O lodo de esgoto gerado em estações de tratamento de esgoto pode conter substancias tóxicas ainda não regulamentadas nas legislações nacionais e internacionais. Dentre elas as genotóxicas tem recebido especial atenção. Este trabalho teve como objetivos avaliar a genotoxicidade de amostras de lodo de esgoto tratado de diferentes Estações de Tratamento de Esgoto (ETE) do Estado de São Paulo com o teste de micronúcleo em Tradescantia e ampliar os conhecimentos sobre o potencial de utilização da Tradescantia pallida em substituição ao clone 4430. Todas as ETEs estudadas apresentaram pelo menos uma amostra positiva para o teste de micronúcleo em Tradescantia sendo necessários mais estudos para elucidar quais os compostos são responsáveis pelo efeito observado. Os resultados sugerem que a Tradescantia pallida pode substituir o clone 4430 no teste de micronúcleo, porém esse ensaio tem aplicabilidade limitada em programas de monitoramento. / The sludge produced in sewage treatment plants can contain toxic substances which are not yet regulated by national and international legislation. Among these, the genotoxic substances are of great concern. The present paper aimed at evaluating the genotoxicity of treated sludge samples collected in different Sewage Treatment Plants (STP) located in the State of São Paul, Brazil. The micronucleus assay in Tradescantia was the test chosen for this evaluation. Another objective of the study was to verify it Tradescantia pallida could replace the clone 4430 in the Trad-MN assay. All the STPs studied have presented at least one positive sample for the micronucleus assay in the Tradescantia. Further studies are required in order to determine which compounds are responsible for the observed effect. The results obtained suggest that T. pallida can replace clone 4430 in the micronucleus assay, however, this assay presents limited applicability in monitoring programs.

Este estudo visou avaliar as implicações do uso da lise celular sobre a produção de lodos e acumulação de nutrientes no efluente do sistema combinado de tratamento (anaeróbio/aeróbio) de despejo sintético simulando esgoto sanitário. O sistema operado era constituído de reator UASB (V = 10,5 l), reator aeróbio (V = 4,4 l) e sedimentador (V = 2,7 l), operando com tempo de detenção hidráulica de 8,0 h, 3,5 h e 2,7 h respectivamente. Durante a fase de controle, acompanhou-se as características de funcionamento do processo sem o emprego da lise celular no lodo de excesso e posteriormente fez-se uso de equipamento de ultra-som para promover a lise do lodo, com retorno posterior do lodo lisado à entrada do reator UASB. Verificou-se que a eficiência média global de remoção de DQO do sistema foi de 90% em ambas as fases considerando DQO efluente filtrada. A conversão de nitrogênio amoniacal a nitrato foi pequena no tanque de aeração e a remoção de fósforo foi insignificante no processo de tratamento, no entanto não ocorreu alteração na qualidade do efluente do sistema em função do retorno do material lisado. Na escala estudada foi freqüente o aparecimento de bulking (controlado pela aplicação de hipoclorito de sódio no sedimentador), fato esse que dificultou a operação do sistema de tratamento e interferiu na manutenção do tempo de retenção celular. Os resultados obtidos da simulação realizada por meio do software GPS-X 4.0, para reator em escala real empregando a lise celular, mostraram acréscimo na concentração de fósforo total no efluente de 30% após 5 anos de operação / The aim of this research is to value the use of cell lyses over the sludge production and effluent nutrient accumulation from a combined treatment system (anaerobic/aerobic) from a synthetic sanitary wastewater. The parts of this system where one UASB reactor (V = 10,5 l), one aeration tank (V = 4,4 l) and one sedimentation tank (V = 2,7 l), hydraulic detention times of 8,0 h, 3,5 h e 2,7 h, respectively. During the control period, the characteristics of the system working without the use of cell lyses were recorded. After this phase, ultrasound equipment was used to cause the sludge lyses and then the sludge was returned to the entrance of the UASB reactor. From these tests we could not observe changes in mean global DQO removal efficiency for the both phases and it was 90% considering filtrated effluent COD. Few ammonia-nitrogen changes into nitrate inside the aeration tank were observed. Phosphorus removal in the treatment system was insignificant, but we could notice no damage to the treatment system caused by the lyses material returned. In the reduced scale of the system bulking events were frequent. This was controlled with sodium hypochlorite at the sedimentation tank, but these events caused operation difficulties and had interfered on the cellular detention time maintenance. Results from a real scale simulation, using cell lyses, done with the GPS-X 4.0 software, show an increase in effluent total phosphorus equal to 30% after 5 years

O presente trabalho avaliou a possibilidade de receber e tratar resíduo de tanques sépticos num sistema dimensionado para tratar esgoto doméstico. Neste sentido, o objetivo deste estudo foi avaliar o co-tratamento deste resíduo numa estação de tratamento de esgoto composta por processo de lodos ativados. Para a realização desta avaliação utilizou-se o modelo matemático ASM1 e o software WRc Stoat 5.0. O modelo ASM1 descreve a remoção de matéria orgânica carbonácea, a nitrificação e a desnitrificação. Para atender ao objetivo proposto, foram realizadas simulações de quatro grupo de cenários, sendo que em cada grupo a ETE operava com uma vazão fixa e foi alterada a parcela de resíduo de tanque séptico a ser tratada no sistema. Para a realização das simulações, previamente realizou-se a estruturação do modelo matemático ao sistema de tratamento selecionado, ajustes dos coeficientes estequiométricos e parâmetros cinéticos e determinaram-se as concentrações de entrada e o fracionamento da DQO e do nitrogênio para o esgoto bruto e para o resíduo de tanque séptico. As simulações geraram como resultado a possibilidade de, num sistema dimensionado para uma vazão média de 180 m3/h e operado com uma vazão de 45 m3/h de esgoto doméstico receber 4,3 m3/h de resíduo de tanque séptico sem comprometer os padrões de lançamento. Já, no caso da mesma ETE operando com 90 m3/h, 135 m3/h e 162 m3/h, as parcelas possíveis de serem recebidas de resíduo de tanque séptico e concomitantemente atendendo aos padrões de lançamento definidos na legislação foram 3,6 m3/h, 3,3 m3/h e 2,9 m3/h. Os resultados obtidos permitem concluir que é viável co-tratar resíduo de tanque séptico com o esgoto doméstico e ao mesmo tempo atender aos padrões de lançamento definidos na legislação, desde que respeitados os fatores limitantes e as cargas máximas. O recebimento e o tratamento do resíduo de tanque séptico em sistemas projetados para esgoto doméstico mostram-se como práticas que podem ser implantados na gestão dos sistemas de esgotamento sanitário. Esta aplicação poderia contribuir para ampliar a correta destinação dos esgotos e consequentemente com a melhoria dos índices de atendimento do esgotamento sanitário. / The present work evaluated the possibility of receiving and treating septic tank residue in a system designed to treat domestic sewage. Therefore, the objective of this study was to evaluate the co-treatment of this residue in a sewage treatment plant with an activated sludge process. The ASM1 model and software WRc Stoat 5.0 were used to perform this evaluation. The ASM1 model describes the removal of carbonaceous organic matter, nitrification and denitrification processes. To attend the proposed objective, simulations of four scenarios group were realized and in each group the system operated with a fixed flow and was changed the portion of septic tank residue. Before running the simulations, the mathematical model was structured to the selected treatment system, adjustments of the stoichiometric coefficients and kinetic parameters and were determined the inputs and fractionations concentration of the COD and nitrogen for the sewage and the septic tank residue. The simulation results show that is possible, in a system designed for an average flow of 180 m3/h and underloaded with a domestic sewage flow of 45 m3/h to receive 4.3 m3/h of septic tank residue without compromising the standards. For systems operating at 90 m3/h, 135 m3/h and 162 m3/h, the possible parcels to be received from septic tank residue without compromising standards defined in the legislation were, respectively, 3.6 m3/h, 3.3 m3/h and 2.9 m3/h. The results allow the conclusion that it is feasible to co-treat septic tank residue with domestic sewage and at the same time respect the standards defined in the legislation, once the limiting flowrates and maximum loads are respected. The acceptance and treatment of septic tank residue in systems designed for domestic sewage are practices that can be implemented in the management of sanitary sewage systems. That can be enplaned to improve the management of sewage systems, therefore, expanding the correct destination of wastewater and consequently contribute to the improvement of sanitary sewage index.

För att kunna möta framtidens striktare reningskrav för avloppsvatten och en ökad belastning på grund av befolkningstillväxt bygger Stockholm Vatten och Avfall (SVOA) om Henriksdals reningsverk inom projektet Stockholms Framtida Avloppsvattenrening (SFA). En av de större förändringarna i det framtida Henriksdals reningsverk är införandet av MBR-teknik, där slam och vatten avskiljs genom membranfiltrering. Separationen medför förändrade egenskaper hos slammet då en större andel av partiklarna kan avskiljas från utgående vatten jämfört med avskiljning från konventionella sedimentationsbassänger. På Hammarby Sjöstadsverk drivs en pilotanläggning där MBR-teknik undersöks inför implementering i framtida Henriksdals reningsverk. Denna studie har undersökt skillnader i mängd partiklar, organiskt innehåll, filtrerbarhet, sedimenteringsegenskaper och förtjockningskapacitet hos överskottslam från MBR-linjen på Hammarby Sjöstadsverk (ÖS-MBR) och Henriksdals reningsverk (ÖS-CAS). Detta för att ge underlag till optimering av framtida slambehandling på Henriksdals reningsverk. Därutöver har massbalans för förtjockningsförsöken beräknats. Resultatet av studien visar att egenskaperna hos ÖS-MBR och ÖS-CAS skiljer sig tydligt för torrsubstans (TS), totalt suspenderade partiklar (TSS) och filtrerbarhet (TTF). Ingen skillnad i slamvolymindex (SVI) kunde verifieras i studien. Efter förtjockning av slammen i en trumsil, med olika polymertillsats, uppvisade ÖS-MBR högre TSS i rejektvattnet än ÖS-CAS. Denna skillnad indikerar att partiklar i ÖS-MBR har mindre benägenhet att binda till polymeren som användes, än partiklar i ÖS-CAS. Det är därför av betydelse att pröva ut rätt typ av polymer vid förtjockning av ÖS-MBR, för att nå målet på en TSS under 1000 mg/L i rejektvattnet. Därtill uppvisade ÖS-MBR högre TS i det förtjockade slammet än ÖS-CAS. Detta skulle kunna indikera att ÖS-MBR är lättare att förtjocka än ÖSCAS, men det kunde dock inte bekräftas av massbalanserna. Slutligen kunde denna studie inte samstämmigt visa på en skillnad i potentialen att förtjocka de båda slammen då fördelningen av partiklar mellan förtjockat slam och rejektvatten varierade i varje försök. Däremot minskade TSS i rejektvattnet med högre dos av polymer medan samma samband inte gällde för TS i det förtjockade slammet där dosen polymer, efter en viss mängd, hade en begränsad påverkan på TS. En viktig aspekt som påverkade förtjockningskapaciteten i denna studie var igensättning av trumsilen. Centrifuger, som kommer att användas i framtida Henriksdals reningsverk, kommer inte uppvisa samma typ av störningar i driften. / To comply with future stricter regulations on treated wastewater and an increasing load on the system due to a growing population, the Stockholm Vatten och Avfall Company (SVOA) is upgrading the Henriksdal wastewater treatment plant within the project Stockholm’s Future Wastewater Treatment (SFA). One of the main changes in the future plant is the introduction of MBR-treatment, where sludge and water will be separated through the use of membranes. This separation will change the composition of the sludge by removing a larger fraction of particles from the effluent than what can be achieved in conventional sedimentation basins. Hammarby Sjöstadsverk operates a pilot plant with a MBR-process, where the technology is evaluated before the implementation in the future Henriksdal wastewater treatment plant. This study examines the difference in the sludge characteristics, i.e. sedimentation, filterability, and the potential for thickening of excess sludge from the MBR-process in Hammarby Sjöstadsverk (ÖS-MBR) and from the activated sludge process in the current Henriksdal wastewater treatment plant (ÖS-CAS). Furthermore, a mass balance and a sensitivity analysis has been used within this study. The study aimed at providing decision support for optimisation of the sludge treatment at the future Henriksdal wastewater treatment plant once the MBR process is implemented. The results of this study show that the characteristics of ÖS-MBR and ÖS-CAS differ considerably in total solids (TS), total suspended solids (TSS) and filterability (TTF). No difference in sludge volume index (SVI) could be verified between the two types of sludges. After thickening in a rotary drum screen with different doses of polymer, the TSS in the reject water was higher for the ÖS-MBR than the ÖS-CAS. This difference indicates that particles in ÖS-MBR are less attracted to the particular thickening polymer used, than the particles in ÖS-CAS. Therefore, it is important to select the correct type of polymer when thickening ÖS-MBR in order to reach the target TSS of 1000 mg/L in the reject water. In addition, the thickened ÖS-MBR showed higher TS than ÖS-CAS. This could indicate that ÖS-MBR would be easier to thicken; however, this is not confirmed by the mass balances. In the end, this study could not conclusively show any trend in the level of thickening between the two types of sludges because the distribution of particles varied in each trial. Nevertheless, while a higher dosage of polymer evidently reduced the TSS in the reject water, the same was not true for the TS in the thickened sludge, which seems to be less affected by the dose of polymer after a certain level. An important consideration in this study was the clogging of the drum screen. However, centrifuges, which will be used in the future Henriksdal wastewater treatment plant, do not have the same operational problems.

O ácido fólico é uma vitamina essencial a reações do metabolismo e crescimento das células, ao promover a síntese de proteínas para a divisão celular. Segundo pesquisas, a aplicação deste no reator de lodos ativados pode contribuir na otimização do tratamento biológico. A parte experimental deste trabalho foi desenvolvida em duas etapas: bioensaios de respirometria sob condições aeróbias, a fim de avaliar os efeitos da adição de ácido fólico na atividade metabólica da microbiota de lodos ativados; e operação de estação piloto de lodos ativados em batelada, para avaliar a influência do ácido fólico na dinâmica da microfauna e no desempenho geral do tratamento. Nos bioensaios de respirometria destacou-se o consumo de oxigênio diante da adição da maior concentração testada - 4,0 mg/L de ácido fólico, com o consumo de até 78% de oxigênio, enquanto que nos frascos controles o consumo médio foi de 50%. O composto Dosfolat, empregado na concentração 2,5 mg/L, também estimulou a respiração basal da microbiota de lodos estudados, como observado pelo consumo de 100% do oxigênio presente após 24 horas de incubação dos sistemas de respirometria. Nos sistemas de lodos ativados em batelada, o ácido fólico e o composto Dosfolat não exerceram influência na eficiência do tratamento e na produção de lodo excedente. Em relação aos aspectos da microbiologia dos sistemas, a adição de ambas as soluções não ocasionou diferenças na composição e diversidade da microfauna, e não influenciou a dinâmica de crescimento das bactérias filamentosas. Porém, nos reatores que receberam adição de ácido fólico e Dosfolat os flocos apresentaram tamanhos superiores, e melhores características morfológicas em relação aos do lodo do reator controle. Portanto, as taxas de respiração observadas com a adição de ácido fólico e de Dosfolat em sistemas de lodos ativados indicam uma tendência de estímulo da atividade metabólica como resposta ao incremento de ácido fólico. Além deste fator, sugere-se que a utilização de ambas as soluções favorece o crescimento das bactérias dos flocos e a formação destes, em detrimento às bactérias livres. / The folic acid is a essential vitamin to metabolism and growth of the cells by promoting the synthesis of proteins for the cellular division. According to some researches, this application in the activated sludge systems can contribute to in the optimization of the biological treatment. The experimental part of this work was developed in two stages: aerobic respirometry biotests, in order to evaluate the effects of the addition of folic acid in the metabolic activity of the microbiotica of activated sludge; and operation of a pilot plant of activated sludge, to evaluate the influence of the folic acid in microorganisms’s dynamics and the performance of the treatment. In the respirometric bioassays was eminence the consumption of oxygen with addition of the highest concentration tested was added - 4.0 mg/L of folic acid, where the consumption of up to 78% of oxygen was observed, whereas in the control the flocs the consumption was 50%. The composed Dosfolat, employee in the concentration 2,5 mg/L, also contribute the microbiota’s activity of the of sludge, as observed by the consumption of 100% of the present oxygen after 24 hours of incubation of the respirometric systems. In the activated sludge systems, the folic acid and Dosfolat didn't exercise influence in the efficiency of the treatment and in the production of sludge. In relation to the aspects of the microbiology, the addition of both solutions didn’t cause differences on the composition and microorganisms’s diversity, and it didn't influence the dynamics of growth of the filamentous bacterias. Even so, the reactors that received addition of folic acid and Dosfolat the flocs presented superior sizes, and improve morphologic characteristics in relation to sludge of the control reactor. Therefore, the breathing rates observed with addition of folic acid and of Dosfolat in activated sludge systems indicate a tendency of incentive of the metabolic activity as answer to the increment of folic acid. Besides this factor, suggests that the use of both solutions favors bacteria growth of the flocs and this formation of these, in detriment to the free bacterias.

O lodo de esgoto gerado em estações de tratamento de esgoto pode conter substancias tóxicas ainda não regulamentadas nas legislações nacionais e internacionais. Dentre elas as genotóxicas tem recebido especial atenção. Este trabalho teve como objetivos avaliar a genotoxicidade de amostras de lodo de esgoto tratado de diferentes Estações de Tratamento de Esgoto (ETE) do Estado de São Paulo com o teste de micronúcleo em Tradescantia e ampliar os conhecimentos sobre o potencial de utilização da Tradescantia pallida em substituição ao clone 4430. Todas as ETEs estudadas apresentaram pelo menos uma amostra positiva para o teste de micronúcleo em Tradescantia sendo necessários mais estudos para elucidar quais os compostos são responsáveis pelo efeito observado. Os resultados sugerem que a Tradescantia pallida pode substituir o clone 4430 no teste de micronúcleo, porém esse ensaio tem aplicabilidade limitada em programas de monitoramento. / The sludge produced in sewage treatment plants can contain toxic substances which are not yet regulated by national and international legislation. Among these, the genotoxic substances are of great concern. The present paper aimed at evaluating the genotoxicity of treated sludge samples collected in different Sewage Treatment Plants (STP) located in the State of São Paul, Brazil. The micronucleus assay in Tradescantia was the test chosen for this evaluation. Another objective of the study was to verify it Tradescantia pallida could replace the clone 4430 in the Trad-MN assay. All the STPs studied have presented at least one positive sample for the micronucleus assay in the Tradescantia. Further studies are required in order to determine which compounds are responsible for the observed effect. The results obtained suggest that T. pallida can replace clone 4430 in the micronucleus assay, however, this assay presents limited applicability in monitoring programs.

Este estudo visou avaliar as implicações do uso da lise celular sobre a produção de lodos e acumulação de nutrientes no efluente do sistema combinado de tratamento (anaeróbio/aeróbio) de despejo sintético simulando esgoto sanitário. O sistema operado era constituído de reator UASB (V = 10,5 l), reator aeróbio (V = 4,4 l) e sedimentador (V = 2,7 l), operando com tempo de detenção hidráulica de 8,0 h, 3,5 h e 2,7 h respectivamente. Durante a fase de controle, acompanhou-se as características de funcionamento do processo sem o emprego da lise celular no lodo de excesso e posteriormente fez-se uso de equipamento de ultra-som para promover a lise do lodo, com retorno posterior do lodo lisado à entrada do reator UASB. Verificou-se que a eficiência média global de remoção de DQO do sistema foi de 90% em ambas as fases considerando DQO efluente filtrada. A conversão de nitrogênio amoniacal a nitrato foi pequena no tanque de aeração e a remoção de fósforo foi insignificante no processo de tratamento, no entanto não ocorreu alteração na qualidade do efluente do sistema em função do retorno do material lisado. Na escala estudada foi freqüente o aparecimento de bulking (controlado pela aplicação de hipoclorito de sódio no sedimentador), fato esse que dificultou a operação do sistema de tratamento e interferiu na manutenção do tempo de retenção celular. Os resultados obtidos da simulação realizada por meio do software GPS-X 4.0, para reator em escala real empregando a lise celular, mostraram acréscimo na concentração de fósforo total no efluente de 30% após 5 anos de operação / The aim of this research is to value the use of cell lyses over the sludge production and effluent nutrient accumulation from a combined treatment system (anaerobic/aerobic) from a synthetic sanitary wastewater. The parts of this system where one UASB reactor (V = 10,5 l), one aeration tank (V = 4,4 l) and one sedimentation tank (V = 2,7 l), hydraulic detention times of 8,0 h, 3,5 h e 2,7 h, respectively. During the control period, the characteristics of the system working without the use of cell lyses were recorded. After this phase, ultrasound equipment was used to cause the sludge lyses and then the sludge was returned to the entrance of the UASB reactor. From these tests we could not observe changes in mean global DQO removal efficiency for the both phases and it was 90% considering filtrated effluent COD. Few ammonia-nitrogen changes into nitrate inside the aeration tank were observed. Phosphorus removal in the treatment system was insignificant, but we could notice no damage to the treatment system caused by the lyses material returned. In the reduced scale of the system bulking events were frequent. This was controlled with sodium hypochlorite at the sedimentation tank, but these events caused operation difficulties and had interfered on the cellular detention time maintenance. Results from a real scale simulation, using cell lyses, done with the GPS-X 4.0 software, show an increase in effluent total phosphorus equal to 30% after 5 years

The survival of three enteroviruses (polio 1, coxsackie B3 and echo 1) and a rotavirus (SA-11) was studied under laboratory conditions. The effects of temperature, dissolved oxygen, detention time, sludge source and virus type on virus inactivation were determined. Temperature was the single most important factor influencing the rate of virus inactivation. No significant differences were found for virus inactivation rates at dissolved oxygen levels between 0.9 and 5.8 mg/l. However, the inactivation rate of the viruses under aerobic conditions was found to be significantly greater than the inactivation rate under anaerobic conditions (−0.77log10/day vs −0.33 log10/day). Sludge source, detention time and virus type did not significantly influence the rate of virus inactivation.

Thesis (MPA.) -- University of Limpopo, 2017 / The World Health Organisation (WHO) and World Bank (WB) state that worldwide access to sanitation has improved with countries in the north having 100% access to sanitation. However, only 64% of the world's population has access to improved sanitation. Sub-Saharan Africa has a noticeable improvement with South Africa improving from 73% in 2010 to 74% in 2014. They further estimate that $260 billion is lost globally each year due to lack of adequate water supply and sanitation. Universal access to water and sanitation would result in an estimated $32 billion in economic benefits per year globally from reductions in health care costs and increased productivity from reduced illness. Sub-Saharan Africa loses an estimated 4.3% ($US694 billion) of its Gross Domestic Product (GDP) each year due to lack of adequate water supply and sanitation. Furthermore, the UNDP (2015) indicates that sanitation is one of the Millennium Development Goals (MDG), however many regions are performing poorly in attaining their declared sanitation targets. South African has not reached its target but it is maintaining its commitment to the provision of sanitation as a basic human right. However, it has left the responsibility to local government to work out how this should be done with no legislation. Currently there is no policy on sanitation and municipalities only develop by-laws that serve as guidelines in managing waste and providing the service. The available literature on this subject speaks very little about the knowledge and understanding that the communities have with regard to faecal sludge management and no study at all deals with the perceptions of people on this issue, particularly around Polokwane Municipality. It is for these reasons that the study was aimed at investigating the perceptions of Polokwane residents regarding alternative faecal sludge management. Methodologically the study used qualitative research approach where in face-to-face interviews and focus group interviews were conducted around Polokwane Municipality. Among the participants interviewed were Ward Councillors, Community Development Workers, Ward Committees and Traditional Authorities. These stakeholders were intentionally chosen as they are at the coalface of service delivery on a daily basis and they are part of the forums that interact with the Municipality on basic services and other related community matters. Data for this study were analysed using thematic data analysis approach. vi  The findings of this study suggest that the “concerned residents” under Polokwane Municipality see themselves being victims and vulnerable to controllable health threats. In addition, the study discovered that the majority of participants were aware of the delegated sewage maintenance duties on the Polokwane Municipality. This study findings further indicated that there is a growing concern among municipal authorities and communities‟ especially in Africa and South Africa in particular, to improve the inadequate faecal management. The objectives of the study were among others to determine the perceptions and awareness of the Polokwane Local Municipality residents regarding alternative faecal sludge management methods. Indeed, it has been discovered that some of the residents are aware of various management methods but expect authority to develop policies and improve the inadequate methods that are currently used in managing faecal sludge. The study among others discovered that this study should be used as a point of reference for municipal projects administration, i.e. for the development of Integrated Development Plan (IDP) on the water and sanitation and faecal sludge management in future. The Ministry of environmental health and management at Polokwane Local Municipality should organise solid and integrated awareness with the community to ensure a healthy environment for all. The study further realised that there is a need to equip most of residents in Polokwane Local Municipality with knowledge on how best man can improve environmental health, as well as how worse can a person destroy the environment. It should be an important task for the Polokwane Local Municipality to ensure that residents understand the faecal sludge management enterprise developments in the area to reduce the incompleteness of the perceptions among the residents. Various faecal sludge methods should be adopted and encouraged among the Polokwane Local Municipality residents in order to promote the preference for the sanitation methods. Key words: Sanitation, Faecal sludge, Faeces, Health hazards and Sub-Saharan Africa

Groundwater is a major and sometimes lone source of drinking water worldwide. The chemical composition of groundwater is a combined product of the composition of water that enters the aquifer and its reaction with various minerals present in the soil and rock mass, which alter the water composition with time and space. Some important factors influencing groundwater quality are (1) physiochemical characteristics o the rocks through which the water circulates; (2) geology of the location; (3) climate of the area; (4) role of microorganisms, which includes oxidative and reductive biodegradation of organic matter; (5)chemical, physical, and mineralogical characteristics of the overburden soils through which the rainwater percolates; and (6) human intrusion affecting the hydrological cycle and degradation in water quality through utilization of water for agricultural and industrial activities. By far the most serious naturally occurring groundwater-quality problem in India derives from high fluoride, arsenic and iron concentrations which are dissolved from the bedrocks by geochemical processes. Presence of excess fluoride in groundwater is identified as a naturally occurring health hazard by the World Health Organization (WHO). Prolonged ingestion of fluoride beyond certain permissible limit leads to ffluorosis, one of the common water-related diseases recognized by the WHO and the United Nations Children's Fund (UNICEF). Endemic fluorosis is now known to be global in scope, occurring on all continents and affecting many millions of people. According to estimates made in the early 1980s, around 260 million people in 30 countries worldwide were drinking water with more than 1 ppm of fluoride. The ultimate source of fluoride in water, soil or biosphere is associated with its distribution in rocks and its dispersion in groundwater. The three most important minerals of fluoride are fluorite (CaF2), cryolite (Na3AlF6) and fluorapatite (Ca5(PO4)3F); cryolite is a rare mineral where as by far the largest amount of fluorine in the earth's crust is in the form of fluorapatite (about 3.5% by weight of fluorine) which is processed almost exclusively for its phosphate content. Fluoride substitutes readily in hydroxyl positions in late-formed minerals in igneous rocks, and in primary minerals especially micas (such as biotites) and amphiboles (such as hornblende). The most important controlling factors influencing fluoride presence in groundwater include: distribution of easily weathered fluoride-bearing minerals, the accessibility of circulating water to these minerals, pH of the percolating water, calcium content of the leaching water, temperature of the percolating water and the soil, exchangeable ions in the percolating water, extent of fresh water exchange in an aquifer, evaporation and evapotranspiration, complexing of fluoride ions with other ions, presence of CO2 and other chemicals in draining water and residence time of the percolating water in soil. High fluoride levels are observed in the groundwater in 19 states of the country. Fluorite, apatite, rock phosphate, phosphorites, phosphatic nodules and topaz are major fluoride bearing minerals in India with varying levels of fluoride content. There are three major fluoride bearing areas in India :1) Gujarat-Rajasthan in the north-west and 2) Chandidongri-Raipur in central India 3) Tamil Nadu-Andhra Pradesh in the south; besides other areas in Karnataka, Bihar, Punjab and in the North-west Himalayas. The total mineral reserves of fluorite, rock phosphate and apatite in the country are estimated at 11.6, 71 and 2.82 million tonnes respectively. The distribution of areas with excess fluoride in groundwater concurs with that of fluorine-bearing minerals. Further high fluoride concentrations are observed from arid and semi arid regions of the country and the areas with advanced stage of groundwater development. An estimated 62 million people, including 6 million children suffer from fluorosis in India because of consuming fluoride-contaminated water. Endemic fluorosis is found to practically exist only in the villages due to lack of piped water supply. The Indian Drinking Water Standard specifies the desirable and permissible limits for fluoride in drinking water as 1.0 and 1.5ppm respectively. De-fluoridation of groundwater is the only alternative to prevent fluorosis in the absence of alternate water source especially for immediate and/or interim relief. De-fluoridation of drinking water in India is usually achieved by the Nalgonda technique or activated alumina process. The Nalgonda method involves addition of aluminum salts (aluminium sulphate and/or aluminium chloride), lime and bleaching powder to water, followed by rapid mixing, flocculation, sedimentation, filtration and disinfection. Only aluminum salt is responsible for removal of fluoride from water .Fluoride removal is achieved in a combination of complexation with polyhydroxy aluminium species and adsorption on polymeric alumino hydroxides (floc). Activated alumina(Al2O3) was proposed for de-fluoridation of water for domestic use in 1930’s and since then it has become one of the most advocated de-fluoridation methods. Activated alumina is a semi crystalline porous inorganic adsorbent and an excellent medium for fluoride removal. When the source water passes through the packed column of activated alumina, fluoride (and other components in the water) is removed via exchange reaction with surface hydroxides on alumina; this mechanism is generally called adsorption although ligand exchange is a more appropriate term for the highly specific surface reactions involved. The fluoride removal capacity of alumina is highly sensitive to pH, the optimum being about pH5.5-6. Significant reduction in fluoride removal by activated alumina is also observed in presence of sulfate and silicate ions. The column needs periodic regeneration once break point(where the effluent concentration is, for example, 2ppm at normal saturation) is reached. For regeneration, the medium is backwashed for 5-10 min and then subjected to two step regeneration with base (NaOH) followed by acid(H2SO4). A major cause for concern with the Nalgonda method is the possibility of formation of residual aluminum and soluble aluminum fluoride complexes in the treated water and a potential breach of the 0.2ppm Indian drinking water standard for aluminium. Concerns with the activated alumina filter method are that the process is pH dependent, with an optimum (pH) working range of 5-6. Further, the activated alumina column requires periodic recharge using caustic soda and acid solutions to rejuvenate the fluoride retention capacity of the column. After 3-4 regenerations the medium has to be replaced. If the pH is not readjusted to normal following the regeneration process, there is a possibility that the aluminum concentration in the treated water may exceed the 0.2ppm standard. Due to the aforementioned drawbacks of the currentde-fluoridation technologies in India that chiefly rely on aluminum based compounds, magnesia(magnesium oxide, MgO) is selected to develop an alternate sustainable de-fluoridation method. The potential of MgO for de-fluoridation has been examined owing to its very limited solubility(6.2mg/L), non-toxicity and excellent fluoride retention capacity. A review of the previous studies on fluoride removal using MgO reveals that the relevant information is essentially scattered. Though studies demonstrated the fluoride removing ability of MgO and brought into focus certain aspects of the fluoride removal mechanism and change in water quality upon MgO addition, vital issues necessary for efficient design and successful field implementation of the de-fluoridation processusing MgO were not addressed. The significant limitations in the earlier works include: influence of process variables(such as MgO dosage, initial fluoride concentration, contact time, temperature, initial solution pH, presence of co-ions and ionic strength) on fluoride retention characteristics (such as removal rate, equilibrium time, capacity) of MgO were not systematically determined, optimum operating parameters/conditions (such as MgO dosage, stirring and settling time) for effective de-fluoridation process applicable to a wide range of groundwater chemical composition and fluoride concentrations were not defined, mechanism of fluoride retention by MgO was not fully understood, issue of lowering the pH of MgO treated water within potable water limits was not comprehensively addressed, safe disposal methods of fluoride bearing sludge were not explored. Failure to address the above issues has impeded the adoption of the MgO treatment method for fluoride removal from water. Scope of the study Present study aims to develop a new sustainable de-fluoridation method, applicable to a wide range of groundwater chemical compositions and fluoride concentrations, based on co-precipitation/precipitation-sedimentation-filtration processes using light MgO. Efforts are made to implement the method at domestic level in a rural area with incidence of high fluoride concentration in groundwater and to understand the status and geochemistry of fluoride contamination in the area. The main objectives of the study include: To determine the fluoride retention characteristics of MgO viz.,rate, equilibrium time and capacity of fluoride retention. To examine the influence of process variables on fluoride retention characteristics of MgO and to determine the optimum operating parameters for effective de-fluoridation process. To understand the mechanism and rate limiting step of MgO de-fluoridation process. To propose methods and specifications to lower the pH of MgO treated water within permissible limits to ensure its potability. To design a simple to use, single-stage domestic de-fluoridation unit. To propose procedures for implementation of the new de-fluoridation method in field. To evaluate the efficiency of the new de-fluoridation method as a useful remedial measure in the fluoride affected areas. To understand the geochemical factors governing the quality of the fluoride rich groundwater and to ascertain the status and geochemistry of fluoride contamination in the area where felid implementation of de-fluoridation method is planned. To characterize the fluoride bearing sludge and propose methods for safe disposal and reuse of fluoride bearing sludge. Organization of the thesis Chapter1 presents an overview of the various aspects of excess fluoride presence in groundwater, remedial measures, and emphasizes the need for a new sustainable de-fluoridation method and defines the scope of present study. Chapter 2 performs a detailed investigation to determine the fluoride retention characteristics of MgO under the influence of various process variables at transient and equilibrium conditions using batch studies. The process variables that have been considered are, contact time, initial fluoride concentration, dosage of MgO, temperature, initial pH, presence of co-ions and ionic strength. Studies to determine the optimum operating parameters for efficient de-fluoridation and to understand some basics of reaction mechanisms involved are also part of this chapter. Chapter 3 examines the true nature of the reaction mechanism between fluoride ions and MgO in aqueous media and the rate-limiting step of the de-fluoridation process by investigating the hydration process of MgO and its influence/relation on fluoride removal. Chapter 4 addresses issues that will assist applying the MgO treatment method for fluoride removal in field such as 1)methods and specifications for lowering the pH of the MgO treated water within permissible limits, 2)design of a simple to use, single-stage de-fluoridation unit, and 3)characterization of the resultant fluoride bearing sludge. Chapter 5 performs a detailed investigation to evaluate the efficiency of the new de-fluoridation method in laboratory and field, and to understand the origin and the geochemicall mechanisms driving the groundwater fluorine enrichment in the area where field implementation of the de-fluoridation unit was planned. Chapter 6 explores an environmentally safe route for the disposal and re-use of fluoride bearing sludge in soil based building materials such as, stabilized soil blocks (produced by cement stabilization of densely compacted soil mass) which are alternative to burnt bricks. Chapter 7 summarizes the major results, observations and contributions from the study.