Search

Assessments of greenhouse gas (GHG) emissions in managed areas are facing various challenges. A non-flow-through, non-steady-state (NFT-NSS) chamber coupled to a frame permanently inserted into the landfilled substrates is a standard method for quantifying GHG emissions in managed areas, such as pulp and paper mill sludge (PPMS) landfill sites. Frequent measurements are needed to minimize uncertainties on GHG emission factors at the landfill site scale. However, maintaining a frame inserted into the substrates for a long time period is often impossible due to landfilling management operations. Therefore, GHG measurements using NFT-NSS chambers placed directly on substrates' surface could be an interesting option. Our objectives were to determine the relationships between CO 2 , CH 4 , and N 2 O fluxes measured with (F + ) and without (F-) a frame inserted in the substrates' surface and to develop correction factors for fluxes measured without a frame. Measurements were made at different PPMS landfill sites in the province of Québec, Canada. Stronger GHG flux relationships were observed at the provincial (across sites) than the specific site scale: the variance in GHG fluxes from F- chambers explained up to 80 % of variance in fluxes from F + chambers. The measured CO 2 , CH 4 , and N 2 O fluxes in F- chambers were on average 53, 78, and 63 % lower, respectively, than those estimated by the models at provincial scale. The correction factors developed with this approach could greatly extend the number of sites where in situ GHG measurements can be done and would help refining GHG inventories at the provincial and national levels., 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 © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Pulp and paper mill sludge (PPMS) is an organic residual generated from the wastewater treatments. PPMS management involves economic, environmental and social costs that will likely increase in the future as landfilling tends to be reduced or banned in certain jurisdictions. The reduction or the banning of landfilling may be considered as a climate change mitigation measure since organic waste disposal is normally associated with greenhouse gas (GHG) emissions. This critical review aims to (1) describe the variety of the current and emerging PPMS management practices that are alternatives to landfilling and (2) underline the crucial need for GHG emission assessments. The management practices of the three main PPMS types (primary, secondary and de-inking) comprised in this review are land application (agriculture, silviculture, land reclamation and composting), energy recovery (combustion, anaerobic digestion, pyrolysis, bioethanol, hydrogen production and direct liquefaction) and integration in materials (biocomposite, cement, asphalt and adsorbent–absorbent). Future research should focus to increase the comprehension of known GHG determinants from the PPMS management practices and reveal unknown factors. Life cycle analyses, based on direct GHG emission measurements, are needed to determine GHG emissions from current and emerging practices and plan a responsible future reduction or banning of landfilling. Such analyses will contribute to assist decision makers in implementing the best PPMS management practices with the least impact on climate change. [ABSTRACT FROM AUTHOR]

To reach the Paris Agreement targets of holding the global temperature increase below 2 °C above the preindustrial levels, every human activity will need to be carbon neutral by 2050. Feasible means for industries to achieve carbon neutrality must be developed and assessed economically. Herein we present a case study on available solutions to achieve net-zero carbon from the get-go for a planned liquefied natural gas (LNG) plant in Quebec, which would classify as a large Canadian greenhouse gas (GHG) emitter. From a literature review, available options were prioritized with the promoter. Each prioritized potential solution is discussed in light of its feasibility and the associated economic opportunities and challenges. Although net-zero carbon is feasible from the get-go, results show that the promoter should identify opportunities to reduce as much as possible emissions at source, cooperate with other industries for CO2 capture and utilization, replace natural gas from fossil sources by renewable sources and offset the remaining emissions by planting trees and/or buying offsets on the compliance and voluntary markets. As some of these solutions are still to be developed, to ensure timely net-zero pledge for the lifespan of the LNG plant, a portfolio and progressive approach to combine offsets and other options is preferable. [ABSTRACT FROM AUTHOR]

• Land application of pulp and paper mill sludge (PPMS) was compared to landfilling. • Impact of each scenario on greenhouse gas (GHG) emissions was assessed. • PPMS landfilling at pilot scale was a substantial source of GHG (N 2 O and CH 4). • Short-term emission factors from land application may be higher than from landfilling. • Long-term emission factors from landfilling could be the highest. Land application of pulp and paper mill sludge (PPMS) may replace landfilling in certain jurisdictions. However, the consequences of this change in management on greenhouse gas (GHG) emissions from PPMS are unknown. Land application may also entail temporary storage by landfilling due to a timing mismatch between PPMS production and application. We quantified direct GHG emissions from landfilled PPMS (pilot scale; N-rich and N-poor types) over two snow-free seasons, and after application of previously landfilled PPMS (LPPMS; < 6-month landfilled) to a clay loam soil cropped to wheat over one snow-free season. Landfilling of N-rich PPMS induced the highest GHG emission factor (EF; 0.26 Mg CO 2 -equivalent Mg−1 dry PPMS) and generated substantial N 2 O emissions (2% of landfilled N), which are neglected by the current assessment methods. Landfilling of N-rich PPMS also resulted in the highest CH 4 emissions (0.6% of landfilled C). Replacing urea with LPPMS to fulfill wheat N requirements did not change field N 2 O-N EFs (1.1–3.5% of applied N) and did not generate CH 4. Short-term (1–2 years) GHG (CO 2 -equivalent) EFs with landfilled N-rich PPMS were 0.54 to 4.48 times the EFs reported in the literature for land-applied PPMS. Long-term EF estimates suggest that landfilled PPMS may increase GHG emissions by up to three times compared to land application. Further research at the industrial scale is warranted to reduce uncertainty on GHG emissions from PPMS landfill sites, fulfill sustainable development goals and determine accurate carbon credits associated with changes in PPMS management practices. [ABSTRACT FROM AUTHOR]