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Technologies and multi-barrier systems for sustainable groundwater recharge and irrigationBesancon, Axelle January 2010 (has links)
Managed aquifer recharge (MAR) consists of artificially replenishing groundwater to facilitate reuse and/or the associated environmental benefits. Meanwhile, soil aquifer treatment (SAT) is a process of geo-purification designed and operated to improve the quality of the infiltrating water and is thus a type of MAR. SAT consists of a basin operating under rotation of drying and wetting periods. Often, SAT involves water of impaired quality applied onto soil and consequently it implies various risks of health, geochemical and physical nature with difficult or irreversible remediation. To study the effect of pre-treatment on SAT a pilot plant including conventional activated sludge (CAS), a membrane bioreactor (MBR), tertiary and secondary vertical flow reed beds (VFRB) and SAT soil columns. The sludge retention time (SRT) in the CAS and MBR processes was changed every 6 months to look at the impact of SRT on SAT. Each unit and treatment train effluent was characterised to determine the impact of effluent quality on SAT performance. This study showed that tertiary VFRB, especially when fed with MBR effluent, was the best option for SAT and irrigation reuse as it provided the best compliance with reuse standards and the best fertilisation potential. However, long-term clogging occurred in SAT after tertiary VFRB, suggesting the need for a longer resting period or shorter wetting period. This study also highlighted the importance of total suspended solids (TSS) content for SAT removal mechanisms and infiltration rate. In particular, SAT fed with high TSS content effluent was susceptible to temperature variation. Hence the duration of wetting and flooding periods should be adapted according to the season. Further, variation in SRT only indirectly affected pollutants removal by the system including CAS treatment set up at 6 d SRT where the N compounds balance was favourable to an autotrophic N removal.
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Waste activated sludge pre-treatment with chlorine dioxide: its impact on pre-existing sludge bulking and its effect on solubilization and anaerobic digester performanceOlubodun, Abisola 16 September 2016 (has links)
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
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Recovery of Phosphorus from HTC Converted Municipal Sewage Sludge / Utvinning av fosfor från HTC-behandlat kommunalt avloppsslamSirén Ehrnström, Matilda January 2016 (has links)
With a growing population but scarce primary phosphorus sources, recycling of the vital element has become an important research area throughout the last decades. Several streams in society are potential resources for recirculation but municipal sewage is considered one of the most available materials. With current technologies in wastewater treatment, over 95 % of the influent phosphorus is captured in the sludge along with a variety of other nutrients. However, due to increasing fractions of pharmaceutical residues and heavy metals also following the sludge, direct use as fertiliser is being phased out in most European countries in favour of extraction methods. Extraction of nutrients from the sludge is problematic mainly because of dewaterability difficulties. Thus, pretreatment of the material is required to access the desired components at a reasonable cost and energy consumption. Hydrothermal carbonisation (HTC) is a technology showing high potential for treatment of wet carbonaceous material without necessity of prior drying. The resulting product is hygenised, essentially free from pharmaceuticals and easily dewatered. In this Master’s thesis principal conditions for release of phosphorus from HTC converted digested sludge under acid leaching have been experimentally investigated. Dependence of time, temperature, dry solids (DS) content of HTC sludge and pH have been studied. Also, differences arising from acid type have been considered by comparing acidulation with sulphuric acid and hydrochloric acid. A short investigation of the recovery of the dissolved phosphorus from leachate by precipitation was also performed where calcium ions were added to both sulphuric and hydrochloric acid leachates. Extraction of phosphorus from HTC converted sludge has shown to be easier than from pure metal phosphates under comparable leaching conditions and pH values. Also, the dissolved phosphorus concentrations obtained in the presence of HTC converted sludge was higher than for theoretical equilibrium concentrations where all phosphorus is in the form of iron(III) or aluminium(III) phosphate. A maximum leachate phosphorus concentration was around 2500 mg/L, recorded in leaching experiments performed at a dry HTC product concentration of 10 % (w/w) in an extraction solution of water acidified with sulphuric acid. Leaching procedures performed at pH values between 2 and 1 with 1 and 5 % DS HTC product resulted in dissolution of 90 % of ingoing phosphorus at an acid charge of 0.5 kg H2SO4/kg DS HTC product. At this chemical charge, release of phosphorus from converted sludge is fast. Similar amounts of dissolved phosphorus were recorded after 15 min as after 16 h retention time. Possibly, time dependence becomes relevant at lower charges. The dissolution of phosphorus is negatively affected by temperature increases at moderate acid loads, and by possibly by hydrochloric acid at pH values below 2. Addition of calcium gave a dissolved phosphorus reduction of 99.9 % in both the sulphuric acid and hydrochloric acid leachates. Gypsum, CaSO4, also precipitates from the sulphuric acid leachate resulting in 67 % more dry mass. Due to high release of metals during acidulation, the precipitate was also contaminated with large fractions of metals in addition to calcium. In summary, this investigation has demonstrated that up to 90 % of the phosphorus content of the HTC converted sludge can be released by acid leaching, and almost 100 % of the phosphorus can be recovered from the leachate by precipitation with calcium ions.
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Biodegradação de cianeto em efluente siderúrgico utilizando lodo da estação de tratamento biológico e lodo liofilizado, em escala laboratorial e planta piloto / Biodegradation assessment of cyanide in steel plant wastewater using its own sludge from the treatment plant on the laboratory scale and pilot plantSouza, Cláudio Márcio do Amaral 02 September 2014 (has links)
A indústria siderúrgica gera seus efluentes com altas concentrações de cianeto. O cianeto é uma substância altamente tóxica que deve ser degradada para ser eliminada do efluente, obedecendo a legislação vigente,Resolução CONAMA nº 430 de 13 de maio de 2011, que fixa os padrões para descarte de efluentes nos corpos receptores.O processo convencional de tratamento físico-químico usado para esta tipologia de efluente é a conversão de cianeto em complexo metálico. Entretanto, este processo é normalmente dispendioso e requer tratamento posterior dos subprodutos gerados, bem como da lama gerada contendo o complexo metálico de cianeto.Uma alternativa ao tratamento físico-químico é o uso da biodegradação por alguns gêneros de bactérias, incluindo Pseudomonas. A biodegradação de efluente siderúrgico contendo cianeto pelo processo de lodo ativado, utilizando microrganismos do tratamento biológico existente, torna-se uma alternativa para substituição parcial do tratamento físico-químico convencional. Logo, este trabalho teve por objetivo principal, avaliar a biodegradação de cianeto em um efluente siderúrgico, utilizando lodo ativado da estação de tratamento biológico e lodo liofilizado comercial. Foram realizados ensaios em escala laboratorial e em planta piloto. Em escala laboratorial, a redução da concentração de cianeto utilizando lodo da estação de tratamento biológico foi de 66% e com o lodo liofilizado comercial, a redução foi de 71%. Os resultados de degradação de cianeto na planta piloto, utilizando o lodo da estação de tratamento biológico e o lodo liofilizado, foram redução de 33% e 69%, respectivamente. Os resultados obtidos demonstraram que houve biodegradação de cianeto tanto em escala laboratorial quanto em planta piloto. A biodegradação de cianeto no efluente siderúrgico com concentrações reduzidas de amônia e fenol, sugere que os microrganismos utilizaram o cianeto como fonte de carbono e nitrogênio, aumentando dessa forma, a taxa de degradação. / The steel industry generates its effluents with high concentrations of cyanide. Cyanide is a highly toxic substance that must be degraded to be eliminated from the effluent complying with current legislation, CONAMA Resolution No. 430 of 13 May 2011 laying down the standards for discharge of effluents into bodies receptores. The conventional physicochemical treatment process used for this type of effluent is the conversion of cyanide into metal complex. However, this process is costly and usually requires further treatment of the byproducts generated, as well the generated sludge containing the metal complex of Cyanide. An alternative to physico-chemical treatment is the use of biodegradation for a few genres of bacteria including Pseudomonas. The biodegradation of steel plant effluent containing cyanide by the activated sludge process, using microorganisms of the existing biological treatment, becomes an alternative to partial replacement of conventional physico-chemical treatment. Therefore, this study was aimed to evaluate the biodegradation of cyanide in a steel plant wastewater using activated sludge from biological treatment station and sludge lyophilized commercial. Tests on laboratory scale and pilot plant were performed. In laboratory scale, the concentration reducing of cyanide using sludge from biological treatment plant was 66% and the commercial lyophilized sludge the reduction was 71%. The results of degradation of cyanide in the pilot plant using biological treatment of mud and sludge lyophilized station were reduced by 33% and 69%, respectively. The results showed that there was biodegradation of cyanide in laboratory scale and pilot plant. The biodegradation of the steel plant cyanide effluent with reduced concentrations of ammonia and phenol, suggests that the microorganisms used the cyanide as source of carbon and nitrogen, thus increasing the rate of degradation.
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Biodegradação de cianeto em efluente siderúrgico utilizando lodo da estação de tratamento biológico e lodo liofilizado, em escala laboratorial e planta piloto / Biodegradation assessment of cyanide in steel plant wastewater using its own sludge from the treatment plant on the laboratory scale and pilot plantCláudio Márcio do Amaral Souza 02 September 2014 (has links)
A indústria siderúrgica gera seus efluentes com altas concentrações de cianeto. O cianeto é uma substância altamente tóxica que deve ser degradada para ser eliminada do efluente, obedecendo a legislação vigente,Resolução CONAMA nº 430 de 13 de maio de 2011, que fixa os padrões para descarte de efluentes nos corpos receptores.O processo convencional de tratamento físico-químico usado para esta tipologia de efluente é a conversão de cianeto em complexo metálico. Entretanto, este processo é normalmente dispendioso e requer tratamento posterior dos subprodutos gerados, bem como da lama gerada contendo o complexo metálico de cianeto.Uma alternativa ao tratamento físico-químico é o uso da biodegradação por alguns gêneros de bactérias, incluindo Pseudomonas. A biodegradação de efluente siderúrgico contendo cianeto pelo processo de lodo ativado, utilizando microrganismos do tratamento biológico existente, torna-se uma alternativa para substituição parcial do tratamento físico-químico convencional. Logo, este trabalho teve por objetivo principal, avaliar a biodegradação de cianeto em um efluente siderúrgico, utilizando lodo ativado da estação de tratamento biológico e lodo liofilizado comercial. Foram realizados ensaios em escala laboratorial e em planta piloto. Em escala laboratorial, a redução da concentração de cianeto utilizando lodo da estação de tratamento biológico foi de 66% e com o lodo liofilizado comercial, a redução foi de 71%. Os resultados de degradação de cianeto na planta piloto, utilizando o lodo da estação de tratamento biológico e o lodo liofilizado, foram redução de 33% e 69%, respectivamente. Os resultados obtidos demonstraram que houve biodegradação de cianeto tanto em escala laboratorial quanto em planta piloto. A biodegradação de cianeto no efluente siderúrgico com concentrações reduzidas de amônia e fenol, sugere que os microrganismos utilizaram o cianeto como fonte de carbono e nitrogênio, aumentando dessa forma, a taxa de degradação. / The steel industry generates its effluents with high concentrations of cyanide. Cyanide is a highly toxic substance that must be degraded to be eliminated from the effluent complying with current legislation, CONAMA Resolution No. 430 of 13 May 2011 laying down the standards for discharge of effluents into bodies receptores. The conventional physicochemical treatment process used for this type of effluent is the conversion of cyanide into metal complex. However, this process is costly and usually requires further treatment of the byproducts generated, as well the generated sludge containing the metal complex of Cyanide. An alternative to physico-chemical treatment is the use of biodegradation for a few genres of bacteria including Pseudomonas. The biodegradation of steel plant effluent containing cyanide by the activated sludge process, using microorganisms of the existing biological treatment, becomes an alternative to partial replacement of conventional physico-chemical treatment. Therefore, this study was aimed to evaluate the biodegradation of cyanide in a steel plant wastewater using activated sludge from biological treatment station and sludge lyophilized commercial. Tests on laboratory scale and pilot plant were performed. In laboratory scale, the concentration reducing of cyanide using sludge from biological treatment plant was 66% and the commercial lyophilized sludge the reduction was 71%. The results of degradation of cyanide in the pilot plant using biological treatment of mud and sludge lyophilized station were reduced by 33% and 69%, respectively. The results showed that there was biodegradation of cyanide in laboratory scale and pilot plant. The biodegradation of the steel plant cyanide effluent with reduced concentrations of ammonia and phenol, suggests that the microorganisms used the cyanide as source of carbon and nitrogen, thus increasing the rate of degradation.
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Comportamento de dois reatores em batelada seqüenciais aeróbios com diferentes idades do lodo e retorno total do lodo em excesso após desintegração com ultra-som / Behavior of two aerobic sequential batch reactors with different sludge ages and total return of excess sludge after disintegration by ultrasoundAndré Luís de Oliva Campos 18 October 2002 (has links)
O estudo teve por finalidade a redução do lodo gerado nos sistema aeróbios mediante recirculação do lodo em excesso, após passar por uma desintegração com ultra-som, ao tanque de aeração de cada reator. Foram utilizados dois reatores seqüenciais aeróbios (A e B) operando em sistema de batelada e com idades do lodo diferentes: 12 e 8 dias respectivamente, e com ciclos de doze horas. Os reatores foram operados em duas etapas. Na etapa inicial, chamada controle, os reatores foram operados por 130 dias sem reciclo do lodo, para se poder avaliar o comportamento e fazer futuras comparações com a etapa posterior, denominada teste. Na etapa controle foram analisados o comportamento da DQO, dos sólidos e dos nutrientes além de serem realizados testes com o ultra-som para a escolha do tempo de exposição e volume de amostra.. O reator A apresentou uma boa remoção de DQO (90,9%), entretanto não apresentou nitrificação completa, chegando apenas na transformação de nitrogênio orgânico a amoniacal. Já a remoção de fósforo foi da ordem de 60%. O reator B também apresentou uma boa remoção de DQO (87,7%) e houve formação de nitrato, embora não completa, e a remoção de fósforo se situou em 57%. Na etapa teste, que durou aproximadamente 90 dias, os reatores foram operados com retorno total do lodo após desintegração com ultra-som. Houve um aumento na DQO afluente devido ao retorno do lodo desintegrado, bem como um aumento nos teores de nitrogênio e fósforo. Houve também um aumento na concentração de sólidos dos reatores, sendo o reator A que apresentou um maior acréscimo. Ambos reatores apresentaram uma mesma eficiência na remoção de DQO (92,0% para o reator A, e 91% para o reator B) se comparado com a etapa controle. Com relação aos nutrientes os reatores apresentaram sensível melhora na nitrificação. O reator A apresentou uma quase completa redução no nitrogênio orgânico, embora não tenha chegado a nitrificação completa. O reator B apresentou uma remoção completa do nitrogênio orgânico. Com relação ao fósforo, a etapa teste apresentou um decréscimo na sua remoção (42% para o reator A e 44% para o reator B). As análises indicaram que a desintegração do lodo e seu retorno ao tanque de aeração não causaram problemas no funcionamento dos reatores, houve uma melhora na nitrificação e não houve uma sensível redução na remoção de fósforo. Comparando com o problema de transporte, tratamento e disposição final de lodo, o estudo de redução de lodos é uma grande alternativa e que merece mais estudos. / The study aims to reduce the sludge generation in aerobic systems by recirculation of the excess sludge after disintegration with a ultrasound set. Two aerobic sequential batch reactors (A and B) were utilized operating with two different sludge ages: 12 and 8 days respectively. The reactors were operated in two stages. In the first stage, called control, the reactors were operated for 130 days, without total sludge recirculation, to promote an assessment and compare with the next stage, called test. In the control stage the behavior of COD, solids and nutrients were analyzed, and tests with ultrasound were performed. The reactor A presented a good COD removal, but not a good nitrification, and a phosphorus removal of 60%. The reactor B presented a good COD removal and a good nitrification, but not complete, and a phosphorus removal of 57%. The test stage the reactors were operated for 90 days, with sludge recirculation after disintegration by ultrasound. There was an increase in influent COD, nitrogen and phosphorus because of sludge recirculation. There was an increase in MLVSS, but reactor A presented a greater increase. Both reactors presented good results in COD removal comparing with control stage. The reactors present a good improvement in nitrification, but not good phosphorus removal regarding to control stage. The analysis showed that sludge disintegration and recirculation to aeration tank not caused any problem in the behavior of the reactors. Comparing to transport, treatment and final disposal problems, the study of sludge reduction is a great alternative that deserves attention.
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A suggestion on uniform sludge and waste handling in the Baltic Sea AreaEklund, Per, Dahlberg, Stefan January 2010 (has links)
The purpose of this thesis is to make a thorough but compact description of the international laws concerning solid garbage generated by vessels and sludge treatment. It is also to construct a pamphlet that can be used as a guide by ports when constructing their own information sheets to the vessels. The questions given to us from Baltic Master II were: what does the international legislation state about waste handling from vessels and in the port facilities, both sludge and solid garbage? Describe routines for receiving sludge, with concern taken to the rules that apply today. Describe routines for receiving sorted garbage and recycling, with concern taken to the rules that apply today. Look at the present symbols and labelling and develop a standard for vessels and port facilities. To solve these questions we choose an investigative method based on a literature study. The research of earlier studies showed that the parties involved consider the waste- and sludgetreatment to be flawed. In some cases the problems are fictitious or exaggerated. The main problem originates from the fact that there are no uniform routines for the interaction between vessel and port. Although there is more then one way to deal with this problem, we have concluded that the best way to improve the present day situation is to implement uniform routines. To make the routines effective they should be developed and agreed upon by the parties involved taking into consideration present day international legislation. In this thesis we present a suggestion on such a routine.
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Comportamento de dois reatores em batelada seqüenciais aeróbios com diferentes idades do lodo e retorno total do lodo em excesso após desintegração com ultra-som / Behavior of two aerobic sequential batch reactors with different sludge ages and total return of excess sludge after disintegration by ultrasoundCampos, André Luís de Oliva 18 October 2002 (has links)
O estudo teve por finalidade a redução do lodo gerado nos sistema aeróbios mediante recirculação do lodo em excesso, após passar por uma desintegração com ultra-som, ao tanque de aeração de cada reator. Foram utilizados dois reatores seqüenciais aeróbios (A e B) operando em sistema de batelada e com idades do lodo diferentes: 12 e 8 dias respectivamente, e com ciclos de doze horas. Os reatores foram operados em duas etapas. Na etapa inicial, chamada controle, os reatores foram operados por 130 dias sem reciclo do lodo, para se poder avaliar o comportamento e fazer futuras comparações com a etapa posterior, denominada teste. Na etapa controle foram analisados o comportamento da DQO, dos sólidos e dos nutrientes além de serem realizados testes com o ultra-som para a escolha do tempo de exposição e volume de amostra.. O reator A apresentou uma boa remoção de DQO (90,9%), entretanto não apresentou nitrificação completa, chegando apenas na transformação de nitrogênio orgânico a amoniacal. Já a remoção de fósforo foi da ordem de 60%. O reator B também apresentou uma boa remoção de DQO (87,7%) e houve formação de nitrato, embora não completa, e a remoção de fósforo se situou em 57%. Na etapa teste, que durou aproximadamente 90 dias, os reatores foram operados com retorno total do lodo após desintegração com ultra-som. Houve um aumento na DQO afluente devido ao retorno do lodo desintegrado, bem como um aumento nos teores de nitrogênio e fósforo. Houve também um aumento na concentração de sólidos dos reatores, sendo o reator A que apresentou um maior acréscimo. Ambos reatores apresentaram uma mesma eficiência na remoção de DQO (92,0% para o reator A, e 91% para o reator B) se comparado com a etapa controle. Com relação aos nutrientes os reatores apresentaram sensível melhora na nitrificação. O reator A apresentou uma quase completa redução no nitrogênio orgânico, embora não tenha chegado a nitrificação completa. O reator B apresentou uma remoção completa do nitrogênio orgânico. Com relação ao fósforo, a etapa teste apresentou um decréscimo na sua remoção (42% para o reator A e 44% para o reator B). As análises indicaram que a desintegração do lodo e seu retorno ao tanque de aeração não causaram problemas no funcionamento dos reatores, houve uma melhora na nitrificação e não houve uma sensível redução na remoção de fósforo. Comparando com o problema de transporte, tratamento e disposição final de lodo, o estudo de redução de lodos é uma grande alternativa e que merece mais estudos. / The study aims to reduce the sludge generation in aerobic systems by recirculation of the excess sludge after disintegration with a ultrasound set. Two aerobic sequential batch reactors (A and B) were utilized operating with two different sludge ages: 12 and 8 days respectively. The reactors were operated in two stages. In the first stage, called control, the reactors were operated for 130 days, without total sludge recirculation, to promote an assessment and compare with the next stage, called test. In the control stage the behavior of COD, solids and nutrients were analyzed, and tests with ultrasound were performed. The reactor A presented a good COD removal, but not a good nitrification, and a phosphorus removal of 60%. The reactor B presented a good COD removal and a good nitrification, but not complete, and a phosphorus removal of 57%. The test stage the reactors were operated for 90 days, with sludge recirculation after disintegration by ultrasound. There was an increase in influent COD, nitrogen and phosphorus because of sludge recirculation. There was an increase in MLVSS, but reactor A presented a greater increase. Both reactors presented good results in COD removal comparing with control stage. The reactors present a good improvement in nitrification, but not good phosphorus removal regarding to control stage. The analysis showed that sludge disintegration and recirculation to aeration tank not caused any problem in the behavior of the reactors. Comparing to transport, treatment and final disposal problems, the study of sludge reduction is a great alternative that deserves attention.
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Ultrasonic treatment of sewage sludge in order to increase biogas yieldsEk, Anders January 2005 (has links)
<p>Biogas, a mixture of methane and carbon dioxide, is produced in the anaerobic digestion of sewage sludge. After anaerobic digestion, the digested sludge is often allowed to degas for one or two days. This gas is seldom utilised, but if the degassing could be accelerated, utilisation would be easier. Ultrasound can be used as a pretreatment method for waste activated sludge. It has a disintegrating effect on the sludge and causes lysis of bacteria in the sludge. It also speeds up the hydrolysis; the limiting step of anaerobic digestion of waste activated sludge. Ultrasound can be used to degas waterbased liquids. Ultrasonic degassing of sewage sludge has not been examined previously. The present study aims to investigate the effect of ultrasound on waste activated sludge as well as the potential of ultrasound to speed up the degassing of digested sludge. A semi-continuous, lab-scale digestion experiment was performed with four reactors: two receiving untreated sludge and two receiving treated sludge. The effect of the sonicator was 420 W and the treatment time was 6 min, which corresponds to an energy input of 8.4 kWh/m<sup>3</sup>. Total solids (TS) of the waste activated sludge was ~3.5 %. The ultrasonic treatment caused an increase in gas production of 13 %. There was no difference in methane content. The concentration of filterable chemical oxygen demand (fCOD) increased 375 %, or from 2.8 % to 11 % of total COD. In terms of energy loss/gain the increase in gas production resulted in a loss of 2.7 kWh/m<sup>3</sup>, i.e. more energy is needed to treat the sludge than the potential energy of the increased gas production. However, if the sludge is thickened to a TS >5 %, a net energy gain should be reached. The effect of ultrasound on the degassing of digested sludge was examined in three barrels. The degassing was measured with and without circulation as well as with ultrasonic treatment. The digested sludge had a gas emission rate of 115 L/(m<sup>3</sup> day). No direct burst of gas occurred due to ultrasonic treatment. Over two days more gas was emitted from the barrel equipped with ultrasound, probably due to an induced post-digestion. Thus, ultrasonic pretreatment of waste activated sludge increases the biogas yield. It is inconclusive, whether ultrasonic treatment of digested sludge effects the degassing or not.</p>
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A suggestion on uniform sludge and waste handling in the Baltic Sea AreaEklund, Per, Dahlberg, Stefan January 2010 (has links)
<p>The purpose of this thesis is to make a thorough but compact description of the international laws concerning solid garbage generated by vessels and sludge treatment. It is also to construct a pamphlet that can be used as a guide by ports when constructing their own information sheets to the vessels. The questions given to us from Baltic Master II were: what does the international legislation state about waste handling from vessels and in the port facilities, both sludge and solid garbage? Describe routines for receiving sludge, with concern taken to the rules that apply today. Describe routines for receiving sorted garbage and recycling, with concern taken to the rules that apply today. Look at the present symbols and labelling and develop a standard for vessels and port facilities. To solve these questions we choose an investigative method based on a literature study. The research of earlier studies showed that the parties involved consider the waste- and sludgetreatment to be flawed. In some cases the problems are fictitious or exaggerated. The main problem originates from the fact that there are no uniform routines for the interaction between vessel and port. Although there is more then one way to deal with this problem, we have concluded that the best way to improve the present day situation is to implement uniform routines. To make the routines effective they should be developed and agreed upon by the parties involved taking into consideration present day international legislation. In this thesis we present a suggestion on such a routine.</p>
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