# Washing Batch Test of Contaminated Sediment:
## 1 Introduction  
The Mediterranean Sea is one of the most congested basins in terms of oil tanker traffic, hosting about 20% of the global traffic, and this makes Mediterranean industrial coasts and harbors exposed to severe contaminations [1]. In particular, the Bay of Augusta (Syracuse, Italy is home to numerous industrial and refining activities that have led to a serious state of contamination, both of the water and the underlying sediments, so as to bring the Bay back into the control area of the National Interest Site (SIN) identified by the DM 468/2001. The contaminated Sites of National Interest (SIN) have been defined on the basis of site characteristics, quantity, and hazardousness of pollutants, extent of the environmental impact in terms of health and ecological risk, and the detriment to cultural and environmental heritage. This pollution is mainly due to the presence of toxic compounds, of an organic and inorganic nature, such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCBs), and heavy metals, but also dioxins, furans, and various pesticides. Among the most important parameters able to influence the transfer of a pollutant, from the water column to the sediments, are of particular interest [2; 3; 4]:  
* the physical and chemical characteristics of the pollutants (hydrophobicity, water/octanol partition coefficient, solubility, oxidation state, biodegradability);
* the surface properties of the particles (ion exchange/adsorption capacity, specific surface, organic matter content, buffer capacity); and
* the chemical and physical characteristics of the portion of water in contact with the sediments (pH, Eh, alkalinity, ionic strength, salinity, temperature). Many of the phenomena and transformations at the base of the transfer from the water column to the sediments are reversible, therefore the sediments can be both the receptor of the contamination and, where contaminated, a potential source of pollution for the aquatic ecosystem [5]. In this context, there are several processing technologies aimed to remove the contaminants present in the sediments and principally aimed to remove the most recalcitrant organic and inorganic contaminants, mainly ex situ. Among the most interesting technologies, thanks to the great managerial flexibility, should be mentioned the extraction and/or washing of sediments. Sediment Washing requires sediment pretreatment aimed at separating the granulometric fractions that compose. Preliminary fractionation reduces the amount of sediment to be treated, which can be limited only to the finest fraction (silt and clay), where most of the pollutants tend to concentrate; on the other hand, the coarser fraction (sand, gravel) may be non-contaminated and, therefore, reusable without treatment. The studies reported in the literature demonstrate the high potential of the washing techniques, which have often been used satisfactorily for the treatment of contaminated land mainly with heavy metals and hydrocarbons. In particular, the treatment of sediment washing allows one to extract the contaminants from the sediment particles and then remove the soluble pollutants. For this purpose, a wide range of chelating agents can be used, such as ionic and non-ionic surfactants, organic and inorganic acids, but also sodium hydroxide and methanol. The inorganic acids include sulfuric acid (H\({}_{2}\)SO\({}_{4}\)) and nitric acid (HNO\({}_{3}\)) [6], while the organic acids include citric acid (C\({}_{6}\)H\({}_{8}\)O\({}_{7}\)) [7; 8] and tartaric acid (C\({}_{4}\)H\({}_{6}\)O\({}_{6}\)) [9]. Determining the effectiveness of a chelating agent for washing trace metal contaminated soils has commonly been done in batch extractions at the laboratory scale. Such flask studies shake the soil with a washing solution, usually for 24 h [10]. Washing solutions and contaminated soils have been mixed in large L:S weight ratios of 5:1 [11] and 10:1 [12]. In this context, the study conducted by [PERSON] et al.