# Food Waste as Feedstock for Anaerobic Mono-Digestion Process
## 2 Physicochemical Properties of Food Wastes  
Due to the fact that anaerobic degradability strongly depends on the physical and chemical characteristics of the input material, the analysis of FW is one of the key important steps in designing and operating anaerobic digesters [19; 39]. However, there is also general agreement that FW characteristics vary significantly. Hence, its heterogeneous nature is a great challenge in the adoption of international standards for the FW disposal and recycling [40]. FW composition can change depending on several factors such as (i) geographical location, (ii) source, (iii) season, (iv) and socioeconomic factors including consumer preferences and habits [7; 40; 41; 42]. Therefore, as it has been indicated in the Introduction, there is a justified need to deepen the knowledge of the parameters of the FW used for the AD process. It is well known that FW includes uneaten food and food preparation leftovers from various sources. Importantly, the selection of the most suitable technology for the AD process of food waste should be made taking into account, among others, its characteristics. On the basis in the present study, physicochemical properties of FW generated throughout the world were analyzed (Table 1). The analysis was conducted for FW that came mainly from university campus canteens, restaurants, cafeterias, hostels and dining halls. The investigations have been focused mainly on the following parameters: pH, total solid (TS) and volatile solid (VS) content, volatile solids to total solids ratio (VS/TS), soluble chemical oxygen demand (sCOD), concentration of VFAs, ammonium nitrogen (NH\({}_{4}\)+-N), and carbon-to-nitrogen ratio (C/N). \begin{table}
\begin{tabular}{l c c c c c c c c c c c c c c} \hline
**Source** & **pH(L)** & **TS**[\(\
u\)**] & **sV**[\(\
u\)**] \\ \hline \multicolumn{12}{l}{red} \\ redatum & \(5.1\pm 0.07\) & \(9.3\pm 0.02\) & \(99.6\pm 0.04\) & N & N & N & N & N & N & N & N & N & 14\(\pm\)0.22 & 78 \\ redatum & \(5.4\pm 0.1\) & N & N \begin{table}
\begin{tabular}{l c c c c c c c c c c c c c c} \hline
**Source** & pH-I & TS[v/cm/g] & VS[v/cm/g] & VS[v/cm/g] & VS[S] & \(\alpha\)COD [g/1] & V[A/g/g] & NNL\({}^{\prime}\)-N [ng/g] & C[N] & N[N] & H[N] & O[N] & CN[N] & **Ref.** \\ \hline garbage & & & & & & & & & & & & & \\ collection & - & 4.4 & 4.1 & 96 & 22 & N1 & N1 & 45 & N1 & N1 & N1 & N1 & [104] \\ company & & & & & & & & & & & & & \\ garbage & & & & & & & & & & & & & \\ collection & - & 10.5 & 10.1 & 09 & 20 & N1 & N1 & 45 & N1 & N1 & N1 & N1 & N1 & [104] \\ company & & & & & & & & & & & & & \\ replacement & 5.4 & 20.8 \(\leq\) 0.05 & 25.9 \(\pm\) 0.05 & N1 & N1 & N1 & N1 & N1 & N1 & N1 & N1 & 203 & [103] \\ Protection Co. & & & & & & & & & & & & & \\ Ltd. & & & & & & & & & & & & & \\ Optimants & 4.6 \(\pm\) 0.2 & N1 & N1 & N1 & 60.3 \(\pm\) 0.35 & 0.28 \(\pm\) 0.02 & N1 & N1 & N1 & N1 & N1 & N1 & [104] \\ Processing & & & & & & & & & & & & & & \\ fields & 4.6 \(\pm\) 0.16 & 24.75 \(\pm\) 0.07 & 22.99 \(\pm\) 0.45 & 92.9 \(\pm\) 0.45 & N1\({}^{\prime}\) & 0.32 \(\pm\) 0.12 & N1 & N1 & N1 & N1 & N1 & N1 & [107] \\  & & & & & & & & & & & & & & \\ regulatory & 4.2 & 30.4 & 28.1 & 92.5 & 120.4 & 2.5 & N1 & N1 & N1 & N1 & N1 & N1 & [108] \\ IFV Internet & & & & & & & & & & & & & & \\ individual yeast & & & & & & & & & & & & & \\ \hlinehlinehlinehlinehlinehlinehlinehlinehlinehlinehline \end{tabular}
\end{table} 
Table 1: Conf. Data analysis has clearly demonstrated that the properties of FW vary significantly (Table 1). Unfortunately, the reported differences pose a great challenge mainly in adopting standards, recycling as well as the valorization of FW [40]. The distributions of values of selected FW parameters in a dataset are presented in Figure 3. It should be pointed out that although in the literature data for simulated FW are available, e.g., [125; 126; 127; 128; 129; 130; 131; 132; 133], in the present study, investigations have been limited to the data obtained for real FW.