Impact of the wastewater-mixing zone on attenuation of pharmaceuticals in natural waters: Implications for an impact zone inclusive environmental risk assessment

Abstract

The direct discharge of untreated wastewater has been identified as an important source of environmental contamination by active pharmaceutical ingredients and other 'down-thedrain' chemicals in developing countries. It necessitates the development of an environmental risk assessment approach for the resulting impact zone. This study was designed to investigate the impact of low level of dilution (<10) on the natural attenuation processes of distribution and degradation within the impact zone. Dilution of the untreated wastewater resulted in increased desorption and corresponding environmental concentrations. The presence/absence of the microbial population in the batches affected the degree of sorption depending on the compound charge (i.e. positive or negative), highlighting an experimental technical bias. The degradation half-lives of acebutolol and diclofenac increased with increasing dilution and resulted in higher environmental persistence. The modelling of the biochemical oxygen demand (BOD) allowed an estimate of the temporal end boundary of the impact zone to be predicted as 24 h. Therefore, it was concluded that most of the investigated compounds would persist beyond the end of the impact zone as defined by the return to environmental BOD concentrations. It is proposed that, within environmental risk assessment protocols, the impact zone should be considered as a semi-natural wastewater treatment area in such a way to allow the estimate of environmental concentrations of pharmaceuticals beyond its end.

Downstream Effects of Industrial Effluents Discharge on Some Physicochemical Parameters and Water Quality Index of River Rido, Kaduna State, Nigeria

“…On the health effects of effluentpolluted water Wang et al [83] showed that casual disposal of industrial waste can result in waterborne diseases such as diarrhoea, giardiasis, typhoid, cholera, hepatitis, jaundice, and cancer. Furthermore, the effects of untreated wastewater discharge on human health in India [84,85], active pharmaceutical ingredient dilution in freshwater systems in low and low-middle income countries [86,87], and the potential effect of developing municipal wastewater treatment infrastructure in China [88] have all been studied. In Tables 7 and 8, the results of water quality index of physico-chemical parameters at both effluent discharge points and areas downstream of River Rido shows that the quality of the river ranged good to excellent at effluent discharge points and areas downstream of River Rido respectively.…”

Groundwater quality

“…In another study using the process of natural attenuation, petroleum hydrocarbon contaminated plume was treated by 60% in 4 years (Lv, Su, Wang, Dai, & Liu, 2018). For some of the active pharmaceutical ingredients, an investigation by Bagnis, Fitzsimons, Snape, Tappin, and Comber (2019) showed at low level of dilution on the natural attenuation processes, the contaminant concentration as well as the risk of environmental persistence beyond the impact zone was reduced.…”

Influences of Spatial and Seasonal Variation on Khabur River Pollution by Municipal Wastewater in Zakho District, Iraq Kurdistan Region

“…[9] reported that the Zakho city releases huge amounts of non-treated sewage sludge in the Khabur river and the sludge produced is worth to be utilized as a cheap source for producing biogas by anaerobic stabilization. The physic-chemical properties of rivers are varied among seasons as in winter more silt and trash are carried with flood water and deposited in rivers, as well as these characteristics are affected by the watersheds that feed the rivers and the spatial location of rivers, especially passing pass through big cities that release many pollutants in rivers [10]. So, this study aims to determine the spatial and seasonal variation of the famous Khabur River in Zakho as well as to assess to what extent the river is contaminated by Zakho municipal wastewater by including several pollution indicators.…”