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The treatment of wastewater is a necessary and legally required reality, which has a direct impact on the benefit of water quality, by avoiding its environmental and landscape deterioration. The country has been installing different urban and industrial liquid waste treatment systems to deal with the degradation of marine, coastal, river and urban environmental systems, caused by the direct discharge of wastewater into the environment. Currently there are several technologies that are applied, depending mainly on the volumes of wastewater to be treated. Among the installed technologies, there are the biodiscs, which are installations of discs with a surface covered with biomass under aerobic conditions that, continuously, consume the organic matter present in the influent wastewater and the lamellar settlers, which have the function of separating the semi-heavy and heavy elements in suspension, which contain wastewater. In the present work, the dynamic behavior patterns of these two technologies installed in a wastewater treatment plant with the use of radiotracers are determined. [ABSTRACT FROM AUTHOR]

Abstract Background Ingrowth-core method is a useful tool to determine fine root growth of standing crops by inserting root-free soil in mesh-bags for certain period of time. However, the root density observed by the method does not directly explain the nutrient uptake potential of crop plants as it varies over soil depth and incubation time. We have inserted an access-tube up to 4.2 m of soil depth with openings directly under crop plants, through which ingrowth-cores containing labelled soil with nutrient tracers were installed, called core-labelling technique (CLT). The main advantage of CLT would be its capacity to determine both root density and root activity from the same crop plants in deep soil layers. We tested the validity of the new method using a model crop species, alfalfa (Medicago sativa) against three depth-levels (1.0, 2.5 and 4.2 m), three sampling spots with varying distance (0–0.36, 0.36–0.72 and > 5 m from core-labelled spot), two sampling times (week 4 and 8), and two plant parts (young and old leaves) under two field experiments (spring and autumn). Results Using CLT, we were able to observe both deep root growth and root activity up to 4.2 m of soil depth. Tracer concentrations revealed that there was no sign of tracer-leakage to adjacent areas which is considered to be advantageous over the generic tracer-injection. Root activity increased with longer incubation period and tracer concentrations were higher in younger leaves only for anionic tracers. Conclusions Our results indicate that CLT can lead to a comprehensive deep root study aiming at measuring both deep root growth and root activity from the same plants. Once produced and installed, the access-tubes and ingrowth-cores can be used for a long-term period, which reduces the workload and cost for the research. Therefore, CLT has a wide range of potential applications to the research involving roots in deep soil layers, which requires further confirmation by future experiments.

The use of substances to diagnose or identify a system specific phase, that is, which function as tracers, is an effective tool in the study of multiple phenomena. There are several kinds of tracers and, within them, radioactive tracers are the most sensitive and used for the study and online diagnosis of many systems, hence their use in industrial processes has an extensive use. However, an authorization from the National Regulatory Body is necessary to use radioactive sources. The safety assessment, the radiation protection program, operational and safety procedures as well as the emergency plan were prepared and presented to the Regulatory Body to apply for authorization. The safety assessment includes the dose estimations for normal operations and potential doses in accidental situations. The safety analysis used the methodology of risk matrixes. As a result, it was obtained that the doses under normal operating conditions comply with the annual limits for occupationally exposed workers and for the public, while the risk levels are predominantly low, so it was concluded that it is possible to carry out the practice under adequate security conditions and the CPHR obtained the operating license. [ABSTRACT FROM AUTHOR]