How is landfill leachate treated?

Waste incineration power generation is currently the best way to deal with waste, but waste incineration will have residual pollutants, and waste leachate is a major problem need to be solved. Landfill leachate is a high-concentration organic wastewater that exists as part of waste in a landfill. This is usually as result of rainwater entering the landfill but is also due to the natural decomposition of organic material along with other liquids and chemicals that have been discarded.

Municipal waste treatment generally uses incineration, but with the increasing amount of garbage, the landfill leachate generated by garbage incineration is also increasing. Moreover, the hazardous substances such as oil and heavy metal pollutants contained in the landfill leachate have great environmental pollution. If direct discharge, it will pollute the air and local water sources, and affects the local production and threaten the health of people. Therefore, we must deal with landfill leachate, and the most widely used treatment technologies are the re-injection method, reverse osmosis method and biochemical treatment method.

1. Re-injection Method

Before choosing to use this treatment method, it is necessary to measure the amount of leachate produced and the heat. This technique is not suitable for the case of high output and low heat. For some landfill leachate with more dry matter, you can take the method of re-injection to increase the combustion rate and reduce the content of harmful substances in the leachate. Re-burning needs to be judged according to the calorific value of the leachate, and using a high-pressure device to spray it. When the heat in the leachate is lower than the combustion standard, it will stop spraying and continue to accumulate in the concentration tank. When the concentration heat and other standards are met again, the spray can be carried out to ensure the treatment efficiency.

2. Reverse Osmosis Method

Reverse osmosis is often used in the treatment of incinerated landfill leachate with high salt concentration. Control the leachate after incineration within the designated area, so as not to cause a greater pollution impact due to infiltration in the soil. The reverse osmosis method is mainly used to increase the concentration of leachate, isolate suspended pollutants, and finally obtain a higher concentration of leachate. Usually the reverse osmosis method is used in combination with other methods, which re-burn the resulting high-concentration liquid to minimize the content of harmful substances.

3. Biochemical Treatment Method

At present, the most widely used biochemical treatment is MBR technology. It is a new high-efficiency wastewater treatment technology that combines high-efficiency membrane separation technology with traditional complete activated sludge technology. Its main advantages including: 

1. The separation device is simple, easy to operate and control, convenient for maintenance management. 

2. The hollow fiber membrane has long service life, less fouling of the membrane group, and reducing pollution; 

3. During the treatment process, the MBR membrane does not undergo phase change and has low energy consumption; 

4. With high separation efficiency, high reliability and small footprint, it could frequent start and stop work, which is very flexible. 

The following are HONGTEK MBR (Membrane Bioreactor) Module for your reference:

In addition to the above three treatment methods, the current research on the treatment of landfill leachate also includes catalytic oxidation, wet oxidation, electro-oxidation, photo-oxidation, etc. These oxidation methods are either easily poisoned by the catalyst or due to consumption of large electricity, so it can not be widely used in the treatment of landfill leachate.