The release of water effluents rich in nutrients such as nitrogen and phosphorus without adequate treatment represents environmental and human health concerns. Growing concerns about these impacts have resulted in increasingly stringent water quality regulations that encouraged the adoption of advanced treatment processes. Microalgae-based advanced wastewater treatment has gained momentum owing to its well-known advantages for advanced wastewater treatment, including the recovering of nutrients for the production of fertilizers, biofuels and fine chemical from microalgal biomass. Nevertheless, the progressive membrane fouling and permeate flux declining hamper the large-scale commercialization of membrane photobioreactors (MPBRs) in the wastewater sector. In order to get a further understanding of the fouling mechanisms and antifouling control strategies, this study investigated the effect of the hydraulic retention time on the fouling development, and the effect of different physical fouling control strategies in the fouling mitigation. A synthetic secondary effluent was continuously fed to three MPBRs operated at different HRTs (12, 24 and 36 hours). Different fouling behaviors were found as the HRT changed, which was confirmed by continuously monitoring the transmembrane pressure (TMP) and by measurements in the biomass and its algal organic matter (AOM) properties. Lowering the HRT resulted in higher fouling rates due to changes in the biomass and AOM properties. Higher HRTs led to lower fouling rates and to a lower organic rejection across the membrane. The retention of small-MW organics in SMPBR12h was found to exacerbate the fouling resistance, whereas the accumulation of large-MW biopolymers enhanced the rejection of organics, despite of not imparting significant resistance in SMPBR24h. In order to assess the impact of different physical fouling control strategies, namely relaxation, backwash and air scouring, OCT in-situ monitoring was employed in MPBR12h to provide real-time information of the fouling layer properties (thickness and relative roughness) and its interaction with the membrane surface. Different fouling mechanisms were observed under different fouling control strategies. MPBRRLX and MPBRBW presented similar fouling rates despite of the lower permeate productivities of the latter. The lowest fouling rates were observed in MPBRSC, where stronger interactions between the membrane and small-MW organics and particles was observed.

The global population is constantly rising and with the consequent increase in demand for clean water, the planet is facing a looming freshwater shortage. At the current rate, cities around the globe could lose as much as two thirds of their freshwater supply by 2050. To tackle this, there has been a huge surge on the investigation of novel wastewater treatment technologies. Advanced oxidation processes (AOPs) have shown great promise in this regard. Recently using microwaves with AOPs has been proven to exhibit improved reaction rates and thus there is a push towards developing processes involving microwaves and AOPs to achieve high water treatment efficiencies. However no methodical studies have been conducted to the best of our knowledge, to take the lab scale improvements successfully on to the pilot scale wastewater treatment system. To design such a system by coupling microwaves with Fenton process is the objective of this microwave assisted catalytic treatment of wastewater (MICROCAT) research project. Multiphysics simulation was used for cavity design optimisation and common pesticides found in agricultural wastewater were used as candidate impurities. A heterogeneous Fenton catalyst was prepared by a multi-stage thermal and chemical treatment of polyacrylonitrile (PAN) mesh on polypropylene support structure in collaboration with De Montfort University (DMU). The PAN meshes, after each stage of the treatment process, have been characterised using the field emission gun scanning electron microscope (FEGSEM) and electron dispersive X-ray spectroscopy (EDX) for microstructure and composition. The catalyst was used to study the decomposition of a model compound (e.g., carbetamide) using microwave radiation as well as conventional heating. Two kinds of trials were carried out constant power and constant temperature to observe the effect of variation of process parameters on the reaction rates. It was seen that the use of microwave heating enhanced the rate of decomposition compared to conventional heating in both scenarios. Attempts were also made to modify the composition of the catalyst and the support structure using polyvinylidene fluoride (PVDF) and carbon based additives (graphite and carbon black) to improve the microwave absorption characteristics. The combination of additive and PAN/PVDF mixtures has the potential to help in designing a suitable fabric support for catalyst that could be more receptive to microwaves, thereby helping to improve the energy efficiency of the process. Thorough investigation of dielectric properties and microwave absorption characteristics of the catalyst and support materials were performed independently. The heating rates of the meshes were monitored using an infrared thermal imaging camera. The absorption efficiencies of materials commonly used to build water treatment reactors such as polypropylene (PP), Fibreglass reinforced plastic (FRP), polyvinyl chloride (PVC), glass, PTFE, and fused quartz were assessed by subjecting them to constant microwave power experiments to ascertain their utility for making the reactor parts To take the successful lab scale results (100 ml) to scalable levels (80000 ml) for field trails, a new microwave reactor system was designed and tested. The cavity design was aided by multiphysics simulation of the electromagnetic field and temperature distribution inside the cavity. The model was created using COMSOL and provided valuable insight in making several design choices and improvements. The material data used in the model was determined both from our characterisation results and from corroborative literature data. The cavity itself was fully constructed using aluminium and the internal components were made using polypropylene and PTFE within the project timeline. The cavity was commissioned and initial testing at end user sites involved experiments measuring the rate of decomposition of carbetamide and other pesticides the results again emphasising that microwave treatment improves the reaction rates both from lab scale and in pilot scale water treatment situations in comparison to conventional treatment systems. This augers well for the generic applicability of the microwave assisted catalytic reactor system and its potential for the efficient treatment of contaminated water from hard to treat agricultural. Industrial, medical and defence waste/pollutants in future. An added advantage is that the developed microwave treatment system is mobile (on an ISO-container) and hence can reach the remote, contaminated site and treat it then and there rather than transporting the contaminated fluid to the treatment plant in a faraway location.

Orientador: Luiz Otávio Saraiva Ferreira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-21T21:54:45Z (GMT). No. of bitstreams: 1 Martins_GabrielSoares_M.pdf: 6495887 bytes, checksum: 4a05e53032d23853568df2eca3d4ecf7 (MD5) Previous issue date: 2012 / Resumo: Medir a qualidade da água sempre foi importante para as agências governamentais, organizações científicas e a própria sociedade manterem o nível de contaminação da água em patamares que não afetem a sobrevivência de nenhum ser vivo. Rastrear de forma mais detalhada e precisa os efluentes industriais que retornam aos rios e lagos das cidades, através da instalação de diversos medidores ao longo das linhas de distribuição de água industriais, auxilia na manutenção da qualidade da água destas fontes naturais. Os medidores existentes atualmente, conhecidos por turbidímetros, são caros, o que impede o amplo monitoramento das linhas de água. O objetivo desta dissertação é a construção de um turbidímetro de baixo custo que seja capaz de auxiliar na avaliação dos efluentes industriais. O turbidímetro proposto é baseado no GLI Método 2 (Great Lake Instruments Method 2), que emprega duas técnicas de espectroscopia: a nefelometria e a turbidimetria. A contribuição dada por esta dissertação está na aplicação da técnica de modulação por amplitude de pulso com amostragem instantânea, muito utilizada em telecomunicações, com o intuito de mitigar qualquer deslocamento do sinal devido às fontes de luz do ambiente e outras interferências do circuito eletrônico. O equipamento consegue medir uma faixa de turbidez de 16 a 4000 NTU. Abaixo de 16 NTU não há precisão nas medidas devido à intensa presença de ruído no sinal nefelométrico. Apesar de não conseguir medir o nível de turbidez aceitável de água apropriada para consumo (5 NTU), considera-se a faixa de medição suficiente para se medir efluentes indústrias e monitorá-los para não que não poluam os rios e reservatórios das cidades / Abstract: Measuring water quality has always been important for government agencies; scientific organizations and society maintain the level of water contamination at levels that do not affect the survival of any living being. Track, with more details and accuracy, the industrial effluents that return to the rivers and the lakes of the cities through the installation of several meters along the water lines of industries, helps maintain water quality of the natural sources. The meters currently existing, known for turbidimeters, are expensive, which prevents the widespread monitoring of water lines. The objective of this dissertation is design a low cost turbidimeter that is able to assist in the assessment of industrial effluents. The turbidimeter proposed is based on the GLI Method 2 (Great Lake Instruments Method 2), which employs two spectroscopic techniques: nephelometry and turbidimetry. The contribution of this dissertation is in applying the technique of pulse amplitude modulation with instantaneous sampling, widely used in telecommunications, in order to mitigate any signal offset due to ambient light sources and interference from the electronic circuit. The equipment can measure a range of 16-4000 turbidity NTU. Below 16 NTU there is no accuracy in measurements because the noise interfering in the nephelometric signal. Although the equipment cannot measure the acceptable turbidity level of drinking water (5 NTU), it is considered sufficient to measure industrial effluents and track them to not pollute the rivers and reservoirs of cities / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

<p>Sustainable food production is about producing more and better with less.As an emerging CEA system, aquaponics integrates recirculating aquaculture systems and hydroponics and can achieve the three SDGs mentioned above. However, challenges in sustainable aquaponics commercialization remains and my thesis addresses the following three layers of sustainable aquaponics  development:  sustainability  assessment,  sustainable  system  design  and management, understanding biological mechanisms for scalability.</p> <p>I conducted acradle-to-gate life cycle assessment (LCA)and compared the environmental performance, on an economic basis, of aquaponics andhydroponics withidentical system design in Indiana, US. Aquaponics produced 45% lower endpoint environmental impact than hydroponics.Electricity use for greenhouse heating and lighting, and water pumping and heating contributed to themajority of the environmental impacts of both systems, which was followed by the production of fishfeed and fertilizers. However, changing the energy source from coal to wind power could make thehydroponic system more environment-friendly than the aquaponic system. This LCA study can provideCEA farmers with the groundwork to reduce the environmental cost of their production.</p> <p>Aquaponics uses bacterial processes and plant nutrient uptake to recover nutrient from aquaculture wastewater. However, little is known which wastewater management strategy, autotrophic or heterotrophic, is best suited for the four objectives: nutrient recovery, system reliability, and growth and physiological welfare of fish and plants. In this study, I found that pH6 had the highest nitrogen (N) use efficiency (NUE) (assimilated by fish and plants, 65.5%) and the lowest N loss as gas (34.5%), followed by pH6M (55.5% and 44.5%,respectively), suggesting that lower pH and less organic carbon in aquaponics could enhance NUE and reduce N loss. pH6M had the highest phosphorus (P) use efficiency (PUE) (assimilated by fish and plants, 65.0%) suggesting that lower pH and organic carbonaddition could facilitate P recovery from wastewater. </p> <p>Reverse osmosis (RO) water enables aquaculture to expand in places where natural water is not desirable and reduces uncertainty in the operation. However, high K+environment of RO in  aquaponics  couldinduce  physiological  stress,  but  adaptation  mechanism  is  unknown. Proteomic analysis revealed up-regulation of stress response proteins and down-regulation of V-type H+-ATPase and other ion transporters, suggesting cellular adaptation of fish to RO water stress. In conclusion, fish was able to accommodate to the RO environment and the benefits of efficient ammonia excretion and increased feed consumption outweighed the stress caused by RO. RO water could be a standardized water source for better animal welfare, reduce uncertainty in production and assist scaling up aquaponics industry.</p>