**2. An Insight into the EU Legislation**

Olive oil is the desired product of the olives industry. Unfortunately, olive mill pomace and wastewater represent undesired by-products, requiring proper disposal treatments because of their complex composition (Figure 1).

The present work aims at discussing only the production and treatment of OMWW. OMWW composition is influenced by different factors, i.e., extraction methods, olives' type and origin, climate conditions, and cultivation/processing practices [21]. In general, it can be mainly summarized as follows (Figure 1): *ca.* 80–83 wt.% consists of water, *ca.* 15–18 wt.% relates to organic compounds (mainly polyphenols, phenols, and tannins), and the remaining 2 wt.% contains inorganic matter (i.e., potassium salts and phosphates). Specifically, phenols levels in OMWW range from 1 to 8 g·L−1, whereas micronutrients and mineral nutrients mainly consist of K2O, and P2O5, which can be found in considerable amounts (2.4–10.8 or 0.3–1.5 g·L−<sup>1</sup> intervals, respectively) [2]. Thus, it is critical to design efficient treatment methods, aligned to precise legislative constraints, whose general panorama is described below.

Concerning the processing of olive residues, the reform of standard agricultural policy related to olive oil does not provide specific provisions for their management [1]. It should be noted that a significant part of EU legislation acts according to Directives. These latter are legislative acts, setting objectives that all EU countries must reach and translate into their national legislation. This means that the member Countries have to adopt and impose complementary measures that should be compliant with the EU directives.

Following this scenario, an example is setting the emission limits and environmental quality standards. Of course, every Country can adopt laws and regulations that can be very different compared to others. Still, in the end, international norms are necessary for a common strategy to manage olive waste. In general, EU legislation governs each member state's framework of national legislation. Several EU laws regulate waste management, and the Waste Framework Directive, WFD (2008/98/EC), acts as core legislation, including

hazardous waste and oil rules [22]. In addition, Landfill Directive 99/31/EC regulates landfill disposal [23]. In this case, the waste producer, such as the olive mill operator, is responsible for managing wastes up to their recovery and disposal [24].

**Figure 1.** Scheme of products and by-products from the olive oil industry.

Here, the crucial point is to classify wastewaters as waste or by-products. If they are considered by-products, their further use as fertilizers with few restrictions is strongly recommended [25]. In this context, the EC Directive 2008/98 (point 22) clarifies the necessity to discriminate well between "waste" and "by-product", but unfortunately, considerable confusion is still present [22]. So, in many cases, law courts have to solve specific issues. To summarize, no EU legislation related to the management of OMWW exists today, and each EU country sets precise standard parameters.
