**2. Waste management hierarchy**

The waste management hierarchy designates the best solutions for managing waste according to what is most suitable for environment [10] and is presented in **Figure 1**.

### **2.1 Prevention**

Priority is given to preventing waste and this entails using less material, waste reduction at source, or retaining products for long [10]. Prevention of waste is advantageous from any waste management strategy such as energy recovery, recycle,

**Figure 1.** *Illustration of the waste hierarchy [10].*

*Evaluating Waste-to-Energy Technologies as a Waste Management Solution for Uganda DOI: http://dx.doi.org/10.5772/intechopen.101904*

and landfill because the production of material that becomes waste as well as its treatment is circumvented. The definition of waste prevention includes avoidance of waste creating products, waste reduction at source, increasing the life cycle of a product, and reuse [11]. According to the World Bank Report, the fastest way to manage and decrease waste is to minimise economic activity because when countries urbanise, their economic wealth grows along with standards of living, disposable incomes, and consumption of goods and services which leads to an increase waste generated [12]. Another suggested solution is moving from a linear to circular economy that is by curtailing resource extraction and material inputs, and improving efficiency through developmental designs, recollection, and recycling [8].

#### **2.2 Reuse and recycle**

Under these stages, the waste producer is required to check, clean, repair, and reuse the material or shift the use of the material to another function. Useless waste is converted into useful materials, and hazardous waste is turned in harmless material hence improving utilisation [10, 11]. Resource recycling promotes economic, social, and environmental benefits because the country saves on natural resources, decreases energy consumption, promotes employment while decreasing waste and pollution. Useless waste is converting into useful materials, and hazardous waste is turned in harmless material hence improving utilisation [11]. An increase in recyclable material in the composition of waste requires reuse and recycle management, while an increase in organic waste or other unrecyclable material would require other management techniques [13].

#### **2.3 Recovery**

Recovery can be through energy recovery techniques and/or using waste for either agricultural purposes or backfilling [10]. Section 3 provides more insight on energy recovery techniques. It involves recovering usefulness from the waste through energy recovery techniques such as anaerobic digestion, fermentation, incineration, gasification and pyrolysis to produce energy (fuel, heat and power), and using waste for backfilling [10]. The recovery of biogas and heat energy from landfills and incineration plants, respectively, will reduce waste generation and help in the appropriate reutilization of resources. Resource utilisation of livestock and manure, agricultural waste, domestic sewage sludge, and other organic SWs during aerobic composting and anaerobic digestion and then recycling the organic substances and nutrients, etc. are some of the efficient ways to realise SW resources and materials recovery systems [11].

#### **2.4 Disposal**

Depending on a country's policies, waste is disposed of through grinding, milling, open dumping, landfilling, and compaction or burned in an incinerator without energy recovery. The waste can also be disposed of in other countries only when it has a market in those specific countries [8, 10, 11].

High income countries mostly dispose through landfilling and thermal treatments while middle- and low-countries mostly dispose by open dumping and poorly managed landfilling. However, the middle-income countries operate with managed dumping processes [12].
