestion for sludge treatment.

Integrated farm system model (IFSM) is a cost effective and efficient method of estimating greenhouse gas (GHG) emissions from dairy farms and analyzing how management strategies affect these emissions. An IFSM (DairyGHG model) was employed in this study to predict the GHG emission and assess the carbon footprints of four dairy farms in Southeast Queensland, Australia. Four representative commercial farms were selected: Farm 1 (220 cows; Jersey), Farm 2 (460 cows; Holstein Friesian), Farm 3 (850 cows; Holstein Friesian) and Farm 4 (434 cows; Holstein Friesian). The animal emission contribution to carbon footprints for Farm 1, 2, 3 and 4 were 54.2, 60.0, 59.6 and 38.6 % respectively for total output. Likewise the manure emission contribution to carbon footprints for Farm 1, 2, 3 and 4 were 30.6, 29.0, 29.0 and 58.3 % respectively. On the basis of per kg of energy corrected milk the amount of GHG produced for Farm 1, 2, 3 and 4 are 0.39 kg CO2Eq, 0.64 kg CO2Eq, 0.54 kg CO2Eq and 1.35 kg CO2Eq respectively. The method and database developed for these dairy farm GHG assessments may be considered an important step towards a harmonized methodology for the quantification of emissions in dairy farms. [ABSTRACT FROM AUTHOR]

The implementation of nitritation/denitritation (Nit/DNit) as alternative to nitrification/denitrification (N/DN) is driven by operational cost savings, e.g. 1.0–1.8 EUR/ton slurry treated. However, as for any biological nitrogen removal process, Nit/DNit can emit the potent greenhouse gas nitrous oxide (N 2 O). Challenges remain in understanding formation mechanisms and in mitigating the emissions, particularly at a low ratio of organic carbon consumption to nitrogen removal (COD rem /N rem ). In this study, the centrate (centrifuge supernatant) from anaerobic co-digestion of pig slurry was treated in a sequencing batch reactor. The process removed approximately 100% of ammonium a satisfactory nitrogen loading rate (0.4 g N/L/d), with minimum nitrite and nitrate in the effluent. Substantial N 2 O emission (around 17% of the ammonium nitrogen loading) was observed at the baseline operational condition (dissolved oxygen, DO, levels averaged at 0.85 mg O 2 /L; COD rem /N rem of 2.8) with ∼68% of the total emission contributed by nitritation. Emissions increased with higher nitrite accumulation and lower organic carbon to nitrogen ratio. Yet, higher DO levels (∼2.2 mg O 2 /L) lowered the aerobic N 2 O emission and weakened the dependency on nitrite concentration, suggesting a shift in N 2 O production pathway. The most effective N 2 O mitigation strategy combined intermittent patterns of aeration, anoxic feeding and anoxic carbon dosage, decreasing emission by over 99% (down to ∼0.12% of the ammonium nitrogen loading). Without anaerobic digestion, mitigated Nit/DNit decreases the operational carbon footprint with about 80% compared to N/DN. With anaerobic digestion included, about 4 times more carbon is sequestered. In conclusion, the low COD rem /N rem feature of Nit/DNit no longer offsets its environmental sustainability provided the process is smartly operated. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHG) emissions from enteric fermentation and manure management of different Indian livestock species were estimated from the latest Indian livestock population data published in 2012 using Intergovernmental Panel on Climate Change Tier 2 (2006) guidelines, and carbon footprints (CF) of different livestock products were assessed in different states of India. Indian livestock produced 304,030, 31,045 and 3978 Gg y −1 in CO 2 equivalent (CO 2 e) of enteric methane (CH 4 ), manure CH 4 and manure nitrous oxide (N 2 O), respectively in 2012. The contributions of GHG by cattle, buffalo, sheep, goat, pig and other animals were 55, 37, 4, 2, 1 and 1%, respectively. Enteric CH 4 was the major source of GHG, accounting for 89.7% of total GHG emissions, followed by manure CH 4 (9.2%) and N 2 O (1.2%). The CF values for milk, meat and eggs ranged widely among the different states of India. The average CF values of fresh milk production were considerably lower for crossbred cows (1.21 kg CO 2 e kg −1 ), followed by buffaloes (1.85 kg CO 2 e kg −1 ) and goats (2.54 kg CO 2 e kg −1 ), and were highest for indigenous cattle (2.96 kg CO 2 e kg −1 ). These trends were also observed for CF values expressed as GHG kg CO 2 e kg −1 milk protein. However, CF values in terms of GHG in kg CO 2 e MJ −1 milk energy output were similar for crossbred cattle and buffaloes (0.41 and 0.42 kg CO 2 e MJ −1 ), but were higher for goats (0.83 kg CO 2 e MJ −1 ) and indigenous cattle (1.0 kg CO 2 e MJ −1 ). The wide range of CF values for milk, meat and eggs in different states of India suggests that CF of livestock products could be reduced substantially through changes in the pattern of livestock population, adoption of improved breeding technologies or crossbreeding programs and status of intensification for different livestock species. [ABSTRACT FROM AUTHOR]

Direct and indirect greenhouse gases emissions of two model municipal WWTPs were estimated using carbon footprint analyses. One WWTP was designed with anaerobic digestion, the other one with simultaneous aerobic stabilization of sewage sludge. Emission factors were derived from literature values. For direct nitrous oxide emissions, a new estimation model based on measurements at eight Austrian WWTPs was applied. Results show that the direct nitrous oxide emission from the activated sludge tanks dominates the carbon footprint of WWTPs with a moderate nitrogen removal. Anaerobic digesters and anaerobic sludge storage tanks can also become a relevant source of direct methane emissions. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N 2 O), a potent greenhouse gas, significantly contributes to the carbon footprint of wastewater treatment plants (WWTPs) and contributes significantly to global climate change and to the deterioration of the natural environment. Our understanding of N 2 O generation mechanisms has significantly improved in the last decade, but the development of effective N 2 O emission mitigation strategies has lagged owing to the complexity of parameter regulation, substandard monitoring activities, and inadequate policy criteria. Based on critically screened published studies on N 2 O control in full-scale WWTPs, this review elucidates N 2 O generation pathway identifications and emission mechanisms and summarizes the impact of N 2 O on the total carbon footprint of WWTPs. In particular, a linear relationship was established between N 2 O emission factors and total nitrogen removal efficiencies in WWTPs located in China. Promising N 2 O mitigation options were proposed, which focus on optimizing operating conditions and implementation of innovative treatment processes. Furthermore, the sustainable operation of WWTPs has been anticipated to convert WWTPs into absolute greenhouse gas reducers as a result of the refinement and improvement of on-site monitoring activities, mitigation mechanisms, regulation of operational parameters, modeling, and policies. [Display omitted] • Standard sampling locations, frequency or duration ensure accurate N 2 O monitoring. • N 2 O emissions in WWTPs contribute considerably to the total carbon footprint. • Parameters control: precise aeration and preferred conditions for microbial growth. • Future work should revisit trade-offs between improved TN removal and N 2 O reduction. [ABSTRACT FROM AUTHOR]

Pyrolysis is a useful alternative to current waste management practices. Manure biochars can be used as C-rich soil amendments, reducing the risk of greenhouse gas (GHG) emissions derived from unpyrolyzed manure decomposition. In this study, two manure biochars and their feedstock were used as soil treatments to evaluate the impact of pyrolysis on CO 2 and N 2 O emissions, C stability, and global warming potential (GWP) for one year under field conditions. The experiment included five treatments: unamended soil (control), pig manure (PM), pig manure biochar (PMB), dairy manure (DM), and dairy manure biochar (DMB). The amendments were applied at a 1% w/w, adding approximately 0.5 kg C m−2. All amendments increased soil CO 2 emissions; however, C mineralization was lower in pyrolyzed manures than in their corresponding feedstocks. CO 2 –C emissions were 8.35%, and 63% of the C from biochar and manure treatments, respectively. Biochars reduced soil N 2 O emissions, producing a negative N 2 O emission factor (N 2 O Ef), whereas manure treatments induced N 2 O fluxes for 105 days, with an N 2 O Ef of 0.27% after one year. Soil C stock variations were 16.4 and 6.58 t CO 2 -eq avoided ha−1 in treatments of biochars and manures, respectively. The mitigation potential of unpyrolyzed manure was affected by the high CO 2 and N 2 O fluxes, whereas the biochar treatments reduced the GWP due to the changes in soil C stock with a low impact on soil emissions. Manure was more stable after pyrolysis, indicating that manure biochars are more favorable as soil amendments for environmental purposes. This could reduce the C footprint of pig and dairy farms, promoting the enhancement of soil C stocks. • C decomposition rate was 7.5 times lower in biochar than in manure. • The N 2 O emission factor of manure was 0.27%, while biochar did not produce avoided N 2 O emissions. • The application of pyrolyzed manure reduced 8 t CO 2 -eq ha−1 compared to the unpyrolyzed manure. [ABSTRACT FROM AUTHOR]

We used life cycle assessment methodology to determine the cradle-to-farmgate GHG emissions for rainfed wheat grown in monoculture or in sequence with the break crops canola (Brassica napus) and field peas (Pisum sativum), and for the break crops, in the south-eastern grains region of Australia. Total GHG emissions were 225 kg carbon dioxide equivalents (CO2-e)/t grain for a 3 t/ha wheat crop following wheat, compared with 199 and 172 kgCO2-e/t for wheat following canola and field peas, respectively. On an area basis, calculated emissions were 676, 677 and 586 kgCO2-e/ha for wheat following wheat, canola and field peas, respectively. Highest emissions were associated with the production and transport of fertilisers (23-28% of total GHG emissions) and their use in the field (16-23% of total GHG emissions). Production, transport and use of lime accounted for an additional 19-21% of total GHG emissions. The lower emissions for wheat after break crops were associated with higher yields, improved use of fertiliser nitrogen (N) and reduced fertiliser N inputs in the case of wheat after field peas. Emissions of GHG for the production and harvesting of canola were calculated at 841 kgCO2-e/ha, equivalent to 420 kgCO2-e/t grain. Those of field peas were 530 kgCO2-e/ha, equivalent to 294 kgCO2-e/t grain. When the gross margin returns for the crops were considered together with their GHG emissions, the field pea-wheat sequence had the highest value per unit emissions, at AU$787/tCO2-e, followed by wheat-wheat ($703/tCO2-e) and canola-wheat ($696/tCO2-e). Uncertainties associated with emissions factor values for fertiliser N, legume-fixed N and mineralised soil organic matter N are discussed, together with the potentially high C cost of legume N2 fixation and the impact of relatively small changes in soil C during grain cropping either to offset all or most pre- and on-farm GHG emissions or to add to them. [ABSTRACT FROM AUTHOR]