<p>Water is a fundamental substance for the existence of life on earth. However, globally there is a freshwater crisis. Hospitals generate exorbitant volumes of effluents (5 to 15 times more toxic than urban ones). Hospital laundry is known for demanding the highest volumes of water, generating a proportional amount of complex effluents with high toxicity and recalcitrance. Adequate treatment for hospital wastewater is always an essential solution. Among all treatment methods, coagulation/flocculation emerges as one of the best alternatives. However, the use of traditional compounds such as aluminium sulfate has caused secondary pollution; its residues are harmful to public and environmental health. In this sense, the present study used natural compounds that do not cause adverse effects, such as chitosan/hydroxyapatite, to clarify the laundry effluents of the largest hospital from the Tocantins. The results showed that the hydroxyapatite associated with chitosan, at pH 6 and dosage of 50 mg/L, reduced the turbidity and apparent colour of these wastewaters by up to 67 and 55%, respectively. With lower performance and higher dosage (60 mg/L), the chitosan gel used (pH 6) promoted a maximum reduction of 35% of the apparent colour and 40% of turbidity.<br></p>

The high consume of crustaceans in human food has generated a large quantities of residues, such as the crab shell of Ucides cordatus (caranguejo-u&ccedil;&aacute;), in Brazil. These residues are disposed in the environment. The development of new materials using crab shells chitin for biotechnological applications in civil construction is of great interest to the scientific community. The residues addition in the cement can reduce electricity consumption, CO2 emissions and other environmental damage from this human activity. Thus, the aims of this study were the use of U. Cordatus residues for hydroxyapatite and chitosan production and the incorporation of these compounds in Portland cement matrix, as a viable alternative to improve the properties of the paste and mortar when fresh or hardened. The crab shells were obtained from a fishermen&#39;s cooperative after meat extraction. The cement for the production of pastes and mortars was CPII F-40 Portland with filer. The proportion of biomaterial in the cement matrix was of 1 to 5% (w/w). The physical and chemical properties of this material were determined in the fresh and hardened states. Biopolimers of the crab shells promoted changes in consistency, reduced setting time of pastes and mortars and an increase in strength to the axial compressive. These changes may be due to the hydrophilic groups of this compound and the greatest water retention that causes increase the number of nucleation points of the cement and paste grains becomes denser and homogeneous. Thus, the addition of biopolimers in the cement matrix may function as a polyfunctional additive. Furthermore, this process contributes to the reduction of environmental damage caused by improper disposal of crab shells and may represent an economic enhancement of this by-product of the food industry.

<p>Water is a fundamental substance for the existence of life on earth. However, globally there is a freshwater crisis. Hospitals generate exorbitant volumes of effluents (5 to 15 times more toxic than urban ones). Hospital laundry is known for demanding the highest volumes of water, generating a proportional amount of complex effluents with high toxicity and recalcitrance. Adequate treatment for hospital wastewater is always an essential solution. Among all treatment methods, coagulation/flocculation emerges as one of the best alternatives. However, the use of traditional compounds such as aluminium sulfate has caused secondary pollution; its residues are harmful to public and environmental health. In this sense, the present study used natural compounds that do not cause adverse effects, such as chitosan/hydroxyapatite, to clarify the laundry effluents of the largest hospital from the Tocantins. The results showed that the hydroxyapatite associated with chitosan, at pH 6 and dosage of 50 mg/L, reduced the turbidity and apparent colour of these wastewaters by up to 67 and 55%, respectively. With lower performance and higher dosage (60 mg/L), the chitosan gel used (pH 6) promoted a maximum reduction of 35% of the apparent colour and 40% of turbidity.<br></p>

<p>Water is a fundamental substance for the existence of life on earth. However, globally there is a freshwater crisis. Hospitals generate exorbitant volumes of effluents (5 to 15 times more toxic than urban ones). Hospital laundry is known for demanding the highest volumes of water, generating a proportional amount of complex effluents with high toxicity and recalcitrance. Adequate treatment for hospital wastewater is always an essential solution. Among all treatment methods, coagulation/flocculation emerges as one of the best alternatives. However, the use of traditional compounds such as aluminium sulfate has caused secondary pollution; its residues are harmful to public and environmental health. In this sense, the present study used natural compounds that do not cause adverse effects, such as chitosan/hydroxyapatite, to clarify the laundry effluents of the largest hospital from the Tocantins. The results showed that the hydroxyapatite associated with chitosan, at pH 6 and dosage of 50 mg/L, reduced the turbidity and apparent colour of these wastewaters by up to 67 and 55%, respectively. With lower performance and higher dosage (60 mg/L), the chitosan gel used (pH 6) promoted a maximum reduction of 35% of the apparent colour and 40% of turbidity.<br></p>

No abstract

Estruturas de concreto armado estão sujeitas a inúmeras manifestações patológicas, sendo a corrosão iniciada pela difusão de íons cloreto uma das mais agressivas e onerosas. Por isso mesmo, diversos estudos têm sido conduzidos para determinar a vida útil dessas estruturas, mas ainda não há pleno consenso. Nesse sentido, este trabalho objetiva estabelecer um padrão de ensaio para determinar a vida útil de estruturas de concreto armado devido a ação dos íons cloreto, além de analisar a variação do coeficiente de difusão ao se utilizar distintas relações água/cimento. Para alcançar tais objetivos, foram adotadas normativas nacionais e internacionais para orientar as etapas de caracterização dos materiais, além da utilização de equações de modelagens de perfis de penetração de cloretos para determinar o coeficiente de difusão e, por consequência, a vida útil da estrutura. Por fim, pôde-se concluir que ao se diminuir a relação água/cimento, houve diminuição da concentração de cloretos em uma determinada camada, proporcionando assim maior vida útil para o concreto armado. Quanto à analise probabilística, foi possível notar que quanto menor a proporção de água e cimento maior o índice de confiabilidade, uma vez que a probabilidade de falhar também reduz. Palavras-chave: Corrosão, Difusão de Cloreto, Vita Útil.

<p>Water is a fundamental substance for the existence of life on earth. However, globally there is a freshwater crisis. Hospitals generate exorbitant volumes of effluents (5 to 15 times more toxic than urban ones). Hospital laundry is known for demanding the highest volumes of water, generating a proportional amount of complex effluents with high toxicity and recalcitrance. Adequate treatment for hospital wastewater is always an essential solution. Among all treatment methods, coagulation/flocculation emerges as one of the best alternatives. However, the use of traditional compounds such as aluminium sulfate has caused secondary pollution; its residues are harmful to public and environmental health. In this sense, the present study used natural compounds that do not cause adverse effects, such as chitosan/hydroxyapatite, to clarify the laundry effluents of the largest hospital from the Tocantins. The results showed that the hydroxyapatite associated with chitosan, at pH 6 and dosage of 50 mg/L, reduced the turbidity and apparent colour of these wastewaters by up to 67 and 55%, respectively. With lower performance and higher dosage (60 mg/L), the chitosan gel used (pH 6) promoted a maximum reduction of 35% of the apparent colour and 40% of turbidity.<br></p>