Инженерно-геологические условия и проект изысканий под строительство 10-ти этажного здания в микрорайоне Восточный (г. Томск)

Данная работа представляет собой проект изысканий на участке строительства жилого 10-ти этажного здания в микрорайоне Восточный города Томска. Цель дипломного проекта – дать характеристику инженерно-геологических условий площадки строительства жилого 10-ти этажного здания в микрорайоне Восточный города Томска и составить проект изысканий под данное здание.This work is a refined project on the site of construction of a residential 10-storey building in the Vostochny micro-district of the city of Tomsk. The purpose of the diploma project is to give a description of the engineering and geological conditions of the construction site for a 10-storey building in the residential area of the Eastern city of Tomsk and to design a refined project for the annotation of the building

Role of extracellular polymeric substances and metals in fouling of membranes in the wastewater treatment

The use of membrane bioreactors (MBRs) for wastewater treatment has been increasing since the 1990s and is gaining more importance due to rising demands for water in general. There is yet one main limitation in full-scale applications of MBRs: the membrane fouling, leading to a substantial loss of membrane performance and subsequently to high costs because of cleaning and replacing the membranes. Since no consensus on the exact fouling phenomenon or a single fouling parameter in MBRs has been reached yet the present study was aiming at characterizing membrane foulants in the full-scale MBR Nordkanal (Düsseldorf, Germany), in pilot-scale MBRs as well as in fermenter-/lab-scale studies. The focus of the present study was on two classes of substances that are known to cause fouling in membrane applications: extracellular polymeric substances (EPS) and metals. The long-term observation of activated sludge, permeate and autopsied membranes from the MBR Nordkanal showed a significant contribution of EPS and iron to membrane fouling. The membrane fouling layers where shown to have the following composition (in weight %): humic substances (39%), carbohydrates (30%), iron (22%) and fatty acids (8%). Contrary to other, mostly pilot-scale studies, biofilm development was not dominant in this full-scale MBR due to vigorous aeration and frequent backwashing of the fibres. Interestingly, precipitations of iron hydroxides were detected on the membranes, even on the permeate side, whereas Ca2+ and Mg2+ were not involved in fouling in this MBR. The retention by the ultrafiltration membranes in the full-scale MBR was shown to be 39 ± 27% for humic acids and 79 ± 30% for carbohydrates (average of 2.5 years of monthly samples) although the molecular weight of the humics fraction was demonstrated to be below the molecular weight cut-off of the membrane. Fatty acids (FA) of microbial origin (C16:0, C18:0) were the dominating FA in EPS of activated sludge flocs, sludge supernatant, permeate and membrane fouling layers in the MBR Nordkanal. A remarkable finding was that a shorter FA of a probable synthetic origin (C9:0) was preferentially deposited into the membranes where it accounted for 10% of the FA in total EPS whereas in sludge floc EPS it was only 1% of total FA concentration. The results from the full-scale study were used to propose a fouling mechanism that is based on complexation and adsorption processes. Iron from the coagulant FeCl3 in form of Fe2+ and Fe3+ is playing a central role in this mechanism as it is able to form complexes with humic acids and with uronic acids that were detected in the microbial polysaccharides of samples of the MBR Nordkanal. For such complexes as well as for fatty acids, reduced electrostatic repulsion, narrowing of the membrane pores and hydrophobic interactions with the membrane material could explain the observed fouling phenomenon. In lab-scale surveys regarding membrane cleaning strategies, it was further verified that citric acid is especially suited to remove iron and EPS from fouled membranes. Moreover, it was demonstrated through lab-scale sludge digestion how soluble Fe2+ can be formed and released together with EPS from the sludge floc matrix under anaerobic conditions. Such conditions also deteriorated sludge properties in terms of filterability and settling behaviour. Finally, in the pilot-scale study it was shown that low sludge retention time (SRT) leads to an excess production of EPS in correlation with deteriorating sludge properties. The formation of fouling layers on the membranes was also more distinct at low SRT, with 40-fold higher amounts of deposited proteins and 5-fold higher concentrations of carbohydrates compared with high SRT. However, membrane permeability was similar at both SRTs. The conclusion for operators of full-scale MBRs in general is that high SRT is beneficial for activated sludge properties. For the specific case of the MBR Nordkanal which is already operated at high SRT (28 d), it can be concluded that the presence of iron in conjunction with anaerobic conditions in the denitrification tank, prior to membrane filtration, is more decisive for the membrane fouling. As shown by results of the present study, the applied cleaning strategy with citric acid in Nordkanal is appropriate for removing the major membrane foulants. For future studies aiming at clarifying distinct fouling parameters and fouling mechanisms, a focus on metal complexation with specific EPS or with wastewater components, as well as the interaction of such complexes with different membrane materials looks promising

Role of extracellular polymeric substances and metals in fouling of membranes in the wastewater treatment

The use of membrane bioreactors (MBRs) for wastewater treatment has been increasing since the 1990s and is gaining more importance due to rising demands for water in general. There is yet one main limitation in full-scale applications of MBRs: the membrane fouling, leading to a substantial loss of membrane performance and subsequently to high costs because of cleaning and replacing the membranes. Since no consensus on the exact fouling phenomenon or a single fouling parameter in MBRs has been reached yet the present study was aiming at characterizing membrane foulants in the full-scale MBR Nordkanal (Düsseldorf, Germany), in pilot-scale MBRs as well as in fermenter-/lab-scale studies. The focus of the present study was on two classes of substances that are known to cause fouling in membrane applications: extracellular polymeric substances (EPS) and metals. The long-term observation of activated sludge, permeate and autopsied membranes from the MBR Nordkanal showed a significant contribution of EPS and iron to membrane fouling. The membrane fouling layers where shown to have the following composition (in weight %): humic substances (39%), carbohydrates (30%), iron (22%) and fatty acids (8%). Contrary to other, mostly pilot-scale studies, biofilm development was not dominant in this full-scale MBR due to vigorous aeration and frequent backwashing of the fibres. Interestingly, precipitations of iron hydroxides were detected on the membranes, even on the permeate side, whereas Ca2+ and Mg2+ were not involved in fouling in this MBR. The retention by the ultrafiltration membranes in the full-scale MBR was shown to be 39 ± 27% for humic acids and 79 ± 30% for carbohydrates (average of 2.5 years of monthly samples) although the molecular weight of the humics fraction was demonstrated to be below the molecular weight cut-off of the membrane. Fatty acids (FA) of microbial origin (C16:0, C18:0) were the dominating FA in EPS of activated sludge flocs, sludge supernatant, permeate and membrane fouling layers in the MBR Nordkanal. A remarkable finding was that a shorter FA of a probable synthetic origin (C9:0) was preferentially deposited into the membranes where it accounted for 10% of the FA in total EPS whereas in sludge floc EPS it was only 1% of total FA concentration. The results from the full-scale study were used to propose a fouling mechanism that is based on complexation and adsorption processes. Iron from the coagulant FeCl3 in form of Fe2+ and Fe3+ is playing a central role in this mechanism as it is able to form complexes with humic acids and with uronic acids that were detected in the microbial polysaccharides of samples of the MBR Nordkanal. For such complexes as well as for fatty acids, reduced electrostatic repulsion, narrowing of the membrane pores and hydrophobic interactions with the membrane material could explain the observed fouling phenomenon. In lab-scale surveys regarding membrane cleaning strategies, it was further verified that citric acid is especially suited to remove iron and EPS from fouled membranes. Moreover, it was demonstrated through lab-scale sludge digestion how soluble Fe2+ can be formed and released together with EPS from the sludge floc matrix under anaerobic conditions. Such conditions also deteriorated sludge properties in terms of filterability and settling behaviour. Finally, in the pilot-scale study it was shown that low sludge retention time (SRT) leads to an excess production of EPS in correlation with deteriorating sludge properties. The formation of fouling layers on the membranes was also more distinct at low SRT, with 40-fold higher amounts of deposited proteins and 5-fold higher concentrations of carbohydrates compared with high SRT. However, membrane permeability was similar at both SRTs. The conclusion for operators of full-scale MBRs in general is that high SRT is beneficial for activated sludge properties. For the specific case of the MBR Nordkanal which is already operated at high SRT (28 d), it can be concluded that the presence of iron in conjunction with anaerobic conditions in the denitrification tank, prior to membrane filtration, is more decisive for the membrane fouling. As shown by results of the present study, the applied cleaning strategy with citric acid in Nordkanal is appropriate for removing the major membrane foulants. For future studies aiming at clarifying distinct fouling parameters and fouling mechanisms, a focus on metal complexation with specific EPS or with wastewater components, as well as the interaction of such complexes with different membrane materials looks promising

Characterization of biphenyl dioxygenase sequences and activities encoded by the metagenomes of highly polychlorobiphenyl-contaminated soils.

Total extracted DNA from two heavily polychlorobiphenyl-contaminated soils was analyzed with respect to biphenyl dioxygenase sequences and activities. This was done by PCR amplification and cloning of a DNA segment encoding the active site of the enzyme. The translated sequences obtained fell into three similarity clusters (I to III). Sequence identities were high within but moderate or low between the clusters. Members of clusters I and II showed high sequence similarities with well-known biphenyl dioxygenases. Cluster III showed low (43%) sequence identity with a biphenyl dioxygenase from Rhodococcus jostii RHA1. Amplicons from the three clusters were used to reconstitute and express complete biphenyl dioxygenase operons. In most cases, the resulting hybrid dioxygenases were detected in cell extracts of the recombinant hosts. At least 83% of these enzymes were catalytically active. Several amino acid exchanges were identified that critically affected activity. Chlorobiphenyl turnover by the enzymes containing the prototype sequences of clusters I and II was characterized with 10 congeners that were major, minor, or not constituents of the contaminated soils. No direct correlations were observed between on-site concentrations and rates of productive dioxygenations of these chlorobiphenyls. The prototype enzymes displayed markedly different substrate and product ranges. The cluster II dioxygenase possessed a broader substrate spectrum toward the assayed congeners, whereas the cluster I enzyme was superior in the attack of ortho-chlorinated aromatic rings. These results demonstrate the feasibility of the applied approach to functionally characterize dioxygenase activities of soil metagenomes via amplification of incomplete genes

Internal Transcribed Spacer 1 Secondary Structure Analysis Reveals a Common Core throughout the Anaerobic Fungi (Neocallimastigomycota)

The internal transcribed spacer (ITS) is a popular barcode marker for fungi and in particular the ITS1 has been widely used for the anaerobic fungi (phylum Neocallimastigomycota). A good number of validated reference sequences of isolates as well as a large number of environmental sequences are available in public databases. Its highly variable nature predisposes the ITS1 for low level phylogenetics; however, it complicates the establishment of reproducible alignments and the reconstruction of stable phylogenetic trees at higher taxonomic levels (genus and above). Here, we overcame these problems by proposing a common core secondary structure of the ITS1 of the anaerobic fungi employing a Hidden Markov Model-based ITS1 sequence annotation and a helix-wise folding approach. We integrated the additional structural information into phylogenetic analyses and present for the first time an automated sequence-structure-based taxonomy of the ITS1 of the anaerobic fungi. The methodology developed is transferable to the ITS1 of other fungal groups, and the robust taxonomy will facilitate and improve high-throughput anaerobic fungal community structure analysis of samples from various environments