Isabel Capela

Application of life cycle assessment to the Portuguese pulp and paper industry

Abstract In this paper, the Life Cycle Assessment (LCA) methodology is applied to Portuguese printing and writing paper in order to compare the environmental impact of the use of two kinds of fuels (heavy fuel oil and natural gas) in the pulp and paper production processes. The results of inventory analysis and impact assessment show that the pulp and paper production processes play an important role in almost all of the analysed parameters, which do not always result in an important contribution to the corresponding impact categories. The substitution of heavy fuel oil by natural gas in the pulp and paper production processes seems to be environmentally positive.

Carbon dioxide emissions from forest operations in Portuguese eucalypt and maritime pine stands

Abstract A methodology for assessing fossil fuel-related carbon dioxide (CO2) emissions from operations performed in eucalypt and maritime pine stands was developed and applied to Portugal. This methodology includes all the operations carried out during site preparation, stand establishment, stand tending, logging and infrastructure establishment. For the year 2000, CO2 emissions for the entire area of maritime pine and eucalypt stands in Portugal were estimated to be 51 and 67 Gg CO2 year−1, respectively. These results demonstrate the more intensive nature of the management activities used in eucalypt stands, as these stands occupied an area approximately 30% smaller than maritime pine stands and produced only 5% more harvested wood than maritime pine stands. Wood logging accounted for approximately 40% of the total annual CO2 emissions in both stands. The results obtained from a sensitivity analysis suggest that annual CO2 emissions from eucalypt and maritime pine stands could be decreased by nearly 20% if, simultaneously, mowing is used instead of disking in clearing/cleaning operations, soil scarification is made by furrowing and ridging instead of ripping followed by subsoiling, and forwarders are used instead of modified farm tractors in wood extraction. A reduction of approximately 30% could be obtained for maritime pine stands if, in addition, natural regeneration is used instead of planting.

Evaluation of the environmental performance of printing and writing paper using life cycle assessment

The paper identifies and assesses the potential environmental burdens associated with the life cycle of printing and writing paper produced in Portugal from Eucalyptus globulus and consumed in Germany. Life cycle assessment methodology is applied in accordance with International Organization for Standardization standards. The life cycle of printing and writing paper covers the following stages: forest, pulp production, paper production, final disposal, energy production, chemical production and transports. The results suggest that pulp production processes have an important contribution to water emissions, resulting in a major contribution to eutrophication. Besides, it plays a major role in renewable energy consumption. Energy production in the grid, printing and writing paper production and transports contribute significantly to air emissions and to non‐renewable energy consumption, and consequently to global warming, acidification and non‐renewable resource depletion. Wastepaper landfilling assumes the predominant role in photochemical oxidant formation. Useful information is provided regarding the stages of the life cycle where improvements should be done in order to achieve an effective reduction of the environmental burdens.

Molasses as an external carbon source for anaerobic treatment of sulphite evaporator condensate.

Failures in stability and COD removal performance often occurred in full-scale anaerobic reactors treating the evaporator condensate from a sulphite pulp mill due to substrate inhibition and occasional contaminations with red liquor (wood cooking liquor). With this work, the beneficial effect provided by the continuous addition of an external carbon source (sugarcane molasses) on the overall performance and stability of the biological process was evaluated. With a moderate addition of molasses the inhibition was mitigated which led to an increase of the COD removal rate from 52% to 77% and a methane production increase from 460 to 1650mld(-1) at an organic loading rate of 2.61g CODl(-1)d(-1). A similar conclusion can be drawn for the case when contamination with red liquor occurs. These results suggest that sugarcane molasses addition may be regarded as a low-cost operational strategy for the anaerobic treatment of sulphite evaporator condensate.

Acidogenic Valorisation of High Strength Waste Products from Food Industry

Awareness concerning the environment and the use of clean technologies is growing worldwide. As a consequence, research on biodegradability and use of renewable resources for industrial processes has been intensive in the last years. In addition, product and process innovation in food industries is widely regarded as an essential element of competition between food companies, as it will improve their business performance. To face these new challenges, relevant changes in the food manufacturing processes may occur, involving for example the use of different raw materials as an ingredient in new food products. As a result, food processing wastewater will contain complex organic compounds with refractory properties that may compromise the biological treatment processes already existing in the wastewater treatment plants (WWTP) and consequently the fulfilment of legal requirements for wastewater discharge. To overcome this situation, segregation of specific wastewater process streams with refractory characteristics and its individual pre-treatment will be important for a viable and stable treatment in the already existing WWTP.