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Aerobic granular sludge (AGS) is a promising technology for wastewater treatment. However, maintaining the granular biomass stability is not trivial. During the long-term operation of AGS systems, we observed that uncontrolled sludge retention time led to the appearance of substantially large and fluffy granules characterized by a dark anaerobic inner core. Such conditions favoured the proliferation of filamentous bacteria and deterioration of AGS properties. Consequently, granules disintegration became inevitable. We decided to assess two operational strategies to supress filamentous overgrowth and recover the granular biomass stability. Strategy 1 involved the enhancement of shear stress by increasing the aeration intensity (from 1.34 to 1.87 cm s−1), while strategy 2 relied on the combination of enhanced aeration and iron (10 mg L−1) addition. The implementation of strategy 1 contributed to decrease the average diameter of AGS (4.7–4.1 mm) and sludge volume index (SVI) (300–110 mL g−1). Nevertheless, filamentous bacteria remained intact. Conversely, prolonged shear stress combined with iron supplementation (strategy 2) led to significant improvements in the physical characteristics of the granules. Very small particles acting as precursors of mature AGS were observed while big-size granules (>4 mm) were no longer detected. Moreover, filamentous overgrowth was controlled and the growth of new granules was stimulated. No adverse effect on the conversion processes (COD and nitrogen removal) was observed in the AGS system and stable granulation was achieved from this period onwards. To better explain the role of the implemented strategies, some hypothesis are presented and discussed. [ABSTRACT FROM AUTHOR]

Aerobic granular sludge (AGS) has been considered a breakthrough within the wastewater treatment sector. However, the long reactor start-up for the formation of granules is challenging and may hinder the spread of this technology. To circumvent this obstacle, inoculation of the reactors with pre-formed granules from existing plants is an interesting approach. In this context, issues related to biomass storage becomes very relevant. In this study, reactivation of aerobic granular biomass after storage was evaluated in a sequencing batch reactor (SBR) designed for achieving simultaneous organic matter, nitrogen and phosphorus removal. Two different scenarios, short (40 days) and long (180 days) storage periods, were assessed, and their influence on the granules physical properties and bioactivity was addressed. The results revealed that the granules stored for a shorter period showed higher resistance to breakage and underwent smooth color changes. On the other hand, the biomass stored for a longer period acquired a dark color and was more susceptible to disruption during reactivation. The granules stored for 6 months become swollen and exhibited an irregular morphology and fluffy structure within the first days of reactivation. Consequently, their settling properties were adversely affected, and some parameters such as the food-to-microorganism ratio had to be adjusted to prevent granules disintegration. Regarding the bioactivity of important microbial functional groups, COD removal was rapidly restored within a few days of SBR operation with the biomass stored for a shorter period. However, it took longer for the biomass stored for 180 days to reach the same performance observed for the granules stored for 40 days. A similar trend is valid for nitrification. In the experiments with sludge stored for a longer time, it took almost twice as long to reach effluent ammonium concentrations lower than 1 mg NH 4 + compared to the test using biomass stored for 40 days. Phosphate removal was strongly affected by biomass storage, especially after 180 days of inactivity, a condition found to be detrimental for polyphosphate-accumulating organisms. Finally, cycle tests were also conducted to assess substrate conversion rates for comparison between different trials and evaluate the influence of temperature (10-35 °C) on nitrification and phosphate removal rates.-1 compared to the test using biomass stored for 40 days. Phosphate removal was strongly affected by biomass storage, especially after 180 days of inactivity, a condition found to be detrimental for polyphosphate-accumulating organisms. Finally, cycle tests were also conducted to assess substrate conversion rates for comparison between different trials and evaluate the influence of temperature (10-35 °C) on nitrification and phosphate removal rates., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Construction and demolition waste represents a significant waste flow, both in Brazil and in other countries. According to specific Brazilian legislation, since 2004 construction and demolition waste can no longer be disposed of in open dumps, municipal solid waste landfills, slopes, waterways and environmental protected areas. Construction and demolition waste should preferably be recycled, but just a small amount of it returns to the construction industry production chain in Brazil. This work aims both to present diagnoses of the construction and demolition waste management in Brazil, the European Union and the United States and to compare their results. It is concluded that Brazil presents performance indicators in relation to construction and demolition waste management well below those found for the other analysed countries. Furthermore, differences and similarities are identified and potentials for improvement in the current situation of construction and demolition waste in Brazil are discussed.

This paper examines potential changes in solid waste policies for the reduction in GHG for the country of Brazil and one of its major states and cities, Rio de Janeiro, from 2005 to 2030. To examine these policy options, trends in solid waste quantities and associated GHG emissions are derived. Three alternative policy scenarios are evaluated in terms of effectiveness, technology, and economics and conclusions posited regarding optimal strategies for Brazil to implement. These scenarios are been building on the guidelines for national inventories of GHG emissions (IPCC, 2006) and adapted to Brazilian states and municipalities' boundaries. Based on the results, it is possible to say that the potential revenue from products of solid waste management is more than sufficient to transform the current scenario in this country into one of financial and environmental gains, where the negative impacts of climate change have created a huge opportunity to expand infrastructure for waste management., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In Brazil most Construction and Demolition Waste (C&D waste) is not recycled. This situation is expected to change significantly, since new federal regulations oblige municipalities to create and implement sustainable C&D waste management plans which assign an important role to recycling activities. The recycling organizational network and its flows and components are fundamental to C&D waste recycling feasibility. Organizational networks, flows and components involve reverse logistics. The aim of this work is to introduce the concepts of reverse logistics and reverse distribution channel networks and to study the Brazilian C&D waste case.

There are very few construction and demolition (C&D) waste recycling centres in Brazil. To encourage the building and operation of new units, data were collected and analysed relating to C&D waste management and recycling in Brazil. Based on the results of this analysis, a conceptual model is presented for conducting viability studies of future C&D waste recycling centres. Applying this model to verify the viability of private recycling centres, the results show that under current market conditions in Brazil, C&D waste recycling centres are not financially feasible based solely on revenue from the sale of processed products. Nevertheless, under the same market conditions, the recycling centres could be economically viable for public authorities depending on the particular circumstances of each municipality. The feasibility, however, depends on continuity and the production volume reached. The conceptual model, the results of its applications and the discussions about the experiences of existing centres can strongly support public authorities and private initiatives in their decision-making about investments in Brazil and in other developing countries.

By mechanical-biological treatment (MBT) of residual municipal solid waste the behaviour of landfills can be significantly improved. After MBT the organic content (COD and BOD5), total organic carbon, and total nitrogen in the leachate, as well as the gas production rate, are reduced to values lower than 90% of the fresh untreated waste. The volume of the stabilized material to be disposed on landfills decreases enormously, by up to 70%. The monitoring effort for a landfill constructed under these conditions is reduced to a minimum and the stabilized material can be used in other ways, as material for reforestation, for cover material or for thermal utilization to produce energy. Environmental conditions are important in MBT, as well as waste characteristics. This paper describes the results of a pilot project of MBT performed in Rio de Janeiro, Brazil. The results have shown that this technology can be used successfully in developing countries, with economy for the society and important results for the environment.