What Works? the Influence of Changing Wastewater Treatment Type, Including Tertiary Granular Activated Charcoal, on Downstream Macroinvertebrate Biodiversity Over Time

Abstract

The present study reviewed the impacts of wastewater on macroinvertebrates over 4 decades in a United Kingdom lowland river. This involved examining changes in chemicals, temperature, flow, and macroinvertebrate diversity from the 1970s until 2017 for a wastewater‐dominated river downstream of Swindon in the United Kingdom (population ~ 220 000). When the wastewater treatment process changed from trickling filter to activated sludge in 1991, biological oxygen demand was nearly halved (90th percentile from 8.1 to 4.6 mg/L), ammonia peaks dropped more than 7‐fold (90th percentile from 3.9 to 0.53 mg/L), whereas dissolved oxygen climbed consistently above 60% saturation (10th percentile from 49 to 64%) at a sampling point 2 km downstream of the wastewater treatment plant. A sustained increase in the number of macroinvertebrate species was evident from that point. River flow did not change, temperature rose slightly, and the major metal concentrations declined steadily over most of the monitoring period. Neither the introduction of phosphate stripping in 1999 nor the use of tertiary granular activated charcoal from 2008 to 2014 had strong positive effects on subsequent macroinvertebrate diversity. That the diversity still had not reached the ideal status by 2016 may be related to the modest habitat quality, agricultural pesticides, and limited recolonization potential in the catchment. The results indicate that urban wastewaters, with their chemical pollutants, are today probably not the biggest threat to the macroinvertebrate diversity of multiply stressed lowland rivers in the United Kingdom. Environ Toxicol Chem 2019;38:1820–1832. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC

Assessing the Impact of Organic and Inorganic Pollutants Released from a Wastewater Treatment Plant on Humans and Aquatic Environment, Al-Hoceima City, Morocco

“…In other study, they paired in vitro impacts of MPs aRnd biotests. The results showed high impact for some substances agreeing with our study (Neale, Ait-Aissa et al 2015).Researchers worked on the impact of changing wastewater treatment process on biodiversity(Johnson, Jürgens et al 2019). After adding a tertiary treatment (activated carbon ltration), they noticed no impact on the aquatic environment.…”

Patterns of invertebrate functional diversity highlight the vulnerability of ecosystem services over a 45-year period

“…36,37,58 For example, where we observed the recovery of functional diversity for aquatic functions after 2000 follows the introduction environmental legislation across the EU aimed at improving wastewater treatment during the 1990s. 36,[58][59][60] Similarly, the increase in pollinator taxonomic diversity and concomitant decline in functional diversity between 1970 and 1990 coincides with the unprecedented expansion of oilseed rape coverage across Great Britain. 61 This led to increases in occupancy of short-tongued generalist bee species, despite the widespread loss of more specialist bee pollinators associated with non-crop habitats.…”

Is water quality in British rivers “better than at any time since the end of the Industrial Revolution”?

“…1 which shows BOD and total ammoniacal N concentrations at Moreden Bridge (downstream of Swindon on the River Ray) from 1976 to 2016, along with an index of ecological quality based on macroinvertebrate monitoring (the ASPT or Average Score Per Taxon is an index for which pollution-tolerant taxa have a low score and pollution-intolerant taxa a high score). There is a clear decrease in concentrations of both BOD and ammonia following upgrading of a failing trickling filter works with an activated sludge plant in 1991 (stimulated by a combination of the UWWTD and the privatisation of the water industry in England and Wales) which appears to be associated with an improvement in ASPT (Johnson et al, 2019).…”