Pulp and paper mill sludge management practices: What are the challenges to assess the impacts on greenhouse gas emissions?

Abstract

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.

Second Generation Bioethanol Production: On the Use of Pulp and Paper Industry Wastes as Feedstock

“…The effluent generated must be treated and most pulp and paper mills treat their own wastewater. Hence, besides rejects, like bark, branches, shives, and fine chips and spent sulfite or black liquors, the main organic waste resulting from the wastewater treatments is pulp and paper mill sludge (PPMS), which is also the largest waste stream generated in terms of volume presenting a low dry solid content [150,151]. Up to one metric ton of wet PPMS can be formed per ton of paper produced, due to the high quantity of water processed [26].…”

“…There is a great variability in PPMS properties, such as organic content, ash content, pH, and heating value. These properties depend on the type of raw material and input, the papermaking process and wastewater cleaning technique [151,152]. Also, the chemical composition of the PPMS produced in different pulp mills has a large variation.…”

“…There are three major PPMS types: primary sludge, secondary sludge, and de-inking sludge. Primary sludge is generated in the primary wastewater treatment, which consists mainly of physicochemical processes, like sedimentation and flotation [151]. Generally, primary sludge is the main mill-generated PPMS and is rich in cellulose fibers, being also composed by clay, ash, fillers, and other inorganic material.…”

PIROLISIS ISOTERMAL SLUDGE CAKE DAN PULP REJECT PABRIK PULP KRAFT (<i>ISOTHERMAL PYROLYSIS OF SLUDGE CAKE AND PULP REJECT FROM KRAFT PULP MILL</i>)

“…Pemanfaatan sludge cake kemungkinan akan meningkat di masa depan sebagai akibat jumlah landfill yang berkurang dan persyaratan yang semakin ketat. Pengurangan atau pelarangan landfill merupakan salah satu upaya mitigasi perubahan iklim karena pembuangan limbah organik dapat melepas gas CH 4 dikaitkan dengan emisi (GRK) gas rumah kaca (Faubert et al, 2016). Metode konversi termal (misalnya melalui proses pembakaran) telah diperkenalkan untuk menggantikan opsi landfill.…”

Pulp and Paper Mill Fly Ash: A Review

“…Currently, pulp and paper mill fly ash (PPFA) is often treated as a nonhazardous commercial waste product and is landfilled at a cost to producers and to society at large. However, landfilling will tend to be reduced or banned in the future due to stringent environmental regulations, rising disposal costs, and the scarcity of landfill space [3][4][5][6][7].…”