Modelling micropollutant fate in sewer systems - A new systematic approach to support conceptual model construction based on in-sewer hydraulic retention time

Analysis of microplastics in the reuse of compost in three agricultural sites (Cádiz, Spain) as a circular economy strategy: detection of micropollutants and incidence of plastic ingestion levels by annelids

The system of fertilizing agricultural soils with sludge or compost from wastewater treatment processes, as one of the principles of the circular economy, can lead to microplastic (MP) contamination. The existing technical standards for fertilization are very recent and do not consider this problem, although there is scientific evidence of their existence. Therefore, this study, on the one hand, evaluates the presence of MPs in agricultural soils, previously treated with sludge or compost from wastewater treatment plants for fertilization, and on the second hand, it studies the effect of these MPs on earthworms in three different locations in the south of Spain. For the study, selected composts deriving from the different stages of the composting process and three fertilized soils with increasing MP doses were followed. Samples were taken from different sections in depth (0-5, 5-10, and 10-20 cm) to study the shape, size, type, and abundance of MPs using infrared spectroscopy (FTIR). The results showed that the most abundant shape was fiber, followed by fragment and finally bulk, for both composts and soils. Regarding size distribution, 100 µm was the predominant size in composts (64.3% ± 9.8), while in the case of soils, the predominant range was from 100 to 500 µm. The prevalent polymers in both, composts and soils, were PTFE, TPE, PP, and PET, with four times higher amounts in composts than in soils. Ingestion of common MPs were also verified in two earthworm species, which ingested concentrations higher than 2.1% w/w. PP was the most ingested MP and Eisenia fetida was more voracious compared with Lumbricus terrestris. Therefore, it can be considered a suitable bioindicator for monitoring microplastic contamination in agricultural soil.

Wastewater-Based Epidemiology for SARS-CoV-2 in Northern Italy: A Spatiotemporal Model

The study investigated the application of Wastewater-Based Epidemiology (WBE) as a tool for monitoring the SARS-CoV-2 prevalence in a city in northern Italy from October 2021 to May 2023. Based on a previously used deterministic model, this study proposed a variation to account for the population characteristics and virus biodegradation in the sewer network. The model calculated virus loads and corresponding COVID-19 cases over time in different areas of the city and was validated using healthcare data while considering viral mutations, vaccinations, and testing variability. The correlation between the predicted and reported cases was high across the three waves that occurred during the period considered, demonstrating the ability of the model to predict the relevant fluctuations in the number of cases. The population characteristics did not substantially influence the predicted and reported infection rates. Conversely, biodegradation significantly reduced the virus load reaching the wastewater treatment plant, resulting in a 30% reduction in the total virus load produced in the study area. This approach can be applied to compare the virus load values across cities with different population demographics and sewer network structures, improving the comparability of the WBE data for effective surveillance and intervention strategies.

The role of the sewer system in estimating urban emissions of chemicals of emerging concern

The use of chemicals by society has resulted in calls for more effective control of their emissions. Many of these chemicals are poorly characterized because of lacking data on their use, environmental fate and toxicity, as well as lacking detection techniques. These compounds are sometimes referred to as contaminants of emerging concern (CECs). Urban areas are an important source of CECs, where these are typically first collected in sewer systems and then discharged into the environment after being treated in a wastewater treatment plant. A combination of emission estimation techniques and environmental fate models can support the early identification and management of CEC-related environmental problems. However, scientific insight in the processes driving the fate of CECs in sewer systems is limited and scattered. Biotransformation, sorption and ion-trapping can decrease CEC loads, whereas enzymatic deconjugation of conjugated metabolites can increase CEC loads as metabolites are back-transformed into their parent respective compounds. These fate processes need to be considered when estimating CEC emissions. This literature review collates the fragmented knowledge and data on in-sewer fate of CECs to develop practical guidelines for water managers on how to deal with in-sewer fate of CECs and highlights future research needs. It was assessed to what extent empirical data is in-line with text-book knowledge and integrated sewer modelling approaches. Experimental half-lives (n = 277) of 96 organic CECs were collected from literature. The findings of this literature review can be used to support environmental modelling efforts and to optimize monitoring campaigns, including field studies in the context of wastewater-based epidemiology.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11157-022-09638-9.