Wastewater Treatment Effluent Reduces the Abundance and Diversity of Benthic Bacterial Communities in Urban and Suburban Rivers

Abstract

bIn highly urbanized areas, wastewater treatment plant (WWTP) effluent can represent a significant component of freshwater ecosystems. As it is impossible for the composition of WWTP effluent to match the composition of the receiving system, the potential exists for effluent to significantly impact the chemical and biological characteristics of the receiving ecosystem. We assessed the impacts of WWTP effluent on the size, activity, and composition of benthic microbial communities by comparing two distinct field sites in the Chicago metropolitan region: a highly urbanized river receiving effluent from a large WWTP and a suburban river receiving effluent from a much smaller WWTP. At sites upstream of effluent input, the urban and suburban rivers differed significantly in chemical characteristics and in the composition of their sediment bacterial communities. Although effluent resulted in significant increases in inorganic nutrients in both rivers, surprisingly, it also resulted in significant decreases in the population size and diversity of sediment bacterial communities. Tag pyrosequencing of bacterial 16S rRNA genes revealed significant effects of effluent on sediment bacterial community composition in both rivers, including decreases in abundances of Deltaproteobacteria, Desulfococcus, Dechloromonas, and Chloroflexi sequences and increases in abundances of Nitrospirae and Sphingobacteriales sequences. The overall effect of the WWTP inputs was that the two rivers, which were distinct in chemical and biological properties upstream of the WWTPs, were almost indistinguishable downstream. These results suggest that WWTP effluent has the potential to reduce the natural variability that exists among river ecosystems and indicate that WWTP effluent may contribute to biotic homogenization.

Effect of abattoir effluents on the physicochemical properties of a receiving watershed in an urban community

“…A similar observation of increase in electrical conductivity downstream as a result of industrial and anthropogenic activities on freshwater systems has been documented (Liu et al, 2012;Drury et al, 2013;Jordaan and Bezuidenhout, 2016). Sulphate level was consistent in upstream and downstream at location 1 but a slight increase of sulphate concentration downstream of location 2 was observed.…”

Ecological and Public Health Implications of the Discharge of Multidrug-Resistant Bacteria and Physicochemical Contaminants from Treated Wastewater Effluents in the Eastern Cape, South Africa

“…However, their abundance may be a feeble indicator of pathogens in environmental waters. Efficient treatment processes, coupled with tertiary treatment steps such as disinfection, can reduce the pathogen loads and other physicochemical contaminants such as biochemical oxygen-demanding substances and nutrient contents, in order to protect human health and the freshwater ecosystems from pollution [20]. E. coli, Shigella, Salmonella and Vibrio spp.…”

Effect of reclaimed water effluent on bacterial community structure in the Typha angustifolia L. rhizosphere soil of urbanized riverside wetland, China

“…A large number of studies have shown that reclaimed water contains residue of halogenated hydrocarbons, heavy metal, antibiotics and other drugs contaminate groundwater when it replenishes river channels, which may produce detrimental effects on microbial communities (Drury et al, 2013). In the case of those pollutants, substantial changes happened in bacterial structure and composition.…”

“…Additionally, in contrast to the upstream, the richness, evenness and diversity of bacterial community in the pool below was extremely low, indicating that there may have been a secondary effect from the RWTP effluent affecting the bacterial community characteristic near the outfall. It is well known that RWTPs are a significant source of disinfection byproducts, antibiotics, heavy metals, pharmaceuticals and pesticides, which may produce detrimental effects on microbial communities (Drury et al, 2013;Proia et al, 2013). Based on these observations, we expected that microbial diversity may be affected by some toxic compounds containing RWTP effluent, which might have contributed to a decrease in bacterial diversity from near the outfall sites, while the recovery of wetland ecosystem by the wetland plant rhizosphere microorganism associated with plants contributed to the rise in bacterial diversity and species richness at the downstream location (Stottmeister et al, 2003).…”

“…Therefore, wetland plant rhizosphere microbial characteristics can sensitively reflect the status of plant and water quality, which are considered ideal indicators of aquatic ecosystems and have been extensively used to assess the degree of toxicity imposed by various pollutants. To the best of our knowledge, most studies have focused on the impacts of wastewater treatment plants (WWTPs) effluent on bacterial communities in the water column and sediment of receiving river (Wakelin et al, 2008;Drury et al, 2013). But few studies have investigated wetland plant rhizosphere bacteria community under reclaimed water disturbance condition.…”