Hanoi Thien Y Environmental Energy JSC has asked for permission for investment and development of two more incinerators (800 tons/incinerator/day) to treat waste at Nam Son landfill.

The project is expected to be implemented over 10 years. After that, the earth surface in the area may be developed into a golf course, a park, or an Industrial Zone.

The Soc Son Waste-to-Energy Plant at Nam Son Waste Treatment Complex has been operational for several years. It receives and treats 4,000-5,000 tons of waste a day, or 60 percent of Hanoi’s total domestic solid waste, and has electricity generation capacity of 90MW. It’s leaders recently have thought of digging up old waste for treatment.

Criticism

According to Ha Dang Son, director of the Center for Energy and Green Growth Research (CEGR), buried waste has high humidity and is mixed with mud and soil, so it is extremely difficult to burn. 

The high humidity is the biggest problem for waste incineration technology, so if burning unearthed waste, the efficiency will be very poor. 

Old landfill is considered a methane mine because there are metals and food in buried waste. If the company turns over the soil, this means opening up the methane mine and discharging the gas into the environment.

“This is not a simple work,” Son commented, adding that the move, if taken, would cause emission of toxic gases from the landfill into the environment.

An expert affirmed that no other country in the world digs up buried waste to incinerate for electricity generation because it is too costly and ineffective. 

If the municipal authorities agree to develop two more incinerators (800 tons per day for each) as proposed, the required investment capital would be around VND3 trillion. 

This means that the investor will make investment in the project only if it can earn more than the figure. So, the question is how to arrange more than VND3 trillion to be spent on waste treatment?

According to the expert, there are many ways to handle old landfills. China and South Korea, for example, have renovated old landfills with expenses just equal to 1/3 of the capital needed to expand the incineration plant. The expenses include landfill environment treatment and landscape improvement.

Expenses to treat leachate and biogas arising after closing landfills are much lower than expenses to dig up old waste and burn it as suggested.

How to treat old landfills?

Dr Hoang Duong Tung, a respected environment expert, believes there are many solutions to the Nam Son landfill and there is no need to dig up waste to burn.

“We need thorough discussions about how to deal with the old landfill to be sure that the treatment is suitable to development programs and it can reach the long-term goal,” he said.

“In this case, we must act for the sake of the entire society, not just for investors’ benefits,” Tung commented. 

According to an expert, the handling of the old landfill could be as follows:

First, use LLDPE (Linear low-density polyethylene) film to cover the surface and surrounding areas to prevent water intrusion, then install a large number of wells which can lead biogas to the earth surface for use. It is also necessary to build a system to collect and lead leachate to a treatment plant or a reservoir for filtration. After the treatment, the leachate will become harmless clean water, and salt mud will be buried. After eight years, the leachate and waste gas will degrade and gradually disappear.

Once the structure of the landfill becomes stable, and the leachate and gas can be controlled, gardening and landscaping will be implemented, and the land area can be developed into a park.

Expressing concern about the plan to expand the plant, Tung said the plant treats 4,000 tons waste a day and is a potential source of pollution. If accidents occur, this will seriously affect the environment as dioxin, furan and other toxic gases will be discharged.

Tam An