**3. Conclusion**

Widespread pollution of surface and underground water resulted largely from increased pollutant discharges from industrial (specially the heavy metals), municipal, and agricultural sources (nutriments such as N and P), excessive water abstraction from the environment, and poor water resource management and enforcement of pollution control regulations. The preservation of water sources from pollutants, NO3ˉ, Cr and Cu, is a major concern, shared by all, public, industrial, scientific, researchers, and decision-makers. Over the past two decades, environmental regulations have become more stringent and require an improved quality of the treated effluents. Consequently, wide ranges of treatment technologies have been developed to remove agricultural and industrial pollutants. The

set of methods presented in this chapter is certainly not exhaustive, but its main objective is to show the diversity of techniques used for NO3ˉ and heavy metal (Cu(II) and Cr(VI)) removal. The choice of one technique over the others depends on several factors such as the cost of processing, ease of reproducing, and the added value, along with the mode of use of the obtained treated water and the occurrence, or lack thereof, of harmful side products. Consequently, the development of new treatment methods is always a topical research topic.
