8 research outputs found
Functionalization of kaolinite for removal of phosphate from urban sewage
The PO43− widespread in urban sewages promotes eutrophication of water sources, with harmful effects to natural life and endanger human health. The removal of PO43− from urban sewage requires treatment at tertiary level, with high costs and low efficiency in most cases. Thus, a functionalization method for surface modification of kaolinite was proposed to improve the removal of PO43− from urban sewage. The kaolinite commercial did not remove PO43- from aqueous solution. However, the functionalized kaolinite (FK) was efficient, with a maximum removal capacity of 8.4 ± 0.1 mg PO43−/L, within less than 1 min of reaction. The removal of PO43- is associated with precipitation of pyromorphite, a mineral with low solubility (Ksp < 10−79,6). Finally, real urban sewage samples (raw and treated) were also tested for removal of PO43- using FK, confirming its effectiveness. The central aspects of this development are: • Functionalized kaolinite (FK), with Pb(II), for removal of PO43− from urban sewage was studied. • The FK was efficient for removal of up to 8.4 mg PO43−/L from aqueous solution, within a short reaction time. • The precipitation of pyromorphite was the mechanism responsible for removal of PO43- and FK efficiency have been confirmed for real urban sewage samples
Viabilidade da Disposição de Lodo Secundário da Ete de Araraquara (SP) em Argissolo Vermelho
No tratamento de águas residuárias o acúmulo de materiais sólidos (lodo) é comumente verificado ao final dos processos, cuja disposição apresenta-se como problemática e dispendiosa. Dentre as formas de reaproveitamento do lodo ou biossólido gerado nas estações de tratamento de esgotos (ETEs), destaca-se a aplicação agrÃcola, permitindo a reciclagem de matéria orgânica e nutrientes ao meio. Baseando-se nos potenciais impactos associados ao descarte do biossólido em solos, os efeitos da aplicação do lodo da ETE do MunicÃpio de Araraquara (SP) em solo do tipo argissolo vermelho foram avaliados. Desta forma, tanques (lisÃmetros) com o solo estudado foram construÃdos e doses distintas de lodo – 500 e 1500 gramas de sólidos totais (ST) por m2 – foram aplicadas em cada tanque. Os lisÃmetros ficaram expostos à s condições ambientes e foram monitorados por aproximadamente quatro meses. Cinco aplicações acumulativas de lodo foram realizadas durante 90 dias. As águas de chuva infiltradas nos tanques foram analisadas para detecção de metais e patogenicidade. A composição quÃmica de gramÃneas eventualmente germinadas nos tanques também foi analisada para detecção de metais e seu poder nutricional. As análises indicaram a ausência de organismos patogênicos nas águas percoladas. Quanto aos teores de metais na água, os valores obtidos foram superiores ao limite de detecção do equipamento utilizado e inferiores aos limites máximos permitidos para classificação de águas doces classe I. Além disso, um acréscimo na fertilidade do solo ao final das aplicações foi observado. Assim, verificou-se que o lodo amostrado apresenta potencial para reuso agrÃcola, ressaltando-se a necessidade da aplicação das doses recomendadas pela legislação vigente e do monitoramento periódico das areas aplicadas
Evaluation of diffusive gradients in thin films technique (DGT) for measuring Al, Cd, Co, Cu, Mn, Ni, and Zn in Amazonian rivers
Studies concerning the lability and bioavailability of trace metals have played a prominent role in the search for contamination of water resources. This work describes the first application yet of the diffusive gradients in thin films technique (DGT) to the determination of the fraction of free plus labile metals in waters from the Amazon Basin. Due to the complexity of the use of DGT for samples with low ionic strength and high organic matter content (characteristic of Amazonian rivers), a new analytical procedure was developed. The method is based on the determinations of apparent diffusion coefficients (Dap) in the laboratory, by performing deployments in samples collected in the corresponding sites of study. The Dap thereby determined is then used for in situ measurements. The suitability of the proposed approach for determination of labile Al, Cd, Co, Cu, Mn, Ni, and Zn in the Amazon River and Rio Negro (English: Black River) was evaluated. Except for Co, Mn (in a deployment at Rio Negro), Ni and Zn (in a deployment at Amazon River), labile in situ measurements were lower or similar to dissolved concentrations, indicating suitability of the proposed approach. © 2013 Springer Science+Business Media Dordrecht