No description available.

No description available.

Azolla filiculoides has been evaluated for the adsorption of trace toxic metals from aqueous solution. The adsorption performance of the material was compared with commercial resins and fitted using the Langmuir and Freundlich models. The Freundlich model described the adsorption of copper and cadmium. Whilst the Langmuir isotherm had the better fit of the mercury data. The assumptions of the Freundlich model include multi-layer adsorption and different functional group binding. Conversely the Langmuir model suggests mono-layer adsorption and can infer single group reactivity. The pH effect on the uptake of the metals was investigated and an increase in removal was observed at higher pH with all the metals studied. The material has been thoroughly characterised using physical methods, such as, scanning electron microscopy X-ray photoelectron spectroscopy and electrophoretic mobility measurements. This enabled conclusions to be made regarding the surface functionality of the solid. Chemical characterisation included direct titrations, revealing a gradual dissociation of acidic groups as the pH increased within the experimental range. Kjeldahl nitrogen and amino acid analysis of several biological materials that have been used in metal sorption experiments showed A. filiculoides as having a large proportion of these cell constituents. The kinetics of metal ion uptake by the biosorbent was investigated and compared with commercially available resins. The kinetics are slower than conventional ion exchange resins and carbon adsorbents but entirely adequate for utilisation in a column process. The mechanism hypothesized for metal ion removal by the biosorbent is primarily attributed to ionogenic groups exchanging ions for copper and cadmium removal. Mercury on the other hand is said to be predominantly involved in a reduction-precipitation reaction on the surface of the adsorbent. Regeneration was successfully accomplished for copper and cadmium after minicolumn trials, with greater than 95 % elution of the metals using 0.1M HCI. The mini column trials showed a sharp breakthrough for these metals singularly and a dynamic equilibrium was observed during multi-metal processing. Mercury removal was much slower and more difficult with the same eluant, achieving a maximum of 50% removal. A method for a semi-continuous biosorbent process has been evaluated and proven to be successful in processing metal laden solution.

An increase in anthropogenic activity has led to the heightened levels of pollution entering aquatic systems. These excessive concentrations of heavy metals, nitrogen (N), and phosphorus (P) in water bodies can lead to several adverse impacts, such as eutrophication and human health risks. Therefore, the removal of pollutants from wastewaters, prior to their discharge into the natural environment, is of paramount importance. However, conventional wastewater treatment (WWT) technologies have their limitations; for instance, large capital/operational costs, and incomplete removal of contaminants. Therefore, innovative and more effective treatment technologies are required. Macro-algae typically have high growth and solar energy conversion rates, and are able to sequester nutrients, utilise CO2, and adsorb metals from aquatic environments. Therefore, algae may have potential applications in WWT. Furthermore, costs could be negated by the production of renewable algal biomass which may have a variety of commercially exploitable applications. However, issues such as poor selection of species or cultivation systems, and a lack of understanding of the influence of biological, chemical and physical factors, particularly in a highly dynamic wastewater environments, has led to varied results and prevented algal WWT becoming a widespread reality. In this thesis the algae Cladophora coelothrix and Cladophora parriaudii were studied as potential organisms for implementation into WWT. In addition to the features mentioned above, Cladophora was selected due to its ubiquity, filamentous morphology, which minimises harvesting costs, as well as their natural dominance and bloom forming behaviour in nutrient-rich environments. The influence of dewatering techniques, environmental factors, and nutrient regime upon the growth, nutrient/metal removal, and biochemical composition of the biomass were assessed. The first aspect of the thesis was an abiotic screening process, in order to investigate the robustness of Cladophora and its suitability for WWT applications on a fundamental level. Good rates of growth (4-13.3% d-1) and nutrient removal (45.2-99.9%) were observed throughout the screening process, except under the most extreme of conditions, e.g. pH 3. This indicated that Cladophora are potentially suitable for treating a broad range of wastewaters and merit further research to improve its potential applicability for WWT applications and commercial realisation. For instance, developing a reliable and accurate method for fresh weight (FW) assessment and hence productivity estimation. The determination of growth rate via FW measurement is one of the most basic aspects of algal biology, yet no standardised method exists for filamentous macro-algae. A variety of FW methods were systematically assessed in terms of accuracy and physiological impact. Methods involving mechanical pressing to dewater the biomass resulted in >25% reduction in the final biomass yield, compared to control cultures. The best method for FW determination employed a reticulated spinner, which was rapid, reliable, and easily standardised. Furthermore, this approach ensured accurate growth estimation with minimal physiological impact, measured as growth, maintenance of structural integrity and nutrient removal. This indicates that the method developed has the potential for widespread application in macro-algal cultivation, as such the method was employed throughout this thesis. The influence of nutrient regime on growth, biochemical composition, and bioremediation capacity was studied for both species of Cladophora. The nutrient regimes tested, representative of a broad variety of wastewaters, included four different N/P ratios, four N sources (ammonium, nitrate, nitrite and urea), and six different equimolar N source combinations provided at two N/P ratios. There were clear differences in performance between the two species, with higher rates of growth observed in all instances by C. parriaudii (4.75-11.2% d-1 vs. 3.98-7.37% d-1). Furthermore, ammonium was removed preferentially, whereas urea was removed secondarily. However, the presence of urea in the medium enhanced growth and uptake of the other co-existing N-forms, and yielded a carbohydrate-rich biomass (37.6-54% DW). These findings demonstrate that algal strain selection is important for treating wastewaters with specific nutrient profiles. In addition, results from this study suggest that nutrient regimes can be tailored to produce biomass with certain properties or characteristics, which make it suitable for further, potentially commercially viable, applications, such as metal biosorption. Since the biochemical characteristics of algal biomass were shown to be affected by nutrient regime, the final chapter describes research investigating the influence of nutritional history on metal biosorption. C. parriaudii was cultivated under different nutrient regimes to produce biomass of varying biochemical composition. This biomass was then used for metal removal, with maximum removal rates ranging from 1.08-2.35 mmol g1, 0.3-0.62 mmol g-1, 0.22-0.48 mmol g-1, and 0.43-0.61 mmol g-1 for Al2+, Cu2+, Mn2+, and Pb2+, respectively. Observations from this work indicate that metal removal is achieved by various mechanisms including adsorption, ion exchange, complexation and micro-precipitation, and that the biosorption efficacy is dependent upon the number and type of functional groups present, which are in turn influenced by the cultures nutrient regime. Overall, this study demonstrates the inter-relatedness of biological, chemical, and physical factors on algal growth, nutrient removal, biochemical composition, and metal biosorption. Results from this work have highlighted the need for standardisation in protocols, increased understanding of the influence of algal selection and nutrient characteristics in bioremediation, and highlighted the importance of considering biological aspects, specifically nutritional history, in biosorption studies.

Despite recent instability in the global supply of phosphate-rock derived fertiliser and the potential for this to continue into the future, the recovery of phosphorus (P) from wastewater treatment systems, where P is abundant and accessible, is well below maximum potential. Considerable resource is spent on removing P from wastewater in order to comply with environmental standards and to protect aquatic ecosystems from eutrophication, yet there is little emphasis on capturing the P in a way that is optimised for re-using it as agricultural fertiliser. To address this lack of innovation in the face of climate change and food insecurity, a concept for a material capable of capturing P from wastewater was developed, with an emphasis on the utilisation of otherwise waste materials and the use of carbon neutral or negative production technologies. Based on the demonstrated P capture properties of coal minewater treatment waste (ochre) and biochar made from anaerobically digested feedstocks, a range of biochars were designed and produced using different mixtures of ochre (“OC”), sourced from the UK Coal Authority Minto minewater treatment scheme in Fife, Scotland and anaerobically digested sewage sludge (“AD”), sourced from the Newbridge wastewater treatment plant in Edinburgh. A first generation of materials consisting of either AD or a 1:1 mixture (dry weight basis) of OC and AD were produced in a small-scale batch pyrolysis unit at two pyrolysis highest treatment temperatures (HTTs) (450 and 550°C) to give the biochars AD450, AD550, OCAD450 and OCAD550. These were tested for their P capture properties in repeated P-exposure experiments with pH buffering in comparison to unpyrolysed ochre, activated carbon and a natural zeolite. After 5 days of repeated exposure to a P solution at a wastewater-relevant concentration (20 mg P l-1) replenished every 24 h, relatively high masses of P were recovered by ochre (1.73 ± 8.93×10-3 mg P g-1) and the biochars OCAD550 (1.26 ± 4.66×10-3 mg P g-1), OCAD450 (1.24 ± 2.10×10-3 mg P g-1), AD450 (1.06 ± 3.84×10-3 mg P g-1), and AD550 (0.986 ± 9.31×10-3 mg P g-1). The biochar materials had higher removal rates than both activated carbon (0.884 ± 1.69×10-2 mg P g-1) and zeolite (0.130 ± 1.05×10-2 mg P g-1). To assess the extractability of recovered P and thus potential plant bioavailability, P exposure was followed by repeated extraction of the materials for 4 days with pH 7-buffered deionised water. The AD biochars retained 55% of the P recovered, OCAD biochars 78% and ochre 100%. Assessment of potentially toxic element (PTE) concentrations in the biochars against guideline values indicated low risk associated with their use in the environment. A second generation of materials were produced to examine the scalability of the concept. Mixtures of AD and OC were pelletised with a lignin binder (89.1:9.9:1.0 ratio, dry weight basis) and AD was pelletised with binder (99:1 ratio, dry weight basis). The pelletised feedstocks were pyrolysed in a bench-scale continuous flow pyrolysis kiln at the same two HTTs to give the pelletised biochars PAD450, PAD550, POCAD450 and POCAD550. Analysis of digested biochar samples compared to the previous generation of biochars showed general similarities between the two groups, apart from the substantially lower Fe content. Sub-samples of the pelletised biochars were exposed to a 20 mg l-1 P solution over 6 days, with the solution replaced every 24 h to give the P-exposed biochars EPAD450, EPAD550, EPOCAD450 and EPOCAD550. To probe the mechanisms of P capture by these materials and how feedstock preparation and pyrolysis conditions affected these, spectroscopic analysis using laser-ablation (LA) ICP-MS, X-ray diffraction, X-ray photo-electron spectroscopy (XPS) and scanning electron microscopy coupled with energy dispersive X-ray was performed. The results highlighted the general importance of Fe minerals in P capture and subsidiary roles for Al, Ca and Si. A 3-week barley (Hordeum vulgare) seedling growth experiment was conducted using the pelletised and P-exposed biochars, in comparison with other biochars produced using feedstock which contained high amounts of PTEs. The biochars were also extracted using a range of different methods used to assess the bioavailability of PTEs and nutrients in soils, and the results compared to digests of barley leaves to identify whether any of these could reliably predict plant bioavailability in biochar. The above ground biomass and its total P concentration of barley grown in a 5% mixture of EPOCAD550 in sand was significantly higher than the control (p < 0.05 and p < 0.01, respectively). A significant positive correlation between mean leaf P mass and dry weight leaf yield (R2 = 0.865, p < 0.001) was found, indicating that dry weight yield could be used as an indicator for the P fertilising capability of biochar for barley seedlings. Element concentrations in unbuffered and buffered and (pH 7) 0.01 M CaCl2 biochar extractions were significantly positively correlated with plant leaf concentration for 6 of the 18 elements investigated, more than any of the other extractions. A longer barley growth experiment was conducted, using rhizoboxes, to test the bioavailability of P in the biochars compared to conventional fertiliser. The pelletised and Pexposed biochars were applied to a sandy loam soil with P constraints. Biochar application rates were based on 2% formic acid extractable P, calculated for summer barley using Index 0 soil. Analysis of total leaf length at harvest (12 weeks), dry weight yield, leaf P concentration and leaf P mass showed no significant differences between the biochar treatments, NPK fertilised and NK fertilised controls. This shows that biochar, when applied at low total application rates based on extractable P, is as effective as conventional fertiliser. Now that AD biochar materials have been shown to have useful phosphorus recycling properties in laboratory experiments, additional work is required to optimise their use in wastewater and agricultural systems. The next stage of research should determine their performance in flow-through filtration systems with simulated and real wastewater effluent, as well as their performance in field trials with different crops of interest to demonstrate their potential as viable alternative fertilisers.

No description available.

The feasibility of using a single vessel reactor for the biological treatment of recalcitrant compounds, namely reactive azo dyes discharged by the textile finishing industry was investigated. A synthetic effluent was derived from real processes to give reproducibility throughout the experimental period. The literature review found that a sequenced treatment of anaerobic then aerobic redox environments was required for the decolourisation and mineralisation of the dyes. Two biological reactor types were accordingly designed, built and tested, the sequencing batch reactor (SBR) and the hybrid anaerobic baffled reactor (HABR).

Despite being the subject of peer reviewed research since the mid-1980s, the conservative nature of the wastewater treatment industry means that the commercial application of membrane aerated biofilm reactors has not realized the potential that the published research demonstrates. The early research demonstrated the ability of membrane aerated biofilm reactors to achieve good levels of pollutant removal from various types of wastewater, but also exposed several weaknesses of the technology (i.e. cost of membranes, control of biofilm thickness) which have prevented the concept of MABfRs being developed in viable wastewater treatment technologies. However, as membrane technology has developed, the cost of suitable membranes has fallen, prompting the research community to revisit the concept. This later batch of research has identified several niche applications where membrane supported biofilms can be used for effective removal of pollutants from water. Using the MABfR for the treatment of secondary effluent as a polishing step is another niche application which has been identified and is examined in this work; leading to the development of a patented treatment technology – the BioSettler.

Made available in DSpace on 2014-06-11T19:27:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-21Bitstream added on 2014-06-13T18:56:05Z : No. of bitstreams: 1 santos_sc_me_jabo.pdf: 2783682 bytes, checksum: aa4f46c105293436eec8cc85842f4187 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste estudo avaliou-se o desempenho de processo anaeróbio, aeróbio e anóxico, utilizando-se um reator anaeróbio compartimentado (ABR de 360 L), com duas câmaras, um filtro aerado submerso (FAS de 160 L), preenchido com anéis de bambu e anéis de plástico de eletroduto corrugado e um reator de fluxo ascendente com manta de lodo (USB de 120 L) anóxico, instalados em série, para o tratamento de águas residuárias de suinocultura, com concentrações médias de sólidos suspensos totais (SST) de 10708 a 17048 mg L-1. Os tempos de detenção hidráulica (TDH) foram de 24 e 12 h no reator ABR; de 7,9 e 3,9 h e de 9,1 e 4,5 h no FAS preenchido com anéis de bambu e anéis de plástico de eletroduto corrugado, respectivamente; e de 7,8 e 3,9 h no reator USB anóxico. O FAS foi submetido a condições de aeração intermitente e contínua. As eficiências médias de remoção de DQOtotal foram de 94 a 99% no sistema de tratamento anaeróbio, aeróbio e anóxico, com carga orgânica volumétrica (COV) de 35,9 a 93,0 g DQOtotal (L d)-1 no reator ABR. As maiores eficiências médias de remoção foram de 99,99; 98; 99; 91; 88; 99 e 94% para os coliformes termotolerantes, DQOdiss, SST, NT, P-total, Cu e Zn, respectivamente, no sistema de tratamento anaeróbio, aeróbio e anóxico, obtendo-se valores mínimos de 1,1 x 103 NMP/100 mL para coliformes termotolerantes e 221 mg L-1 para DQOtotal. A porcentagem de CH4 no biogás do ABR variou de 76 a 84%; de N2 no reator USB anóxico chegou a 74%, com COV de 13,1 g DQOtotal (L d)-1 e TDH de 4 h. Os valores da atividade específica da microbiota do lodo das câmaras do ABR apresentaram diferenças, evidenciado a habilidade de separação das fases hidrolítica, acidogênica e metanogênica. A caracterização morfológica do biofilme do FAS, por meio de microscopia óptica, indicou alta diversidade morfológica, a qual pode estar associada a sistemas de tratamento biológico estáveis / In this study it was evaluated the performance of the anaerobic, aerobic and anoxic process in an anaerobic baffled reactor (ABR of 360 L), with two chambers, a submerged aerated filter (SAF of 160 L), filled with bamboo rings and plastic rings, and an anoxic upflow sludge blanket reactor (USB of 120 L), installed in series, for swine wastewater treatment, with mean total suspended solid (TSS) concentration from 10708 to 17048 mg L-1. The hydraulic detention times (HDT) were 24 and 12 h in the ABR reactor; 7,9 e 3,9 h and 9,1 e 4,5 h in the SAF filled with bamboo rings and plastic rings, respectively; 7,8 and 3,9 h in the anoxic USB reactor. Conditions of intermittent and continuous aeration were applied at the SAF. The mean of CODtotal removal efficiencies ranged from 94 to 99% in the anaerobic, aerobic and anoxic treatment system under organic loading rate (OLR) of 35,9 to 93,0 g total COD (L d)-1 in the ABR reactor. The highest mean removal efficiencies were of 99,99; 98; 99; 91; 88; 99 e 94% for thermotolerant coliforms, dissCOD, TSS, TN, total-P, Cu and Zn, respectively, in the anaerobic, aerobic and anoxic treatment system, obtaining minimum values of 1,1 x 103 MPN/100 mL for thermotolerant coliforms and 221 mg L-1 for CODtotal. The CH4 percentage in the biogas ABR ranged from 76 to 84%; the N2 percentage in the anoxic USB reactor reached 74%, with COV of 13,1 g total COD (L d) -1 and HDT of 4 h. The observed values of microbial specific activity of the sludge in the ABR‟s chambers were significantly different, evidenced the ability to phase separation hydrolytic, acidogenic and methanogenic. The SAF biofilm morphology, through optical microscopy, indicated a high morphological diversity, which may be associated with stable biological treatment systems

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009 / This project was started as a result of strict environmental and health regulations together with a demand tor cost effective operation of wastewater treatment plants (VVWTPs). The main aim of this project is how to keep effluent concentration below a prescribed limit at the lowest possible cost. Due to large fluctuations in the quality and quantity of the influent concentrations, traditional control methods are not adequate to achieve this aim The major drawback with these methods is that the disturbances affect the process before the controller has time to correct the error (Olsson and Newell, 1999: 454). This problem is addressed through the use of modern control systems. Modern control systems are model based predictive algorithms arranged as feed-forward controllers (Olsson and Newell. 1999: 454). Normally a controller is equipped with a constant set point; the goal In this project is to calculate an optimal DO trajectory that may be sampled to provide a varying optimal set-point for the Activated Sludge Process, In this project an optimal control problem Is formulated using DO concentration as a control variable. This requires a model of the process to be controlled a mathematical expressions of the limitations on the process input and output variables and finally the objective functional. which consists of the objectives of the control. The structures of the Benchmark plant (developed within the COST 682 working group) and the Athlone WWTPs are used to implement this opt.mat control strategy in MATLAB. The plant's full models are developed based on the mass balance principle incorporating the activated sludge biological models: ,ASM1, ASM2, ASM2d and ASM3 (developed by the IWA working groups). To be able to develop a method that may later on be used for online control, the full models are reduced based on the technique In Lukasse (1996). To ensure that the reduced models keep the same prediction capabilities as the full models, parameters of the reduced models are calculated based on the Least Squares principle, The formulated optimal control problem is solved based on the decompostion-coorcdination method that involves time decomposition in a two layer structure. MATLAB software [5 developed to solve the problems for parameter estimation. fun and reduced mode! simulation. and optimal control calculation for the considered different cases of plant structures and biological models. The obtained optimal 00 trajectories produced the effluent state trajectories within prescribed requirements. These DO trajectories may be implemented in different SCADA systems to be tracked as set points or desired trajectories by different types of controllers.