Renato Castiglia Feitosa

Comparative study of fecal bacterial decay models for the simulation of plumes of submarine sewage outfalls.

In the literature, analytical models have been shown to be extremely useful for estimating the decay rates of coliform as fecal indicator microorganisms, providing reliable predictions of bathing conditions in coastal and continental waters. Although a number of different formulations have been developed in the literature, each one may only be suitable for specific environments, and no comparison between these methods has ever been carried out. In the present article, a comparative analysis of bacterial decay models, calculated by eight different formulations, was performed in coastal outfall plumes, considering identical environmental conditions of solar radiation, temperature and salinity. A statistical approach was applied to identify the differences in means and in behaviors of the results obtained in the various simulations. The results indicate good agreement between bacterial decay rates calculated with at least four methods that were considered more reliable, and at least one of the models was shown to be suitable for estimating bacterial decay rates under night-time conditions, considering only the combined influences of temperature and salinity. Moreover, under daytime conditions, it provides consistent decay rates when compared with measurements taken in the field.

Retrofitted green roofs and walls and improvements in thermal comfort

Increased urbanization has led to a worsening in the quality of life for many people living in large cities in respect of the urban heat island effect and increases of indoor temperatures in housing and other buildings. A solution may be to retrofit existing environments to their former conditions, with a combination of green infrastructures applied to existing walls and rooftops. Retrofitted green roofs may attenuate housing temperature. However, with tall buildings, facade areas are much larger compared to rooftop areas, the role of green walls in mitigating extreme temperatures is more pronounced. Thus, the combination of green roofs and green walls is expected to promote a better thermal performance in the building envelope. For this purpose, a modular vegetated system is adopted for covering both walls and rooftops. Rather than temperature itself, the heat index, which comprises the combined effect of temperature and relative humidity is used in the evaluation of thermal comfort in small scale experi...

Coupling bacterial decay and hydrodynamic models for sewage outfall simulation

The evaluation of wastewater concentrations in coastal environments has to be accurate for water quality control. The description of the physical process in a comprehensive model is a complex task. Due to the different spatial and temporal scales involved, the use of different numerical models is required: far-field hydrodynamic models; near-field and pollutant transport models. In this paper, a coupled application of these models is described. Capabilities and limitations of modelling techniques applied to wastewater mixing and dispersion from submerged multiport discharges are discussed for environmental impact analysis. The recommended procedure combines a near-field mixing zone model, such as NRFIELD, with the Lagrangian far-field flow and water quality models within SisBaHia® (http://www.sisbahia.coppe.ufrj.br/). The results showed that the model coupling improves the description and analysis of treated wastewater discharges over large scales. This allows a more realistic evaluation of the environmental impact due to domestic sewage discharges in coastal waters.

Ocean outfalls as an alternative to minimizing risks to human and environmental health

Submarine outfalls are proposed as an efficient alternative for the final destination of wastewater in densely populated coastal areas, due to the high dispersal capacity and the clearance of organic matter in the marine environment, and because they require small areas for implementation. This paper evaluates the probability of unsuitable bathing conditions in coastal areas nearby to the Ipanema, Barra da Tijuca and Icaraí outfalls based on a computational methodology gathering hydrodynamic, pollutant transport, and bacterial decay modelling. The results show a strong influence of solar radiation and all factors that mitigate its levels in the marine environment on coliform concentration. The aforementioned outfalls do not pollute the coastal areas, and unsuitable bathing conditions are restricted to nearby effluent launching points. The pollution observed at the beaches indicates that the contamination occurs due to the polluted estuarine systems, rivers and canals that flow to the coast.