INTERFERÊNCIA DE PARTÍCULAS SÓLIDAS NA TRANSFERÊNCIA DE MASSA AR-ÁGUA EM COLUNA DE AERAÇÃO

Estudou-se a transferencia de massa ar-agua em coluna de aeracao com taxa de aplicacao superficial de 21,5 m3/m2.h a 86,1 m3/m2.h. Variou-se o nivel liquido de 1,0 m a 3,5 m e a vazao de 500 L/h ate 2000 L/h. As configuracoes estudadas forneceram uma equacao potencial em que o coeficiente de transferencia de massa global e funcao da vazao de aeracao, cujo intervalo obtido foi de 0,008 s-1 ate 0,042 s-1. Com relacao a influencia da turbidez por meio da utilizacao de formazina e talco industrial, independente da porcentagem adotada da secao transversal da particula solida que fica aderida a area interfacial da bolha, a comparacao realizada com e sem adicao de composto quimico mostrou que, pricipalmente quando a comparacao e realizada com a formazina, nao ha influencia da turbidez devido a enorme mobilidade das bolhas que nao possibilitam a adesao das particulas solidas. O comportamento nao-monotonico constatado para os estudos com o talco industrial e que diminuiu consideravelmente sua eficiencia de transferencia de massa. A metodologia de quantificacao de reducao da area interfacial de contato aqui proposta possui aceitacao em coluna de aeracao com reduzida taxa de aplicacao superficial vinculada a nao ocorrencia de coalescencia. Palavras-chave: transferencia de massa ar-agua, coluna de aeracao, area interfacial de contato, formazina, talco industrial. ABSTRACT In this paper it was studied the mass transfer air-water in column of aeration with a superficial application rate from 21.5 m3/m2.h to 86.1 m3/m2.h. The liquid level varied from 1.0 m to 3.5 m and the flow from 0.5 m3/h to 2.0 m3/h. The studied configurations provided a potential equation where the overall mass transfer coefficient is a function of the aeration flow, with interval from 0.008 s-1 to 0.042 s-1. Regarding the influence of the turbidity through the use of formazine and industrial pownder, independent of the adopted percentage of the transversal section of the solid particle that is adhered to the interfacial area of the bubble, the comparison carried through with and without chemical composition addition showed that, mainly when the comparison is carried through with the formazine, the influence of the turbidity does not exist, due to enormous mobility of the bubbles that do not make possible the adhesion of solid particles. The no-monotonic behavior evidenced for the studies with industrial pownder is that it reduced considerably the efficiency of mass transfer. The methodology of quantification of the reduction superficial contact area proposed has acceptance in column of aeration with reduced superficial application rate associated with not occurrence of coalescence. Keywords: mass transfer air-water, colunm of aeration, contact interfacial area, formazine, industrial powder.