Estudo comparativo entre dois sistemas descentralizados de tratamento de esgoto doméstico instalados no Centro de Estudos Ambientais e de Desenvolvimento Sustentável da UERJ

Abstract

The uncontrolled growth combined with a lack of investment in the sanitation sector has placed Brazil in the 118th position in the ranking of countries with access to basic sanitation. The dispersed population and the difficulty of access in many isolated communities and rural settlements bring complexity to the provision of this right to a portion of the population. One of the advantages of decentralized wastewater treatment is that it can be treated near the source, reducing the need for large investments in facilities and the implementation of extensive sewerage networks to transport the generated wastewater to the wastewater treatment plant. The objective of this study was to operate, monitor, and compare the treatment efficiencies of two decentralized wastewater treatment systems installed at CEADS, Vila de Dois Rios, Ilha Grande, RJ. One of them is the Engineered Ecosystem, which combines a conventional treatment system consisting of anaerobic, aerobic, and anoxic tanks with an ecological system composed of constructed wetlands. The other one is the Advanced Anaerobic Wastewater Treatment System, composed solely of conventional anaerobic systems. The monitoring of the systems was conducted in three stages: (i) data collection from the CEADS facilities, (ii) description of the treatment technologies implemented in each of the analyzed systems, as well as their operations and maintenance, and (iii) collection, conditioning, and analysis of the effluents. Analyzing the average of the treated effluent (final effluent) from each system, the overall efficiency of the monitored parameters, and their compliance with the current regulations that determine the limits for effluent discharge into water bodies, the Engineered Ecosystem presented better results in all parameters. On the other hand, the Advanced Anaerobic Wastewater Treatment System exceeded the discharge limits for many of the analyzed parameters, such as dissolved oxygen, biochemical oxygen demand, and total suspended solids. Despite the Engineered Ecosystem having higher operational costs due to energy consumption, requiring more frequent maintenance for macrophyte pruning, and needing a larger area for installation, it showed better overall efficiency in removing all the analyzed parameters throughout the months of research, thus contributing to a greater preservation of water quality after the discharge of treated effluent into the environment.