Treating leachate from discharge standards to reuse for irrigation, public and civil sanitation.

1. Leachate

What is leachate?

Leachate is water collected from waste, or from areas with waste, landfills and landfills. Rainwater or groundwater passing through areas containing waste will wash away the materials in the waste (or the leachate available in the waste itself) to create leachate.

The water from the landfill comes into contact with organic and inorganic waste in the landfill, washing away and dissolving them, forming leachate. Therefore, leachate contains many toxic pollutants, including organic compounds, heavy metals, chemical compounds, pathogenic bacteria and viruses, etc.

1.1 Overview of leachate

Because it is a wastewater stream generated from a landfill, the concentration of pollutants, bacteria, and toxic chemicals is very high. Such as: high to very high COD and BOD, nitrogen, ammonia, sulfide, heavy metals, germs, pathogenic bacteria, arsenic, …

The composition and properties of leachate depend on factors such as:

• Source of waste.
• Waste composition.
• Terrain, vegetation and climate conditions of the landfill area.
• Landfill burial and operation methods.
• Hydrogeological conditions in the area.

At landfills, the pollution index value varies depending on the composition of the waste and the age of each landfill. Total dissolved solids (TDS) in leachate ranges from 1,000 – 60,000 ppm. BOD5 and COD range from 100 – 60,000 ppm. Normally, the pollution concentration will be highest when the landfill is about 2-3 years old. After that, this concentration will tend to decrease gradually. However, it cannot be reduced to the level that meets the discharge standards into the environment. The issue of leachate treatment still needs to be focused on and concerned.

1.2 Impact of leachate on humans and the environment

1.2.1 Impact of leachate on human health

When leachate enters underground water sources or water supply systems. It will pollute drinking water and domestic water in the surrounding area. Pollutants in leachate such as heavy metals, toxic chemicals and bacteria can be harmful to health. Causing cancer, dermatological diseases, poisoning, developing epidemics, etc.

1.2.2 Impact of leachate on the environment

Leachate seeps into soil, groundwater, rivers, streams or lakes, etc., thereby reducing water quality. This pollution can adversely affect animal and plant life in the aquatic environment. This causes negative impacts on the ecosystem and biodiversity.

• Disrupts the natural ecosystem
• Decreases biodiversity
• Disrupts the food chain
• Diseases arise in the ecosystem
• Causes soil quality to decline
• Air pollution
• Affects the landscape

Vietnam is among the 20 countries with the largest amount of waste in the world. In 2020, there were more than 900 domestic waste landfills with data in the system (not including spontaneous landfills). Of which, only 20% of landfills are sanitary. This means that waste and leachate treatment is an inevitable and challenging problem.

2. Leachate treatment problem

Leachate treatment is the process of removing pollutants and impurities in leachate. To ensure that the treated water meets environmental standards for discharge or reuse.

Leachate treatment measures include pre-treatment water treatment systems, fine filtration systems, RO ultrafiltration systems, disinfection systems, etc.

The treatment technology process often includes a combination of many different methods. The goal is to achieve the highest efficiency and meet the requirements of each specific project.

Treatment systems need to be designed, built and operated correctly to ensure efficiency. And the important requirement is to comply with environmental regulations. Let’s learn about some regulations in the treatment and reuse of leachate.

3. Some regulations in the treatment of leachate

Leachate treatment is an urgent issue to protect the environment and ensure human health. Each agency and implementing unit needs to clearly understand the regulations and standards in wastewater management and treatment. From there, they can have the right solutions in investing and managing their waste treatment plants.

Below are some regulations that are often referred to in leachate treatment:

3.1 Environmental protection law

Most countries have regulations regarding environmental protection, including leachate. These regulations require that leachate be treated and disposed of safely and without causing environmental pollution.

3.2 Waste management

Waste management regulations often require businesses and organisations to collect, treat and dispose of leachate in a safe and organised manner. This may include the use of sewerage systems and waste treatment systems.

3.3 Water treatment standards

There are specific technical standards for leachate treatment to ensure that the treatment process meets wastewater quality requirements and does not harm the environment. These standards may include:

• Water quality testing methods.
• Allowable limits for water quality.
• And testing procedures.

3.4 National technical regulations on leachate quality

Authorities often monitor and test leachate quality based on national technical regulations. Legal and administrative penalties are imposed for violations of leachate management regulations.

National technical regulations on wastewater quality of landfills in Vietnam are QCVN 25:2009 BTNMT and QCVN 40:2011 BTNMT.

To reduce the amount of leachate generated, policies and regulations always encourage the recycling and reuse of materials and resources from waste.

4. Cost of leachate treatment in 2023

Leachate has a very high concentration of pollution. Therefore, the process of treating leachate requires the participation of many technological processes and modern equipment. Therefore, the cost of collecting and treating water is from medium to high. Depending on each collection plant or the capacity of the treatment system.

Below are some cost groups related to leachate treatment in 2023 in Vietnam:

• The cost of collection and treatment at solid waste treatment plants/areas is about 100,000 VND to 130,000 VND.

Investment and operating costs also depend on many factors such as construction location, capacity, leachate properties, output requirements, etc. In particular, the treatment method and technology are factors that greatly affect the investment cost of the leachate treatment system.

Let’s review some of the popular leachate treatment methods today according to section 5 below.

5. Leachate treatment method

5.1 Phytoremediation of leachate

Phytoremediation of leachate is a method of using some species of plants with special metabolic capabilities, they will absorb substances in water and clean leachate naturally. This process is also known as leachate treatment using green landscape, vegetation system.

5.2 Leachate treatment by coagulation – flocculation method

Coagulation is a common method used to separate solids and organic substances from leachate. The coagulation-flocculation method consists of two main processes: coagulation and flocculation.

The coagulation process uses chemicals to break the bonds of particles in water (metals, organic and inorganic solids, biological remains, plants, etc.) to form particles that can stick together. After the coagulation process, the particles stick together to form flocs, which is called the flocculation process.

Not only for leachate, the coagulation-flocculation method is always included in most wastewater treatment processes. After the coagulation method, a flocculation tank or settling tank is often used to collect flocs.

5.3 Electrochemical coagulation method

Electrocoagulation is a method that uses the principle of coagulation of pollutants in water through the process of creating flocculants using an electric field.

5.4 Leachate treatment by microbiological method

Microbiological method (also known as biological method) is a method that uses microorganisms (or bacteria) to remove pollutants in water based on their life activities.

This method is often used after the physicochemical process with the purpose of reducing polluting components in water such as metals and hazardous components. Highly effective in treating COD, BOD, Nitrogen, Phosphorus, …

5.5 Wastewater treatment with RO membrane

Treating leachate with RO (Reverse Osmosis) membrane is a method of using pressure to push water through a semi-permeable membrane, retaining solids, organic substances, ions and other dissolved substances. Only water molecules are allowed to pass through the membrane.

Leachate is pre-treated by pre-treatment process before entering the RO system. Pre-treatment process includes chemical methods, coagulation, flocculation, physical, etc. Pre-treatment helps remove necessary substances for wastewater to meet standards before entering the RO system.

Depending on the RO membrane technology, the wastewater after the pre-treatment process must meet low or high water quality standards.

Clean water treated after the RO system can meet the reuse standards depending on the selected membrane technology. Or it can be further treated by other methods when it does not meet the standards according to current regulations on leachate management.

6. Technological process

The technological process of leachate treatment is a combination of water treatment methods so that the leachate after treatment meets the prescribed standards.

The technological process is developed when engineers design and propose implementation plans. They are shown on drawings through design drawings or technological process diagrams. Deploying the technological process of leachate treatment into operation is called a leachate treatment system.

The technological process of wastewater treatment usually includes the following treatment processes:

• Pretreatment: Solid separation; Oil and grease separation; Flotation; Physicochemical treatment (Precipitation process; Coagulation process;
• Adsorption process; ….); Fenton; Stripping; …
• Biological treatment: Biological anaerobic process; Biological pond process; ….
• Membrane treatment: RO membrane (Reverse Osmosis); UF membrane (Ultrafiltration); NF membrane (Nanofiltration; ….
• Disinfection: using chemical products, ultraviolet rays or ozone to kill bacteria, viruses and pathogens.
• Water quality adjustment: pH balance, ….

Depending on the scale and specific requirements of each project, a suitable technological process is developed. It is necessary to design and operate the system accurately to ensure efficiency and compliance with environmental regulations.

Below is a technological process for wastewater treatment implemented by TVTS for our project:

7. Some leachate treatment plants

The application of advanced technology in the process of waste and leachate treatment is also being promoted and focused on. Waste and leachate treatment plants have been established. Not only does it help reduce environmental impacts, but it also utilizes resources from waste and creates renewable energy sources to serve human life.

7.1 Some of the world’s largest wastewater treatment plants are listed as follows:

7.1.1 Fresh Kills Leachate Treatment Plant (USA)

The Fresh Kills Landfill in Staten Island, New York, was one of the largest landfills in the world before it closed in 2001.

Today, the Fresh Kills landfill is being converted into a park and leachate treatment plant. The plant’s treatment capacity is approximately 95,000 to 125,000 GPD (Gallons per day), equivalent to 360 to 473 m3/day.night.

7.1.2 Puente Hills Leachate Treatment Plant (USA)

The Puente Hills treatment plant in Los Angeles, California, is one of the largest and most modern in the world.

With the capacity to process millions of tons of waste each year and recycle more than 90% of the waste produced, leachate is treated and reused. In addition, methane gas produced from the waste is rocketed to generate energy.

The facility has been fully operational since January 1987. The Puente Hills plant is designed to produce 50 MW of total electricity, equivalent to the energy needs of approximately 70,000 households. (Source: Los Angeles Country Sanitation Districts).

7.2 Information on some large landfills in Vietnam

7.2.1 Phuoc Hiep Waste Treatment Plant, Ho Chi Minh City, Vietnam

Phuoc Hiep landfill is one of the largest landfills in Ho Chi Minh City, Vietnam. Located in Phuoc Hiep commune, Cu Chi district, about 20 km southwest of the city center.

Phuoc Hiep landfill has been in operation since the 1990s. It has become one of the most important landfills in waste treatment in this area.

However, due to overload, Phuoc Hiep landfill has caused many environmental problems and controversies. The problems include environmental pollution, odor, groundwater pollution and air pollution. In addition, the landfill also causes difficulties in planning and land use in the area.

To solve this problem, the authorities have implemented more modern waste treatment measures. By August 30, 2022, Ho Chi Minh City Urban Environment Company Limited had accepted landfill cell No. 4 (with a capacity to treat about 6 million tons of waste). In addition, landfill No. 3 at Phuoc Hiep Waste Treatment Site was completed to put into reserve operation (According to the Environment and Urban Newspaper).

7.2.2 Luong Hoa Landfill, Khanh Hoa, Vietnam

Luong Hoa solid waste landfill is the garbage collection site of Nha Trang City with a volume of about 450 – 500 tons/day and night.

Luong Hoa leachate treatment plant has been put into operation since December 2014. Leachate from the landfill is treated to meet QCVN on leachate. It will then be transferred to the Southern wastewater treatment plant.

7.2.3 Khanh Son Landfill, Da Nang, Vietnam

Khanh Son landfill is the place to receive and treat waste from the entire city of Da Nang. The landfill currently in operation is landfill No. 6, with a capacity of nearly 1 million m3 of waste.

This landfill has a total construction area of ​​77,000 m2, of which the landfill area is more than 46,000 m2. The rest are auxiliary items such as: power supply system; lighting; lightning protection system; internal roads; equipment; ….

With the city’s waste volume of about 1,150 tons of waste/day and night. It is estimated that this landfill can treat waste for nearly 2 years.

7.2.4 Da Phuoc Waste Treatment Complex is located in Binh Chanh District, Ho Chi Minh City.

This is a waste treatment area in the form of landfill. The landfill has been in operation since 2007. Operated by Vietnam Waste Treatment Company Limited (VWS). The landfill’s processing capacity is 10,000 tons of waste per day.

7.3 Leachate treatment system provided by TVTS in Vietnam

7.3.1 Leachate treatment system in Huong Thuy commune, Thuy Phuong, Thua Thien Hue. Capacity 215 m3/day and night.

Technology: TSRO Membrane Module – ROCHEM

Influent wastewater quality parameters: TDS < 8,500 ppm; COD < 20,000 ppm

Wastewater quality parameters after treatment: TDS < 500 ppm; COD < 50 ppm; Meets Type A, QCVN 25:2009/BTNMT

Construction location: Thuy Phuong solid waste treatment area.

7.3.2 Leachate treatment system at Binh Duong Water – Environment Joint Stock Company. Capacity 250m3/day and night.

Technology: TSRO Membrane Module – ROCHEM

Influent wastewater quality parameters: TDS < 12,000 ppm; COD < 3,000 ppm

Wastewater quality parameters after treatment: TDS < 500 ppm; COD < 50 ppm; Meets Type A, QCVN 25:2009/BTNMT

Construction location: WASTE TREATMENT BRANCH – BINH DUONG WATER – ENVIRONMENT JOINT STOCK COMPANY

TVTS has supplied and stably operated more than 10 leachate treatment systems in Vietnam. Large landfills, treatment areas, and waste-to-energy plants meet reuse standards. The conservation and regeneration of water resources is a very important issue for us. Water is life, and only with water can we have a future.

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8. Save energy, resources and recycle waste

Waste and leachate treatment will contribute to saving resources and protecting the environment. From treating to meet discharge standards or reusing for appropriate purposes.

Saving energy from turning waste into fuel for power plants. Using waste-to-energy and supplying electricity to the national grid.

All of the above activities contribute to protecting the environment. Reducing the impact on the climate, saving resources and reducing the amount of waste produced. If we make these small changes together, it will have a big impact. Creating a more sustainable future for our planet.

The cost of collection and treatment at solid waste treatment plants/areas is about 100,000 VND to 130,000 VND.