*2.1.1.1 Organic pollutants*

*Water Chemistry*

**2. Water quality**

a significant number of pollutants.

**2.1 Water pollution and pollutants**

*2.1.1 Classification of water pollutant*

Water availability not only depends on the quantity of water, but also on the water quality, the physical structures, laws, regulations, and socioeconomic factors that control its demand and use [1]. The quality of water is defined by a set of general parameters, such as dissolved oxygen (DO), alkalinity, pH, hardness, conductivity, salinity, turbidity, etc. These properties are mostly linked to the geological and ecological characteristics of the water body basin, and although they have a large spatial variability, they are maintained within certain ranges in each specific water body [2, 3]. In fact, degradation in quality of water bodies (surface or underground) has become more apparent because of the increase of economic activity as well as the insufficiency of proper sanitation. This increase is generating

Water pollution happens when the amounts of pollutants (chemical, physical, or biological) discharged into the water body can no longer be contained by the natural ecosystem. Furthermore, two types of water pollution can be identified: (i) accidental pollution that is punctual and often of large scale and (ii) chronic pollution corresponding to the discharge of permanent pollutants with low doses. The European water framework directive (2000/60/EC) has defined "pollutant" as any artificial substance made by man and dispersed in environment and which is likely able to generate an impact [4]. In addition, water pollutants are those that make water unfit for consumption or degrade some of its properties [5, 6]. However, it seems difficult to define "pollutant" while knowing that the environmental fate of numerous chemicals reveals that most are causing severe to moderate

health hazards and are significantly harmful to the environment [26].

floating materials, oil, grease, foams, clay minerals, and others.

*Classification of water pollutants as dissolved and undissolved substances.*

Water pollutants are divided into various categories; each category of pollutants has its own proper means of entering the environment and its own particular hazards. In general, pollutants present in water/wastewater are dissolved or undissolved substances (as illustrated in **Figure 1**). Dissolved pollutants are all substances that are dissociable and transformed into cations and anions. These pollutants are divided in two categories, organic and inorganic substances, while undissolved pollutants are precipitated components, suspended solids (SS), colloidal materials,

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**Figure 1.**

Organic compounds accommodate carbon and commonly other elements such as hydrogen, oxygen, nitrogen, sulfur, and others. Diverse organic matters occur naturally in water or from anthropogenic sources. These organic compounds may be considered contaminants if their concentrations adversely affect an aquatic system [7]. Furthermore, the organic matter is divided into two types (dissolved and particulate organic matter) depending on their origin and solubility [8]. Organic pollutants can be further divided into (i) oxygen-demanding contaminants, (ii) synthetic organic contaminants, and (iii) crude oil and various petroleum products.
