Philosophiae Doctor - PhD / The popularization and health benefits associated with the "Mediterranean diet" saw a world wide increase in the production and consumption of processed olives and olive oil. During the brining of table olives large quantities of processed olive waste water is seasonally generated. This blackish-brown, malodours liquid is rich in organic and phenolic compounds, which cause environmental problems upon discarding. Currently, processed wastewater is discarded into large evaporation ponds where it poses serious environmental risks. The biodegradation of organic substrates present in the olive wastewater is inhibited by the high concentrations of phenolic compounds.

In recent years, due to the continuous development of machinery, electronics, leather, chemical companies and dry-cleaning industry, more and more chlorinated hydrocarbons accumulate in the soil, causing serious harm to the environment. The accumulation of chlorinated hydrocarbons and the teratogenic, carcinogenic, and mutagenic hazards seriously threaten human health. Therefore, the remediation of chlorinated hydrocarbons is imminent. Under this premise, in-situ bioremediation has gradually received attention. For in situ bioremediation of soil contaminated with chlorinated hydrocarbons, the most commonly used methods are biostimulation alone, bioaugmentation alone, and a combination with biostimulation and bioaugmentation. The removal rate of trichloroethylene in the case of using biostimulation products alone is significantly lower than that of using bioaugmentation products alone. The removal rate of trichloroethylene by biostimulation products alone does not exceed 60%, and “DCE pause” occurred, but did not occur in the case of using bioaugmentation products. The removal rate of trichloroethylene by bioaugmentation products is generally higher than 98%, and it will promote the degradation of trichloroethylene or tetrachloroethylene to non-toxic ethylene. Therefore, only cases containing bioaugmentation can achieve non-toxic degradation of chlorinated hydrocarbons and take into account the high removal rate of them. In addition, the biostimulation duration is significantly shorter.

Eutrophication is an increase in primary plant nutrients (Nitrogen [N] and Phosphorus [P]) in oceans, estuaries and lakes. The consequences of eutrophication are harmful algal blooms (HABs), resulting in algal toxin production and the depletion of oxygen as the extensive biomass decays. P is often the limiting nutrient and is viewed as a significant environmental problem. Most of the excess P that enters aquatic ecosystems originates from anthropogenic sources such as fertilizers, sewage, animal wastes, compost, crop residues, and wastewater. Over time, one of the main reservoirs of P becomes organic P (Po). We investigated the chemical nature and dynamics of P in cyanobacteria, horse manure, stormwater treatment areas, and rice fields. To better understand the chemical nature of P, the identification of specific P compounds was required, which was achieved through 31P nuclear magnetic resonance (NMR) spectroscopy. We investigated how paramagnetic metals and quadrupolar nuclei cause severe line broadening, peak shifts, and decreased the signal to noise ratio. Results revealed that certain Po forms are readily bioavailable to Microcystis aeruginosa. Additionally, the potential heterotrophic use of the organic portion (e.g., glucose, glycerol) of these P compounds are indicated for the growth and persistence of Microcystis aeruginosa. We showed that the cultivation of rice (Oryza sativa L.) had been found to effectively reduce P from agrarian soil and water through plant uptake and, therefore, minimizing downstream eutrophication. Soil, water, sugarcane, and rice plants at two different stages were analyzed for twelve different elements. Finally, we examined how a “relic” agrarian ditch in Stormwater Treatment Area 1 East (STA-1E) can be used for the retention and sequestration of P and other nutrients. The STAs were established to capture P from agricultural and other sources before reaching the Everglades. Retained P is primarily stored in the wetland soils and sediments, generated through a collection of interrelated physical, chemical, and biological processes. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Orientador: Wanderley José de Melo / Resumo: O mercúrio (Hg) é um metal potencialmente tóxico e não essencial para os organismos. Alternativas menos onerosas e ambientalmente corretas como a remediação com uso de plantas e bactérias podem recuperar áreas contaminadas. Por isso, avaliou-se, em ambiente controlado, o potencial de remediação de plantas e bactérias em Latossolo Vermelho eutroférrico (LVef) contaminado com HgCl2 em diferentes doses de Hg2+. Na primeira etapa, 5 kg de LVef foram contaminados com solução de HgCl2, em delineamento inteiramente casualizado com 4 tratamentos: controle positivo (sem Hg2+) e tratamentos com 5 mg kg-1 de Hg, 24 e 36 mg kg-1 de Hg2+, base seca, em 5 repetições e mantidos por 75 dias com plantas Hibiscus cannabinus para avaliar seu efeito remediador. A quantificação do Hg total foi por espectrofotometria de absorção atômica. O tratamento com 24 mg kg-1 de Hg apresentou fitomassa seca da raiz maior que dos demais. De modo geral, LVef foi responsável por reter maior concentração do Hg do que as plantas. O Hg acumulou em maior proporção nas raízes do que na parte aérea, sendo maior o acúmulo com aumento da dose. A planta que recebeu a dose de 36 mg kg-1 Hg acumulou 2,57 mg kg-1 de Hg por planta, diferindo dos demais tratamentos. Concluiu-se que o LVef adsorveu maior concentração de Hg do que as plantas. O H. cannabinus apresentou resistência a diferentes concentrações de Hg no solo e pode ser considerado como planta potencial estabilizadora de Hg2+, pois acumulou maior concentração de Hg... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Mercury (Hg) is a potentially toxic metal and not essential for organisms. Less costly and environmentally sound alternatives such as plant and bacterial remediation have been used to recover contaminated areas. Therefore, in a controlled environment, the potential for remediation of plants and bacteria in an Oxisol contaminated with HgCl2 at different doses of Hg2+ was evaluated. In a first experiment, 5 kg of Oxisol were contaminated with HgCl2 solution, in a completely randomized design with 4 treatments: positive control (without Hg2+) and treatments with 5 mg kg-1 Hg, 24 and 36 mg kg-1 Hg2+, dry basis, and 5 repetitions and maintained for 75 days with Hibiscus cannabinus plants to assess its remediation potential. Total Hg quantification was by atomic absorption spectrophotometry. The 24 mg kg-1 Hg treatment presented higher root dry weight than the others. In general, LVef was responsible for retaining higher Hg concentration than plants. Hg accumulated to a greater extent in the roots than in the shoots, with greater accumulation with increasing dose. Plant that received the dose 36 mg kg-1 Hg accumulated 2,57 mg kg-1 Hg per plant, differing from the other treatments. It was concluded that Oxisol adsorbed higher Hg concentration than plants. H. cannabinus showed resistance to different soil Hg concentrations and can be considered as a potential Hg2+ stabilizing plant because it accumulated higher Hg concentration in the roots than in the shoots. In the second experimen... (Complete abstract click electronic access below) / Doutor

Selenium (Se) in the aquatic environment is predominantly found as the soluble selenium oxyanions; selenate (SeO42-), and selenite (SeO32-). These oxyanions are toxic, and they readily bio-accumulate in the food chain. However, numerous studies have proven the viability of microbial remediation in reducing them to elemental selenium (Se0) which is considered to be biologically inert and relatively less toxic. Of the various microorganisms that have been employed in Se bioremediation, Pseudomonas stutzeri NT-I has shown great potential in removing high concentrations of SeO42- and SeO32-. Of these two selenium oxyanions, SeO32- is more toxic, is the most reactive and is usually found in mildly oxidising acidic environments. Therefore, the focus of this study is on selenite. In this study Pseudomonas stutzeri NT-I was used in aerobic batch reduction of various SeO32- concentrations (0.5 to 10 mM) to Se0 under already known optimum conditions of temperature 35±2 °C, pH 7 – 8 and salinity 5 g.L-1 NaCl. The selenium (Se) reduction efficiency of strain NT-I was assessed under varying conditions, such as the presence and absence added nitrogen and glucose substrates, inhibited metabolic activity and bacterial cells. Moreover, the variation in the different parameters such the oxidation reduction potential (ORP), metabolic activity (MA) and the concentrations of SeO32-, glucose and total organic carbon (TOC) were also monitored. Key results indicated that the rate and amount of SeO32 reduction was influenced by the concentration to be reduced. For an initial SeO32- concentration of 0.5 mM, reduction was gradual and after 36 h, approximately 75 % had been reduced to Se0 which was equivalent to 0.375 mM. In the reduction of 10 mM SeO32- however, the reduction rate was rapid and even though the overall percentage reduction averaged around 18 %, this was equivalent to 1.8 mM This indicated that the increased initial reduction rate was a result of increased biomass activity in response to increased selenite concentration. This response is likely a defence mechanism employed by strain NT-I to detoxify its surrounding in elevated SeO32- concentrations. The results of these biological experiments were modelled, and the non-growth kinetics were found to fit the adapted Monod equation with k_s and k_Se values of 4.723 mM and 2.869 mmol.(h.g)-1 respectively. Pseudomonas stutzeri NT-I’s capability of being able to survive in very high selenium concentrations make it an attractive and versatile microbial species suitable for the bioremediation of selenium laden industrial wastewater. / Dissertation (MSc (Applied Science: Environmental Technology))--University of Pretoria, 2020. / Chemical Engineering / MSc (Applied Science: Environmental Technology) / Restricted

As underdeveloped nations continue to industrialize and the world population continues to increase, the need for energy, natural resources, and goods will lead to ever increasing heavy metal concentrations in various waste streams that can have damaging effects on plant life, wildlife, and human health. The focus of this study is to understand the impact of individual heavy metals on Nannocholoropsis salina microalgae growth and understand the potential of microalgae to be used as a bioremediation tool for contaminated water systems. Individual metals (As, Cd, Cr, Co, Cu, Pb, Ni, Hg, Se, and Zn) were introduced into growth media. For each metal a baseline concentration was determined based on reported concentrations at various municipal and industrial wastewater sites. In addition to the baseline concentrations, experimentation was conducted at 10X and 40X the baseline to evaluate the potential for severely contaminated systems. Biological growth experimentation was performed in triplicate at the various contaminant concentrations and at 3 different light intensities. Results show nickel significantly reduced growth, while the other metal contaminated systems showed growth between 89% and 99% of the control. Increased heavy metal concentrations resulted in progressively lower growth rates. Lipid analysis shows most baseline metal concentrations slightly decrease or have minimal effects in lipid content. Metals analysis on the biomass showed the majority of the metals in the systems containing Cd, Co, Cu, and Pb were sorbed by the microalgae with minimal metals remaining in the growth media illustrating the effectiveness of microalgae to effectively bioremediate contaminated systems when contamination levels are sufficiently low to not detrimentally impact productivity. Microalgal biomass in the systems containing As, Cr, Ni, and Se showed decreased ability to sorb metal ions. Results show at moderate contamination levels, microalgae can be an effective tool for bioremediation.

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The accumulation of industrial contaminants in the natural environments have rapidly become a serious threat for human and animal life. Fortunately, there are microorganisms capable of degrading or transforming environmental contaminants. The present dissertation work aimed to understand the genomic basis of microbial degradation and resistance. The focus was the genomic study of the following bacteria: a) Pseudomonas fluorescens NCIMB 11764, a unique bacterium with specific enzymes that allow cyanide adaptation features. Potential cyanide degradation mechanisms found in this strain included nit1C cluster, and CNO complex. Potential cyanide tolerance genes found included cyanide insensitive oxidases, nitric oxide producing gene, and iron metabolism genes. b) Cupriavidus sp. strain SK-3 and strain SK-4. The genome of both bacteria presented the bph operon for polychlorinated biphenyl (PCB) degradation, but we found differences in the sequences of the genes. Those differences might indicate their preferences for different PCB substrates. c) Arsenic resistant bacterial communities observed in the Atacama Desert. Specific bacteria were found to thrive depending on the arsenic concentration. Examples were Bacteroidetes and Spirochaetes phyla whose proportions increased in the river with high arsenic concentrations. Also, DNA repair and replication metabolic functions seem to be necessary for resistance to arsenic contaminated environments. Our research give us insights on how bacteria communities, not just individually, can adapt and become resistant to the contaminants. The present dissertation work showed specific genes and mechanisms for degradation and resistance of contaminants that could contribute to develop new bioremediation strategies.

The objective was to compare pentachlorophenol (PCP) degradation in contaminated groundwater by indigenous and bio-augmented (Sphingobium chlorophenolicum and Burkholderia cepacia) PCP degrading bacteria. Indigenous bacteria were identified by cloning and sequencing of 16S rDNA fragments while PCP concentrations were determined by GC-ECD. Gene expression for PCP degrading enzymes: chlorophenol 4-monooxygenase (TftD, B. cepacia) and pentachlorophenol-4-monooxygenase (pcpB, S. chlorophenolicum), was determined by RT-PCR. B. cepacia, a PCP degrading bacteria was identified as dominant indigenous bacteria. PCP concentrations correlated negatively with PCP tolerant bacteria and relative fold gene expression in treatments with air-sparging (phase2) compared to without air-sparging (phase1). PCP concentrations decreased and TftD or pcpB expressions were higher in treatments inoculated with B. cepacia (49%, 10.7 fold) or S. chlorophenolicum (32%, 7 fold), respectively, than un-inoculated (indigenous) or mixed culture inoculated treatments. Thus bio-augmentation of indigenous bacteria with B. cepacia or S. chlorophenolicum resulted in more PCP degradation than indigenous bacteria.