# The Emergence of Antibioticstics Resistance Genes, Bacteria, and Micropollutants in Grey Wastewater
## 3 Irrigation with Treated GW  
Existing GW treatment systems are not designed to remove EMPs, ARBs, and ARGs, which remain in the effluent. According to [PERSON] et al. [36], the filter bed biofilm contributes to the ARB community in the treated effluents. Thus, the reuse of GW may pose a severe public health risk by disseminating resistance, especially if humans are exposed to places where ARBs are present [104]. ARBs may persist in the environment and disperse ARGs to other bacteria [33]. Evidence shows that the environment plays a vital role in AMR development, dissemination, and transmission [105]. Only a handful of research has focused on the effect of irrigation with treated GW or treated wastewater (TWW) on ARG and ARB in soils. Soil is considered one of the largest ARG environmental reservoirs [106]. Treated GW used for garden irrigation and landscaping introduces significant quantities of ARGs into soil habitats that might have previously been unexposed [107; 108; 109]. Moreover, treated GW irrigation might promote the maintenance of ARGs in soils; however, [PERSON] et al. [110] stated that antibiotic resistance levels in the soil are increased temporally by anthropic activities, but their persistence is not guaranteed. It should be emphasized that even undisturbed soils contain highly abundant and diverse levels of ARB due to antibiotic-producing soil fungi or bacteria [110]. A systematic overview of studies is given in Table 3 according to the year of publication. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Research** & **Location** & **Findings** & **Reference** \\ \hline Field irrigated with TWW or fertilizer-amended water & Israel & - & in soils irrigated with fertilizer-amended water, the _Nitrosospira_ populations were dominant & [111] \\  & & - & _Nitrosomonas_ populations were dominant in TWW irrigated soils. & \\ \hline Fields subjected to short wastewater irrigation regime for more than 15 years & Senegal & - & no change in the total bacterial community & \\ \hline short- and long-term irrigation with municipal wastewater & Tunisia & - & TWW irrigation led to changes in the genetic structure of bacterial communities & [113] \\ \hline Field irrigated with TWW or potable water. & Israel & - & irrigation with TWW did not result in the transfer of fecal indicator bacteria or microbial pathogens to the irrigated soil & [114] \\ \hline Fields irrigated with either TWW or freshwater & Israel & - & soil irrigated with freshwater contained a similar or higher relative abundance of ARGs and ARBs & [115] \\ \hline Household gardens irrigated with either treated GW or freshwater & Israel & - & soils irrigated with GW and freshwater had the same pathogen levels & [116] \\ \hline Five fields irrigated with TWW directly or from rivers that receive effluent, compared to fields without irrigation & China & - & no difference in ARB between irrigated and non-irrigated soils, while the concentration of ARGs in irrigated soil was higher & [117] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: A summary of studies investigating the effects of treated greywater on the presence of ARGs and ARBs in the soil. Both [PERSON] et al. [111] and [PERSON] et al. [112] assessed the fate of ammonia-oxidizing bacteria (AOB) in short- and long-term irrigated soils. In both studies, the results suggested that TWW irrigation produces shifts in the AOB population in the soil. [PERSON] et al. [111] revealed that _Nitrosomonas_ strains dominate the AOB population in TWW-irrigated soils. In contrast, the AOB populations were dominated by _Nitrosospira_ strains in soils irrigated with freshwater. Nevertheless, no apparent changes were observed in community function despite shifts in the microbial community. Additionally, [PERSON] et al. [112] saw no differences in microbial activity or microbial biomass comparing the two treatments. Long-term irrigation with TWW led to changes in the genetic structure of bacterial communities, as reported by a study by [PERSON] et al. [113]. [PERSON] et al.