It is useful to think of the entire artificial recharge operation as a water source undergoing a series of treatment steps during which its composition changes. The constituent of potential concern depend not only on the character of the source water, but also on its treatment prior to rechacharge ( pretreatment) , changes occur as it moves through the soil and aquifer ( soil - aquifer processes), and treatment after withdrawal for use (postreatment) . For details consult https://www.nap.edu --read

Well,

In addition to what is mentioned in the answer above, since you are asking about injections in dry climatic conditions, it is preferable to have a vertical injection using wells to obtain a large feed volume but this will be at the expense of the purification process shown by the soil in the case of artificial recharge across the surface water ponds,

sincerest appreciation

The main impediment to recharging usable GW aquifers with municipal TSE (treated sewage effluent) is the existence of the many different types of micropollutants (emerging contaminants in the US) that remain in the TSE after standard secondary, even tertiary, wastewater treatment. These micropollutants include pharmaceuticals, preservatives, endocrine-disrupting compounds, fire-fighting chemicals. While they are in low concentrations individually, they can potentially biomagnify in animal and human receptors if the GW discharges into a spring or stream.

One of the solutions tried in the Gulf countries (e.g., UAE) and in places like Singapore (NuWater), is to use advanced water treatment (e.g., advanced oxidation followed by Reverse Osmosis (AO-RO)) after the municipal WWT in order to enhance the quality of the water by removing most, if not all, of the measurable TOC. Even then, such water is not allowed for unrestricted potable use; in the Al Nahda Farms pilot project in the UAE, it is was used in a limited way for agriculture, while in Singapore, NuWater's main clients are in industry (according to Harry Seah of PUB/NuWater).

As one of the responders to this question pointed out, there are some mineral-water interactions in soil that can remove some of the micropollutants (mainly ionizable organics) in TSE. We ran a project along these lines in my lab a couple of years ago. The project showed some promising results. We have to put together a manuscript soon to get this out.

As Bayan Hussien writes, one of the difficulties comes from the speed of injection. In fact, problems can be classified into two categories: qualitative and quantitative, between which it is necessary to make a trade-off. If the quantities to be injected are large, water purification may not have time to take place. Then it also depends on the objective pursued: is it to reuse the water injected into the groundwater later as drinking, industrial or agricultural water, or is it simply a matter of limiting salt intrusions, for example?

Finally, hazards (even in arid environments, it rains from time to time) can disrupt the overall dynamics. Regarding flow dynamics and the search for sustainability, some additional elements can be found in the articles: Viability_analysis_for_the_sustainable_management_of_renewable_resources? and also Optimality_of_greedy_and_sustainable_policies_in_the_management_of_renewable_resources?, both on ResearchGate

I wonder if physical concerns are serious issues (e.g. blockage of injection wells with time, retention time of TE in GW aquifers, etc)!! Also how to compare between discharging of TE to rivers in some counties and to groundwater in arid countries?!!! In both cases we need some treatment before using river water or groundwater.