# A Critical Review of SCWG in the Context of Available Gasification Technologies for Plastic Waste
## 1 Introduction  
Plastics are very versatile material which, due to their properties, have replaced many of the traditional materials in the last century [1]. Compared to wood, they are more resistant to attack by microorganisms, molds, and atmospheric agents and so more durable in time. Some plastics such as plexiglass or polycarbonate are used in place of glass, thanks to their high transparency, lightness, and greater impact resistance. They are widely used also in the construction sector as excellent thermal and acoustic insulators, to replace traditional materials such as glass wool or cork. Finally, thanks to their low cost, they are used for disposable containers and products. For this set of characteristics, plastic is considered an indispensable material in our daily life and it covers various important sectors such as health and food, transport, safety and protection, sport, industry innovations [2; 3]. Especially in the medical field, plastic has some characteristics that make it irreplaceable, such as the possibility of making sterile, hypoallergenic instruments, devices, prostheses. Global plastic production is continuously growing and has reached an annual production of 360 million tons (Mt) worldwide in2018 [4]. Despite the Directive 2008/98/EC of the European Parliament and Council, which should help the European Union to approach a \"recycling society\" by trying to avoid waste production and use waste as resources [3], in Europe, plastics production almost reached 62 million tons and the greatest demand for plastic material is related to packaging (39.9%), as shown in Figure 1[4]. Typical polymers used for packaging are PP (polyppropylene), PE-LD (low density polyethylene), PE-LLD (low linear density polyethylene), HDPE (high density polyethylene), PS (polystyrene), EPS (expanded polystyrene), PVC (polyvinyl chloride), and PET (polyethylene terephthalate) [5; 6]. Packaging has many applications not only for the storage and transport of products but also in guaranteeing their integrity and protection from humidity, breakage, dust, and microorganisms [7]. Massive uses of packaging are typical of the food, beverage, cosmetics, and pharmaceutical industries [8]. Waste plastic material from packaging is nowadays one of the major environmental problems due to its short usage time, low biodegradability, high resistance to ageing, and the big volume occupied (caused by its low bulk density) [9]. The environmental impacts of packaging are very serious and concern air and water pollution [10]. An example is the recent discovery of 238 tons of plastic waste on the Cocos (Keeling) Island group, in the Indian Ocean [11]. Plastic debris are accumulating in increasing quantities in the marine environment, originating huge plastic islands. When polymers are exposed to UVB radiation, to the oxidative properties of the atmosphere, and to the hydrolytic properties of seawater, they become more and more fragile over time, breaking into smaller and smaller pieces originating thus into microplastics (MPs), known to cause a bio magnification problem [9; 12]. The packaging sector is constantly growing and this represents a huge risk to the environment [8]. For this reason, the European Commission in 2018, developed \"a strategy for plastic material in circular economy\" (COM(2018) 28 final, Brussels, 16.1.2018), establishing that by 2030, all plastic packaging placed on the European market must be reusable or can be cost-effectively recycled [13]. In recent years, there has been a greater sensitivity towards waste management and its disposal in landfills. Different approaches were then examined, such as reuse to date, recycling, and energy recovery. According to statistics from Plastic-the Facts 2019 [4], in Europe the 32.5% of plastic materials is recycled, the 42.6% is sent to energy recovery, and the rest (24.9%) is landfilled.