Submitted by Eduarda Figueiredo (eduarda.ffigueiredo@ufpe.br) on 2015-03-12T15:08:37Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Eveline P Aquino_versão PDF.pdf: 1247530 bytes, checksum: 653990a1e91057588a690bd2715e2919 (MD5) / Made available in DSpace on 2015-03-12T15:08:37Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Eveline P Aquino_versão PDF.pdf: 1247530 bytes, checksum: 653990a1e91057588a690bd2715e2919 (MD5) Previous issue date: 2012-02-28 / Este trabalho objetivou investigar o fitoplâncton da área estuarina do rio dos Passos, Pernambuco, Brasil, no que se refere à sua biomassa, composição e variação espacial e sazonal, em resposta às características ambientais locais. As amostragens foram realizadas em frequência mensal, em quatro pontos do estuário, no período de agosto de 2009 a julho de 2010, durante as baixa-mares, em maré de sizígia. Foram obtidos os dados referentes à pluviosidade, profundidade local, temperatura, transparência e amostras da água com auxílio de garrafa de Kitahara para medidas de salinidade e clorofila a. As amostras fitoplanctônicas foram obtidas através de arrasto de rede horizontal (malha de 64μm) e em seguida fixadas em formol neutro a 4%, para posterior análise em microscópio óptico. Foram calculados os valores de abundância relativa, frequência de ocorrência, riqueza de espécies, diversidade específica e equitabilidade. Os dados foram tratados através de análise de variância e correlação canônica. Quanto à composição fitoplanctônica, foram identificados 129 táxons, representados pelas diatomáceas (73%), seguidas pelas cianobactérias (18%), clorofíceas (4%), dinoflagelados (4%) e euglenofíceas (1%), sendo que 32% apresentaram características ticoplanctônicas, seguidas pelas marinhas planctônicas oceânicas (28%) e neríticas (24%), dulciaquícolas (10,6%) e tipicamente estuarinas (5,3%). A distribuição das espécies foi uniforme, porém a diversidade foi baixa, em decorrência da dominância de poucas espécies: as diatomáceas Cylindrotheca closterium (Ehrenberg) Lewin & Reimann, Chaetoceros subtilisCleve, Bacillaria paxillifera(O. F. Müller) Hendeye a cianobactéria Johannesbaptistiasp., as quais apresentaram relação significativa com as variáveis ambientais. Estiveram relacionadas diretamente com a pluviosidade asespéciesC. subtilis e Johannesbaptistiasp., e inversamente C. closterium e B. paxillifera. Esta última esteve em relação diretamente proporcional com a salinidade e transparência da água, enquanto que as demais estiveram em correlação inversa com estas variáveis, sendo esta condição semellhante para os valores de biomassa algal. Salinidade e transparência da água são as variáveis possivelmente condicionantes da biomassa e espécies fitoplanctônicas, necessitando de estudos futuros para ser analisada a clorofila a em função de outras variáveis físicas, químicas e biológicas, não abordadas neste estudo.

La Seine est un écosystème profondément affecté par les activités humaines. Il a subi des changements améliorant le traitement des eaux usées parisiennes et les apports diffus de l'agriculture. Des campagnes de prélèvements en profils longitudinaux ont été menées à l'amont et à l'aval de la station d'épuration Seine-Aval (step SAV) pour décrire la dynamique de l'azote et des activités des micro-organismes nitrifiants et la comparer aux observations disponibles antérieures à l'implémentation d'un traitement de l'azote. Les résultats prouvent que la step SAV rejette moins d'ammonium et plus d'organismes nitrifiants mais avec un développement plus lent et moins important qui disparaissent en aval améliorant le déficit en oxygène en Seine. De plus, le bilan et le rôle du phosphore ont été démontrés avec des apports au milieu fluvial diminués d'un facteur 2.7 depuis le début des années 2000. La mesure expérimentale des paramètres de l'adsorption du phosphore sur la matière en suspension a permis d'affirmer que ceux-ci sont influencés par les rejets des stations d'épuration mettant en oeuvre un traitement du phosphore. Nous montrons, par modélisation, que la dynamique de développement des algues est sensible au processus d'adsorption du phosphore. Les changements apparus dans la fréquence et l'intensité des blooms algaux en Seine peuvent s'expliquer par la réduction de la charge ponctuelle en phosphore. Avec des concentrations en orthophosphates proches de la limitation dans les secteurs amont, une modélisation précise de l'apparition du phytoplancton à l'échelle du bassin versant reste cependant encore difficile avec les outils mécanistiques actuels que nous avons développés. / The Seine river system is an ecosystem deeply affected by human activities. The new water quality requirements have led to significant changes. We provided an overview of nitrogen transfers in the Seine basin. We conducted sampling campaigns in order to describe the dynamics of nitrogen and nitrification. Furthermore, we compared our results with the observations before the implementation of nitrogen treatment at the wastewater treatment plant Seine Aval (WWTP SAV). The results proved that the WWTP discharges less ammonium and more nitrifiers but with a slower development than before. These communities disappear downstream, without causing low oxygen concentrations in the lower Seine and its estuary, as they did before... A simplified modelling of nitrogen concentrations and nitrification before and after the implementation of nitrogen treatment helped to reproduce the past and the present trends.Moreover, the assessment of the fluxes and the analysis of the role of phosphorus were realized. The inputs to the river system have been reduced almost three times in the early year 2000. The experimental measurement of phosphorus sorption characteristics onto suspended solids has shown that particles could be affected by the discharges coming from the WWTP SAV after the introduction of an advanced treatment. We show also by modelling, that the algal growth is very sensitive to adsorption process. The changes in frequency and amplitude of algal blooms observed in the Seine can be explained by the reduction of point phosphorus loadings. The modelling of algal blooms throughout the entire basin remains difficult with the currently available mechanistic tools.

Magister Scientiae (Biodiversity and Conservation Biology) / This study investigated the role of grazing as a possible cause for the upper limit of distribution of algae on a typical South African south coast. / South Africa

Domoic acid (DA) is a naturally occurring cyanotoxin, which upon ingestion, is responsible for amnesic shellfish poisoning (ASP) in both humans and animals. Produced by the marine diatom, Pseudonitzschia, DA is accumulated by a number of marine organisms including shellfish, clams and mussels which upon consumption can lead to headaches, nausea and seizures. Possessing a variety of functional groups the structure of DA contains three carboxyl groups, a pyrrole ring and a potent conjugated diene region allowing for binding to glutamate receptors in the dorsal hippocampus of the brain causing the described detrimental effects. Although limitations have been placed regarding the amount of DA that may be contained in seafood no limitations have been placed on the amount present in drinking water. Natural degradation of the toxin may occur through reactive oxygen species such as the hydroxyl radical and singlet oxygen at the conjugated diene region. In this work the photooxidation of DA via singlet oxygen has been studied using sorbic acid as a model compound. The three major reaction pathways observed during the photooxdiation process for both acids include 2 + 4 cycloaddition to produce endoperoxides , 2 + 2 reaction to afford aldehydes and ketones or an ene reaction to generate hydroperoxides. Under similar reaction conditions for SA and DA, the endoperoxide has been seen to be the major product for photoxidation of SA while the hydroperoxide has been seen to be the dominant product during photooxidation of DA.

The Sundays Estuary is permanently open to the sea and has been described as channel-like along its entire length with a narrow intertidal area (mostly less than 5 - 6 m in width). The estuary experiences regular freshwater inflow with large supplies of nutrients, derived from the Orange River transfer scheme and agricultural return flow. In particular, nitrate concentrations are high as a result of fertilisers used in the Sundays River catchment area. The objectives of this study were to measure microalgal biomass and community composition and relate to flow, water quality and other environmental variables. Surveys in August 2006, March 2007, February, June and August 2008 showed that salinity less than 10 percent mostly occurred from 12.5 km from the mouth and this was also where the highest water column chlorophyll a (>20 μg l-1) was found. Different groups of microalgae formed phytoplankton blooms for the different sampling sessions, which were correlated with high chlorophyll a. These included blooms of green algae (August 2006), flagellates (March 2007), dinoflagellates (June 2008) and diatom species (February and August 2008). The dominant diatom (Cyclotella atomus) indicated nutrient-rich conditions. Green algae and diatoms were associated with low salinity water in the upper reaches of the estuary. Flagellates were dominant throughout the estuary particularly when nutrients were low, whereas the dinoflagellate bloom in June 2008 was correlated with high ammonium and pH. Maximum benthic chlorophyll a was found at 12.5 km from the mouth in February, June and August 2008 and was correlated with high sediment organic and moisture content. Benthic diatoms were associated with high temperature whereas some species in June 2008 were associated with high ammonium concentrations. The middle reaches of the estuary characterise a zone of deposition rather than suspension which would favour benthic diatom colonization. Phytoplankton cells settling out on the sediments may account for the high benthic chlorophyll a because maximum water column chlorophyll a was also found in the REI zone (where salinity is less than 10 percent and where high biological activity occurs) in the Sundays Estuary.

The phenomenon of rapid algal blooms in response to nutrient overloads has been adapted to treat synthetic domestic wastewater. Various algal consortia collected from several eutrophied water bodies were subject to high density algal culture (upto 106-107 cells/mL) and screened for rapid algal growth, pollutant removal, nutrient recovery under mixotrophy and auto-flocculation. When tried in laboratory scale algal ponds, these algal consortia showed growth rates between 0.15 and 1.07 d-1. Results indicate that Chlorella occurred frequently among most consortia although not always the largest in number. While individual algal species varied in growth rates among these consortia, the log phase for most of these algae lasted 4-5 d after which the algal species began to flocculate between day 5-8 at different rates. The flocculation stage lasted between Day 6-8 wherein about 65% cells flocculated during monsoon and over 90% in winter. Although over 90% removal of N and 80% removal of P occurred in this period, the net N and P harvested as flocculated algae ranged from ~30-50% and ~40-70%, respectively. A consortia approach, wherein algal cells auto-flocculate after reaching a high cell density and nutrient removal provides an easy, low energy and sustainable approach to simultaneous wastewater treatment as well as energy and nutrient recovery from domestic wastewaters.

Rapid urbanization has led to the generation of enormous wastewater after independence. The domestic wastewater generated in municipalities is rich in nutrients such as carbon, nitrogen and phosphorus along with other ions. The generated wastewater due to lack of adequate appropriate infrastructure including low treatment efficiencies are either untreated or partially treated and are let into water bodies. Present sewage treatment plants (STP’s) in the city are either under capacity or malfunctioning and hence are unable to meet the growing demand of burgeoning urban population. Water bodies have the ability to uptake nutrients (remediation by algae, bacteria, macrophytes) provided the wastewater inflow does not exceed the threshold. However, the sustained flow of wastewater beyond the water body’s treatment ability has led to the serious problem of nutrient enrichment in surface water bodies which is evident from algal bloom and profuse growth of invasive exotic macrophytes. This necessitates cost effective environmentally sound treatment options. The current research focuses on the characterisation of domestic wastewater fed ponds/lakes, understanding of nutrient regimes in wastewaters, pond dynamics, nutrient transformation and resource recovery. This has aided in devising an algae based treatment system for Bangalore city. The interplay between various biotic and abiotic factors governs water quality in a water body. Regular monitoring helps in characterisation of the water body and also helps in identifying the sources of external input (if any) to the system. Wastewater generated in urban localities in India, due to lack of adequate appropriate infrastructure including low treatment efficiencies are untreated or partially treated and are let into water bodies. Understanding the nature of the wastewater flow regimes and the turnover of biota with prevalent nutrient conditions is required to design treatment systems. Treatment involves breakdown of complex organism forms into simpler forms and transformations of organic nutrients into inorganic forms that are finally absorbed and assimilated by microbes as algae and bacteria. In wastewater fed urban pond systems, an array of microphytes as well as macrophytes grow and help in nutrient cycling in the system and still manage to remove nutrients to satisfactory levels. However, sustained inflow of wastewater with high nutrients results in the deterioration of the system as nutrient input exceed the supportive and assimilative capability resulting in proliferation of macrophytes, algal blooms, froth formations rendering the system anoxic that results in the loss of functional abilities of the urban pond systems. This biota in the system plays a major role in nutrient removal and recycles. Understanding the nutrient cycling aspects of urban wastewater fed systems is essential to find out the key players in treatment and for devising a sustainable treatment option with resource recovery. The review of wastewater generation, treatment systems highlight shortfall of the treatment systems and need for sustainable treatment for removal and recovery of nutrients such as C, N and P. Characterisation of Varthur water body (spatial extent 220 ha) located in the south of Bangalore city has been done through monthly monitoring for 18 months with the analyses of physico-chemical and biological. The analysis showed BOD removal of 70% (filterable) when the lake functioned as an anaerobic–aerobic lagoon for 6 months at an estimated residence time of 5 days. During this period, the biota of the lake, especially primary producers such as algae, treat the water through remediation of nutrients to nearly standard water quality levels. However, the growth and spread of invasive exotic macrophytes such as water hyacinth rendered the lake anaerobic which reduces its ability (due to absence of low algae) to treat the water. This highlights the role of algae especially Chlorophycean members as Chlorococcum sp., Chlorella sp. and Monoraphidium sp. in treating urban domestic wastewater and the scope for introducing algal ponds/lagoons to treat wastewater treatment and it may be used in a larger number of small towns to enable local reuse of water. The entire pond systems comprises of various components that are deeply affected by the biotic and abiotic factors in the system. Hence, studies on major biotic components were conducted especially on algae and macrophytes and the impact of abiotic factors as wind, light, and precipitation with seasonality’s. The diurnal and spatio-temporal variations in the dissolved oxygen as well other treatment parameters were used for zonation through multivariate analysis. Physico-chemical parameters confirm the nutrient enrichment (high Amm.-N) in the water body due to the sustained inflow of wastewater. High levels of nutrients together with BOD have resulted in the lower DO levels affecting the biological life. Study on biota revealed macrophytes altering the photosynthetic regime in the algae in water bodies thus, creating anoxia and nutrient re-suspension. The multivariate analysis showed three distinct zones (clusters) on the basis of physico-chemical variables and nutrient concentrations in the lake. The sedimentary C and N analysis showed a steady increase in the C: N ratio as a function of residence time. Importance of the various sub-systems in the water body in terms of nutrient uptake and accumulation showed algal systems to be efficient. C budgeting accounted to ~ 7 t/d i.e. ~2574 t/y, indicated that the lake is an accumulator of C. An estimated relatively high gas emission across the water/air interface (17 t/d) to carbon burial into sediments (2.3 t/d) further indicates very high emissions compared to sedimentation showing the dominance of internal C cycles. The overall mass balance, gas exchange and carbon burial balance showed Varthur water body as a major emitter of C due to high primary production, substantive allochthonous carbon inputs and intensive anthropogenic activities in the water body. Gaseous carbon emission accounted for 28 % of the total Influx C. The spatial profile of N in sediment ranged from 2280-3539 mg/kg of sediment dry mass. Very low value of N:P ratio in sediments suggested possible N limitation. The determination of ammonification and nitrification showed lower nitrification rates than the ammonification rates. The potentially mineralisable nitrogen content in Varthur pond sediments varied greatly from 21.65% to 75.54% and was strongly correlated (r2=0.85) to sedimentary TN. N budgeting showed NH4-N as the predominant Nr form for microbial uptake and is the major mechanism for nitrogen removal, followed by the sedimentation process. Bacterial biomass, algal biomass and macrophyte biomass accounted for 14, 4 and 1% N removal, respectively. Ammonium concentration and nitrification accounted for 27% and 2%, respectively. While bacterial uptake remained fairly constant throughout the year, micro-algae was the major player during monsoon and winter and macrophytes dominated Nr capture during summer among autotrophs. From the estimates, it has been observed that nearly 55% Nr was recovered, recycled as cell mass and transferred to a crop system when such N-captured water is used for irrigating fodder crops. About 45% of N input into the system was lost and methods to reduce this loss need to be evolved in the future. The spatial profile of P in sediment ranged from 2111.35-3982.03 mg/kg of sediment dry mass. Inorganic-P (IP) ranging from 1270.27-3505.73 mg/kg was found to be the major fraction (61.16-91.56%) of sedimentary P. High p values in both water columns and sediments showed potential P excess conditions. P concentrations in micro and macro-algae collected during the due course of the study (on dry biomass basis) were 0.347% and 0.939% P respectively. The P fractionation revealed metal oxide bound P (NaOH-P) and constituted major fraction of IP indicating, high concentrations of Fe and Al in sediments. High concentrations of sedimentary N and P indicated possible higher trophic status (bio-productivity/unit volume) signifying its towering nutrient status evidenced from the rank order of P fractions: NaOH-P > HCl-P > NH4Cl-P, which is specific for highly enriched water bodies. P budgeting showed that bulk of the P is trapped in sediment layer with a potential of ~50 % recovery from the sediments indicating, ~70% P retention within the system. The biotic components such as bacteria, algae and macrophytes accumulates a substantial amount of P, immobilising ~139, ~482 and ~131 tonness/yr of P. The sequential P extraction shows that ~70 % of sediment bound P is readily reducible during anoxic conditions which can potentially become bio-available to trigger algal growth. Assessment of treatment efficiency of facultative algal ponds, showed moderate treatment levels with 60 % total COD removal, 50% of filterable COD removal; 82% of total BOD removal and 70% of filterable BOD removal. The N removal efficiency was lower. However, a rapid decrease in the suspended solids after a faster euglenoids growth indicated particulate C removal by algal ingestion. Euglenoides dominated the facultative pond and Chlorophycean members were more abundant in the maturation ponds owing to variable surface BOD loadings. Significant correlations between algal biomass and nutrients indicate the importance of the type and nature of algal communities that can be used as an efficient tool for predicting the dynamics of various phases in wastewater treatment systems. Detailed morphological analysis of dominant algal species i.e. euglenoides was also performed. Euglenophycean members (>14 species) sampled from various locations in the facultative pond based system showed various striae patterns and distinct nano channels on the cell surface that might have possible role in cell secretions. Comparative assessment of treatment systems reveal that algal pond systems performed well under higher organic load with a COD removal efficiency of 70%, TN removal efficiency of 73% and TP removal efficiency of 22%. However, the facultative pond based systems were effective in suspended solid (SS) removal up to 93% and BOD removal up to 82%. The conventional wastewater treatment systems were efficient in terms of SS removal up to 88%, COD removal up to 74% and BOD removal up to 63%, but were highly ineffective in nutrient removal. The evaluation of treatment processes in mechanically aerated systems, facultative ponds and large shallow lake based systems in terms of capital and annual O&M costs, COD removal cost and land requirements reveals that the mechanical systems require 5 times more capital and O&M costs than ponds. The treatment systems were also ranked in terms of the total annual cost (e.g., capital, manpower, chemical, repair, electricity, land). It showed that algal pond systems followed by facultative pond based system are economically better choice than mechanical technologies. Finally, it was found that the large pond based systems could be economically the best option for the developing countries considering all factors, including economic viability and treatment efficiency. The treatment efficiency analysis showed that algal pond systems were the most effective options for treating urban wastewater. Culturing native wastewater species in growth media and wastewaters, assessment of efficient cell disruption and solvent systems, lipid profiles of wastewater algal species were studied. Wastewater grown algal species as Euglena sp., Spirogyra sp., Phormidium sp., Lepocinclis ovum, and Chlorococcum sp. are comparatively rich in lipids. These algae grow mixotrophically and can store substantial amount of wastewater carbon as TAG’s in varied environments. Among the different cell disruption methods used for the study, sonication was the most effective. The combination of maceration and methanol: chloroform: water (2:1:0.8, v/v) (Bligh and Dyer’s, solvent) gave highest lipid extraction yield among other combinations. Further more these wastewater algae as Lepocinclis ovum and Chlorococcum sp. were found to grow better in wastewaters. Increased lipid content was recorded during the cell cultures with accumulation of quality FAME with high saturates predominated by C16-C18 fatty acids. These wastewater algal lipids are suitable for bio-energy generation with potential biomass productivity (6.52 t/ha/yr) of wastewater-grown species as Euglena. The studies on Euglena sp. showed mixotrophic mode that offers an efficient removal of TOC, N and P from domestic wastewater without any pre-treatment. Lipid profiles of the extracted algal oil were similar to the vegetative feedstock oils, indicating a good quality fuel for energy generation. Mixed algal consortia’s bioremediation potential (removal of nutrients) with the scope for biofuel production highlights self flocculating abilities of algal consortia aided in the effective treatment of wastewater with substantial algal harvest. Studies on cultivating wastewater algal consortia in novel cascading algal parcel flow reactor (CAPFR) operating in continuous mode showed 70-80 % nutrient and ~90 % C removal with in a residence time of ~4 days with highest cell densities (0.91 g/l) and productivities (0.26 g/l/d) in the last stages. The lipid contents varied from 26-28 % with highest lipid productivities ~58 mg/l/d in the 2nd phase of the bioreactor. Most of the lipids were associated with the pigments as chlorophyll and carotenoids. Furthermore, the algal rector removed bacteria up to 4 log orders. Essential cations and phosphates were responsible for self clumping of algal biomass in the final stages with a high internal P content within the cell. The algal biomass also showed substantial exothermic peaks and high heat values (~18 MJ/kg). Studies on continuous cultivation of Dictyosphaerium sp. showed that this species could adapt to wastewater conditions and also showed good nutrient removal at lower HRT (2.5 days). The high biomass productivities with high lipid content (~36%) at low HRT in the continuous mode offer potential options for economic and feasible nutrient removal with biofuel production. Investigations on city wastewaters showed low nutrient ratio indicating C limitations and possible scope for algal wastewater treatment. Integration of algal ponds in the present treatment network requires an additional land ranging from ~0.37 to 2.75 ha to treat an MLD of wastewater depending on the nutrient content and influent waters fed to algal systems. The treatment plants require an additional ~1.6 ha of land to treat 1 MLD of wastewater considering an average N and P values of 18 and 5 mg/l. The continuous algal bio-processes implemented at decentralised levels would help in the economical ways for nutrient removal and recycling of the nutrient free waters after treatment. This meets multiple objectives of low cost treatment of wastewater, nutrient recovery and fuel production. Algal nutrient capture and consequent biofuel production would ensure sustainability through i) water purification ii) nutrients capture and iii) biofuel to meet the growing energy demand, and would be an optimal treatment option for urban wastewater. The thesis consists of 10 chapters and basically deals with the development of a sustainable and economically viable bioprocess for wastewater treatment and biomass production. Chapter 1 provides a brief introduction to wastewater; domestic wastewater composition, generation and treatment in developing nations and in the country and review of the various techniques for treatment of domestic wastewaters, advantages of algal processes in nutrient removal (C, N and P) and production of valued by-product such as lipid generation, for its use as biofuel. Chapter 2 is based on primary field investigations in a wastewater fed urban water body/pond systems involving monthly sampling and analysis of various physico-chemical and biological parameters. Assessment of treatment capabilities of the continuous systems through detailed characterisation of treatment parameters is explained in the second chapter. Chapter 3 discusses the role of the major biotic (algae and macrophytes) and abiotic factors in nutrient transformations, the diurnal variations in parameters especially dissolved oxygen, multivariate spatio-temporal analysis of functional abilities for zoning, the activities in the sludge/sediment and transitions in the CN ratio as a function of residence time. Chapter 4 involves studies in C, N and P quantification and budgeting in such pond systems and partitioning of the nutrients and their distribution in various biotic and abiotic subsystems. This chapter also highlights the major nutrient losses from the system and un-utilised nutrient stocks, paving way for beneficial use of nutrients from such man made lagoon wastewater systems. Chapter 5 discusses the mechanisms and efficacies of algal pond based treatment systems through a detailed study and highlight its advantages over the mechanical ASP based systems. This has been done through a comparative assessment of treatment efficiency, economics and environmental externalities. This study also provides necessary insights and potential of wastewater algal species such as Euglena for its abilities in nutrient removal and biomass generation. This provides insights to algal treatment options for optimal resource recovery and utilisation from wastewaters. Chapter 6 focuses on testing the growth, biomass and lipid production of various wastewater algae isolated from treatment ponds. The chapter identifies suitable cell disruption and extraction routes for efficient lipid extraction and assesses the potential of these wastewater grown algae for regional and national biofuel production. Chapter 7 discusses the effectiveness of wastewater grown Euglena sp. and algal consortia in nutrient removal and as a source of lipids for biofuel generation. Chapter 8 involves the design and operation of a continuous algal (uni-algal/algal consortia) bioreactor devised taking insights from earlier field based studies and their potential as efficient urban wastewater treatment systems. Chapter 9 discusses the present nutrient levels in the city wastewaters and also an analysis of the temporal and spatial variation of nutrients in city sewers and elaborates the scope for integration of the algal modules i.e. continuous algal bioreactors (designed in the previous chapter) into existing STP’s. Chapter 10 elaborates significant contributions and outcome of the research.

The Indian River Lagoon (IRL) spans approximately one-third of the east coast of Florida and faces numerous harmful algal blooms. The potentially toxic diatom, Pseudonitzschia, has been observed in many locations of the IRL. The goal of this study was to obtain a better understanding of the factors contributing to population dynamics of Pseudo-nitzschia in the southern IRL system. Bi-monthly surface water samples were collected for 18 months from five locations. Cell counts enumerated all microphytoplankton, and environmental data was collected at sampling sites throughout the study by the Indian River Lagoon Observatory Network. Six species of Pseudonitzschia were isolated and characterized through 18S Sanger sequencing and scanning electron microscopy, all showed toxicity. Surface water samples also showed domoic acid (DA) presence. We report the first known occurrence of Pseudo-nitzschia micropora in the IRL and the first known DA production from this taxon. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

MESHWR / Department of Ecology and Resources Management / The presence of harmful algal blooms (HABs) and cyanobacteria toxins in drinking water sources are known to pose a great threat to humans. The main aim of this study was to use molecular technique to determine the origins of the cyanobacteria species at Musina raw water abstraction point by identifying and comparing the non-toxic and toxic cyanobacteria species in the Limpopo River and some of its tributaries based on the phylogenetic analyses of 16S rRNA gene. The Musina water treatment plant is located downstream of a weir and the Beit bridge on the Limpopo River and the raw water supply is abstracted from 22 boreholes of which 14 are along the Limpopo River and 8 boreholes are inside the Limpopo River channel. The bottom sediments samples were collected from these rivers: Limpopo, Crocodile, Mokolo, Mogalakwena, Nzhelele, Lephalale, Sand rivers (South Africa); Notwane (Botswana), Shashe River and Mzingwane River (Zimbabwe). The physical-chemical analysis of the bottom sediments showed the availability of nutrients, nitrates and phosphates, in excess of 0.5 mg/l for most the of rivers, alkaline pH and salinity in excess of 500 mg/l. Total genomic DNA were extracted from cyanobacteria species on the bottom sediments and Polymerase Chain Reaction (PCR) method was used to detect the genetic profile of the cyanobacteria species. Molecular identification of cyanobacteria was based on PCR amplification and sequencing of the 16S rRNA gene. The 16S rRNA gene was absent from sediments of the Mogalakwena and Lephalale rivers but present in all other selected rivers. The cyanotoxins detection was also based on PCR by amplification of microcystin/nodularin and cylindrospermopsin polyketide synthetase genes. Most of the samples showed no amplification of the toxin genes. While two samples showed the amplification of cylindrospermopsin polyketide synthetase gene (Sand River and Nzhelele River Next to Tshipise) and two samples showed amplification for microcystin/nodularin synthetase gene, Crocodile River and Mzingwane River. The first was the confirmation of similarity of samples from Crocodile River downstream of hartbeespoort Dam and Shashe River to Leptolyngbya boryana with 99% bootstrap confidence. The similarity of sample from Musina borehole to Sand River upstream to Alkalinema pantanalense with 98% bootstrap. Thus, the presence of toxic genes may imply the presence of toxic cyanobacteria species in the river sediments and may be hazardous to humans because rural communities and commercial farmers abstract water from Limpopo River catchment for human consumption, livestock and irrigation. The waters of the Limpopo River basin also provide drinking water to wildlife and a habitant for aquatic organisms/animals.

MENVSC / Department of Ecology and Resource Management / Satellite remote sensing techniques have been proved to be the best methods for quantifying chlorophyll-a levels by estimating algal concentrations in water bodies. Harmful algal blooms (HABs) are posing a significant threat to the many water bodies in South Africa. This study aims at developing remote sensing solution to estimate chlorophyll concentrations in water bodies of Vhembe district municipality using recently launched Landsat 8 OLI. It is the first study to provide quantitative water quality information for the Vhembe region’s water bodies from a time series of satellite remotely sensed data and in-situ laboratory data. The objectives of this study was to evaluate spatial and temporal distributions of algae in water bodies and fish-ponds, to assess water quality parameters, namely: chlorophyll-a and turbidity and to compare data obtained from satellite remote sensors with in situ data. The 30 meters spatial resolution multispectral Landsat 8 OLI for 2016, 2017 and 2018 were used to derive chlorophyll-a estimate from an existing model at three water bodies. The chlorophyll-a concentrations measured during in-situ were employed to validate the Landsat derived chlorophyll-a estimates. The results from this study shows that Landsat derived chlorophyll-a estimates are correlating with field measurements. In all the reservoir, it was detected that there is low content of harmful algal blooms and thus the water bodies are in good condition since the chlorophyll-a concentrations were very low (ranging from 0 to 0.6 mg.m-3). In conclusion, it can be stated that Landsat 8 OLI sensor has the potential to map inland water bodies dominated with algal blooms at certain extent. It can further be stated that Landsat 8 OLI is suitable for monitoring the growth of HABs in aquatic ecosystem and is cost effective. This study also evaluated the potential of Banana peels powder and K2SO4 to inhibits the growth of algae (batch experiment). The water samples were collected at Tshifulanani and Lwamondo fish ponds where there are floating algae. The samples were collected seasonally and analysed for pH, water temperature, Total Dissolved Solids, Electrical conductivity, Dissolved Oxygen, turbidity, chlorophyll-a and absorbance. From the laboratory experiments, there was a variation in the values of absorbance (0.936A-1.234A), PH (7.1-8.3), EC (63.1- 87.9 μs/cm), TDS (52.6-69.7mg/L), water temperature (25.5-29.3°C) and Dissolved oxygen (5.3-7.1mg/L). The concentration of chlorophyll-a for Tshifulanani and Lwamondo fish ponds ranges were (2.14-15.96 mg/m-3) and (0.65-15.66 mg/m-3) respectively. A batch experiment was conducted to determine the potential of banana peels powder on inhibition of algal blooms in water samples by measuring absorbance at 750nm. It can be concluded in this study that banana peels have a potential to inhibits the growth of algae in fish ponds. The Absorbance has shown a rapid v decrease from 0.936A to Zero from day 1 to day 7 respectively. The inhibition of cyanobacteria by banana peels is followed using Potassium sulphate in treating the algal blooms in water samples. Both banana peels and potassium Sulphate has shown a positive response in treatment of algae on the batch experiment. The results of this study revealed that high concentration of physico-chemical parameters promote the growth of cyanobacteria in fish ponds but does not have negative effects on the fish except the oxygen competition with algal blooms. The statistical analysis in correlating the chl-a field measurements and remotely sensed data showed a positive outcome where K values were very high from 70% to 89%. These results show high level of agreement of correlation values of field chlorophyll-a concentration and satellite remotely sensed variables. / NRF