Evaluation of low-cost sensors to integrate in a water quality monitor for real-time measurements.

Low-cost sensors integrated with the Internet of Things can enable real-time environmental monitoring networks and provide valuable water quality information to the public. However, the accuracy and precision of the values measured by the sensors are critical for widespread adoption. In this study, 19 different low-cost sensors, commonly found in the literature, from four different manufacturers are tested for measuring five water quality parameters: pH, dissolved oxygen, oxidation-reduction potential, turbidity, and temperature. The low-cost sensors are evaluated for each parameter by calculating the error and precision compared to a typical multiparameter probe assumed as a reference. The comparison was performed in a controlled environment with simultaneous measurements of real water samples. The relative error ranged from - 0.33 to 33.77%, and most of them were ≤ 5%. The pH and temperature were the ones with the most accurate results. In conclusion, low-cost sensors are a complementary alternative to quickly detect changes in water quality parameters. Further studies are necessary to establish a guideline for the operation and maintenance of low-cost sensors.

Low-Cost Water Quality Sensors for IoT: A Systematic Review.

In many countries, water quality monitoring is limited due to the high cost of logistics and professional equipment such as multiparametric probes. However, low-cost sensors integrated with the Internet of Things can enable real-time environmental monitoring networks, providing valuable water quality information to the public. To facilitate the widespread adoption of these sensors, it is crucial to identify which sensors can accurately measure key water quality parameters, their manufacturers, and their reliability in different environments. Although there is an increasing body of work utilizing low-cost water quality sensors, many questions remain unanswered. To address this issue, a systematic literature review was conducted to determine which low-cost sensors are being used for remote water quality monitoring. The results show that there are three primary vendors for the sensors used in the selected papers. Most sensors range in price from US$6.9 to US$169.00 but can cost up to US$500.00. While many papers suggest that low-cost sensors are suitable for water quality monitoring, few compare low-cost sensors to reference devices. Therefore, further research is necessary to determine the reliability and accuracy of low-cost sensors compared to professional devices.

Technical potential of electricity production from municipal solid waste disposed in the biggest cities in Brazil: landfill gas, biogas and thermal treatment.

This article presents an analysis of possibilities for electrical energy production by using municipal solid waste disposed in the biggest Brazilian cities. Currently, the municipal solid waste in Brazil is collected and disposed of at landfills, but there are also other technologies, which in addition to dealing with the garbage can also provide benefits in terms of energy provision. The following scenarios were studied in this work: electricity production from landfill gas (reference scenario); incineration of all municipal solid waste; anaerobic digestion of organic waste and incineration of refuse-derived fuel fractions after being separated in separation plants. According to this study, the biggest cities in Brazil generate about 18.9 million tonnes of municipal solid waste per year (2011), of which 51.5% is biogenic matter. The overall domestic consumption of electricity is 480,120 GWh y(-1) in Brazil and the municipal solid waste incineration in the 16 largest cities in the country could replace 1.8% of it using incinerators. The city of São Paulo could produce 637 GWh y(-1) with landfill gas, 2368 GWh y(-1) with incineration of municipal solid waste and 1177 GWh y(-1) with incineration of refuse-derived fuel. The latter two scenarios could replace 27% and 13.5% of the residential electrical energy consumption in the city. This shows that thermal treatment might be a viable option of waste-to-energy in Brazil.

Determinação de Cd, Cr e Pb no leite e na alimentação bovina do Brasil / Determination of Cd, Cr and Pb in milk and in cattle feed in Brazil

A contaminação do leite é uma das maiores preocupações sanitárias em função de seu grande consumo pela população, e pela enorme extensão do país, o que limita a fiscalização adequada. Apesar de estudos científicos indicarem contaminação do leite com elementos traço tóxicos, não há qualquer estratégia do Estado para detecção e prevenção destes componentes no leite. O presente trabalho investigou a ocorrência de chumbo, cádmio e cromo em amostras de leite in natura e em leite processado e com o propósito de identificar possíveis fontes de contaminação. No leite in natura e no leite processado houve evidência de contaminação por estes elementos traço, muitas vezes em níveis acima do permitido pela legislação brasileira. A mais provável fonte de contaminação foi o sal mineral utilizado na alimentação bovina.

The contamination of milk is one of the major health concerns because it is largely consumed bypopulation, and the huge extension of the country limits the adequate inspection of this product.Although scientific studies have indicated the occurrence of milk contamination with toxic trace elements,no government policy for the detection and prevention of these components has been available. Thisstudy aimed at investigating the occurrence of lead, cadmium and chromium in samples of raw milk andprocessed milk in an attempt to identify the possible sources of contamination. Both the in natura rawmilk and the processed milk evidenced the contamination with these toxic trace elements, and usually atlevels above those permitted by Brazilian legislation. The most probable contamination source was themineral salt employed for feeding cattle.

Determination of fenoterol and salbutamol in pharmaceutical formulations by electrogenerated chemiluminescence.

Fenoterol and salbutamol were determined by electrogenerated chemiluminescence (ECL) coupled with flow injection analysis (FIA), using Ru(bpy)(3)(2+) as the luminescent substance. Fenoterol and salbutamol oxidize together with the ruthenium 2,2-bipyridyl at a platinum electrode, which leads to an increase in the luminescent intensity, and this increase is proportional to the analyte concentration. For fenoterol a linear calibration curve within the range from 1.0x10(-5) to 1.0x10(-4)mol l(-1) was obtained with a correlation coefficient of 0.998 (n=5) and for salbutamol the linear analytical curve was also obtained in this range with a correlation coefficient of 0.995 (n=5). The relative standard deviation was estimated as < or =2.5% for 3x10(-5)mol l(-1) for fenoterol solution and as < or =1.3% for 5.0x10(-5)mol l(-1) salbutamol solution for 15 successive injections. The limit of detection for fenoterol was 2.4x10(-7)mol l(-1) and for salbutamol was 4.0x10(-7)mol l(-1). Fenoterol and salbutamol were successfully determined in drug tablets and the soluble components of the matrix did not interfere in the luminescent emission. The results obtained using the luminescent methodology were not statistically different from those obtained by UV-spectrophotometry at 95% confidence level.

Estudo fotoquímico da dipirona na presença de ß e γ ciclodextrina / Photochemistry study of the dipyrone in the presence of ß and γ cyclodextrin

Neste trabalho foi estudado o efeito da irradiação por luz UV na substância ácido 1-fenil-2,3-dimetil-5-pirazolona-4-metilaminometanossulfônico (dipirona) em solução aquosa e complexada em ß e γ ciclodextrinas. Inicialmente, estudaram-se as características fotofísicas do ácido em meio aquoso, em seguida verificou-se a fotoestabilidade da substância comparando com as mesmas em cavidades de ciclodextrinas. Foi utilizado um modelo cinético de decomposição de primeira ordem para obter as constantes de decomposição aparente da dipirona em meio aquoso e em cavidades de ciclo dextrina. O encapsulamento da dipirona em ciclodextrina de uma forma geral causa uma estabilização frente a fotólise por luz UV.

In this work it was studied the effect of the irradiation UV in the substance 1-phenyl-2,3-dimethyl-5-pyrazolone-3-4-methylaminomethanosulphonic acid in aqueous solution and complexed in ß and γ cyclodextrin. Initially, it was studied the photophysics caracteristics of the acid in aqueous solution, soon afterwards verified the photostability of the substance in cyclodextrin cavities using a first order kinetic model. The encapsulament in cyclodextrin of the dipyrone in a way general cause a stabilization front the photolysis for UV light.