Maria Gorethe de Sousa Lima

Septic tank combined with anaerobic filter and conventional UASB: results from full scale plants

Anaerobic digestion is an important alternative for domestic wastewater treatment, especially in warm climate regions. Two full-scale anaerobic schemes were investigated: septic tank combined with anaerobic filter (STANF) and conventional UASB reactors. Treated effluents from these systems were subjected to disinfection by chlorination. The operational performance of 56 full-scale plants (36 STANF and 20 UASB) provided a realistic view. Findings showed that the plants operated with low OLR (< 2.0 kg COD/m3.day). Despite this, the removal of organic material was below values suggested by the literature (around 60% for COD). A removal of 4.0 Log10 units of total coliform and E. coli can be reached with residual chlorine (RCL) of at least 2.0 Cl-Cl2/l. Although UASB plants have performed better, improvement of maintenance is needed in both treatment configurations.

Theoretical/Experimental Study of an Upflow Anaerobic Sludge Blanket Reactor Treating Domestic Wastewater

This work reports a theoretical and experimental study to evaluate the fluid dynamic of an Upflow Anaerobic Sludge Blanket reactor (UASB), treating domestic wastewater in a pilot scale. Simulations were developed using the Ansys CFX 10.0. For validating the numerical results, an experimental study was conducted by monitoring the total concentration of suspended solids in the effluent and pressure along the reactor. The comparative analysis between the numerical and experimental results of the pressure and sludge concentration in the outlet of the reactor presented few differences, being considered satisfactory.

MODIFICAÇÕES NAS PROPRIEDADES DOS SOLOS DE UMA ÁREA DE MANEJO FLORESTAL NA CHAPADA DO ARARIPE

The Araripe Plateau in the tropic semi-arid region is characterized by great environmental diversity. The Araripe National Forest and several forest management units (FMU) are located in this area with mostly red-yellow Oxisols. The goal of this study was to identify a basic indicator that could represent a set of physical, chemical and biological properties of soils of the Plateau. Multivariate analysis was used to indicate changes in soil properties of a FMU. Soil samples were analyzed in triplicate (0-20 cm layer), from 15 points of the FMU and four points of the National Forest. Nine soil properties were selected to characterize differences between preserved and exploited sites, including those in recovery phases. The results show that two principal components account for approximately 76 % of the variance of the data: the first indicator of biological, chemical and physical soil quality and the second indicator of soil compaction. Multivariate cluster analysis of the first principal component group showed the formation of three sub-groups: the National Forest sub-group and two sub-groups of the FMU in different recovery stages. The Tukey test (5 % significance) applied to the grouping of organic matter content of soils agreed with results from multivariate cluster analysis. This indicates that this organic matter can be used as main indicator of changes in soil properties for the study area.