RESUMO

This research analyzes the use of natural shrimp shell and commercial chitin for biosorption of metal ions in surface runoff. Investigation of the use of these biosorbent materials in drainage systems becomes a management measure for two extremely important issues in Brazil, fish waste management and the surface runoff quality. Methodological procedures involved treatments with different amounts of unprocessed shrimp shell and commercial chitin (5g and 10g) for 200mL of a compensatory drainage mechanism (infiltration swale). The contact time of biosorbent and runoff was 24h and removal of metal ions Fe, Mn, Zn, Cu, Ni, Pb, and Cr was studied. Tests with unprocessed shrimp shell showed high concentrations of metallic ions (Pb, Ni, and Cu) causing contamination of the environment. However, the two biosorbents presented good removal of specific metallic ions (Fe, Mn, Zn, and Cr). These results indicate the need for a biosorbent pre-treatment prior to full-scale use. We indicate the need for a more detailed investigation of water quality in the environment used for shrimp farming. Tests with commercial chitin presented satisfactory results for two concentrations tested. Tests with 10g of commercial chitin allowed removal of all tested metal ions (Fe, Mn, Zn, Cu, Ni, Pb, Cr) with removal percentage between 6.7% and 84.4%. This efficiency may be related to the chitin's composition (shrimp, crustaceans, and crab) and to the chemical process applied to the product prior to commercialization.

Assuntos

RESUMO

In this work, an adsorbent coal was characterized and its sorption properties for the removal of iron and manganese from aqueous solutions were determined. Energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) identified the presence of quartz, magnetite and manganese oxide in the adsorbent coal. The results of the adsorption isotherms verified the adsorption of iron and manganese by adsorbent coal showing a linear behaviour and indicated that chemisorption and physisorption occurred. The kinetic results were best adjusted to the pseudo-second order model with a 0.999 correlation coefficient. The results showed that the adsorbent coal could be used efficiently for the removal of iron and manganese from aqueous solutions.

Assuntos

RESUMO

Neste trabalho, avaliou-se o desempenho de um biorreator à membrana em batelada sequencial para a remoção de nutrientes (nitrogênio e fósforo) de esgoto sanitário. O reator, construído em escala piloto, foi operado durante 241 dias com tempo total de ciclo de 4 horas, sendo 5 minutos para alimentação, 55 minutos para a fase anóxica e 180 minutos para as fases de aeração e filtração (simultaneamente). Ao longo do monitoramento, foram empregados dois fluxos de filtração: 5,55 e 11,1 L.m-2.h-1, que resultaram nas taxas de troca volumétrica de 5 e 10%, respectivamente. As eficiências médias de remoção de Demanda Química de Oxigênio total, nitrogênio amoniacal e nitrogênio total alcançadas foram de 99, 98 e 96%, respectivamente. Em relação à remoção de fósforo, observou-se inicialmente um baixo rendimento do reator, sendo verificado ao longo do tempo, no entanto, uma tendência de melhora na remoção desse nutriente, atingindo eficiência média de 74% entre os dias 158 e 241. A utilização do fluxo de filtração de 5,55 L.m-2.h-1 proporcionou uma operação estável ao biorreator à membrana em batelada sequencial no que se refere à pressão transmembrana, tendo sido atingido o valor limite de 0,7 bar apenas uma vez em 181 dias de operação, ao passo que, com fluxo de 11,1 L.m-2.h-1, esse limite foi atingido 3 vezes em 55 dias.

This study evaluated the performance of a membrane bioreactor sequencing batch, in pilot scale, to remove nutrients (nitrogen and phosphorus) from domestic wastewater. The reactor was operated for 241 days with a total cycle time of 4 hours, with 5 minutes for feeding, 55 minutes for the anoxic phase and 180 minutes for the aeration and filtration phases (simultaneously). Throughout the monitoring, two filtration flows were employed: 5.5 and 11.1 (critical flux) L.m-2.h-1, which resulted in the volume exchange rates of 5 and 10%, respectively. The removal efficiencies of total Chemical Oxygen Demand, ammonia nitrogen and total nitrogen were achieved by 99, 98 and 96%, respectively. Regarding phosphorus removal, a poor performance was observed in the beginning of the experiment; however, a tendency of improvement in the removal of this nutrient was further verified, reaching an efficiency average of 74% between the operational days 158 and 241. The flux filtration at 5.55 L.m-2.h-1 has provided a membrane bioreactor sequencing batch stable operation in relation to transmembrane pressure since it reached the limit value of 0.7 bar only once in 181 operational days, while for 11.1 L.m-2.h-1 it was observed 3 times in 55 days.