Please use this identifier to cite or link to this item: https://hdl.handle.net/10321/874
DC FieldValueLanguage
dc.contributor.advisorBux, Faizal-
dc.contributor.advisorPillai, Sheena Kumari Kuttan-
dc.contributor.authorRamdhani, Nishanien_US
dc.date.accessioned2013-07-30T06:58:45Z
dc.date.available2014-02-11T12:32:57Z
dc.date.issued2013-07-30-
dc.identifier.other447419-
dc.identifier.urihttp://hdl.handle.net/10321/874-
dc.descriptionSubmitted in fulfilment for the requirements for the Degree of Doctor of Technology: Biotechnology, Durban University of Technology, Durban, South Africa, 2013.en_US
dc.description.abstractNitrification is a crucial step in biological nutrient removal (BNR) processes, mostly carried out by a group of nitrifying bacteria which includes ammonia-oxidising bacteria (AOB) and nitrite-oxidising bacteria (NOB). Nitrification failure has proven to be a common operational problem in full-scale wastewater treatment plants (WWTP) since nitrifying bacteria are very sensitive to sudden changes in environmental or plant operating conditions. The current investigation was carried out to advance our understanding of the distribution of nitrifying bacterial populations and their performance at three different BNR plants in KwaZulu-Natal, South Africa. The latest molecular techniques such as fluorescent in situ hybridisation (FISH)-confocal scanning laser microscopy (CSLM), polymerase chain reaction (PCR) and real-time quantitative PCR (Q-PCR) were applied to detect and quantify nitrifying bacteria. When using FISH to target the nitrifying population, it necessitated optimising pre-treatment protocols of the samples to improve accuracy during quantification. Sonication was found to be the superior method of dispersion based on the least disruption of nitrifier cell integrity, irrespective of the sludge type. The effect of plant configurations and wastewater characteristics on the distribution of the nitrifying bacterial population and subsequently on the nitrification performance was evaluated using FISH and PCR. FISH results revealed the dominance of Nitrosomonas (AOB), Nitrobacter (NOB) and Nitrospira (NOB) for all BNR plants. The 16S rRNA analysis of PCR products using genus-specific primers, revealed the presence of more than one species of the same group at these plants. Nitrosomonas spp. including Nitrosomonas halophila, Nitrosomonas eutropha, Nitrosomonas europaea, Nitrosomonas aestuarii and an unidentified Nitrosomonas spp. were found to dominate among the AOB and Nitrobacter vulgaris, Nitrobacter alkalicus, Nitrobacter hamburgensis and an unidentified Nitrobacter spp. were the dominant species for NOB. Among these species, Nitrosomonas aestuarii, Nitrosomonas europaea, Nitrobacter hamburgensis were detected only from the industrial wastewater samples. The efficiency of two commonly used techniques viz., FISH and Q-PCR for the detection of nitrifiers from WWTP were also studied and compared, specifically targeting Nitrobacter sp. Even though there were slight variations in the quantification results, changes in the Nitrobacter community at these plants were consistent for both FISH and Q-PCR results. Both techniques have their own limitations and advantages. This study has helped to add to the platform of understanding the distribution and activity of nitrifying bacteria by correlating population dynamics with the operational parameters at full-scale level. The observations made in this study will assist researchers and engineers to minimise future nitrification failure at full-scale BNR plants. This study also confirmed the highly complex activities of wastewater treatment processes, which is dependant on a number of factors. Specific AOB or NOB predominant in wastewater rather suggests that the wastewater type and characteristics may contribute to significantly different microbial environments. Among the AOB, Nitrosomonas dominated at all BNR plants throughout the study period and for NOB both Nitrobacter and Nitrospira were found in significant numbers but their dominance varied across the plants. These dissimilar, distinct distribution patterns could be attributed to their environment which in turn impacted on the nitrification performance of the system. It was also noted that the co-existence of more than one group of these communities at the same plant could help the plant escape complete functional failures such as nitrification, due to sudden changes in temperature and substrate concentrations, as this function can be performed by different groups. Although it would have been meritorious to conduct a nitrogen balance in this study, this was not possible since the research focused on full-scale systems.en_US
dc.description.sponsorshipNational Research Foundationen_US
dc.format.extent175 pen_US
dc.language.isoenen_US
dc.subject.lcshNitrifying bacteriaen_US
dc.subject.lcshNitrificationen_US
dc.subject.lcshSewage--Purification--Biological treatmenten_US
dc.subject.lcshSewage--Purification--Nutrient removalen_US
dc.subject.lcshSewage disposal plants--South Africa--KwaZulu-Natalen_US
dc.titleDetection and quantification of nitrifying bacteria from South African biological nutrient removal plantsen_US
dc.typeThesisen_US
dc.dut-rims.pubnumDUT-002424en_US
dc.description.levelDen_US
dc.identifier.doihttps://doi.org/10.51415/10321/874-
local.sdgSDG05-
local.sdgSDG06-
local.sdgSDG15-
item.languageiso639-1en-
item.openairetypeThesis-
item.cerifentitytypePublications-
item.openairecristypehttp://purl.org/coar/resource_type/c_18cf-
item.fulltextWith Fulltext-
item.grantfulltextopen-
Appears in Collections:Theses and dissertations (Applied Sciences)
Files in This Item:
File Description SizeFormat
Ramdhani_2013.pdf6.25 MBAdobe PDFThumbnail
View/Open
Show simple item record

Page view(s) 50

1,398
checked on Dec 22, 2024

Download(s) 10

2,103
checked on Dec 22, 2024

Google ScholarTM

Check

Altmetric

Altmetric


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.