A qualitative risk assessment model for water reuse: Risks related to agricultural irrigation in Brazil.

Urbanization and industrialization are increasing extreme weather events, causing water quantity and quality reduction. Global water scarcity impacts 32.5 % of the urban population and is growing. Brazil has also witnessed water scarcity, notably in the southeast (2014-2015) and south (2019-2020), with reservoirs dropping below 20 % capacity. Water reuse is vital for mitigating scarcity, though it presents risks due to contaminants. Risk analysis studies are crucial for evaluating contamination sources, pathways, and exposure scenarios in water reuse practices. Various methodologies, including quantitative, semi-quantitative, and qualitative analyses, can be employed. Given the uncertainty and diverse factors, qualitative methods are recommended for non-potable water reuse risk analysis. This work presents a qualitative risk analysis methodology that allows to evaluate non-potable water reuse categories. It assesses factors affecting human health and the environment, considering exposure scenarios, characteristics of the receptors, and sources of reused water. The risk analysis of water reuse was carried out focusing on agricultural reuse, considering as alternatives the irrigation of soybean and sugarcane crops. By reviewing literature, the probability of occurrence and the magnitude of impact of the risk factors were identified and rated, using an increasing relative numeric scale. This process resulted in an overall risk value for comparing agricultural irrigation alternatives. The obtained results indicate a promising risk analysis model that can be adjusted and applied to various water reuse modalities and key factors. This adaptable risk analysis model is mainly related to water treatment methods, prompting the proposal of risk control measures.

Contaminants of emerging concern reduction and microbial community characterization across a three-barrier advanced water treatment system.

This research investigated the removal of contaminants of emerging concern (CECs) and characterized the microbial community across an advanced water treatment (AWT) train consisting of Coagulation/Flocculation/Clarification/Granular Media Filtration (CFCGMF), Ozone-Biological Activated Carbon Filtration (O3/BAC), Granular Activated Carbon filtration, Ultraviolet Disinfection, and Cartridge Filtration (GAC/UV/CF). The AWT train successfully met the goals of CECs and bulk organics removal. The microbial community at each treatment step of the AWT train was characterized using 16S rRNA sequencing on the Illumina MiSeq platform generated from DNA extracted from liquid and solid (treatment media) samples taken along the treatment train. Differences in the microbial community structure were observed. The dominant operational taxonomic units (OTU) decreased along the treatment train, but the treatment steps did impact the microbial community composition downstream of each unit process. These results provide insights into microbial ecology in advanced water treatment systems, which are influenced and shaped by each treatment step, the microbial community interactions, and their potential metabolic contribution to CECs degradation.

Microbiological characterization of biofilm from different immobilization structures used in submersed aerobic biofilters in domestic effluent treatment at the city of Joinville, Brazil.

The objective of this work was to develop a polymeric structure for a biofiltration unit of domestic effluents through microbiological immobilization, capable of promoting the efficient removal of pollutants, meeting local/national Brazilian standards and/or legislation while providing low environmental impact on their production. Four different structures were tested, namely, polypropylene casings without filling material (TF1); polypropylene casings filled with expanded polystyrene grains (TF2); polypropylene casings, filled with polyurethane foam (TF3); and polypropylene casings, filled with polyvinyl chloride pellets (TF4). A flow of 0.216 m3 d-1 was applied to the system, and the biofilters operated in sequential batches with a hydraulic retention time of 6 h. The efficiency potential of the four immobilization structures was verified regarding biochemical and chemical oxygen demand, total ammoniacal nitrogen and total phosphorus. Microbiological analysis of the formed biofilm, performed with the 16S library sequencing method, with amplification of the 16S rRNA V3 and V3-V4 genomic regions, showed a high diversity of microbiological colonization in the four immobilization structures, with better results and consequently greater community stability in TF2. It is recommended using the filter bed made up of unfilled casings, followed by the one filled with expanded polystyrene grains.

Survey data on perceptions of water scarcity and potable reuse from water utility customers in Albuquerque, New Mexico.

The data presented in this article were collected using a large-scale public survey distributed through the mail to a random sample of 4000 water utility residential account holders in Albuquerque, New Mexico, USA. The survey collected data on a variety of water-related topics, including water scarcity, climate change, water use at home, perceptions of water sources and water quality, conservation habits, level of acceptance of two potable water reuse scenarios, and level of trust in a variety of entities. The survey also collected demographic data from respondents. Account holders received one of four survey versions, three of which provided different sets of educational material to test different motivations for accepting potable water reuse, and one provided no educational material. The survey was designed and administered using the Tailored Design Method, which involved focus groups, individual debriefing sessions, and a pre-test with members of the sample population to refine the survey instrument, and included a system of five contacts mailed out over a period of several months to maximize response rate. Mail-in and electronic response options were available, and the response rate was 46% (n = 1831). The data were compiled using Survey Monkey and organized using Microsoft Excel and RStudio. The data set featured in this article provides raw survey data plus additional variables created by grouping and consolidating answer options in the raw data. This is the first and most comprehensive set of data known to the authors on public perceptions of water resources and reuse in an arid inland community, and the authors have published open access papers based on this data set, which are linked to this paper. Water managers, planners, engineers, and utilities may be interested in using the data as a point of comparison for their own study on community knowledge of water resources and acceptance of water reuse or in examining the data for relationships not yet explored in the literature.