A systematic review of the water treatment sludge toxicity to terrestrial and aquatic biota: state of the art and management challenges.

Safe drinking water' supply is an essential service and depends directly on the water treatment that produces water treatment sludge (WTS) as a product, whose final destination varies and remains a challenge. The ecotoxicity assessment of the WTS address the ecological implications of the WTS disposal but these information is still scarce in the literature. In this sense, we did a systematic review of the ecotoxicological studies on WTS using databases from six platforms. From the 785 papers recovered; 16 studies were eligible and showed the ecotoxicity assays' applicability to evaluate the WTS. We discussed WTS ecotoxicity considering sample characterization; terrestrial and aquatic toxicity assays; and WTS challenges. WTS proved to be a highly heterogeneous matrix composed mainly of coagulant precipitates, including Al and Fe. Studies lack consensus concerning the most representative/sensitive species for evaluating WTS' toxicity. Crustaceans were the most studied aquatic group, although algae species were more sensitive. Besides, soil ecotoxicity assessed only plant growth, and a single study used the earthworm. Even papers used bioassays to indicate the recycling WTS' feasibility, there is a lack of specific legislation regarding the WTS reuse. Furthermore, are necessary a regulation for WTS management that involves an ecological risk assessment.

Polyethylene microplastics and substrate availability can affect emergence responses of the freshwater insect Chironomus sancticaroli.

Pollution caused by polyethylene microplastics (MP) has been reported for aquatic environments worldwide. However, despite recurrent research for several aquatic organisms, the effects of MP on the emergence stage of freshwater insects from tropical environments are little known. This study is the first to assess the emergence of the Brazilian native species Chironomus sancticaroli Strixino & Strixino, 1981 when exposed to primary polyethylene microplastics (size 40-48 µm). We performed two exposure scenarios, with a substrate (standard assays) and without substrate (as a stressful experience), and recorded emergence responses. The MP did not affect the species' emergence rate, but these rates were statistically different for the standard and stressful exposure scenarios. In bioassays without substrate, the high concentrations of MP caused anticipation of the insect's emergence (5-6 days). On the other hand, female emergence time was longer than males in standard bioassays. The substrate absence caused a slight increase in the left female wing's length and the potential female fecundity. These findings suggest that the polyethylene microplastics and substrate availability can affect the emergence dynamics of the tropical insect C. sancticaroli.

Global occurrence of SARS-CoV-2 in environmental aquatic matrices and its implications for sanitation and vulnerabilities in Brazil and developing countries.

This paper includes a systematic review of the SARS-CoV-2 occurrence in environmental aquatic matrices and a critical sanitation analysis. We discussed the interconnection of sanitation services (wastewater, water supply, solid waste, and stormwater drainage) functioning as an important network for controlling the spread of SARS-CoV-2 in waters. We collected 98 studies containing data of the SARS-CoV-2 occurrence in aquatic matrices around the world, of which 40% were from developing countries. Alongside a significant number of people infected by the virus, developing countries face socioeconomic deficiencies and insufficient public investment in infrastructure. Therefore, our study focused on highlighting solutions to provide sanitation in developing countries, considering the virus control in waters by disinfection techniques and sanitary measures, including alternatives for the vulnerable communities. The need for multilateral efforts to improve the universal coverage of sanitation services demands urgent attention in a pandemic scenario.

Does Addition of Phosphate and Ammonium Nutrients Affect Microbial Activity in Froth Treatment Affected Tailings?

We examined greenhouse gas (GHG) production upon the addition of ammonium and phosphate to mature fine tailing (MFT) samples from Alberta's Pond 2/3 (at 5 and 15 m) and Pond 7 (12.5 m) in microcosm studies. The methane production rate in unamended Pond 2/3 MFT correlated with sample age; the production rate was higher in the less dense, more recently discharged MFT samples and lower in the denser, deeper sample. Adding small amounts of naphtha increased methane production, but there was no correlation with increasing naphtha, indicating that naphtha may partition into bitumen, reducing its bioavailability. Although non-detectable phosphate and low ammonium in the pore water indicate that these nutrients were potentially limiting microbial activity, their addition did not significantly affect methanogenesis but somewhat enhanced sulphate and nitrate reduction. Neither ammonium nor phosphate were detected in the pore water when added at low concentrations, but when added at high concentrations, 25-35% phosphate and 30-45% ammonium were lost. These ions likely sorbed to MFT minerals such as kaolinite, which have microbial activity governed by phosphate/ammonium desorption. Hence, multiple limitations affected microbial activity. Sulphate was less effective than nitrate was in inhibiting methanogenesis because H2S may be a less effective inhibitor than NOx- intermediates are, and/or H2S may be more easily abiotically removed. With nitrate reduction, N2O, a potent GHG was produced but eventually metabolized.

Intermittent aeration strategy for azo dye biodegradation: A suitable alternative to conventional biological treatments?

Most solutions for biological treatment of azo dyes are based on conventional anaerobic-aerobic processes, but transition to full scale demands technology simplification and cost reductions. We suggest a new approach, in which aeration is intermittently supplied for simultaneous removal of color and toxic metabolites in a single compartment. Effects of aeration strategy and glucose concentration on decolorization and organic matter removal were assessed using factorial design (32) and response surface analysis. Bioreactors were inoculated with microorganisms previously acclimated to Direct Black 22 (DB22), which was the azo compound used in this study. Assays performed with synthetic textile wastewater showed that long-term decolorization was not impaired at a moderate level of aeration (4 hourly-cycles per day). Aerated batches presented lower color removal velocities, but these negative impacts were offset by increasing initial glucose concentration. Higher degrees of mineralization of the azo compound and higher organic matter removals were achieved in intermittently aerated experiments, which led to lower toxicity to Daphnia magna. Biomolecular analysis revealed that the microbial community structure was strongly associated with operational efficiency parameters. These findings suggest intermittent aeration can be implemented to accomplish enhanced azo dye biodegradation.

Chironomus sancticaroli generation test: A new methodology with a Brazilian endemic insect.

This paper presents a new ecotoxicological test to investigate the response of a Brazilian endemic insect Chironomus sancticaroli through its life cycle and its future generations. This test can evaluate differences between the endpoints analyzed in diverse generations, describing the long-term impact of a substance or matrix effects along the time of exposure. Despite earlier papers already present the generation test with Chironomus riparius, there are still no studies with long-term test applied to C. sancticaroli. In this sense, this study evaluated different conditions for the development of a methodology that prolonged the duration of the test and allowed the best sampling of the organism on environmental toxicity tests. The distinct conditions tested were: volumes of test solution, frequency of feed, number of larvae, type of vessel and test solution replacement. The best condition for the C. sancticaroli generation test includes the exposition of 20 larvae to 340 or 500 mL of test solution, 60 g formulated sediment, feeding with Tetramin® each 10 days and, from a spawn, a new test will be prepared with the same characteristics of the previous one. This new methodology can reveal toxic effects along the exposure time and brings advances on toxicology area. •Prolonged testing makes it possible to analyze the long-term effects•The methodology "C. sancticaroli generation test" allows to evaluate the responses of organisms in different life cycles•The methodology allows to analyze the effects of substances in liquid medium and environmental quality through exposure to sediment.

Microbial Characterization of Methanogenic and Iron-reducing Consortium in Reactors with Polychlorinated Biphenyls.

Recent papers have confirmed current environmental pollution and the continuous release of polychlorinated biphenyls (PCBs) despite the prohibition of its manufacture worldwide. As the dehalogenating microorganisms are able to remove halogens from various analogous compounds, the characterization of PCB metabolisms can improve the degradation of similar compounds. Thus, this study extensively evaluated the microbial community developed in methanogenic and iron-reducing reactors. The horizontal-flow anaerobic reactor (HAIB) with real waste of Aroclor (1 mL L-1) was fed with mineral medium, ethanol, and sodium formate. Bacteria belonging to Thermotogaceae (Thermotogae), Geobacteraceae, Chloroflexi, Proteobacteria, and Firmicutes (Clostridium) were identified in the HAIB reactor. Bacteria belonging to the Chloroflexi, Firmicutes, and Geobacteraceae are associated with the degradation of hydrocarbons and could be related to the Aroclor waste in this paper. Furthermore, 5.26 × 1012 cells gTVS-1 of iron-reducing bacteria were quantified by the most probable number method in the HAIB reactor, suggesting that this group has an important role in aromatic degradation. Moreover, the evaluation of methanogenic and iron-reducing microorganisms in batch reactors with Aroclor 1260 was performed and the biomass growth was not affected by the addition of PCB. The methane production reached 0.38 µmol CH4 gTVS-1 and the iron reduction attained 90% in batch reactors. Through microbial analyses from HAIB and batch reactors, lower diversity was evidenced in the presence of PCB. This paper indicates the relevant role of iron-reducing organisms and Chloroflexi, Geobacteraceae, and Firmicutes group in PCB metabolism.