Influence of storms on the emission of pollutants from sewage into waters

Hydrodynamics and phosphorus loading in an urbanized river channel influences response to future managed change: Insights from advection-dispersion modelling

There is a need to understand what makes certain targeted measures for in-river phosphorus load reduction more effective than others. Therefore, this paper investigates multiple development scenarios in a small lowland polluted river draining an urban area (The Cut, Bracknell, UK), using an advection-dispersion model (ADModel-P). A comparative analysis is presented whereby changes in concentrations and fluxes of soluble reactive phosphorus (SRP) and organic phosphorus (OP) have been attributed to specific transformations (mineralization, sedimentation, resuspension, adsorption-desorption, and algal uptake) and correlated to controlling factors. Under present day conditions the river stretch is a net source of SRP (10.4 % increase in mean concentration) implying a release of previously accumulated material. Scenarios with the greatest impact are those based on managed reduction of phosphorus load in sources (e.g., 20 % increase in afforestation causes an in-river SRP and OP reduction of 1.3 % to 12.6 %) followed by scenarios involving changes in water temperature (e.g., 1 °C decrease leads to in-river SRP reduction around 3.1 %). Measures involving increased river residence time show the lowest effects (e.g., 16 % decrease in velocity results in under 0.02 % in-river SRP and OP reduction). For better understanding downstream persistence of phosphorus pollution and the effectiveness of mitigation measures the research demonstrates the importance of establishing when and where reaches are net adsorbers or desorbers, and whether sedimentation or resuspension is important.

The H9c2(2-1) cell-based sulforhodamine B assay is a non-animal alternative to evaluate municipal wastewater quality over time

The present study validates the potential of the in vitro H9c2(2-1) cell-based sulforhodamine B (SRB) assay to evaluate the temporal variability of wastewater quality. The impact of effluent disposal on water quality and the efficiency of the wastewater treatment process were also assessed. To correlate standard analytical method results with in vitro results, a total of 16 physicochemical parameters, such as nutrients, pH, chemical oxygen demand, total suspended solids and metals, were determined in both raw and treated wastewater samples. Results revealed that the H9c2(2-1) cell-based SRB assay has an enormous potential to evaluate municipal wastewater quality over time and to discriminate influent and effluent toxic characteristics, as well as for water quality monitoring and surveillance of the efficacy of treatment processes. Finally, the gathered results alerted to the impact of phosphates in a biological system, leading us to recommend the selection of this parameter as a potential environmental health indicator.

Assessment of road run-off and domestic wastewater contribution to microplastic pollution in a densely populated area (Flanders, Belgium)

Plastics are omnipresent in our daily life. Unfortunately, the produced plastics will partly end up in the environment including aquatic ecosystems. People often refer to littering or illegal waste dumping as sources of plastic emission to the environment. However, daily-life sources could also, unknowingly, contribute considerably to the total microplastic pollution in the ecosystem. Hence, there is an urgent need to study these potential sources. In this research, two common sources, i.e. domestic wastewater and road run-off from tire and road wear particles, were studied in detail to quantify the relative contribution of both domestic sources towards microplastic pollution in freshwater ecosystems in Flanders, Belgium. This assessment shows that every person (in studied area) emits on average 1145 microplastics (25-1000 μm) daily through domestic wastewater, resulting in a yearly discharge of 418,000 microplastic particles per person. The road run-off samples contained between 0.02 and 9.2 mg tire wear particles per litre per day, which corresponds to an emission of 10.8 mg tire wear particles per driven vehicle km. The gross and net emissions of both above mentioned microplastic sources were extrapolated to the whole Flanders region using an emission model. From the yearly gross microplastic pollution in the domestic wastewater, 623 kg (20%) will be discharged in the freshwater. The highest losses originated from the households that have a private drain or are not (yet) connected to an active wastewater treatment plant. In Flanders, the yearly net microplastic emission into the aquatic environment of tire wear particles is estimated to be 246 tonnes (38%), mainly from the direct run-off from the road surface. Based on the results, specific mitigation measures can be installed to reduce the emission of microplastics towards the freshwater ecosystem. Other sources should be quantified in a similar way for a more holistic strategy to counteract plastic pollution.

Effects of Trace Metals and Municipal Wastewater on the Ephemeroptera, Plecoptera, and Trichoptera of a Stream Community

Abundances of EPT larvae sampled in a Central European locality affected by mining and smelting, as well as by the continual inflow of treated communal wastewaters (WWs), were recorded. High concentrations of trace metals in water (maximum 1200 µg·L-1 for zinc) and sediments (maximum 140,000 mg·kg-1 in dry weight for lead) were found at the most contaminated sites. The highest loads of pesticides, pharmaceuticals, and illegal drugs were found under the WW effluent. Other associated factors such as the physicochemical parameters of the water and alterations to microhabitats were also evaluated and taken into account. Although EPT richness was lower at affected sites, abundances did not fall. Stoneflies were dominant at unaffected sites, while caddisflies dominated at affected sites. Only baetid mayflies were detected at the sites contaminated by trace metals and WWs; ephemerellid, heptageniid, and leptophlebiid mayflies were absent from these sites. The site contaminated by trace metals was also inhabited by numerous limnephilid caddisflies, in which limb malformations were detected in up to 11.8% of all specimens of a single taxon. Downstream from the entrance of the WWs, the locality was dominated by hydropsychid caddisflies. The increasing prevalence of predator or passive filter-feeding strategies in these EPT communities was significantly related to increasing water conductivity and acute ecosystemic exposure to 'poorly treated' WWs.