Pic: Wikimedia Commons 

We have been observing an increase in the number of waste-to-energy plants being established in the GCC region. While ‘waste to energy’ undoubtedly offers some advantages, including the mitigation of methane emission from open landfills, questions remain whether feeding of an undifferentiated and quite heterogeneous mixed input is optimum when the aim is to achieve resource efficiency and move towards a circular economy. This is where pretreatment of the mixed input takes precedence. It offers the following advantages: 

Direct positive effects  

Since the input material is heterogeneous and fluctuating in terms of volume and breakdown, it is of utmost importance to remove bulky and harmful objects and to create combustibles with constant properties. This leads to an increased uptime of the incineration process and most importantly to a constant  temperature in the furnace. The resulting benefits are obvious. 

1. Increased uptime in the feeding system
2. Constant calorific value allowing maximum throughput
3. Even combustion without cold or hot spots
4. Less peaks of pollutant concentration of the exhaust air 

Additional revenue streams

A state-of-the-art pretreatment generates additional revenue streams. Modern concepts offer a high degree of flexibility regarding by-pass options based on sensors and AI-based waste composition analysis. For example, it is possible to decide whether recyclables are sufficiently present or whether material is more suitable as combustible. This allows us to find the optimum processing costs. There are several plants in Europe which have retrofitted their facilities to add a pretreatment MRF prior to their existing Waste to Energy process. No new plants are coming up without a pretreatment MRF. This enables a seamless process from waste delivery to energy and electricity generation. Typically, next to removal of bulky and harmful objects, the following separations take place:

1. Recovery of polymers such as PET, HD-PE, LD-PE, PP, PS and more
2. Remaining Mixed Plastics (MPO) as a feedstock for chemical recycling 
3. Recovery of aluminium 
4. Production of Residue Derived Fuels (RDF) for the cement industry
5. Organic rich fine fraction for further treatment in anaerobic digestion and/or composting

CO2 taxation and Public Awareness

Amidst today’s global business environment and a growing debate over plastics and plastic pollution, it is crucial to have a pretreatment MRF to “save plastic from the flames”. Several European countries have introduced CO2 Emissions Tax. Germany was among the firsts to introduce the tax in 2021 and in 2024, it announced that emissions from waste incineration will be subject to a CO2 tax of €40/tonne (which is equivalent approx.160 AED) in the current year, with an increase to €50/tonne in 2025. The new tax will be charged depending on certain content factors. The most important are the calorific value and the percentage of biogenic content in the waste, which is defined by given waste code numbers. As for biogenic content, the CO2 tax will vary greatly depending on how the fossil content in the waste is taxed.

Business case

Given a typical waste morphology in the GCC region, it can be assumed that approx. 35% in mass will be removed by a state-of-the-art MRF depending on the composition. The decrease in mass also leads to a reduction in the total calorific value. The average calorific value [MJ/kg] remains almost constant, as the completely moist material and the high-calorific fractions are eliminated. Since the remaining input flow to the incinerator is no longer composed of harmful and bulky objects, the resulting higher availability naturally compensates for this to a certain extent. And, of course, the operator can generate considerable revenues from the recyclables. The organic fraction which will be removed from the mixed input early in the process can be used for fermentation and/or composting. All in all, a pretreatment MRF has a clearly positive impact on the business case. The average investment will be in the range of some 10% compared to the incineration part plus exhaust air treatment. 

Thomas Baldt is an expert in solid waste management and recycling with two decades of experience. He is founder and CEO of Experts4Recycling, a firm of consulting engineers, with company locations in Austria and the United Arab Emirates.