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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Identification and evaluation of internal leakages of a BFB Boiler integrated within a pulp and paper mill.

Gomez, Adrian January 2018 (has links)
Alternative fuels like biomass have become really popular in the last decades as a substitute to fossil fuels. One of the most used technologies in Sweden for the obtention of the energy from the biomass is its direct combustion in a boiler. Bomhus Energi is a company with the purpose of creating steam and district heating for Billerudkorsnäs pulp and paper mill in Gävle and district heating for the city by operating a biomass BFB boiler. Despite being a quite new boiler, there are many sources of errors, losses and unnecessary costs. Between huge number of different losses that can happen in this kind of industrial boilers, the concern about internal leakages is not usually popular among plant designers and operators. This often leads to forget about them or not giving the importance that they could have.This study consists on, firstly, an analysis of different boiler equipment that have potential possibilities of internal leakages by mass and energy balances and by the tracking of possible mass losses. The second point of this thesis is to evaluate the cost of internal leakages that could have happen before, in order to be aware of how important they are. Additionally, measures are proposed in order to avoid or reduce the duration of the internal leakages, where the most common problem is the ignorance of their existence. This study focuses partially on the valve condition and maintenance. It is highly important to carry out valve maintenance procedures at least once per year during the general stop of the plant. Checking and verifying valve perfect conditions, can avoid a waste of a huge quantity of money just by replacing some internal elements that are possibly damaged due to the extreme working conditions. This small damages in valve can lead to a non-proper water tightening, which will be increasing its leakage over time. In the present paper, possible internal leakages through the valves belonging to the feedwater, steam drum, preheater and pressure vessel in general have been the principal aim. The key of this study was to take into account that biggest part of the draining system and valves that are supposed to be closed end in the Bottom blowdown tank. By then a deep study was done regarding this tank. The results show that there is a clear relationship between mass that is getting loss from feedwater tank and pressure vessel and the necessary cooling flow in the bottom blowdown tank. This means that if the cooling flow increases at the same rate as a possible leakage in mass and energy balance, there is an internal leakage somewhere in the system. The author proposes add an alarm to the DCS system in order to alert the plant operations of possible internal leakages. On the other hand, this paper also recommends to carry out a general valve maintenance per year and check which of them could be leaking, a general stop is the perfect time for carrying it out.In conclusion, the study finds that internal leakages can be even automatically detected if the system is provided with the necessary tools for it. The study concludes that internal leakages are not impossible to detect and their cost is non-negligible: the latest two internal leakages in the boiler, happened in the last two years, were from the feedwater draining system and from the steam drum heating loop with a total cost of 200,000 SEK (4240 SEK/day during 47 days) and 263,000 SEK (2120 SEK/day during 124 days) respectively. Additionally, days after the study, the plant general stop was carried out, finding that 12 valves were leaking due to internal damage. The cost of repairing the broken or damaged elements were almost negligible compared with the expected savings estimated in 2 Million SEK per year.
32

Development of technological competitiveness by integrating instruments and automation in process machinery

Kauppinen, S. (Sakari) 25 May 1999 (has links)
Abstract The Finnish chemical forest industry has undergone a profound structural change over the past two decades. The basic industry is increasingly focusing its product development investments on its own products and operations while the development of processes and process machinery is left to specialised companies. At the same time the purchases of the pulp and paper industry are becoming larger: there is a shift from single device purchases to larger functional units. This research studies the Finnish process machinery industry serving the needs of the pulp and paper industry and its product development environment and strategies, and evaluates the ability of selected case companies to design integrated process solutions. Particularly the role of measurement and automation technology in these solutions is under closer scrutiny. Aspects of product life cycles and technology management, together with various procedures and operating models for innovation and product development processes, are discussed on the basis of the literature. The empirical part of the research was carried out as a case study with several Finnish companies manufacturing machinery and equipment for the chemical forest industry. The results show that the strategies of the studied industry are still very much dominated by the traditional emphasis on machinery design and construction. The change in the customers' purchasing behaviour towards ever larger units and functions is reflected particularly as increasingly large delivery projects. The units required by the customers are put together in the project phase, using parts and components developed in isolation from each other. There is very little evidence of actual product development, design or producing of integrated process solutions. In those cases where the design work has explicitly aimed at an integrated functional unit, the result has been a process that the customer can easily purchase and where the supplier's expertise in processes and process control is already included in the package. Designing integrated process solutions takes more than technical expertise and capability: the strategy, organisation, and product development process of the supplier company must support the integration of different technologies and expertise areas in the product. Instead of the traditional serial product development it is imperative that the questions of process design, process machinery, and process control are treated and solved simultaneously. The in-house expertise and networking of research and development must be promoted in such a way that the capabilities necessary to include the required technologies and expertise areas in a product project are already available when the product is being specified and designed.
33

Isolation and characterization of the cellulose synthase promoters of Eucalyptus trees

Creux, N.M. (Nicole Marie) 01 July 2008 (has links)
Cellulose is one of the most abundant biopolymers on earth and is an important commodity for industries such as the pulp and paper industry. Cellulose is deposited into the plant cell walls by a complex of membrane bound enzymes known as cellulose synthases. A number of cellulose synthase (CesA) genes, which encode for different cellulose synthase proteins, have been identified from plant species such as Eucalyptus, Populus and Arabidopsis. Mutant and expression profile analysis of the CesA genes indicated that a set of three CesA genes are associated with secondary cell wall formation, while a different set of CesA genes are associated with primary cell wall formation. The aim of this study was to investigate the transcriptional regulation of the different members of the CesA gene family in Eucalyptus. The promoter regions were comparatively analysed with the orthologous regions in Arabidopsis and Populus using bioinformatics tools to identify putative regulatory motifs that playa role in CesA genes regulation. Six Eucalyptus CesA gene promoters were isolated using genome walking. The Eucalyptus promoter regions and the orthologous promoter regions from Populus and Arabidopsis were analysed using TSSP (Transcriptional start site plant promoter prediction) and NNPP (Neural network promoter prediction) software packages. The software packages predicted the transcriptional start sites of the genes and the core regulatory elements such as the TATA-box and initiator elements. The in silico results were compared among species and it was found that the predicted transcriptional start sites and the core elements of the CesA gene promoters showed substantial structural conservation. The promoter regions were used in a comparative in silico analysis with the orthologous promoter regions from Arabidopsis and Populus to identify putative regulatory motifs. This is the first study in which the promoters of the CesA gene family are characterized in Arabidopsis, Populus and Eucalyptus. Three software packages (Weeder, POCO and MotifSampler) were used to analyse the promoter regions and identify over-represented motif sequences. A number of key stem-specific and xylem-specific motifs such as the AC-motif and G-box motif were identified as well as a number of novel motifs. Although all of the predicted motifs identified here will have to be functionally tested, the results of this study provide a good map for directed deletion studies and functional testing of the CesA promoters. / Dissertation (MSc (Genetics))--University of Pretoria, 2009. / Genetics / unrestricted
34

Modelling of suspended solids effluent from a pulp and paper mill

Hedman, Jens January 2020 (has links)
This study examines the wastewater treatment system on BillerudKorsnäs integrated pulpand paper mill at Karlsborg, with focus on the effluent of suspended solids. Due to lowerregulatory limits for the emissions of suspended solids BillerudKorsnäs is looking forways to improve the efficiency of the wastewater treatment. Therefore, this study seeksto create a statistical model for the emissions of suspended solids and to find which factorsin the production, wastewater treatment and surrounding environment that affects theemissions. The purpose of the study is to extend the current understanding of the treatmentsystem to create a base for future decisions. The methods used for the modelling areElastic net regression and Random forest classifier, which were selected for the variableselection properties they provide. Unfortunately, the results show that the fitted modelscan only explain a small part of the variation of the emissions of suspended solids.The lack of fit in the models indicate that the current data is not sufficient to explain thevariation in the emissions of suspended solids. During the study deficiencies in the datacollection has been detected and improvements to overcome these deficiencies are proposedin the hope of creating more reliable data for the company and to create a betterbasis for future studies. / Denna studie undersöker avloppsvattenreningen på BillerudKorsnäs integrerade massaoch pappersbruket i Karlsborg, med fokus på utsläppen av suspenderade ämnen. Pågrund ut av sänkta gränser för utsläppen av suspenderade ämnen undersöker BillerudKorsnäsmöjligheter för att öka effektiviteten i avloppsvattenreningen. Därför försöker dennastudie att skapa en statistisk modell för utsläppen av suspenderade ämnen och undersökavilka faktorer i produktion, avloppsvattenrening, och omgivande miljö som påverkar utsläppen.Syftet med studien är att förbättra förståelsen för avloppsvattenreningen och attskapa beslutsunderlag för framtida förbättringar. Metoderna som används i modellernaär Elastic net regression och Random forest classifier, vilka valdes för deras variabel selectionegenskaper. Resultaten för modellerna visar att modellerna endast kan förklara enliten del av variationen i utsläpp av suspenderade ämnen. Det dåliga resultatet indikeraratt nuvarande data inte är tillräckligt för att skapa den typ av modeller som används. Understudien så har brister i datainsamlingen upptäckts, och förbättringar för att överbryggadessa brister är föreslagna med ändamål att göra insamlad data mer pålitlig och skapa enbättre bas för framtida studier.
35

Sludge from pulp and paper mills for biogas production : Strategies to improve energy performance in wastewater treatment and sludge management

Hagelqvist, Alina January 2013 (has links)
The production of pulp and paper is associated with the generation of large quantities of wastewater that has to be purified to avoid severe pollution of the environment. Wastewater purification in pulp and paper mills combines sedimentation, biological treatment, chemical precipitation, flotation and anaerobic treatment, and the specific combination of techniques is determined by the local conditions. Wastewater treatment generates large volumes of sludge that after dewatering can be incinerated and thus used for bio-energy production. Sludge is currently viewed as biofuel of poor quality due to its high water content, and some mills treat it solely as a disposal problem. Two strategies have been identified as feasible options to improve the energy efficiency of sludge management. One is drying using multi-effect evaporation followed by incineration. The other is anaerobic digestion of the wet sludge to produce methane. This thesis explores the energy balances of sludge management strategies in pulp and paper mills with special focus on anaerobic digestion. The first part consists of a system analysis, used to evaluate some wastewater treatment processes and sludge management, and the second part of empirical studies of anaerobic digestion of pulp and paper mill sludge. It was shown that the use of energy for aeration in aerobic biological treatment should be kept to the minimum required for acceptable quality of the processed water. Additional aeration for reduction of the generated sludge will only result in reduced energy generation in a subsequent methane generation stage. In the second part of the thesis, it is shown that anaerobic digestion is a feasible option for sludge management as it leads to production of high value biogas. Co-digestion with grass silage, cow/pig manure or municipal sewage sludge should then be used to counteract the low nitrogen content of pulp and paper mill sludge.
36

Utvärdering av avloppsvattenreningen vid Hallsta Pappersbruk : Kartläggning av inkommande avloppsvatten och optimering av driftparametrar

Ramberg, Anna January 2005 (has links)
<p>Hallsta paper mill uses large amounts of water during the pulp and paper making processes. The wastewater is treated in two separate activated sludge processes referred to as BIO 1 and BIO 2. The main aim is to reduce the organic substance content, measured as COD (Chemical Oxygen Demand) before the wastewater is released into the environment. Since the effluent produced is very rich in organic substances, the addition of nitrogen (N) and phosphorus (P) are necessary to give satisfactory treatment results. Problems with sludge bulking sometimes occur which lead to increased levels of suspended matter and nutrients in the effluent. Periods of high concentration of phosphorus is also of great concern. The aim of this study is to investigate the causality behind the sludge bulking, with the help of scientific literature and analysis of previously compiled data using multivariate data analysis. COD and nutrients present in the influent will also be surveyed to identify variations in concentration caused by the paper making process.</p><p>The scientific literature points toward low nitrogen and phosphorus levels as the major causes of the bulking sludge, as this leads to increased growth of filamentous bacteria to the detriment of the preferred flocculating species. A full scale experiment was conducted in an attempt to evaluate sufficient dosage levels of N and P to reduce this problem. The experiment has produced stabile results with low percentages of suspended organic matter and nutrients.</p><p>Evaluation of the previously collected data using Multivariate Data Analysis did not lead to any correlation between variables being found, other than the impact of sludge concentration on COD-reduction. No relevant explanation to periods of high phosphorus levels could be found neither in the scientific literature nor in the multivariate data analysis.</p><p>Bleaching of the paper pulp, with hydrogen peroxide and lye, results in a subsequent increase in COD concentration in the wastewater. The study shows an increased COD in the water approximately 12 hours after the increased dosing of these bleaching agents. Also the amounts of easily degradable COD increases following increased dosage of hydrogen peroxide and lye. The content of easily accessible phosphorus in the influent represents a minimum of 25 % and 20 % of the amount theoretically required for BIO1 and BIO2 respectively. The influent levels of nitrogen represents 33 % and 100 % for BIO1 and BIO2 respectively.</p><p>From this study it has been possible to deduce that a controlled dosage of nutrients in relation to the incoming level of COD, is of great importance to the efficient treatment of COD rich effluent in the systems under investigation at Hallsta Papermill.</p> / <p>Vid Hallsta Pappersbruk används stora mängder vatten vid tillverkningen av massa och papper. Det förorenade processvattnet renas i två separata anläggningar, BIO1 och BIO2, båda med biologisk rening av typen aktivt slam. Avloppsvattnets höga halter av kolföreningar, vilka analyseras som COD (Chemical Oxygen Demand), kräver extra tillsats av kväve och fosfor för att erhålla tillfredsställande reningsresultat. I den biologiska reningen uppstår periodvis problem med slamsvällning, något som resulterar i höga utsläpp av suspenderat material och organiskt bundna näringsämnen. Även perioder med höga fosforutsläpp förekommer. Syftet med examensarbetet är att genom litteraturstudier och analys av historiska data, med hjälp av multivariat dataanalys, utreda orsakerna till problemen. Även en kartläggning av variationerna i inkommande avloppsvatten med avseende på COD och lättillgängliga näringsämnen genomförs.</p><p>Utifrån information från litteraturen tyder problemen med slamsvällning ofta på bristande tillgång på kväve och fosfor vilket bland annat kan resultera i kraftig tillväxt av filamentösa bakterier. För att komma till rätta med problemen startades ett styrt försök med beräknade optimala doseringskvoter. Försöket resulterade i stabil drift för båda anläggningarna med låga utsläppsnivåer av både suspenderat material och näringsämnen.</p><p>Resultatet från utvärderingen av driftsdata med multivariat analys visar att slamhalten har betydelse för COD-reduktionen i BIO1. Någon förklaring till problemen med höga fosforutsläpp har inte framkommit vare sig ur litteraturstudie eller multivariat dataanalys.</p><p>Vid alkalisk oxiderande blekning av termomekanisk pappersmassa ökar den totala COD-koncentrationen i avloppsvattnet i samband med höjd dosering av blekkemikalier. Studien visar att en ökad COD-koncentration kan observeras i vattnet in till BIO1 ca 12 timmar efter förhöjd dosering av blekkemikalier. Samtidigt ökar andelen lättnedbrytbart COD till följd av ökad blekningsgrad. Kartläggningen av inkommande vatten visar att mängden lättillgängligt kväve i avloppsvattnet in till biologierna motsvarar ca 33 % och 100 % av det teoretiskt beräknade behovet för BIO1 respektive BIO2. För fosfor uppgår motsvarande till minst 25 % respektive 20 % för BIO1 och BIO2.</p><p>Under examensarbetets gång har det kunnat konstateras att dosering av närsalter i förhållande till inkommande mängd COD är av stor vikt för en väl fungerande rening av det COD-rika avloppsvattnet vid Hallsta Pappersbruk.</p>
37

Strategic raw material supply for the particleboard-producing industry in Europe : Problems and challenges

Trischler, Johann January 2016 (has links)
Particleboard was invented to increase the utilization of wood and it soon became an important core material for furniture production. Nowadays, other industries such as the pulp and papermaking industry and the thermal energy recovery industry claim the same type of raw material. This leads to increasing competition and higher prices than in the past when that kind of wood raw material was widely available and of low price. The particleboard-producing industry is therefore seeking opportunities to reduce the competition and ensure the future supply of lignocellulosic raw material for their products. The purpose of the work summarised in this thesis was to investigate the strategic supply of lignocellulosic raw materials for particleboard production and to evaluate alternatives for the supply of lignocellulosic raw material for particleboard production. To encompass the complex field of strategic raw material supply, several publications have considered different stages along the supply chain. These papers range from empirical studies to practical tests on a laboratory scale. In this thesis, some of the papers are linked together, building the base for the overall results. The results show that the task of increasing the supply of lignocellulosic raw material as primary raw material source is limited by several factors, but that improved product design coupled with a suitable recycling concept can greatly increase the availability of lignocellulosic raw material as a secondary source. Alternatively, the use of non-wood plants might be an opportunity to substitute wood as raw material but there are still some problems relating to the particle properties which must be overcome first.
38

The determination of core competencies of Sappi Forest Product Division as a basis of establishing future development

Khan, Imtiaz January 2004 (has links)
Thesis (M.B.A.)-Business Studies Unit, Durban Institute of Technology, 2004 iii, 111 leaves / The purpose of this study was to determine the core competencies of Sappi Forest Product division as a basis for establishing future developments. The literature focused on the resource-based view where the analysis of the firm’s internal resources and capabilities can be used as the starting point of strategy. / M
39

Obtenção de um efluente sintético do processo de branqueamento da indústria de papel e celulose / Obtainment of a synthetic effluent of the bleaching process in a pulp and paper mill

Momenti, Thiago José 10 May 2002 (has links)
A necessidade de produção de papel por processo ambientalmente corretos é um grande desafio. A polpa celulósica branqueada gera um dos efluentes mais problemáticos e estudados atualmente. O tipo de efluente na planta de branqueamento é mais importante que a quantidade gerada. O efeito da DBO no corpo receptor desse resíduo não é o principal problema, o problema está na geração dos compostos organoclorados, que estão dissolvidos nesse efluente. Muitas substâncias desse grupo são tóxicas e também podem ter efeitos carcinogênicos e mutagênicos. O estudo desse tipo de efluente em sistemas de tratamento biológico é de extrema importância e é tema de diversos trabalhos científicos. Entretanto, há algumas dificuldades relacionadas com a viabilidade de composição, a obtenção, o manuseio e o armazenamento de amostras desse tipo de efluente em laboratórios de pesquisa. O objetivo desse trabalho foi, portanto, obter um efluente sintético em escala laboratorial, sob condições controladas, que pudesse simular o comportamento de um efluente gerado em uma planta de branqueamento, quando em um sistema de tratamento biológico. Para isso, partiu-se de uma amostra de polpa celulósica não-branqueada e realizou-se a etapa de branqueamento no laboratório sob condições semelhantes às industriais, obtendo-se assim, o efluente desejado, que foi chamado de Efluente Sintético. A comparação foi realizada através da caracterização físico-química deste efluente e de um efluente de uma planta industrial de branqueamento, chamado de Efluente Industrial. Reatores anaeróbios operando em batelada foram utilizados para avaliação do comportamento destes influentes de tratamento biológico. Observou-se que o comportamentos de ambos os efluentes pôde ser considerado semelhante. A avaliação foi feita através do acompanhamento da produção de gás metano e eficiências de remoção de DQO e AOX. / The necessity of producing paper by environmental friendly processes is a big challenge; bleached cellulose pulp produces one of the most problematic and studied kind of effluent nowadays. The kind of effluent produced in the bleaching mill is more important than the quantity of this effluent. The effect of the BOD of this effluent in the receiving water is not the main problem, the problem is on the generation of organochlorines compounds that are dissolved in this effluent. A lot of substances of this group are toxic and can show carcinogenic and mutagenic effects. The study of effluent in biologic systems of treatment is extremely important and is theme of a variety of scientific works. However, there are some difficulties related to the variability of composition, the obtainment, the handling and the storage of samples of this kind of effluent in a research laboratory. Therefore, the purpose of this work was to obtain a synthetic effluent in a laboratory scale, under controlled conditions, that could simulate the behavior of an effluent produced in a bleaching mill, when in a biological system of treatment. For this, it was used a sample of a unbleached cellulose pulp and it was done the stage of bleaching in the laboratory under similar conditions to the mill\'s, obtaining in this way the desired effluent, that was called Synthetic Effluent. It was done a comparison between this effluent and a bleaching mill effluent, that was called Industrial Effluent, by a physical and chemical characterization. It was used anaerobic batch reactors to make a evaluation of the behavior of these effluents in a biological system of treatment. It was observed that the behavior of both effluents can be considered similar. The evaluation was done by the observation of methane gas production and by the efficiencies of COD and AOX removal.
40

Avaliação da degradação ambiental por meio de testes de toxicidade com sedimento e de análises histopatológicas em peixes / Evaluation of environmental degradation by means of sediment toxicity tests and histopathological tests on fish

Meletti, Paulo Cesar 14 August 2003 (has links)
As cidades e as atividades industriais e agrícolas geram uma infinidade de substâncias, muitas vezes desconhecidas, que quando lançadas nos corpos de água receptores podem por em risco a biota local e até mesmo a saúde humana. O presente trabalho avaliou o estado de degradação ambiental nas bacias dos rios Piracicaba, Mogi Guaçu (ambas no estado de São Paulo) e Tibagi (estado do Paraná), tendo como ferramentas os testes de toxicidade de sedimentos com peixes, em laboratório e in situ, análises histopatológicas dos animais expostos e análises físicas e químicas da água e do sedimento. Foram realizadas, ainda, análises das alterações histológicas em peixes expostos ao efluente final de indústria de papel e celulose, atividade presente nas três bacias estudadas. Os organismos-teste selecionados foram a espécie nativa de peixe Serrapinnus notomelas (Characiformes, Characidae) e a espécie padronizada, exótica, Danio rerio (Cypriniformes, Cyprinidae). As preparações histológicas foram realizadas com os peixes inteiros, possibilitando a análise dos órgãos-alvo brânquias, rim e fígado, em um mesmo corte. Nenhum organismo morreu após 96 horas de exposição às amostras de sedimento. No entanto, as análises histológicas revelaram alterações importantes, as quais foram sistematizadas para o cálculo do Índice de Alterações Histológicas (IAH) e do Valor Médio de Alterações (VMA), por órgão e por espécie, para cada localidade estudada. Os sedimentos provenientes das localidades de Sumaré (rio Atibaia) e de Piracicaba (rio Piracicaba) foram os mais tóxicos a ambas as espécies, de acordo com os índices calculados, seguidos pelos sedimentos de Campinas (rio Atibaia), Limeira (rio Jaguari) e Americana (rio Piracicaba). Os sedimentos da bacia do rio Mogi Guaçu foram menos tóxicos, mas aqueles provenientes das localidades Mogi Guaçu e Luiz Antônio (ambos a jusante de indústrias de papel e celulose) provocaram alterações renais e hepáticas significativas em D. rerio. Apesar de terem sido observadas alterações importantes nos peixes de ambas as espécies, expostas aos sedimentos da bacia do rio Tibagi, estas não foram tão intensas e freqüentes como aquelas observadas nos peixes expostos aos sedimentos das localidades das outras bacias hidrográficas. As análises físicas e químicas comprovaram a crítica situação de degradação do ambiente aquático na bacia do rio Piracicaba e alertam para os cuidados que deverão ser tomados com relação a esta e às bacias dos rios Mogi-Guaçu e Tibagi, cujos recursos estão sendo cada dia mais explorados. As graves alterações observadas nas brânquias, rim e fígado dos peixes expostos ao efluente de indústria de papel e celulose indicaram que o monitoramento da toxicidade desse tipo de efluente deve ser realizado por ferramentas mais sensíveis, tais como as análises histopatológicas em peixes. / Urban and industrial activities generate a large number of substances, frequently unknown, that if discharged into water body receptors can put at risk the whole aquatic biota, as well as human health. The present work evaluated the state of environmental degradation in the basins of rivers Piracicaba, Mogi Guaçu (both in São Paulo state) and Tibagi (Paraná state), using as tools the toxicity tests with sediments and fishes as test-organisms, for both laboratory and in situ evaluations, together with histopathological analyses of exposed animals and chemical and physical analysis of sediments and water. Also, histological alterations in fishes exposed to the final pulp-mill effluent were analyzed. The species selected as test-organisms were the native species of fish Serrapinnus notomelas (Characiformes, Characidae) and the standard exotic species Danio rerio (Cypriniformes, Cyprinidae). Hystological preparations were performed with whole fish specimens, what allowed the analysis of the target-organs: gills, kidney and liver in the same section. No fish mortality was found after 96 hours exposition to the sediment samples. Nevertheless histological analyses revealed important alterations, which were used to calculate the histological alteration index (IAH) and the mean value of alterations (VMA), for each organ and species, in each locality evaluated. Sediments coming from Sumaré (Atibaia river) and Piracicaba (Piracicaba river) were the most toxic to both species, according to the calculated index, followed by the sediments from Campinas (Atibaia river), Limeira (Jaguari river) and Americana (Piracicaba river). The sediments of Mogi Guaçu riber basin had a lower toxicity, but those coming from Mogi Guaçu and Luiz Antônio (both localities placed downstream pulp-mill plants) have caused significant alterations in kidney and liver of D. rerio. Although important alterations were found for both species of fish exposed to the sediments from Tibagi river basin, these were not as intense and frequent as those observed in the fishes exposed to the sediment from the other localities studied. Physical and chemical analysis corroborated the critical degree of environmental degradation of Piracicaba river basin and must be considered as an early warning for the measures that must be taken in relation to this and also to Mogi-Guaçu and Tibagi basins, where resources are increasingly being overexploited. The severe damage found in gills, kidney and liver of fishes exposed to the pulp-mill effluent suggest that monitoring this type of effluent must include a high sensibility tool, as the histopatological analysis on fish.

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