Many industries use, or produce, metal-containing solutions which must be treated for reuse or discharge to sewer. One such treatment is biological and both living and dead materials have been investigated for the abstraction of metal ions from solution. Studies on systems containing only a single biosorbent are well documented, and mostly involve optimisation of biosorption capacities and metal uptake rates through modification of Biological Support Particle (BSP) size and surface characteristics. Literature on dual biosorbent studies is sparse. The commercial application of biosorption technology in wastewater treatment remains largely unexplored and unexploited. The primary objective here was to assess the potential of forced-upflow packed-bed bioreactors, containing dual biological sorbents, for treating a synthetic wastewater containing copper, zinc and cadmium, at both laboratory- and pilotscale. Pine bark was selected as BSP since it is an abundant, relatively cheap, agricultural waste product in South Africa, and is known to sorb metal ions. Initial experiments aimed to optimise biofilm development on the pine bark surfaces, since microbial biomass is also known to sequester metal ions. Systems comprising either one, or both, these biosorbents were compared for their efficiency in metal removal. The effects of type, size, and state of decomposition, of the pine bark, the addition of supplementary nutrients (Voermolas) and the mixing conditions, on the metal biosorption capacity and reaction kinetics of the systems were also studied. All experiments were conducted at an initial metal concentration of 100mg.ℓ⁻¹with both composted and uncomposted pine bark as BSP. The former supported microbial colonisation and resisted biofilm sloughing, but degraded rapidly causing engineering difficulties. Uncomposted pine bark showed the same ability, but was also physically more robust. Organic compounds leached from the pine bark did not hinder microbial colonisation of the BSP; rather they served as additional nutrients. Literature studies suggest that these compounds would not significantly compromise the COD or increase the toxicity of the final effluent. Biofilms developed without supplementary nutrients, but Cd²⁺ and Zn²⁺ were sorbed more effectively in bioreactors containing Voermolas (39% and 38% Cd²⁺ removal, 36% and 32% Zn²⁺ removal, in 0.2% and 0.1% Voermolas solutions respectively) than in unsupplemented systems (25% Cd²⁺ removal and 20% Zn²⁺ removal). Conversely, Cu²⁺ was removed most efficiently in the absence of supplementary nutrients. Based on biosorption of the target metal ions, 0.1% (v/v) Voermolas was the most effective concentration of supplementary nutrients. Raw, un-colonised pine bark nuggets (16-24mm), and plastic bioballs (commercially available, bespoke BSP), were compared in laboratory-scale bioreactors by measuring the decrease in residual metal ion concentrations over time, and changes in the solution pH. These experiments showed that the two BSPs did not differ significantly in their performance as a support matrix, or as a metal sorbent (30.6% and 32.6% of metal ion remained in solution when using bioballs and pine bark respectively). However, the presence of a biofilm on both these BSPs, improved the overall performance of the bioreactors significantly (for the bioball BSP, residual metal ion levels decreased from 30.6%, in the absence of a biofilm, to 11.0% with a biofilm present. Similarly, for the pine bark BSP, residual metal ion levels decreased from 32.6%, in the absence of a biofilm, to 7.3% with a biofilm present). A cost comparison of the two BSPs showed that raw pine bark nuggets were available at less than 0.1% of the cost of the bioballs. At pilot-scale, modelled kinetic data compared poorly with experimentally determined results, but minimum residual metal concentrations for Cu (1.7mg.ℓ⁻¹) and Zn (4.2 mg.ℓ⁻¹) were below South African (eThekwini Municipality) regulatory limits for discharge to sewer (5mg,ℓ⁻¹ for both), and sea outfall (3mg.ℓ⁻¹ Cu and 20mg.ℓ⁻¹ Zn). However, for Cd the final residual metal concentration (5.6mg.ℓ⁻¹) was above the regulatory discharge threshold for any receiving system. Although some of the effluents from the system investigated could not be legally released into the municipal sewer system without further remediation, the study showed that a system combining living and dead biomass in a single reactor is capable of significantly reducing dissolved metal concentrations in synthetic wastewaters without temperature or pH adjustment. Furthermore, such a system can operate at pilot-scale, where a pine bark matrix represents a significant cost saving over conventional plastic BSPs. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

This study revealed that ammonium ion exchange of natural zeolite could be a feasible method of nitrogen removal and recovery from permeate from anaerobic membrane bioreactors (AnMBRs). NaCl concentrations optimized for chemical regeneration in batch experiments did not match those in continuous column tests. Instead, the mass ratio of Na+ to Zeolite-NH4+-N was significant for improving regeneration efficiency in column experiments; this mass ratio was 750 g Na+/g Zeolite-NH4+-N required for regeneration efficiency over 90% in 2 hours at pH 9. ???To decrease the NaCl dose in regeneration of exhausted zeolite, a high pH regeneration method was developed using an NaCl concentration of 10 g/L at pH 12 (the mass of Na+ to Zeolite-NH4+-N of 4.2 ) which achieved a regeneration efficiency about 85%. The recovery of ammonium nitrogen from the exhausted zeolite was assessed with air stripping followed by ammonia collection in an acid scrubber. The effects of shaking and air stripping were investigated in batch tests and the results showed the superiority of air stripping over shaking. Liquid circulation and air flow rates were varied for optimization of ammonia recovery in a continuous zeolite-packed column combined with a regeneration chamber and a stripping column. The liquid circulation rate had no significant effect on either the regeneration efficiency or the ammonia transfer efficiency from ammonium nitrogen to ammonia gas, while the ammonia transfer efficiency significantly increased with the air flow rate.??? Furthermore, the effect of pH on ammonia recovery was tested. Both the regeneration efficiency and the ammonia transfer efficiency were significantly improved with increasing pH. When the pH was increased from 9.5 to 12, the regeneration efficiency increased from 9.2% to 84% and the ammonia transfer efficiency increased from 54% to 92%. The nitrogen recovery process that combines zeolite ammonium exchange and air stripping can decrease chemical costs for regeneration of exhausted zeolite and efficiently collect ammonium nitrogen to be reused as fertilizers. Hence, the integrated nitrogen process can resolve the challenge of nitrogen removal in anaerobic membrane bioreactors treating organic wastewater in sustainable manners.

This study was carried out to investigate performance of a Vacuum Rotating Membrane (VRM) type membrane bioreactor (MBR). During the study, the VRM plant was erected from scratch and operated in METU campus. The plant was composed of two tanks. First one was about 100 m3 and it was used for biological treatment / the second tank, about 30 m3, was used as filter chamber. The permeate flow rate was adjusted between 6 and 8.5 m3/h giving a hydraulic retention time (HRT) of 18 hours during the study. In the aeration tank, dissolved oxygen (DO) was adjusted to between 4 and 0.1 mg/L to see the effect of the dissolved oxygen concentration on the process. In the filter chamber, total of 540 m2 flat sheet membrane surface were used for the separation of the treated wastewater from the activated sludge. During the 140 days of operation, MLSS concentration increased from 2.5 g/L to 20 g/L. A 99.99% BOD removal and above 95% COD removal were achieved most of the time during the study. At the time when organic loading rate was between 0.35 and 0.1 kg COD/ kgVSS-day, sludge production was very low. Therefore, sludge retention time (SRT) was taken as infinite. The turbidity in the effluent was less than 1 NTU at all the time, and was below that of the tap water. In the aeration tank, 100% Total-N removal was observed when DO was 2 mg/L and MLSS was 8.36 mg/L on 80th day of operation. This indicates that simultaneous nitrification and denitrification was taking place at these conditions. Later, N-removal decreased when DO was deliberately decreased to 0.1 mg/L in the aeration tank to prevent nitrification / for treated wastewaters were intended to be used for irrigation. Since the pores of the membrane were 0.038 &amp / #956 / m, treated wastewaters were sterile with respect to bacteria

An Entrapped-Mixed-Microbial-Cell (EMMC) process was investigated for its simultaneous removal of carbon and nitrogen in a single bioreactor with the influent COD/N ratio varying from 4 to 15 and influent alkalinity of 140 mg CaCO3/L and 230 mg CaCO3/L. The reactor was operated with alternate schedules of intermittent aeration. Two different sizes of carriers (10 * 10 * 10 mm3 and 20 * 20 * 20 mm3) were studied. The medium carrier (10 * 10 * 10 mm3) system presents higher nitrogen removal and COD removal compared to the large carrier system. The nitrogen removal efficiency is related to the ratio of COD/N in the influent. With the increase of the COD/N ration in the influent, the nitrogen removal efficiency is increased. The average reductions of nitrogen were over 92% and the average reductions of SCOD and BOD5 are over 95% and 97%, respectively, in the medium carrier system. This is operated at the HRT of 12 hours and 0.5 hour aeration and 2 hours of non-aeration, and the COD/N ratio of 15 in the influent. Changing alkalinity from 140 to 230 mg CaCO3/L has no effect in both large and medium carriers for the nitrogen removal efficiency. The pH, oxidation – reduction potential (ORP) and dissolved oxygen (DO) were used to monitor the biological nitrogen removal. It was found that the ORP (range from -100 to 300 mV) can be used to provide better effluent quality measured as total-nitrogen of less than 10 mg/L. Also, the impact of influent COD/N ratio on the effluent quality (measured as Inorg.-nitrogen) for the EMMC process is very important. Compared to other two compact biological wastewater treatment processes, membrane bioreactor (MBR) and moving bed biofilm reactor (MBBR), the EMMC process with the intermittent aeration has higher removal efficiencies of carbon and nitrogen, easier operation, lower O&M cost, lower energy requirement, and more compact. The total cost requirement is less than $3.27 per 1000 gallons (3.785 m 3) of treated settled domestic sewage per day. It is apparent that the EMMC process is technically feasible for the simultaneous removal of carbon and nitrogen under the operation on a schedule of intermittent aeration and suitable to be used for replacement or upgrading of existing treatment plant at land limited area.

Licentiatavhandling (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2006. / Härtill 2 uppsatser.

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on July 9, 2009. Major professor: Kristen O'Halloran Cardinal, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Engineering, with a Specialization in Biomedical Engineering." "April 2009." Includes bibliographical references (p. 114-121). Also available on microfiche.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 145-161).

A engenharia de tecidos é uma área de pesquisa que busca alternativas para a regeneração de tecidos danificados. Uma subárea dessa nova ciência faz uso das células-tronco, capazes de participar do processo de regeneração tecidual. As células são cultivadas em suportes porosos chamados de biomateriais ou scaffolds. As células-tronco mesenquimais de polpa de dente são células multipotentes e fáceis de serem obtidas. A policaprolactona, polímero atóxico, tem sido vastamente utilizada na fabricação de scaffolds devido as suas propriedades mecânicas, adequadas para a regeneração de alguns tecidos. A cultura dinâmica em biorreatores vem sendo utilizada pela sua capacidade de mimetizar as condições do ambiente natural das células-tronco no organismo humano. O objetivo do presente trabalho foi definir um protocolo de cultivo de células-tronco mesenquimais da polpa de dente em scaffolds de policaprolactona em multicamada, utilizando biorreatores de perfusão. Os biorreatores foram projetados com base em informações presentes na literatura. Os scaffolds de policaprolactona foram produzidos por electrospinning e apresentaram um diâmetro de 15 mm, aproximadamente 300 μm de espessura e diâmetro médio das fibras de 0,98 ± 0,24 μm. O cultivo estático, para fins de comparação, foi realizado em triplicata. Para o cultivo dinâmico, analisaram-se 3 diferentes vazões: 0,1 mL.min-1, 0,08 mL.min-1 e 0,05 mL.min-1. Nos dias 1, 3 e 7 de cultivo celular as análises de viabilidade celular foram realizadas pelo ensaio de WST-8, a citotoxicidade pela dosagem de LDH e de adesão celular pela histologia.. As células cultivadas nos scaffolds do topo da estrutura em camadas apresentaram maior viabilidade celular para as vazões de 0,1 e 0,08 mL.min-1 entre os dias 1 e 7 do cultivo celular. O cultivo dinâmico realizado na vazão de 0,05 mL.min-1 obteve um número baixo de células viáveis em todos os dias de análise. No cultivo estático, a viabilidade celular aumentou do primeiro ao sétimo dia de cultivo, mas permaneceu abaixo da maior vazão testada. As análises de histologia confirmaram a presença de células nas superfícies dos scaffolds. Os níveis maiores de citotoxicidade foram encontrados para o cultivo dinâmico, principalmente para a vazão de 0,1 mL.min-1, bem como foi observada maior viabilidade celular para essa vazão. Ainda é necessário repetir ambos os cultivos para confirmar os resultados e validar o protocolo definido para os experimentos. No entanto, no cultivo dinâmico, a vazão de 0,1 mL.min-1 proporcionou resultados promissores para o sistema de perfusão utilizado, podendo comprovar as vantagens do cultivo dinâmico de células-tronco para a medicina regenerativa. / Tissue engineering is an area of research which seeks for alternatives for the regeneration of damaged tissue. A sub-area of this new science uses stem cells, which are able to participate in the process of tissue regeneration. The cells are cultivated in porous supports called biomaterials or scaffolds. The mesenchymal stem cells from teeth pulp are multipotent cells and are easily obtained. Polycaprolactone, an atoxic polymer, has been extensively used in the production of scaffolds, due to its mechanical properties which are suitable for the regeneration of certain types of tissue. The dynamic cultivation using bioreactors is currently used because of its capacity to immitate the conditions of the natural environment of stem cells in the human organism. The aim of the present study has been to define a protocol for the cultivation of mensechymal stem cells from teeth pulp in multi-layered polycaprolactone scaffolds in perfusion bioreactors. The bioreactors were designed based on current information available in the literature. The polycaprolactone scaffolds were produced by electrospinning and had a diameter of 15 mm, with approximately 300 μm thickness and an average fiber diameter of 0.98 ± 0.24 μm. The static cultivation for use as a comparison was carried out in triplicate. Three different flow rates were analyzed for cellular cultivation: 0.1 mL.min-1, 0.08 mL.min-1 and 0.05 mL.min-1. The cellular viability analyses were carried out by WST-8 assay, cytotoxicity through an LDH dosage and cellular adhesion by histology on days 1, 3 and 7 of the cellular cultivation. The cultivated cells on the scaffolds, which were above the structure in layers, presented greater cellular viability when the flow rates 0.1 and 0.08 mL.min-1 were used, between days 1 and 7 of the cellular cultivation. When the flow rate of 0.05 mL.min-1 was used in the dynamic cultivation, the lowest number of viable cells in all the days of the analyses was observed. In the static cultivation, cellular viability increased between the first and seventh day of cultivation but remained lower than the dynamic cultivation with the higher flow rate tested. The histological analyses confirmed the presence of cells on the surface of the scaffolds. Both the greatest levels of cytotoxicity and cellular viability were observed in the dynamic cultivation, mainly with the flow rate of 0.1 mL.min-1. It is necessary to repeat both the cultivations to confirm the results and to test the efficiency of the protocol defined by the experiments. However, in the dynamic cultivation, the flow rate of 0.1 mL.min-1 presented promising results for the perfusion system of this study, showing the advantages of the dynamic cultivation of stem cells for regenerative medicine.

A engenharia de tecidos é uma área de pesquisa que busca alternativas para a regeneração de tecidos danificados. Uma subárea dessa nova ciência faz uso das células-tronco, capazes de participar do processo de regeneração tecidual. As células são cultivadas em suportes porosos chamados de biomateriais ou scaffolds. As células-tronco mesenquimais de polpa de dente são células multipotentes e fáceis de serem obtidas. A policaprolactona, polímero atóxico, tem sido vastamente utilizada na fabricação de scaffolds devido as suas propriedades mecânicas, adequadas para a regeneração de alguns tecidos. A cultura dinâmica em biorreatores vem sendo utilizada pela sua capacidade de mimetizar as condições do ambiente natural das células-tronco no organismo humano. O objetivo do presente trabalho foi definir um protocolo de cultivo de células-tronco mesenquimais da polpa de dente em scaffolds de policaprolactona em multicamada, utilizando biorreatores de perfusão. Os biorreatores foram projetados com base em informações presentes na literatura. Os scaffolds de policaprolactona foram produzidos por electrospinning e apresentaram um diâmetro de 15 mm, aproximadamente 300 μm de espessura e diâmetro médio das fibras de 0,98 ± 0,24 μm. O cultivo estático, para fins de comparação, foi realizado em triplicata. Para o cultivo dinâmico, analisaram-se 3 diferentes vazões: 0,1 mL.min-1, 0,08 mL.min-1 e 0,05 mL.min-1. Nos dias 1, 3 e 7 de cultivo celular as análises de viabilidade celular foram realizadas pelo ensaio de WST-8, a citotoxicidade pela dosagem de LDH e de adesão celular pela histologia.. As células cultivadas nos scaffolds do topo da estrutura em camadas apresentaram maior viabilidade celular para as vazões de 0,1 e 0,08 mL.min-1 entre os dias 1 e 7 do cultivo celular. O cultivo dinâmico realizado na vazão de 0,05 mL.min-1 obteve um número baixo de células viáveis em todos os dias de análise. No cultivo estático, a viabilidade celular aumentou do primeiro ao sétimo dia de cultivo, mas permaneceu abaixo da maior vazão testada. As análises de histologia confirmaram a presença de células nas superfícies dos scaffolds. Os níveis maiores de citotoxicidade foram encontrados para o cultivo dinâmico, principalmente para a vazão de 0,1 mL.min-1, bem como foi observada maior viabilidade celular para essa vazão. Ainda é necessário repetir ambos os cultivos para confirmar os resultados e validar o protocolo definido para os experimentos. No entanto, no cultivo dinâmico, a vazão de 0,1 mL.min-1 proporcionou resultados promissores para o sistema de perfusão utilizado, podendo comprovar as vantagens do cultivo dinâmico de células-tronco para a medicina regenerativa. / Tissue engineering is an area of research which seeks for alternatives for the regeneration of damaged tissue. A sub-area of this new science uses stem cells, which are able to participate in the process of tissue regeneration. The cells are cultivated in porous supports called biomaterials or scaffolds. The mesenchymal stem cells from teeth pulp are multipotent cells and are easily obtained. Polycaprolactone, an atoxic polymer, has been extensively used in the production of scaffolds, due to its mechanical properties which are suitable for the regeneration of certain types of tissue. The dynamic cultivation using bioreactors is currently used because of its capacity to immitate the conditions of the natural environment of stem cells in the human organism. The aim of the present study has been to define a protocol for the cultivation of mensechymal stem cells from teeth pulp in multi-layered polycaprolactone scaffolds in perfusion bioreactors. The bioreactors were designed based on current information available in the literature. The polycaprolactone scaffolds were produced by electrospinning and had a diameter of 15 mm, with approximately 300 μm thickness and an average fiber diameter of 0.98 ± 0.24 μm. The static cultivation for use as a comparison was carried out in triplicate. Three different flow rates were analyzed for cellular cultivation: 0.1 mL.min-1, 0.08 mL.min-1 and 0.05 mL.min-1. The cellular viability analyses were carried out by WST-8 assay, cytotoxicity through an LDH dosage and cellular adhesion by histology on days 1, 3 and 7 of the cellular cultivation. The cultivated cells on the scaffolds, which were above the structure in layers, presented greater cellular viability when the flow rates 0.1 and 0.08 mL.min-1 were used, between days 1 and 7 of the cellular cultivation. When the flow rate of 0.05 mL.min-1 was used in the dynamic cultivation, the lowest number of viable cells in all the days of the analyses was observed. In the static cultivation, cellular viability increased between the first and seventh day of cultivation but remained lower than the dynamic cultivation with the higher flow rate tested. The histological analyses confirmed the presence of cells on the surface of the scaffolds. Both the greatest levels of cytotoxicity and cellular viability were observed in the dynamic cultivation, mainly with the flow rate of 0.1 mL.min-1. It is necessary to repeat both the cultivations to confirm the results and to test the efficiency of the protocol defined by the experiments. However, in the dynamic cultivation, the flow rate of 0.1 mL.min-1 presented promising results for the perfusion system of this study, showing the advantages of the dynamic cultivation of stem cells for regenerative medicine.

Made available in DSpace on 2014-10-09T12:48:54Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:11Z (GMT). No. of bitstreams: 1 09617.pdf: 5595560 bytes, checksum: 5a054c653d88ec87b2d3c979b79b00b5 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao [Mestrado] / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:00/09008-4