## 2 Materials and Methods  
The OFMSW used in this paper is a variegate waste from the restoration sector, consisting mainly of food scraps and food preparation derivatives. The thermosetting resin used in this work for the inertialization of OFMSW is a urea formaldehyde (UF) powder polymer, produced by Sadepan Chemical Company as SADECOL P 100N. It is supplied as fine powder/granules with defined grain size and a viscosity of \(60\div 130\) mPa s at 20 \({}^{\circ}\)C. The first proposed OFMSW transformation process is called dual step, since the reduction of the bacterial activity and the setting reaction of the polymeric matrix are performed separately. In this process, the OFMSW is firstly subjected to a grinding process followed by stabilization, which is performed by means of UV/ozone exposure or a thermal treatment. After, the stabilized and finely ground OFMSW and UF powder are mixed in a water slurry, which can be processed by a pressure-free process, as reported in the scheme of Figure 1.  
The water content for each ground OFMSW batch was evaluated by thermogravimetric analysis (TGA); for this purpose, a Netzsch STA 409 simultaneous thermal analyzer ([PERSON], Verona, Italycity, state abbrev if USA, country) was used, heating samples from room temperature to 700 \({}^{\circ}\)C with a heating rate of 10 \({}^{\circ}\)C/min in N2 atmosphere. Ten replicates were performed in order to measure the water amount in OFMSW. The stabilization step, i.e., the sterilization of the OFMSW, was performed by means of:  
1. UV/ozone treatment. The UV/ozone radiation method was implemented by means of a Hg UV lamp (HG 1000 ULTRA, JELOSIL SrI, Vimodrone MI, Italy company, city, state abbrev if USA,  
Figure 1: Simplified scheme relative to the dual-step OFMSW-treatment process. country) with a radiation intensity on the surface of the sample of 9.60 W/mm\({}^{2}\), working in air atmosphere. The ground OFMSW samples were exposed to Hg UV lamp irradiation for a time ranging from 1 h to 5 h.
2. Thermal treatment. Three different thermal treatments were performed by exploiting humid or dry conditions. * OFMSW was exposed to T = 100 \({}^{\circ}\)C for 20 min (with relative humidity of 90%) in a climatic chamber (Binder, Guangdong, China city, state abbrev if USA, country). * OFMSW was exposed at T = 100 \({}^{\circ}\)C for 30 min (dry environment) in an oven (Lenton, Hope Valley, UK city, state abbrev if USA, country). * OFMSW was exposed at T = 120 \({}^{\circ}\)C for 20 min (dry environment) in an oven (Lenton). The effectiveness of each sterilization method was evaluated by means of _in-vitro_ microbiological tests by spreading OFMSW treated samples on agar plates. Nutrient agar (0.3% wt/v beef extract, 0.5% wt/v peptone, 1.5% wt/v agar) was used as a non-selective medium supporting growth of a wide range of organisms. The agar medium was pre-sterilized in an autoclave at 121 \({}^{\circ}\)C for 30 min and dispensed into Petri dishes. The agar plates were allowed to solidify for about 30 min in a biosafety cabinet. Each sample was picked up with a sterile inoculating loop and spread over the surface of the medium. Then, the plates were incubated at 37 \({}^{\circ}\)C overnight and, after incubation, they were visually inspected for macroscopic growth of bacterial colonies. In the inertialtion step, stabilized OFMSW was mixed with water and UF-based SADECOL P 100N resin, in order to produce a slurry, which was then cured at T = 120 \({}^{\circ}\)C for 1 h. After curing and water evaporation, a UF/ OFMSW composite was obtained, which was characterized by means of thermal, physical and mechanical tests. For comparison purpose, a formulation without OFMSW was also realized. The compositions of the two mixtures produced by the two step process (P100N UF, OFMSW_P100N UF) are reported in Table 1. As preliminary approach, the ratio 70/30 between the solid phase (which includes the matrix and the dried OFMSW) and water was chosen. Tests on different compositions are shown in the second part of the present paper [17].