ABSTRACT
RESUMO Com a escassez da disponibilidade de água doce e o aumento da demanda de água no mundo e no Brasil, uma das alternativas são os sistemas de dessalinização de água, que removem os sais das águas salobra ou salgada. Este estudo teve como objetivo avaliar a eficiência de um sistema piloto de dessalinização de água salobra a qual foi obtida a partir da mistura de águas do mar e de rio até atingir concentração de sólidos dissolvidos totais (SDT) de 1.500 mg.L-1. O sistema piloto de dessalinização, com capacidade de 1,0 m3.h-1, é composto de ultrafiltração (UF) e abrandamento como pré-tratamento à osmose reversa (OR). Foram realizadas análises de qualidade da água na entrada e saída das unidades de tratamento relativas a SDT, condutividade elétrica, turbidez, pH, cor aparente, alcalinidade, dureza total, cálcio, magnésio, cloreto, sulfato e temperatura. Foram avaliadas a pressão osmótica, o fluxo de filtração e a taxa de recuperação de água no sistema de OR. Com os resultados obtidos, conclui-se que a eficiência de remoção de SDT e condutividade foi de 99%. A UF foi eficiente na remoção de turbidez, enquanto a OR apresentou maiores eficiências de remoção de sais. O sistema piloto de tratamento foi capaz de remover todos os parâmetros estudados. A taxa de recuperação na OR foi de 74,64%.
ABSTRACT Considering the shortage of fresh water availability and an increased demand for water in the world, including Brazil, one of the alternatives for water supply are water desalination systems, which remove salts from brackish or seawater. The objective of this study was to evaluate the efficiency of pilot water desalination system treating brackish water which was obtained mixing fresh water and seawater up to reach 1,500 mg L-1 of total dissolved solids (TDS) concentration. The pilot desalination plant with production capacity of 1.0 m3 h-1 is composed of ultrafiltration (UF) and softener working as a pre-treatment to reverse osmosis (RO). Experiments were performed to analyze some water quality parameters as TDS, electrical conductivity, turbidity, pH, apparent color, alkalinity, total hardness, calcium, magnesium, chlorides, sulfates, and temperature. Osmotic pressure, filtration flow and water recovery rate were also measured for the RO. Analyzing the result obtained, it can be concluded that the efficiency of TDS removal and conductivity were 99%. UF was efficient in removing turbidity, whereas RO reached higher salt removal efficiencies. The pilot plant system could remove all water quality parameters studied. Recovery rate in RO was 74.64%.
ABSTRACT
Abstract Waste produced by the construction sector is a problem that has grown over the last few years. Construction and demolition waste makes up about 50% by mass of the total solid waste produced in Brazil. One alternative by which to reduce this volume is recycling this material in the form of aggregates. However, it is necessary to analyze the environmental risk that the use of recycled aggregates can entail for adjacent soil and the water table. The purpose of this work was to evaluate pervious concrete samples that contained recycled aggregates and to subject them to leaching tests. The results were compared with the limits established by the Italian methodology. Aggregates with 10, 25, 50, and 100% ceramic were used, as well as a recycled concrete aggregate and a natural aggregate. With the exception of the 25% ceramic trial, all the treatments introduced chromium to the water in which they were immersed, with accumulated concentrations varying from 0.009 to 0.099 mg L-1. Cadmium was found in higher quantities, with cumulated concentrations between 0.104 and 0.417 mg L-1. Sulfate concentrations were higher after 24 h of immersion, with a maximum release of 71.7 mg L-1. The concrete made with 100% ceramic aggregate leached more chromium and sulfate than the other aggregates.