**1. Introduction**

Pyrolysis is the thermochemical decomposition of organic matter into noncondensable gases, condensable liquids, and a solid residual coproduct, biochar or charcoal in an inert environment (i.e., in the absence of oxygen) [1].

In a singular pyrolysis reactor, oxygen must be excluded otherwise more of the gas, oils, and char will burn, thereby losing products and reducing efficiency. Pyrolysis has historically been implemented to produce useful substances such as methanol, acetone, acetic acid, and creosote from wood in predominantly batch process retorts prior to petrochemical production routes [2].

Nowadays, pyrolysis has great potential to convert waste such as plastic/ rubber/biomass into valuable products, such as fuels, power, heat and other valuable chemicals and materials to achieve maximum economic and environmental benefits. For instance, liquid oil produced from different types of plastic waste had higher heating values (HHV) in the range of 41.7–44.2 MJ/kg similar to that of conventional diesel. Therefore, it has the potential to be used in various energy and transportation applications after further treatment and refining [3].

Municipal Solid Waste (MSW) is mainly derived from the disposal of general waste streams that include green waste, food waste, and miscellaneous products (ie, leather, textile, metal scraps), which can be separated as noncompostable materials [4]. Although most MSW ends up in unsightly landfill sites, a significant quantity has been used to produce different value-added products such as compost, feedstuffs, and biogas [5].

Most mixed MSW technologies attempt to treat large quantities of heterogeneous mixed waste streams. This can be appealing to governments which do not want to source separate waste and seek a single, technological solution. However, the approach of looking for a technology fix for mixed waste treatment presents unique challenges, and is not as successful as more comprehensive source separation strategies. Gasification, pyrolysis and plasma arc technologies are most applied for homogeneous material streams. The heterogeneous nature of MSW is not well suited to this type of technology [6].

Andrew and Jumoke's review [7] has shown that when appropriate system boundaries are applied, a MSW pyrolysis plant for self-sustaining energy from waste is thermodynamically unproven, practically implausible, and environmentally unsound. No practical examples of a self-sustaining MSW pyrolysis plant, using either gas, oil, or char were found.

For homogeneous material streams, an approach of energy saving is pretreatment of the waste, by removing wet organics and inert material while retaining the high-energy plastics in the waste stream. In the process of converting organic solid waste into energy, besides the major thermal cracking energy consumption, a variety of additional energy consumption would incur e.g. feedstock sorting, conditioning, drying, shredding, pyrolysis gas cooling/condensation, combustible gases cleaning…How to reduce the energy consumption in each link to achieve the ultimate goal of reducing total energy consumption and increasing energy efficiency in the entire process.

Moisture is present in all solid organic waste (even visibly dry material), existing at both surface and cellular level, therefore unless drying is set outside the system boundary it must be included in energy balances. Prior to the pyrolysis process occurs, removing this water from the solid organic waste is highly energy intensive due to the high latent and sensible enthalpy demands in both liquid and steam phases, and high enthalpy of vaporization [8]. These endothermic phenomena are known as parasitic enthalpy demand, and are well understood from extensive work with steam cycles. Therefore, dehydration and drying outside the pyrolysis system under controllable temperature and a good ventilation cycle are preference that has a much better effect than that in a relatively closed pyrolysis reactor and save more energy.

During the pyrolytic conversion, the process of transforming long-chain hydrocarbons into short-chain hydrocarbons needs an extraneous energy supply to drive the process so this is provided allothermally from electricity or by burning additional fuels. Generally speaking, catalytic pyrolysis is a major technique to obtain more oil or combustible gas at relatively low temperatures and low energy consumption. Apart from this, this study will first review the published experimental results of artificially speeding up the aging of raw materials for some common organic solid wastes under different conditions e.g. temperature, natural or artificial ultraviolet light. Second, to propose using this method in the pre-treatment of raw materials to reduce the energy consumption of thermal cracking from longchain to short-chain, and finally shortening the thermal cracking time and reducing energy consumption.

### **2. Sources of solid waste**

Polymer degradation can be caused by heat (thermal degradation), light (photodegradation), ionizing radiation (radio degradation), mechanical action, or by fungi, bacteria, yeasts, algae, and their enzymes (biodegradation). The deleterious

### *Accelerate the Aging of Polymer as Energy-Saving Method Prior to the Pyrolysis Process DOI: http://dx.doi.org/10.5772/intechopen.99995*

effects of weathering on polymers generally has been ascribed to a complex set of processes in which the combined action of UV light and oxygen predominant.

The overall light-initiated process in the presence of oxygen generally is referred to as oxidative photodegradation or photooxidation. A pure thermal effect in possible because oxygen is always present and so the process is thermaloxidative degradation [9].

There are many different modes of polymer degradation. These are very similar since they all involve chemical reactions that result in bond scission.
