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Nowadays, several mechanisms are used to treat wastewater, including wetland systems. This low-cost, emerging technology system shows significant results in the treatment of industrial dairy effluents on an experimental scale. The experimental systems (prototype) were built by plastic bombs, with the first stage of vertical subsurface flow and the second of horizontal subsurface flow. The effluent was stored in a reservoir and distributed by gravity, followed by root zones filled with the filter material (layers of gravel and coarse sand). The species used were Pistia stratiotes, Eichhornia crassipes and Vetiveria zizanioides, however the first species did not adapt to the system. The system showed satisfactory results regarding the COD removal efficiency of 62.13% ± 14.70, total solids 87.18% ± 2.26, turbidity 96.43% ± 3.37, total phosphorus 97.53% ± 2.15 and total nitrogen 32.08% ± 3.98. However, BOD removal was less, reaching efficiencies between 9 and 10% ± 5. The parameters of pH and sedimentable solids, on the other hand, reached the release standards established in the current legislation. Actualmente, se utilizan varios mecanismos para tratar las aguas residuales, incluido el sistema de humedales. El sistema de humedales construidos son sistemas filtrantes compuestos por macrófitos acuáticos adheridos a un macizo, a través del cual discurren los efluentes. Este sistema de tecnología emergente y de bajo costo presenta resultados significativos en el tratamiento de efluentes industriales de productos lácteos a escala experimental. Los sistemas experimentales (prototipos) se construyeron utilizando bidones de plástico, siendo la primera etapa un flujo subsuperficial vertical y la segunda un flujo subsuperficial horizontal. El efluente se almacenó en un reservorio y se distribuyó por gravedad, seguido de zonas de raíces rellenas con material filtrante (capas de grava y arena gruesa). Las especies utilizadas fueron Pistia stratiotes, Eichhornia crassipes y Vetiveria zizanioides, pero la primera especie no se adaptó al sistema. El sistema mostró resultados satisfactorios en relación a la eficiencia de remoción de DQO de 62,13% ±14,70, sólidos totales 87,18% ±2,26, turbidez 96,43% ±3,37, fósforo total 97,53% ±2,15 y nitrógeno total 32,08% ±3,98. Sin embargo, la remoción de DBO fue menor, alcanzando eficiencias entre 9 y 10% ±5. Los parámetros de pH y sólidos sedimentables alcanzaron los estándares de liberación establecidos en la legislación vigente. Atualmente, utilizam-se diversos mecanismos para tratamento de águas residuárias, dentre estes o sistema de wetlands. Wetlands são sistemas filtrantes compostos de macrófitas aquáticas aderidas a um maciço, por onde o efluente escoa. Esse sistema de tecnologia emergente e baixo custo apresenta resultados significativos no tratamento de efluentes industriais de laticínios em escala experimental. Os sistemas experimentais (protótipos) foram construídos por bombonas plásticas, sendo o primeiro estágio de fluxo subsuperficial vertical e o segundo de fluxo subsuperficial horizontal. O efluente foi armazenado num reservatório e distribuído por gravidade, seguido por zonas de raízes preenchidas com o material filtrante (camadas de brita e areia grossa). As espécies utilizadas foram Pistia stratiotes, Eichhornia crassipes e Vetiveria zizanioides, porém a primeira espécie não se adaptou ao sistema, que apresentou resultados satisfatórios em relação à eficiência de remoção de DQO de 62,13% ±14,70, sólidos totais 87,18% ±2,26, turbidez 96,43% ±3,37, fósforo total 97,53% ±2,15 e nitrogênio total 32,08% ±3,98. Porém, a remoção de DBO foi inferior, atingindo eficiências entre 9 e 10% ±5. Já os parâmetros pH e sólidos sedimentáveis atingiram os padrões de lançamento estabelecidos na legislação vigente.

Filter systems are widely used in petrochemical plants for removing solid impurities from hydrocarbon oils. The backwash is the cleaning process used to remove the impurities on the sieves of the filters without a need to interrupt the operation of the entire system. This paper presents a case study based on the actual project of a filter system in a petrochemical plant, to demonstrate the significant effect of vibration on the structural integrity of piping. The induced vibration had led to the structural fatigue failure of the pipes connecting the filter system. A preliminary assessment suggested that the vibrations are caused by the operation of backwashing of the filter system. A process for solving the vibration problem based on the modal analysis of the filter system using the commercial finite element software for simulation is therefore proposed. The computed natural frequencies of the system and the vibration data measured on site are assessed based on the resonance effect of the complete system including the piping connected to the filters. Several approaches are proposed to adjust the natural frequencies of the system in such a way that an optimal and a reasonable solution for solving the vibration problem is obtained. Published version

The contamination of groundwater sources by pathogenic bacteria poses a public health concern to communities who depend totally on this water supply. In the present study, potentially low-cost filter materials coated with silver nanoparticles were developed for the disinfection of groundwater. Silver nanoparticles were deposited on zeolite, sand, fibreglass, anion and cation resin substrates in various concentrations (0.01 mM, 0.03 mM, 0.05 mM and 0.1 mM) of AgNO(3). These substrates were characterised by SEM, EDS, TEM, particle size distribution and XRD analyses. In the first phase, the five substrates coated with various concentrations of AgNO(3) were tested against E. coli spiked in synthetic water to determine the best loading concentration that could remove pathogenic bacteria completely from test water. The results revealed that all filters were able to decrease the concentration of E. coli from synthetic water, with a higher removal efficiency achieved at 0.1 mM (21-100%) and a lower efficiency at 0.01 mM (7-50%) concentrations. The cation resin-silver nanoparticle filter was found to remove this pathogenic bacterium at the highest rate, namely 100%. In the second phase, only the best performing concentration of 0.1 mM was considered and tested against presumptive E. coli, S. typhimurium, S. dysenteriae and V. cholerae from groundwater. The results revealed the highest bacteria removal efficiency by the Ag/cation resin filter with complete (100%) removal of all targeted bacteria and the lowest by the Ag/zeolite filter with an 8% to 67% removal rate. This study therefore suggests that the filter system with Ag/cation resin substrate can be used as a potential alternative cost-effective filter for the disinfection of groundwater and production of safe drinking water.

Water is very important to human beings. Although human life can exist for many days without food, the absence of water for only a few days has fatal consequences. A wide variety of commercial water treatment systems are available for application to treat very small quantities, such as for individual homes or taps. These can treat virtually any water quality problem. It is important to have a good understanding of the specific water quality problems before selecting water treatment system. It is also important that products be tested and approved by a qualified independent certification organization to have confidence that the device will indeed perform as the vendor claims. The present study aimed to assess the bacteriological quality of drinking water in some household water filter systems inBenghazi city. The study was carried out on a total of 600 water samples (300 tap water samples and 300 filter water devices samples). All water samples were examined for enumeration of viable heterotrophic bacteria by pour plate method and enumeration of total coliforms (TC) by both the multiple tube fermentation (MTF) and membrane filtration (MF) methods and for thermotolerant coliforms (TTC), Fecal streptococci (FS), and Pseudomonas aeruginosa (P. aeruginosa) by the MF method. According to Libyan guidelines, out of 600 examined drinking water samples 76.8% were acceptable. The highest percentage of acceptable samples was revealed from reverse osmosis (RO) system (90.7%), followed by charcoal filter (83.3%), tap water distribution system (DS) (82.3%), and only 54.7% from tap water tanks. It was concluded from this study that filtered water samples were found to be superior to tap water samples as regards their bacteriological aspects. In addition, P. aeruginosa was considered as an excellent indicator for the efficiency of the water filters.