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Sludge production in the wastewater treatment sector is consistently increasing and represents a critical environmental and economic issue. This study evaluated an unconventional approach for treating wastewater generated from the cleaning of non-hazardous plastic solid waste during the plastic recycling process. The proposed scheme was based on sequencing batch biofilter granular reactor (SBBGR) technology, which was compared with the activated sludge-based treatment currently in operation. These treatment technologies were compared regarding sludge quality, specific sludge production, and effluent quality to highlight whether the reduced sludge production shown by SBBGR corresponded to an increase in the concentration of hazardous compounds in the sludge. The SBBGR technology showed remarkable removal efficiencies (TSS, VSS, and NH 3  > 99 %; COD >90 %; TN and TP > 80 %) and a sludge production six-fold lower than the conventional plant (in terms of kgTSS/kg COD removed ). Biomass from the SBBGR did not show a significant accumulation of organic micropollutants (i.e., long-chain hydrocarbons, chlorinated pesticides and chlorobenzenes, PCB, PCDD/F, PAH, chlorinated and brominated aliphatic compounds, and aromatic solvents), whereas a certain accumulation of heavy metals was observed. Furthermore, an initial attempt to compare the operating costs of the two treatment approaches revealed that the SBBGR technology would provide 38 % savings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

In order to mitigate the potential effects on the human health which are associated to the use of treated wastewater in agriculture, antibiotic resistance genes (ARGs) are required to be carefully monitored in wastewater reuse processes and their spread should be prevented by the development of efficient treatment technologies. Objective of this study was the assessment of ARGs reduction efficiencies of a novel technological treatment solution for agricultural reuse of municipal wastewaters. The proposed solution comprises an advanced biological treatment (Sequencing Batch Biofilter Granular Reactor, SBBGR), analysed both al laboratory and pilot scale, followed by sand filtration and two different disinfection final stages: ultraviolet light (UV) radiation and peracetic acid (PAA) treatments. By Polymerase Chain Reaction (PCR), the presence of 9 ARGs (ampC, mecA, ermB, sul1, sul2, tetA, tetO, tetW, vanA) were analysed and by quantitative PCR (qPCR) their removal was determined. The obtained results were compared to the reduction of total bacteria (16S rDNA gene) and of a faecal contamination indicator (Escherichia coli uidA gene). Only four of the analysed genes (ermB, sul1, sul2, tetA) were detected in raw wastewater and their abundance was estimated to be 3.4±0.7 x10(4) - 9.6±0.5 x10(9) and 1.0±0.3 x10(3) to 3.0±0.1 x10(7) gene copies/mL in raw and treated wastewaters, respectively. The results show that SBBGR technology is promising for the reduction of ARGs, achieving stable removal performance ranging from 1.0±0.4 to 2.8±0.7 log units, which is comparable to or higher than that reported for conventional activated sludge treatments. No reduction of the ARGs amount normalized to the total bacteria content (16S rDNA), was instead obtained, indicating that these genes are removed together with total bacteria and not specifically eliminated. Enhanced ARGs removal was obtained by sand filtration, while no reduction was achieved by both UV and PAA disinfection treatments tested in our study., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The electrochemical degradation of six of the most widely used iodinated contrast media was investigated. Batch experiments were performed under constant current conditions using two DSA® electrodes (titanium coated with a proprietary and patented mixed metal oxide solution of precious metals such as iridium, ruthenium, platinum, rhodium and tantalum). The degradation removal never fell below 85% (at a current density of 64 mA/cm(2) with a reaction time of 150 min) when perchlorate was used as the supporting electrolyte; however, when sulphate was used, the degradation performance was above 80% (at a current density of 64 mA/cm(2) with a reaction time of 150 min) for all of the compounds studied. Three main degradation pathways were identified, namely, the reductive de-iodination of the aromatic ring, the reduction of alkyl aromatic amides to simple amides and the de-acylation of N-aromatic amides to produce aromatic amines. However, as amidotrizoate is an aromatic carboxylate, this is added via the decarboxylation reaction. The investigation did not reveal toxicity except for the lower current density used, which has shown a modest toxicity, most likely for some reaction intermediates that are not further degraded. In order to obtain total removal of the contrast media, it was necessary to employ a current intensity between 118 and 182 mA/cm(2) with energy consumption higher than 370 kWh/m(3). Overall, the electrochemical degradation was revealed to be a reliable process for the treatment of iodinated contrast media that can be found in contaminated waters such as hospital wastewater or pharmaceutical waste-contaminated streams., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Sequencing batch biofilter granular reactor (SBBGR) is a recently developed biological wastewater treatment technology characterised by a very low sludge production, among other numerous advantages. Even if costs for sludge treatment and disposal are mainly dependent on the amount of sludge produced, sludge properties, especially those linked to solid-liquid separation, play a key role as well. In fact, such properties deeply influence the type of treatments sludge has to undergo before disposal and the final achievable solids concentration, strongly affecting treatment and disposal costs. As sludge from SBBGR is a special mixture of biofilm and aerobic granules, no information is available so far on its treatability. This study addresses the characterisation of the sludge produced from SBBGR in terms of some physical properties (settling properties, dewaterability, rheology). The results show that such sludge is characterised by good settling and dewatering properties, adding a new advantage for the full-scale application of SBBGR technology., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Textile wastewater is difficult to treat as it usually contains considerable amounts of different pollutants, which are often recalcitrant, toxic and inhibitory. Therefore, complex treatment schemes based on the sequence of various steps are usually required for an effective treatment. This explains why textile effluents are often treated in centralized plants and sometimes mixed with municipal wastewater. The adoption of new technologies for on-site treatment, instead, would be optimal, deeply reducing treatment costs. An innovative technology exhibiting several characteristics appropriate for the attainment of such a goal is sequencing batch biofilter granular reactor (SBBGR). To assess the suitability of this technology, two lab-scale reactors were operated, treating mixed municipal-textile wastewater and a pure textile effluent, respectively. Results have demonstrated that mixed wastewater can be successfully treated with very low hydraulic retention times (less than 10 hours). Furthermore, SBBGR shows to be an effective pre-treatment for textile wastewater for discharge into sewer systems. The economic evaluation of the process showed operative costs of 0.10 and 0.19 € per m(3) of mixed wastewater and textile wastewater, respectively., (Copyright © 2011 Elsevier B.V. All rights reserved.)

An innovative process based on ozone-enhanced biological degradation, carried out in an aerobic granular biomass system (SBBGR--Sequencing Batch Biofilter Granular Reactor), was tested at pilot scale for tannery wastewater treatment chosen as representative of industrial recalcitrant wastewater. The results have shown that the process was able to meet the current discharge limits when the biologically treated wastewater was recirculated through an adjacent reactor where a specific ozone dose of 120 mg O3/L(influent) was used. The benefits produced by using ozone were appreciable even visually since the final effluent of the process looked like tap water. In comparison with the conventional treatment, the proposed process was able to reduce the sludge production by 25-30 times and to save 60% of operating costs. Molecular in situ detection methods were employed in combination with the traditional measurements (oxygen uptake rate, total protein content, extracellular polymeric substances and hydrophobicity) to evaluate microbial activity and composition, and the structure of the biomass. A stable presence of active bacterial populations was observed in the biomass with the simultaneous occurrence of distinctive functional microbial groups involved in carbon, nitrogen and sulphate removal under different reaction environments established within the large microbial aggregates. The structure and activity of the biomass were not affected by the use of ozone., (2010 Elsevier Ltd. All rights reserved.)

This paper reports the results of an investigation aimed at evaluating the performance of an innovative technology (SBBGR system - Sequencing Batch Biofilter Granular Reactor), characterised by a low sludge production, for treating municipal wastewater at demonstrative scale. The results have shown that even at the maximum investigated organic load (i.e., 2.5 kg COD/m(3) d), the plant removed 80% of COD, total suspended solids and nitrogen content with relative residual concentrations lower than the Italian limits for discharge into soil. The process was characterised by a very low sludge production (i.e., 0.12-0.14 kg TSS/kg COD(removed)) ascribable to the high sludge age in the system (thetac >120 d). Molecular in situ detection methods and microscopy staining procedures were employed in combination with the traditional measurements (oxygen uptake rate and total protein content) to evaluate both the microbial activity and composition, and the structure of the biomass. A stable presence of active bacterial populations (mainly Proteobacteria) was found within compact and dense aggregates., (Copyright 2009 Elsevier Ltd. All rights reserved.)

The paper reports the results of an experimental investigation aimed at evaluating the role of hydrodynamic conditions on generation and main properties of granular biomass grown under aerobic conditions in a periodic packed bed reactor. During the start-up period, the trend of the hydrodynamic shear forces, calculated by a methodology previous developed by authors, provided a key for explaining the process of biomass granulation. The granular biomass was characterized by a high density (i.e., 70-120 gVSS/Lbiomass) that permitted to achieve a biomass concentration such high as 20-38 gVSS/Lbed. The biomass density increased with the increase of shear forces. The EPS (Extracellular Polymeric Substances) content of the biomass (5-7% of the total organic matter) was not affected by hydrodynamic shear forces as well as the biomass protein content. Periodic packed bed reactor applied to a municipal wastewater showed performances very satisfactory with high efficiencies removal (around 90%) for both COD and ammonia, up to an applied organic loading value of 5.7 kgCOD/m3.d, and negligible sludge production.

The paper reports the results of an investigation aimed at evaluating the performances of a periodic biofilter (SBBR) for treating municipal wastewater. The investigation was carried out at laboratory scale on real primary effluent coming from a municipal wastewater treatment plant located in Southern Italy. The SBBR was designed for carbon and nitrogen removal through one single stage. The results have shown that even at maximum organic load (i.e., 7 kg COD/m3.d), the COD in the effluent was lower than 60 mg/L. TKN removal efficiencies resulted high (i.e. 90-95%) up to an organic load of 5.7 kg COD/m3.d corresponding to a nitrogen load of 0.8 kg TKN/m3.d. NO3-N concentration in the treated effluent was lesser than 6 mg/L although in the SBBR treatment cycle no anoxic phase was scheduled. This indicated that denitrification extensively took place in the biofilter. The process was characterized by high suspended solids removal (about 90%) and by a negligible sludge production (lower than 0.01 kgVSS/kgCODremoved). In the SBBR, biomass grew as granules and was characterised by different measurements (biomass concentration, cellular protein and biomass density). Biomass density resulted very high, i.e. 200 gTSS/Lbiomass, and this permitted to achieve a biomass concentration such high as 40 gTSS/Lbed. Such biomass concentration did not cause any decrease of biomass metabolic activity as proved by its total protein content (29% of organic matter) and maximum oxygen uptake rate value (i.e. 50 mgO2/gVSS h).

The paper reports the results of an investigation aimed to evaluate the influence of hydrodynamic conditions on physical and biochemical characteristics of granular sludge obtained in a SBBR system. Biomass density resulted very high, i.e. 70-125 gTSS/L(biomass), and this permitted to achieve a biomass concentration such high as 17-45 gTSS/L(bed). An appropriate equation proved that the pressure loss, an easily measurable parameter, can be used for biomass porosity measurement and indirect assessment of biomass concentration in the biofilter. As for biomass biochemical characterisation, the EPS (Extracellular Polymeric Substances) content was rather low (5-7% of the total organic matter) and mostly made up of proteins whereas the cellular protein content, a parameter frequently used as an indicator of microorganisms activity, was high (30-60% of total organic matter).