This book presents a state-of-the-art report on the treatment of pulp and paper industry effluents using anaerobic technology. It covers a comprehensive range of topics, including the basic reasons for anaerobic treatment, comparison between anaerobic and aerobic treatment, effluent types suitable for anaerobic treatment, design considerations for anaerobic treatment, anaerobic reactor configurations applied for treatment of pulp and paper industry effluents, present status of anaerobic treatment in pulp and paper industry, economic aspects, examples of full scale installations and future trends.

The pulp and paper industry is a large producer of wastewater and sludge, putting high pressure on waste treatment. In addition, more rigorous environmental legislation for pollution control and demands to increase the use of renewable energy have put further pressure on the pulp and paper industry’s waste treatment, where anaerobic digestion (AD) and the production of methane could pose a solution. Kraft pulping makes up 80% of the world production of virgin wood pulp, thus, the wastewaters from this sector represent a large unused potential for methane production. There are three main types of substrates available for AD at pulp and paper mills, the wastewaters, the primary sludge/fibre sludge, and the waste activated sludge. AD treatment of these streams has been associated with several challenges, such as the presence of inhibiting compounds or low degradability during AD. The aim of this thesis was to experimentally address these challenges and potentials, focusing on wastes from kraft mills. Methane potential batch tests showed that many wastewater streams still posed challenges to AD, but the alkaline elemental chlorine-free bleaching stream and the condensate effluents had good methane potentials. Further, the methane potential of kraft mill fibre sludge was high, and co-digestion of kraft mill fibre sludge and waste activated sludge was feasible in stirred tank reactors with sludge recirculation. By increasing the organic loading in a pilot-scale activated sludge facility and thereby lowering the sludge age, the degradability of the waste activated sludge was improved. The higher wastewater treatment capacity achieved by this method provides an opportunity for the mills to increase their pulp and paper production. Further, by dewatering the digestate after AD and returning the liquid to the activated sludge treatment, costs for nutrient supplementation can be reduced. In conclusion, the thesis shows that AD of wastes from the kraft pulp and paper industry was feasible and carried many benefits regarding the generation of methane as a renewable energy carrier, improved wastewater treatment and reduced costs. Different strategies on how AD may be implemented in the kraft pulp and paper industry were formulated and discussed. Produktionen av pappers- och massa genererar stora mängder avloppsvatten, vilket ställer höga krav på en effektiv vattenrening. Därtill har skärpta regler för utsläpp till vatten och luft tillsammans med en ökad efterfrågan på användning av förnyelsebar energi ytterligare ökat trycket på vattenreningen inom pappers-och massaindustrin, där anaerob nedbrytning med metanproduktion som följd skulle kunna utgöra en lösning. Produktionen av sulfatmassa (en kemiskt kokad pappersmassa) utgör 80% av den globala nyproduktionen av massa, vilket innebär att avloppsvatten från denna sektor representerar en stor outnyttjad potential för metanproduktion. Det finns huvudsakligen tre typer av substrat tillgängliga för rötning vid pappers- och massabruk, avloppsvatten, primärslam/fiberslam, och aktivt slam/överskottsslam. Flera utmaningar är kopplade till anaerob nedbrytning av dess strömmar, såsom förekomst av inhiberande ämnen eller låg nedbrytbarhet. Målet med avhandlingen var att bemöta dessa utmaningar, med ett särskilt fokus på behandling av avloppsströmmar från sulfatbruk. Metanpotentialtester visade att många av avloppsvattnen fortfarande var svåra att behandla med anaerob nedbrytning, men att alkaliska blekeriströmmar och kondensatströmmar vid sulfatbruk visade lovande metanpotentialer. Massafiber från sulfatoch sulfitbruk uppvisade höga metanpotentialer, och en stabil kontinuerlig samrötning av fiberslam och aktivt slam från sulfatbruk uppnåddes vid hög organisk belastning och låg hydraulisk uppehållstid i omrörda tankreaktorer med slamåterföring. Resultaten visade vidare att den låga nedbrytbarheten hos aktivt slam kunde bemötas genom att sänka slamåldern i den luftade anläggningen, med högre metanpotential i slammet som följd. Via denna metodik erhålles en högre vattenreningskapacitet, vilket innebär att bruken kan öka sin produktion av papper och massa. Dessutom kan rötresten avvattnas och den kvarvarande vätskan återföras till den luftade anläggningen för att minska behovet av näringstillsatser. Sammanfattningsvis visar avhandlingen att anaerob nedbrytning av avloppsströmmar från sulfatbruk var fullt möjlig och innebar många fördelar, i form av metanproduktion, förbättrad kapacitet för vattenrening och reducerade kostnader jämfört med dagens teknik. Olika möjligheter för implementering av anaerob teknik vid sulfatbruk har också formulerats och diskuterats.

Ce compte rendu porte sur les travaux de recherche, de développement et de démonstration de techniques anaérobies pour le traitement des eaux usées produites par l'industrie agro-alimentaire et celle des pâtes et papiers. On y traite des principes de base de la technologie anaérobie et de leur application dans des secteurs particuliers de ces industries. Sont également incluses des informations sur l'efficacité du processus anaérobie ainsi que des considérations de nature économique et énergétique.

Pulp and Paper Industry: Emerging Waste Water Treatment Technologies is the first book which comprehensively reviews this topic. Over the past decade, pulp and paper companies have continued to focus on minimizing fresh water use and effluent discharges as part of their move towards sustainable operating practices. Three stages—basic conservation, water reuse and water recycling—provide a systematic approach to water resource management. Implementing these stages requires increased financial investment and better utilization of water resources. The ultimate goal for pulp and paper companies is to have effluent-free factories with no negative environmental impact. The traditional water treatment technologies that are used in paper mills are not able to remove recalcitrant contaminants. Therefore, advanced water treatment technologies are being included in industrial wastewater treatment chains aiming to either improve water biodegradability or its final quality. This book discusses various measures being adopted by the pulp and paper industry to reduce water consumption and treatment techniques to treat wastewater to recover it for reuse. The book also examines the emerging technologies for treatment of effluents and presents examples of full-scale installations. Provides thorough and in-depth coverage of advanced treatment technologies which will benefit the industry personnel, pulp manufacturers, researchers and advanced students Presents new treatment strategies to improve water reuse and fulfill the legislation in force regarding wastewater discharge Presents viable solutions for pulp and paper manufacturers in terms of wastewater treatment Presents examples of full-scale installations to help motivate mill personnel to incorporate new technologies

Pulp and paper production has increased globally and will continue to increase in the near future. Approximately 155 million tons of wood pulp is produced worldwide and about 260 million is projected for the year 2010. To be able to cope with increasing demand, an increase in productivity and improved environmental performance is needed as the industry is also under constant pressure to reduce and modify environmental emissions to air and water. The authors give updated information on various biotechnological processes useful in the pulp and paper industry which could help in reducing the environmental pollution problem, in addition to other benefits. Various chapters deal with the latest developments in such areas as raw material preparation, pulping, bleaching, water management, waste treatment and utilization. The book also covers the environmental regulations in various parts of the world as well as the role of biotechnology in reducing environmental problems.