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The Sequencing Batch Biofilter Granular Reactor (SBBGR) is a promising wastewater treatment technology characterized by high biomass concentration in the system, good depuration performance and low sludge production. Its main drawback is the high energy consumption required for wastewater recirculation through the reactor bed to ensure both shear stress and oxygen supply. Therefore, the effect of low recirculation flow on the long-term (38 months) performance of a laboratory scale SBBGR was studied. Both the microbial components of the granules, and their main metabolic activities were evaluated (heterotrophic oxidation, nitrification, denitrification, fermentation, sulphate reduction and methanogenesis). The results indicate that despite reduced recirculation, the SBBGR system maintained many of its advantageous characteristics., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Wastewaters generated by many economically relevant industrial activities contain recalcitrant organic compounds which pass unaltered through biological stage of the treatment plant making it difficult to meet the discharge limits currently in force. Therefore, an additional treatment is usually required to remove these compounds. In this study, the application of ozonation together with biological treatment was investigated. In particular, the effectiveness of biological degradation followed by or integrated with ozonation for treating the effluents produced by three environmentally relevant activities (i.e., leather and textile processing and municipal waste landfilling) are compared in the present paper. The results show that biological treatment followed by ozonation does not guarantee depurative levels sufficient for discharge for landfill leachates and tannery wastewater. On the contrary, thanks to the synergy between biological degradation and ozonation, integrated treatment significantly improves the process performance for all the investigated wastewaters, thus allowing the discharge limits to be met., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The present paper reports the results of an investigation aimed at evaluating the effectiveness of magnesium ammonium phosphate precipitation (MAP), commonly called struvite, for removing ammonia from a mature municipal landfill leachate. MAP precipitation was carried out at laboratory scale by adding phosphoric acid and magnesium oxide as external sources of phosphorus and magnesium, respectively, and regulating the pH at 9.0. The effect of Mg:NH(4):PO(3) ratio was studied. Due to the low solubility of MgO, a low ammonia removal efficiency (i.e. 67%), with a rather high residual concentration, was obtained when the stoichiometric molar ratio was applied. However, by doubling the amount of magnesium oxide (i.e. by using a molar ratio of 2:1:1), ammonia removal efficiency increased up to 95% with a residual concentration compatible with a successive biological treatment. The struvite produced in the present study showed a composition close to the theoretical one. Furthermore, the precipitate was characterized by a heavy metal content much lower than that of typical raw soil, excluding any concern about heavy metal contamination in the case of its use as a fertilizer. The economic analysis of the process showed that ammonia can be removed at a cost of 9.6 euro/kg NH(4)-N(removed). This value can be greatly reduced, however, if the value of the struvite produced is considered., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

This paper reports the results obtained during an investigation aimed at transferring to the demonstrative scale an aerobic granular biomass system (SBBGR--Sequencing Batch Biofilter Granular Reactor) integrated with ozonation for the efficient treatment of tannery wastewater. The results show that the integrated process was able to achieve high removal efficiencies for COD, TSS, TKN, surfactants and colour with residual concentrations much lower than the current discharge limits. Furthermore, the process was characterised by a very low sludge production (i.e., 0.1 kg dry sludge/m(3) of treated wastewater) with interesting repercussions on treatment costs (about 1 euro per m(3) of wastewater).