From June to November 2007, a microscopic analysis was conducted on the activated sludge from eleven selected wastewater treatment plants (WWTP's) belonging to the City of Cape Town. The primary objective was the identification of the dominant and secondary filamentous organisms. Other important criteria included were the floe character, diversity, filament index (Fl) and identification of the protozoan and metazoan communities. The operational data determined from routine analyses of the sludge, influent and effluent were used to assess the relationship of the filamentous population to wastewater characteristics and to compare this with previous findings. Fl values of >3 and dissolved sludge volume indices (DSVI's) of >150 were chosen as representing the possibility of bulking conditions being present. The five most prevalent dominant filaments were Type 0092, Type 1851, actinomycetes, Microthrix parvicella and Type 021N, being present in 74%, 31%, 22%, 17% and 14% of samples respectively. Type 0092 did not appear to be associated with bulking in any of the WWTP's, although it was often incidentally present as a co-dominant species when bulking conditions existed. All three WWTP's with the Modified Ludzack-Ettinger configuration harboured Type 1851 as the major dominant species, irrespective of whether the plants treated domestic or industrial effluent. Conditions suggestive of bulking were present in two of these WWTP's. Contrary to expectations, Type 1851 was often found as a dominant species where domestic waste was the primary influent. Type 021N and actinomycetes were strongly implicated when bulking occurred. The overgrowth of these filaments appeared to be related to factors such as nutrient deficiency (Type 021N) or the presence of large amounts of low molecular weight substances in the influent. Microthrix parvicella did not cause major bulking problems. There was a strong association between low levels of nitrates/nitrites in the clarifier supernatant and good phosphorous removal, irrespective of the configuration of the WWTP. The converse was also true. / Thesis ((M. Environmental Science))--North-West University, Potchefstroom Campus, 2009.

From June to November 2007, a microscopic analysis was conducted on the activated sludge from eleven selected wastewater treatment plants (WWTP's) belonging to the City of Cape Town. The primary objective was the identification of the dominant and secondary filamentous organisms. Other important criteria included were the floe character, diversity, filament index (Fl) and identification of the protozoan and metazoan communities. The operational data determined from routine analyses of the sludge, influent and effluent were used to assess the relationship of the filamentous population to wastewater characteristics and to compare this with previous findings. Fl values of >3 and dissolved sludge volume indices (DSVI's) of >150 were chosen as representing the possibility of bulking conditions being present. The five most prevalent dominant filaments were Type 0092, Type 1851, actinomycetes, Microthrix parvicella and Type 021N, being present in 74%, 31%, 22%, 17% and 14% of samples respectively. Type 0092 did not appear to be associated with bulking in any of the WWTP's, although it was often incidentally present as a co-dominant species when bulking conditions existed. All three WWTP's with the Modified Ludzack-Ettinger configuration harboured Type 1851 as the major dominant species, irrespective of whether the plants treated domestic or industrial effluent. Conditions suggestive of bulking were present in two of these WWTP's. Contrary to expectations, Type 1851 was often found as a dominant species where domestic waste was the primary influent. Type 021N and actinomycetes were strongly implicated when bulking occurred. The overgrowth of these filaments appeared to be related to factors such as nutrient deficiency (Type 021N) or the presence of large amounts of low molecular weight substances in the influent. Microthrix parvicella did not cause major bulking problems. There was a strong association between low levels of nitrates/nitrites in the clarifier supernatant and good phosphorous removal, irrespective of the configuration of the WWTP. The converse was also true. / Thesis ((M. Environmental Science))--North-West University, Potchefstroom Campus, 2009.

From June to November 2007, a microscopic analysis was conducted on the activated sludge from eleven selected wastewater treatment plants (WWTP's) belonging to the City of Cape Town. The primary objective was the identification of the dominant and secondary filamentous organisms. Other important criteria included were the floe character, diversity, filament index (Fl) and identification of the protozoan and metazoan communities. The operational data determined from routine analyses of the sludge, influent and effluent were used to assess the relationship of the filamentous population to wastewater characteristics and to compare this with previous findings. Fl values of >3 and dissolved sludge volume indices (DSVI's) of >150 were chosen as representing the possibility of bulking conditions being present. The five most prevalent dominant filaments were Type 0092, Type 1851, actinomycetes, Microthrix parvicella and Type 021N, being present in 74%, 31%, 22%, 17% and 14% of samples respectively. Type 0092 did not appear to be associated with bulking in any of the WWTP's, although it was often incidentally present as a co-dominant species when bulking conditions existed. All three WWTP's with the Modified Ludzack-Ettinger configuration harboured Type 1851 as the major dominant species, irrespective of whether the plants treated domestic or industrial effluent. Conditions suggestive of bulking were present in two of these WWTP's. Contrary to expectations, Type 1851 was often found as a dominant species where domestic waste was the primary influent. Type 021N and actinomycetes were strongly implicated when bulking occurred. The overgrowth of these filaments appeared to be related to factors such as nutrient deficiency (Type 021N) or the presence of large amounts of low molecular weight substances in the influent. Microthrix parvicella did not cause major bulking problems. There was a strong association between low levels of nitrates/nitrites in the clarifier supernatant and good phosphorous removal, irrespective of the configuration of the WWTP. The converse was also true. / Thesis ((M. Environmental Science))--North-West University, Potchefstroom Campus, 2009.

A number of advanced pre-treatment techniques and methods have been evaluated for the sole purpose of improving digestibility of waste activated sludge. The pre-treatment of waste activated sludge (WAS) offers the benefit of releasing solubilized substrates, making them readily available to be utilized in the anaerobic digestion process. Other potential benefits include: reducing shock loading to the digester, improving overall digestibility and potentially providing filament / foaming control. Chlorine dioxide, a well-known disinfectant and oxidizing agent has been utilized in many drinking water processes around the world. Its use in wastewater treatment processes however is limited; especially in Canada where legislation has prevented its use for final effluent disinfection. As an oxidizing agent, chlorine dioxide induces cell rupture resulting in the release of soluble material, which when fed into the digester, may serve as readily available substrate for active microorganisms. This mode of action creates the potential for chlorine dioxide to be used as a sludge pre-treatment agent to improve digester performance and in alleviating pre-existing filamentous sludge bulking. This study was conducted using waste activated sludge obtained from the City of Winnipeg’s South End Water Pollution Control Centre (SEWPCC), with the following objectives: 1. Determine the efficacy of chlorine dioxide in alleviating pre-existing filamentous sludge bulking; 2. Determine chlorine dioxide ability to increase WAS solubilization; and 3. Define impact of chlorine dioxide on anaerobic digester performance. WAS pre-treatment using chlorine dioxide was found to be effective in alleviating filamentous bulking. This is significant as filamentous bulking in the activated sludge may lead several problems downstream. Following pre-treatment, sludge bulking was determined to be alleviated as observed by photomicrographic evidence and as measured by a 57% decrease in the stirred sludge volume index (sSVI). Particulate COD solubilization increased by 60%, 76%, and 74% over the untreated sludge for WAS pre-treated with 25, 50, and 100 mg ClO2/L (v/v), respectively. The pre-treatment of sludge using chlorine dioxide did not have any negative impact on digester performance although it also did not lead to improved performance. The volatile solids destruction and COD removal remained unchanged for both untreated and pre-treated sludge. Chlorine dioxide pre-treatment did not affect anaerobic digestion even at the lowest SRT evaluated; it is possible to decrease the digester SRT to as low as 6 days while maintaining the solids destruction and COD removal capability. Biogas production did not improve with increasing chlorine dioxide dosage during pre-treatment but also was not hindered by the pre-treatment agent. Chlorine dioxide was shown to alleviate filamentous bulking and improve solubility and has the potential to improve digester performance without negative impacts to the digester. However, the full benefit of the pre-treatment method may only be realized for complex “difficult to disintegrate” sludge types. / October 2016

O processo de lodos ativados consiste em um tratamento biológico amplamente utilizado nas estações de tratamento, para remoção de matéria orgânica, devido à qualidade do efluente ao final do processo. Essa remoção é realizada por microrganismos que atuam neste sistema como bactérias, protozoários, metazoários e organismos filamentosos, como fungos e bactérias, formadores de flocos biológicos. Para garantir a eficiência deste processo deve haver um equilíbrio da microbiota dentro do reator aeróbio e o controle do número de filamentosos, tendo em vista que seu excesso no sistema pode causar o intumescimento do lodo (bulking) interferindo na qualidade do efluente gerado. O presente estudo teve como objetivo testar a eficiência de uma solução de 0,001% de peróxido de hidrogênio (H2O2) no controle de microrganismos filamentosos em lodos provenientes de duas indústrias, farmacêutica e alimentícia, reduzindo assim os riscos relacionados à utilização desta substância em grandes volumes. Foram realizadas análises microscópicas do lodo para avaliação quantitativa e monitoramento da atividade biológica dos reatores, essa avaliação serviu como base para a análise qualitativa a partir do índice de Madoni (1994) gerando um Índice Biótico do Lodo (IBL). Foram realizados outros testes, como IVL e teste de respiração, sendo os resultados destes testes comparados a fim de avaliar a eficiência da solução de H2O2 e sua interferência no processo. A solução de H2O2 foi eficiente em ambos os experimentos, mostrando através dos testes de TCO e TCOe não haver interferência desta solução no metabolismo da microfauna; os resultados do IBL mostraram uma boa qualidade do lodo para ambos experimentos e a partir desta análise foi observado que a elevação de temperatura, acima de 30,0C, causa interferência no sistema levando a uma redução do IBL. Os resultados de IVL não demonstraram diferença entre os valores dos reatores controle e tratado, porém a avaliação do tamanho dos flocos e filamentos mostrou que o aumento na concentração da solução de H2O2 levou a um controle na quantidade de filamentosos nos reatores tratados que reduziram em tamanho e quantidade. / The activated sludge process consists in a treatment largely used in biological treatment plants for removal of organic matter, because of the quality of the effluent at the end of the process. This removal is accomplished by microorganisms which act in this system as bacteria, protozoa, metazoan and filamentous organisms such as fungi and bacteria, forming biological flocs. To ensure efficiency of this process must be a balance of microbiota in the aerobic reactor and control the number of filaments, in order that its excess in the system may cause sludge swelling (bulking) interfering with the quality of the effluent. The present study aimed to test the efficacy of a 0.001% solution of hydrogen peroxide (H2O2) in control of filamentous microorganisms in sludge from two industries, pharmaceutical and food, thereby reducing the risks related to the use of this substance in large volumes. Analyses microscopic sludge to quantitative evaluation and monitoring of the biological activity of the reactors, this assessment was the basis for the qualitative analysis from the Madonis index (1994) generating a Sludge Biotic Index (IBL). Other tests were performed as IVL and then breath test, and the results of these tests being compared in order to evaluate the efficiency of H2O2 solution and their interference in the process. A solution of H2O2 was efficient in both experiments, showing through the TCO and TCOe tests, that this solution not be interference with the metabolism of microfauna, the IBL results showed a good quality of the sludge for both experiments and from this analysis revealed that the temperature over 30,0C, causes interference in the system leading to a reduction in the IBL. The results IVL showed no difference between the control and treated reactors, but the evaluation of the size of the flocs and filaments showed that increasing the solution concentration of H2O2 led to control the amount of filamentous treated in reactors which have reduced in size and quantity.

O processo de lodos ativados consiste em um tratamento biológico amplamente utilizado nas estações de tratamento, para remoção de matéria orgânica, devido à qualidade do efluente ao final do processo. Essa remoção é realizada por microrganismos que atuam neste sistema como bactérias, protozoários, metazoários e organismos filamentosos, como fungos e bactérias, formadores de flocos biológicos. Para garantir a eficiência deste processo deve haver um equilíbrio da microbiota dentro do reator aeróbio e o controle do número de filamentosos, tendo em vista que seu excesso no sistema pode causar o intumescimento do lodo (bulking) interferindo na qualidade do efluente gerado. O presente estudo teve como objetivo testar a eficiência de uma solução de 0,001% de peróxido de hidrogênio (H2O2) no controle de microrganismos filamentosos em lodos provenientes de duas indústrias, farmacêutica e alimentícia, reduzindo assim os riscos relacionados à utilização desta substância em grandes volumes. Foram realizadas análises microscópicas do lodo para avaliação quantitativa e monitoramento da atividade biológica dos reatores, essa avaliação serviu como base para a análise qualitativa a partir do índice de Madoni (1994) gerando um Índice Biótico do Lodo (IBL). Foram realizados outros testes, como IVL e teste de respiração, sendo os resultados destes testes comparados a fim de avaliar a eficiência da solução de H2O2 e sua interferência no processo. A solução de H2O2 foi eficiente em ambos os experimentos, mostrando através dos testes de TCO e TCOe não haver interferência desta solução no metabolismo da microfauna; os resultados do IBL mostraram uma boa qualidade do lodo para ambos experimentos e a partir desta análise foi observado que a elevação de temperatura, acima de 30,0C, causa interferência no sistema levando a uma redução do IBL. Os resultados de IVL não demonstraram diferença entre os valores dos reatores controle e tratado, porém a avaliação do tamanho dos flocos e filamentos mostrou que o aumento na concentração da solução de H2O2 levou a um controle na quantidade de filamentosos nos reatores tratados que reduziram em tamanho e quantidade. / The activated sludge process consists in a treatment largely used in biological treatment plants for removal of organic matter, because of the quality of the effluent at the end of the process. This removal is accomplished by microorganisms which act in this system as bacteria, protozoa, metazoan and filamentous organisms such as fungi and bacteria, forming biological flocs. To ensure efficiency of this process must be a balance of microbiota in the aerobic reactor and control the number of filaments, in order that its excess in the system may cause sludge swelling (bulking) interfering with the quality of the effluent. The present study aimed to test the efficacy of a 0.001% solution of hydrogen peroxide (H2O2) in control of filamentous microorganisms in sludge from two industries, pharmaceutical and food, thereby reducing the risks related to the use of this substance in large volumes. Analyses microscopic sludge to quantitative evaluation and monitoring of the biological activity of the reactors, this assessment was the basis for the qualitative analysis from the Madonis index (1994) generating a Sludge Biotic Index (IBL). Other tests were performed as IVL and then breath test, and the results of these tests being compared in order to evaluate the efficiency of H2O2 solution and their interference in the process. A solution of H2O2 was efficient in both experiments, showing through the TCO and TCOe tests, that this solution not be interference with the metabolism of microfauna, the IBL results showed a good quality of the sludge for both experiments and from this analysis revealed that the temperature over 30,0C, causes interference in the system leading to a reduction in the IBL. The results IVL showed no difference between the control and treated reactors, but the evaluation of the size of the flocs and filaments showed that increasing the solution concentration of H2O2 led to control the amount of filamentous treated in reactors which have reduced in size and quantity.