In the transition toward green energy, Waste-to-Energy (WtE) has emerged as a strategic solution that not only addresses the growing challenge of urban waste pollution but also provides a continuous source of renewable electricity to the national grid.

However, operational experience from many WtE plants in Vietnam and other developing countries reveals a significant challenge: frequent unplanned outages of the incineration furnace, power generation efficiency falling below design values, and excessively high operation and maintenance costs across the treatment process. The root cause often does not lie in the incineration technology itself but rather in the quality and consistency of the incoming waste stream.

For the incineration furnace to operate stably 24/7, waste shredding technology is far more than a mere supporting process—it is a mandatory pre-treatment link that determines the efficiency and lifespan of the entire WtE plant.

Unlike the strictly sorted waste streams found in European countries, municipal solid waste (MSW) and industrial waste in Vietnam exhibit extremely complex characteristics:

• No source segregation: High-moisture organic waste is mixed together with plastics, textiles, packaging, wood, tires, and bulky waste.

• Inconsistent waste size: Ranging from small plastic bags to bulky waste masses, coiled cables, and wooden pallets several meters long.

• High moisture content: Water trapped inside sealed plastic bags and bottles/containers prevents natural moisture evaporation within the waste storage pit (tipping hall/bunker).

If this “raw” waste stream is fed directly into the feed hopper and onto the grate, the plant will face a series of operational risks: hopper blockages (waste jamming), uneven combustion, excessive consumption of auxiliary fuel (oil/gas) for ignition support, and the risk of emergency furnace shutdown (downtime).

The application of dedicated waste shredding machinery/equipment at the pre-treatment stage brings about decisive changes to the thermal combustion process:

a. Size Reduction (Sizing) – Ensuring Even, Vigorous Combustion

 

Modern WtE incinerators (particularly rotary grate or chain grate types) require waste to have a standardized particle size (typically below 100 mm – 150 mm).

• When waste is shredded into smaller pieces: The external surface area of the waste in contact with combustion air increases by tens of times.

• Result: Waste ignites faster, and the drying – volatile combustion – burnout process occurs continuously and consistently across the grate. This effectively eliminates “smoldering combustion” (incomplete combustion that generates excessive black smoke and unburned residue/bottom ash).

 

b. Moisture Release – Increasing Actual Heating Value

 

Lower Heating Value (LHV) is the most critical combustion indicator for driving the power generation turbine. Water trapped inside sealed waste is a key cause of reduced heating value.

• High-torque shredder blades tear apart all types of packaging, plastic bags, and sealed styrofoam boxes, releasing the water trapped inside.

• This free water then drains out easily through the leachate extraction/pressing system in the waste bunker, lowering the waste’s moisture content from 10% – 15% before the waste is grabbed by crane and fed into the furnace.

 

c. Reducing Auxiliary Fuel Costs & Protecting the Grate

 

When raw waste pieces are oversized, furnace chamber temperature tends to drop below the standard threshold (850ºC). When this happens, the system is forced to automatically inject auxiliary oil/gas to maintain temperature.

• Shredded waste ensures a stable, self-sustaining flame, helping the plant save billions of VND in auxiliary fuel costs each year.

• At the same time, shredded waste distributes the load evenly across the grate surface, minimizing localized overheating that can cause grate bar warping and damage.

 

d. Emission Control & Environmental Protection

 

One of the greatest concerns surrounding WtE technology is the formation of dioxin and Furan toxins – an extremely toxic group of compounds capable of causing cancer in humans.

According to thermodynamic principles, dioxins/furans are only completely decomposed when flue gas reaches a temperature above 400°C, with a minimum residence time of 2 seconds and an appropriate excess oxygen level.

• If unshredded raw waste is incinerated, large waste masses that combust incompletely create “cold spots” within the combustion chamber, creating favorable conditions for dioxin re-synthesis.

• When waste is finely shredded and combusted thoroughly: the flame maintains a uniformly high temperature throughout the entire combustion chamber, suppressing dioxin formation right at the combustion stage. This in turn minimizes the chemical costs (activated carbon, lime powder) required for the costly downstream flue gas treatment system.

 

To withstand the harsh working intensity at WtE pre-treatment stations or waste bunkers, shredding equipment must meet the following stringent technical standards:

Investment in a Waste-to-Energy (WtE) system is a multi-million-dollar undertaking that requires optimization across the entire technology chain. However, underestimating or cutting costs in the input waste pre-treatment stage is often the shortest path to operational risk, increased maintenance costs, and a direct negative impact on the project’s financial performance.

A modern pre-treatment system is not only responsible for reducing particle size and homogenizing the feedstock but also determines the quality of the input fuel for the incineration furnace or the RDF/SRF production line. Solutions from TANA and BMH Technology have been widely applied in numerous WtE projects around the world, helping to optimize the sorting, shredding, and standardization of waste—thereby improving energy recovery efficiency and minimizing unplanned downtime.

In particular, the TANA Shark line of slow-speed shredders is renowned for its ability to effectively process a wide range of complex waste streams, including municipal solid waste, industrial waste, bulky waste, and C&D (construction & demolition) waste, delivering uniform material size and reducing the risk of blockages in downstream systems.

Meanwhile, BMH’s TYRANNOSAURUS® solutions and RDF/SRF fuel processing systems help produce a stable-quality fuel source that meets the stringent requirements of WtE and cement plants.

In practice, the right investment in pre-treatment technology is not an added expense but a strategic investment — one that protects the plant’s multi-million-dollar assets, ensures long-term operational performance, and maximizes profitability from the waste-to-energy conversion process.