Ocorrência e caracterização de Giardia e Cryptosporidium em águas captadas para abastecimento público no município de Cajamar-SP e avaliação do risco

Introdução: O risco à saúde humana ocasionado pela contaminação biológica de águas captadas para abastecimento público é realçado pela ocorrência de surtos de doenças associadas aos protozoários Giardia e Cryptosporidium, que possuem baixas doses infecciosas e alta capacidade de sobrevivência no ambiente, além de serem capazes de resistir ao processo tradicional de desinfecção da água (cloração). Partindo-se da hipótese de que há um risco elevado de infecção por estes protozoários pela ingestão de água tratada por métodos convencionais e que fazem uso de mananciais superficiais impactados por contaminação biológica, resultando num possível incremento da incidência de diarréias, este estudo se propôs a verificar a ocorrência destes protozoários em águas captadas para abastecimento público no município de Cajamar-SP, caracterizar sua patogenicidade e avaliar o risco associado ao seu consumo através da água tratada. Métodos: Foram coletadas 48 amostras do ribeirão dos Cristais no ponto de captação da estação de tratamento de água, semanalmente, durante 12 meses (de 16/05/2013 a 21/05/2014). A detecção e a análise da concentração dos protozoários foram realizadas de acordo com Método 1623.1 da United States Environmental Protection Agency e a extração e caracterização dos espécies/genótipos de Giardia e Cryptosporidium foi realizada através metodologias moleculares e seqüenciamento. O risco de infecção pela ingestão de cistos de Giardia e oocistos de Cryptosporidium presentes na água tratada foi calculado usando a ferramenta da Avaliação Quantitativa do Risco Microbiológico, a partir dos dados de concentração dos patógenos obtidos pelo Método 1623.1, eficiência de remoção dos (oo)cistos durante o processo convencional de tratamento da água, modelo dose-resposta e taxa de ingestão diária de água para indivíduos menores de 5 anos e maiores de 21 anos. Resultados: Cistos de Giardia foram detectados em 83,3% das amostras (40/48), com concentrações variando desde o limite de detecção (<0,1) até 8,6 cistos/L. Oocistos de Cryptosporidium foram etectados em 37,5% das amostras (18/48), com concentrações variando desde o limite de detecção (<0,1) até 2 oocistos/L. As espécies/genótipos encontrados (Giardia intestinalis A e B e Cryptosporidium parvum e hominis) são característicos de contaminação antrópica e são frequentemente identificados em estudos epidemiológicos como responsáveis por surtos. A estimativa do risco anual de infecção por Giardia foi de 3,3x10-3 (IC95% 4,6x10-3) para crianças e de 11,5x10-3 (IC95% 13,3x10-3) para adultos, enquanto o risco por Cryptosporidium foi de 1,1x10-3 (IC95% 1,7x10-3) para crianças e de 3,9x10-3 (IC95% 5,0x10-3) para adultos. O incremento da incidência de diarréias foi observado no cenário de estudo após um acidente que resultou em transbordamento de esgotos não tratados no manancial, coincidindo com o aumento na detecção de (oo)cistos. Conclusão: Os resultados evidenciaram que a vulnerabilidade do ribeirão dos Cristais a contaminações biológicas pode culminar em um risco elevado de infecção e adoecimento por Giardia e Cryptosporidium através da ingestão de água tratada. Portanto, o caso é preocupante, tanto do ponto de vista do tratamento e abastecimento de água potável, quanto da degradação e contaminação do manancial, evidenciando a necessidade de se estabelecer medidas de intervenção direcionadas a promover a qualidade da água e garantir sua segurança

Disposição de resíduos gerados em estações de tratamento de água em estações de tratamento de esgoto

O presente trabalho foi realizado em duas fases. Na primeira, foram estimados os efeitos produzidos nos decantadores primários de uma ETE, após receber resíduo da ETA-SC, que utiliza sulfato de alumínio como coagulante. Foram realizados ensaios em colunas de sedimentação, onde os parâmetros SST, SSV, cor, turbidez, DQO, coliformes totais, Escherichia coli e parasitas, pesquisados no sobrenadante, diminuíram com o aumento da quantidade de resíduo adicionado. Com relação aos sedimentos obtidos nas colunas de sedimentação, foi encontrada maior quantidade de ST e menor resistência específica nos lodos provenientes das colunas que receberam os resíduos da ETA-SC. No teste de atividade metanogênica, a concentração molar de metano foi reduzida nos sistemas que receberam resíduo da ETA-SC, influenciando negativamente no desenvolvimento dos microrganismos metanogênicas. As espécies de microrganismos do gênero Methanothrix sp foram inibidas, sendo encontradas em maior número no frasco-reator controle e em menor quantidade a medida que se aumentou a quantidade do resíduo adicionado. Nesta etapa foi constatado que o resíduo da ETA-SC poderá apresentar interferências negativas sobre a digestão anaeróbia do lodo produzido em decantadores primários de uma ETE. Na segunda fase, na estação piloto, composta de lagoa de aeração seguida de lagoa de sedimentação, que recebeu resíduo da ETA-Fonte, que utiliza cloreto férrico como coagulante, foi verificado que tal resíduo melhorou a qualidade do efluente em termos de DQO, DBO, SST, turbidez, cor, amônio, nitrato, NTK e fosfato total. Os parâmetros ST, SDT, cloreto, nitrito, condutividade e pH não apresentaram diferenças significativas. Em relação ao exame microscópico não houve influências negativas no licor misto das lagoas de aeração. O lodo formado nas lagoas de sedimentação piloto apresentou-se em maior quantidade na lagoa que recebeu resíduo da ETA-Fonte. Neste lodo a resistência específica a filtração foi menor em comparação ao lodo da lagoa que não recebeu resíduo da ETA-Fonte. A desidratação deste lodo por centrifugação necessitou menor quantidade de polieletrólito. Baseado neste estudo não foi verificado interferências que possa impedir o lançamento do resíduo da ETA-Fonte na ETE-Araraquara.

Caracterização de água de lavagem de filtros em estações de tratamento de água de filtração direta

The water supply and treatment is considered as a great benefit considering that, if done efficiently, provides public health. However, considering the WTP (Water Treatment Plant) is an industry, with its inputs and waste generation, they must be constantly evaluated and monitored to verify the best and most appropriate way to process and dispose their waste, minimizing therefore the potential impacts to the environment. By volume, the most significant waste is the rapid filter backwash water. It is very common the disposal of this waste without treatment in water sources, which are used, for the most part, as a water supply source of a downstream population. This study evaluated quantitative and qualitative parameters in filter backwash water in three WTP - Itaitinga, Maranguape and Pacatuba, located in Ceará State, northeast of Brazil. It was found that the Maranguape WTP, in terms of treatment capacity, is the larger. The Itaitinga WTP is the one that consumes more water during filters washing. The Pacatuba WTP exhibited higher concentration of total suspended and settleable solids, COD and aluminum in the filters backwash water. It is noteworthy that the settleable solids and total suspended solids in all three WTP are above the effluent discharge standard recommended by Resolution 154/2002 of SEMACE (State Superintendent of Environment of Ceará). It was concluded that the filter backwash water from the study WTP exceeded the allowed values for legislation to be disposed directly into surface water bodies. It is suggested as an alternative to treat and recycle the filter backwashing water the construction of sludge settling ponds.

Composição do fitoplâncton e cianotoxinas em um reservatório utilizado para o abastecimento público: o efeito do tratamento de água convencional.

Florações de cianobactérias nocivas ocorrem frequentemente em reservatórios brasileiros, devido ao incremento de nutrientes pela eutrofização e pelas mudanças climáticas, como o aquecimento global. Estas florações alteram a qualidade dos corpos hídricos, produzindo compostos de gosto e odor e cianotoxinas, que representam um problema para as Estações de Tratamento de Água (ETAs). Estes compostos, quando dissolvidos na água dificultam os tratamentos convencionais. Além das cianobacérias, um dinoflagelado exótico tem ocorrido em águas doces brasileiras, incluindo reservatórios utilizados para o abastecimento público. Os reservatórios de Caxias do Sul (RS – Brasil) são gerenciados pelo Serviço Autônomo Municipal de Água e Esgoto (SAMAE) e apresentam um histórico de florações de cianobactérias nocivas, como Dolichospermum Bory de Saint-Vincent ex Bornet & Flahault e Microcystis (Kützing) ex Lemmermann, dentre outras. Além disso, desde 2012, tem ocorrido nestes reservatórios florações de Ceratium furcoides. Este organismo quando em extensas florações tem sido relacionado à perda da qualidade dos corpos hídricos. O reservatório Maestra foi construído entre os anos de 1965-1970 e abastece 22% da população de Caxias do Sul. Este reservatório fornece água para a ETA Celeste Gobatto, que utiliza o método convencional de tratamento da água. Este trabalho esta estruturado em três capítulos. O primeiro consiste de uma revisão bibliográfica de assuntos relavantes acerca do histórico do monitoramento da qualidade dos reservatórios no Brasil, da biologia de algas e cianobactérias, e as principais cianotixinas e acidentes devido à intoxicação no Brasil. Além disso, é feita uma breve revisão sobre o tratamento convencional da água, mostrando a importância de cada etapa para a remoção das impurezas, de acordo com os padrões de potabilidade da Portaria 2914. O segundo capítulo é manuscrito na forma de artigo científico intítulado “Composição de algas, cianobactérias e cianotoxinas no reservatório Maestra – Caxias do Sul, RS – Brasil”. Este estudo foi realizado entre janeiro de 2012 a abril de 2013. O terceiro capítulo consta de um manuscrito na forma de artigo científico, intitulado “Efeito do tratamento de água convencional na remoção de algas, cianobactérias e cianotoxinas em uma Estação de Tratamento de Água Convencional”. A eficiência de remoção foi avaliada em escala piloto, em uma Estação de Tratamento de Água de Caxias do Sul – RS a qual utiliza o método convencional de tratamento.

Aplicação de sistemas inteligentes à optimização de um sistema de tratamento de água

Um dos principais problemas que estação de Tratamento de Água do Monte Novo tem vindo a apresentar é o aparecimento de teores em manganês na água tratada, que por vezes ultrapassam o valor paramétrico estabelecido no Decreto-Lei 306/07, 27 de Agosto (50 g dm-3). Este trabalho permitiu relacionar resultados de várias determinações analíticas efectuadas no laboratório da empresa Águas do Centro Alentejo e, através deles construir modelos fundamentados em técnicas e Descoberta de Conhecimento em Base de Dados que permitiram responder ao problema identificado. Foi ainda possível estabelecer a época do ano em que é mais provável o aparecimento de teores elevados manganês na água tratada. Além disso, mostrou-se que a tomada de água desempenha um papel relevante no aparecimento deste metal na água tratada. Os modelos desenvolvidos permitiram também estabelecer as condições em que é provável o aparecimento de turvação na cisterna de água tratada. Estas estão relacionadas com o pH, o teor em manganês e o teor em ferro. Foi ainda realçada a importância da correcção do pH na fase final do processo de tratamento. Por um lado, o pH deve ser suficientemente elevado para garantir uma água incrustante e, por outro, deve ser baixo para evitar problemas de turvação na cisterna da água tratada. ABSTRACT; The present study took place in the water treatment plant of Monte Novo. This study aimed for solutions to the problem of high values of manganese concentration in the treated water, in some periods of the year. The present work reports models for manganese concentration and for turbidity using Knowledge Discovery Techniques in Data Bases.

Evaluación fisicoquímica y microbiológica del agua potable de la planta potabilizadora del cantón Chordeleg

tratamiento debe ser evaluado y controlado periódicamente, para garantizar su calidad para el consumo humano. El objetivo principal del presente estudio fue evaluar mediante un estudio físico-químico y microbiológico el Sistema de Calidad y Tratamiento del Agua que se efectúa en la Planta Potabilizadora del cantón Chordeleg. Se realizó un estudio no experimental, de campo, descriptivo y de corte no longitudinal. Para el análisis físico-químico se evaluaron 176 muestras en las 8 semanas, realizando 1 muestreo al día. En cada muestreo se realizó el análisis de 11 muestras que corresponden: 2 muestra de agua cruda, 2 muestras de agua pre-filtrada, 6 muestras de agua filtrada y 1 muestra de agua tratada realizándose un total de 22 muestras a la semana, en los cuales se determinó los parámetros físico-químicos: temperatura, sólidos totales disueltos, turbiedad y color, pH, dureza, alcalinidad, hierro, sulfato, nitritos, nitratos y cloro libre residual; parámetros microbiológicos: Coliformes totales y fecales. Los resultados obtenidos en las pruebas realizadas, mediante el análisis estadístico demostraron que los parámetros fisicoquímicos cumplen con lo establecido en la norma INEN 1108-2014, mientras que en los parámetros microbiológicos se estableció que los Coliformes fecales se encuentran dentro del rango establecido por la norma INEN 1108-2014 y los Coliformes totales fuera de lo establecido por la OMS(ausencia).

Nanofiltration for the treatment of coke plant ammoniacal wastewaters

This work addresses the treatment by nanofiltration (NF) of solutions containing NaCN and NH(4)Cl at various pH values. The NF experiments are carried out in a Lab-Unit equipped with NF-270 membranes for model solutions that are surrogates of industrial ammoniacal wastewaters generated in the coke-making processes. The applied pressure is 30 bar. The main objective is the separation of the compounds NaCN and NH(4)Cl and the optimization of this separation as a function of the pH. Membrane performance is highly dependent on solution composition and characteristics, namely on the pH. In fact, the rejection coefficients for the binary model solution containing sodium cyanide are always higher than the rejections coefficients for the ammonium chloride model solution. For ternary solutions (cyanide/ammonium/water) it was observed that for pH values lower than 9 the rejection coefficients to ammonium are well above the ones observed for the cyanides, but for pH values higher than 9.5 there is a drastic decrease in the ammonium rejection coefficients with the increase of the pH. These results take into account the changes that occur in solution, namely, the solute species that are predominant, with the increase of the pH. The fluxes of the model solutions decreased with increased pH. (C) 2010 Elsevier B.V. All rights reserved.

Expression of a plant-derived peptide harboring water-cleaning and antimicrobial activities.

Drinking water is currently a scarce world resource, the preparation of which requires complex treatments that include clarification of suspended particles and disinfection. Seed extracts of Moringa oleifera Lam., a tropical tree, have been proposed as an environment-friendly alternative, due to their traditional use for the clarification of drinking water. However, the precise nature of the active components of the extract and whether they may be produced in recombinant form are unknown. Here we show that recombinant or synthetic forms of a cationic seed polypeptide mediate efficient sedimentation of suspended mineral particles and bacteria. Unexpectedly, the polypeptide was also found to possesses a bactericidal activity capable of disinfecting heavily contaminated water. Furthermore, the polypeptide has been shown to efficiently kill several pathogenic bacteria, including antibiotic-resistant isolates of Staphylococcus, Streptococcus, and Legionella species. Thus, this polypeptide displays the unprecedented feature of combining water purification and disinfectant properties. Identification of an active principle derived from the seed extracts points to a range of potential for drinking water treatment or skin and mucosal disinfection in clinical settings.

Anaerobic treatment of deinking pulp plant effluents

Anaerobic treatment as a first biological stage in wastewater treatment is nowadays a well-established technology in recycled paper processing mills using closed water circuits. Today further developed high-rate processes and especially high-tower reactors are also able to handle lower organic loads and become therefore feasible for deinking pulp plant effluents. The interest in the anaerobic method is based on a positive energy balance in form of biogas production and low biomass yield from the process. The anaerobic treatment method was researched and its suitability for the deinking pulp plant effluents was tested experimentally at Stora Enso Maxau mill. In the theory, the deinking pulp process is introduced and the effluents from the deinking process are characterized. The anaerobic treatment is brought up in depth in terms of its use for the deinking effluents, and different kind of reactor types are presented. In addition, other wastewater treatment methods are shortly introduced with the focus on tertiary treatment. Static biodegradability tests were carried out for the wastewaters both anaerobically and aerobically. Based on the results, the deinking effluents can be degraded anaerobically, and inhibition to the methanogenic bacteria was not noticed. In the aerobic static test a good performance of the existing wastewater treatment plant at Maxau mill was proved. Later on pilot trials with sequential anaerobic-aerobic treatment were carried out for the deinking effluents. The anaerobic reactor used was a so called internal circulation reactor. The results confirmed that the combination of the anaerobic treatment and the aerobic activated sludge process is a suitable method for deinking wastewaters with a COD reduction as good as with a two stage aerobic method. When combined with the outstanding quality of the produced biogas and the cost savings acquired from the lower sludge production, the anaerobic treatment was found to be an especially favorable treatment method.

International Advanced Water Technologies Centre, IAWTC/LADEC and LUT 2013 : Questionnaire Responses from Russian Drinking Water and Wastewater Treatment Plants

In this report, information is published concerning Russian water and wastewater treatment plants. The information is based on a questionnaire sent to 70 water and wastewater treatment plants in 2012-2013. The questionnaire was prepared by the International Advanced Water Technologies Centre (IAWTC) and Lahti Development Company (LADEC). The questions dealt with an assessment of the present state, the need for changes, renovation, investments, and how to improve the efficiency of the operation by training and investments. A significant need to renew the old pipelines, constructions, and processes was clearly evident. The aggregated answers can be utilized in Russia as internal benchmarking in order to arrange training and plant visits, which were requested in many of the answers. Sharing this open report with the respondents can aid networking and awareness of HELCOM requirements which relate to waste water treatment plants discharging their waste water directly or indirectly into the Baltic Sea. The aim of this report is to provide information for Finnish small and medium size companies (SMEs) as regards possible water related exportation to different parts of Russia.

Eliminating non-renewable CO2 emissions from sewage treatment: An anaerobic migrating bed reactor pilot plant study

The aim of this work was to demonstrate at pilot scale a high level of energy recovery from sewage utilising a primary Anaerobic Migrating Bed Reactor (AMBR) operating at ambient temperature to convert COD to methane. The focus is the reduction in non-renewable CO2 emissions resulting from reduced energy requirements for sewage treatment. A pilot AMBR was operated on screened sewage over the period June 2003 to September 2004. The study was divided into two experimental phases. In Phase 1 the process operated at a feed rate of 10 L/h (HRT 50 h), SRT 63 days, average temperature 28 degrees C and mixing time fraction 0.05. In Phase 2 the operating parameters were 20 L/h, 26 days, 16 degrees C and 0.025. Methane production was 66% of total sewage COD in Phase 1 and 23% in Phase 2. Gas mixing of the reactor provided micro-aeration which suppressed sulphide production. Intermittent gas mixing at a useful power input of 6 W/m(3) provided satisfactory process performance in both phases. Energy consumption for mixing was about 1.5% of the energy conversion to methane in both operating phases. Comparative analysis with previously published data confirmed that methane supersaturation resulted in significant losses of methane in the effluent of anaerobic treatment systems. No cases have been reported where methane was considered to be supersaturated in the effluent. We have shown that methane supersaturation is likely to be significant and that methane losses in the effluent are likely to have been greater than previously predicted. Dissolved methane concentrations were measured at up to 2.2 times the saturation concentration relative to the mixing gas composition. However, this study has also demonstrated that despite methane supersaturation occurring, microaeration can result in significantly lower losses of methane in the effluent (< 11% in this study), and has demonstrated that anaerobic sewage treatment can genuinely provide energy recovery. The goal of demonstrating a high level of energy recovery in an ambient anaerobic bioreactor was achieved. An AMBR operating at ambient temperature can achieve up to 70% conversion of sewage COD to methane, depending on SRT and temperature. (c) 2006 Wiley Periodicals, Inc.

Optimization of flocculation process and continuous filtration for sea water primary treatment filtration to reduce SDI for entree to reverse osmosis system

Today , Providing drinking water and process water is one of the major problems in most countries ; the surface water often need to be treated to achieve necessary quality, and in this way, technological and also financial difficulties cause great restrictions in operating the treatment units. Although water supply by simple and cheap systems has been one of the important objectives in most scientific and research centers in the world, still a great percent of population in developing countries, especially in rural areas, don't benefit well quality water. One of the big and available sources for providing acceptable water is sea water. There are two ways to treat sea water first evaporation and second reverse osmosis system. Nowadays R.O system has been used for desalination because of low budget price and easily to operate and maintenance. The sea water should be pretreated before R.O plants, because there is some difficulties in raw sea water that can decrease yield point of membranes in R.O system. The subject of this research may be useful in this way, and we hope to be able to achieve complete success in design and construction of useful pretreatment systems for R.O plant. One of the most important units in the sea water pretreatment plant is filtration, the conventional method for filtration is pressurized sand filters, and the subject of this research is about new filtration which is called continuous back wash sand filtration (CBWSF). The CBWSF designed and tested in this research may be used more economically with less difficulty. It consists two main parts first shell body and second central part comprising of airlift pump, raw water feeding pipe, air supply hose, backwash chamber and sand washer as well as inlet and outlet connections. The CBWSF is a continuously operating filter, i.e. the filter does not have to be taken out of operation for backwashing or cleaning. Inlet water is fed through the sand bed while the sand bed is moving downwards. The water gets filtered while the sand becomes dirty. Simultaneously, the dirty sand is cleaned in the sand washer and the suspended solids are discharged in backwash water. We analyze the behavior of CBWSF in pretreatment of sea water instead of pressurized sand filter. There is one important factor which is not suitable for R.O membranes, it is bio-fouling. This factor is defined by Silt Density Index (SDI).measured by SDI. In this research has been focused on decreasing of SDI and NTU. Based on this goal, the prototype of pretreatment had been designed and manufactured to test. The system design was done mainly by using the design fundamentals of CBWSF. The automatic backwash sand filter can be used in small and also big water supply schemes. In big water treatment plants, the units of filters perform the filtration and backwash stages separately, and in small treatment plants, the unit is usually compacted to achieve less energy consumption. The analysis of the system showed that it may be used feasibly for water treating, especially for limited population. The construction is rapid, simple and economic, and its performance is high enough because no mobile mechanical part is used in it, so it may be proposed as an effective method to improve the water quality and consequently the hygiene level in the remote places of the country.

Fluoride Concentrations In The Water Of Maringá, Brazil, Considering The Benefit/risk Balance Of Caries And Fluorosis.

Current Brazilian law regarding water fluoridation classification is dichotomous with respect to the risks of and benefits for oral diseases, and fluoride (F) concentrations less than 0.6 or above 0.8 mg F/L are considered outside the normal limits. Thus, the law does not consider that both caries and fluorosis are dependent on the dosage and duration of fluoride exposure because they are both chronic diseases. Therefore, this study evaluated the quality of water fluoridation in Maringá, PR, Brazil, considering a new classification for the concentration of F in water the supply, based on the anticaries benefit and risk of fluorosis (CECOL/USP, 2011). Water samples (n = 325) were collected monthly over one year from 28 distribution water networks: 20 from treatment plants and 8 from artesian wells. F concentrations were determined using a specific ion electrode. The average F concentration was 0.77 mg F/L (ppm F), ranging from 0.44 to 1.22 mg F/L. Considering all of the water samples analyzed, 83.7% of them presented from 0.55 to 0.84 mg F/L, and according to the new classification used, they would provide maximum anticaries benefit with a low risk of fluorosis. This percentage was lower (75.4%) in the water samples supplied from artesian wells than from those distributed by the treatment plant (86%). In conclusion, based on the new classification of water F concentrations, the quality of water fluoridation in Maringá is adequate and is within the range of the best balance between risk and benefit.

Biodegradability and toxicity assessment of bleach plant effluents treated anaerobically

As part of an experimental project on the treatment of bleach plant effluents the results of biodegradability and toxicity assessment of effluents from a bench-scale horizontal anaerobic immobilized bioreactor (HAIB) are discussed in this paper. The biodegradability of the bleach plant effluents from a Kraft pulp mill treated in the HAIB was evaluated using the modified Zahn-Wellens test. The inoculum came from a pulp mill wastewater treatment plant and the dissolved organic carbon (DOC) was used as the indicator of organic matter removal. The acute and chronic toxicity removal during the anaerobic treatment was estimated using Daphnia similis and Ceriodaphnia silvestrii respectively. Moreover, the evaluation of chromosome aberrations (CA), micronucleus frequencies (MN) and mitotic index (IM) in Allium cepa cells were used as genotoxicity indicators. The results indicate that the effluents from the anaerobic reactor are amenable to aerobic polishing. Acute and chronic toxicity were reduced by 90 and 81%, respectively. The largest CA and MN incidence in the meristematic cells of A. cepa were observed after exposure to the raw bleach plant effluent. The HAIB was able to reduce the acute and chronic toxicity as well as chromosome aberrations and the occurrence of micronucleus.

Combination of an anaerobic process with O(3), UV and O(3)/UV for cellulose pulp bleaching effluent treatment

Recent studies have shown that partial oxidation by advanced oxidation processes (AOP) is able to transform hard-to-degrade compounds and increase their biodegradability. In this work, anaerobic treatment was followed by ozonation, UV radiation and ozonation in the presence of UV radiation, to treat bleaching effluents from a cellulose kraft Pulp plant. The anaerobic reactor (horizontal anaerobic immobilized Sludge bed, HAISB) was Used as a pretreatment to reduce the efficient organic load before applying ACIP. The ozone treatments were applied in three different pH environments (3, 8 and 10) with retention times of 10, 30, 45 and 60 min. COD and adsorbable organic halogens (AOX) removal efficiencies at the HAISB were approximately 50%, while the BOD removal efficiency reached 80%. Ozonation promoted further removal of AOX and COD so that the combined efficiency reached 96% for AOX and 70% for COD. In the oxidation process, BOD was either removed in small quantities or actually increased, as intended, so that a second biological treatment would be able to complete the treatment. The maximum increase in the BOD(5)/COD ratio (biodegradability indicator) Occurred at pH 8, reaching 104% for ozonation at a dosage of 1540 mg(O3).L(-1). Applying UV radiation alone resulted in lower values: a 34% increase ill the BOD(5)/COD ratio and a 76% AOX removal efficiency. These results indicate that the combination of anaerobic treatment with ozonation or ozonation/UV radiation improves the treatability of cellulose pulp bleaching efficients and that the resulting wastewater is suitable for further biological treatment under aerobic conditions with a low level of toxic compounds from the halogenated family.