Landfill leachate from municipal solid waste landfills is a major environmental concern and a worldwide problem because of its heavy contamination and treatment complexity of such wastewater.
In fact, the leachate wastewater produced from landfills can migrate to and contaminate the soil surface and groundwaters if not treated properly.
In this article we will examine the best treatment solutions and systems for landfill leachate wastewaters.
What Is Leachate Wastewater from Solid Waste Landfill?
Landfill leachate wastewater originates from the waste disposal processes and is caused principally by precipitation percolating through waste deposited in a landfill.
Landfill leachate contains various contaminants (i.e. organic and inorganic pollutants), of which the composition and content varies with geographic location, waste composition, age, pH, moisture content, and other landfill site characteristics.
Leachate wastewater always requires pre-treatment on-site to meet standards to discharge to wastewater treatment plants. In case of discharge into surface water this wastewater needs to be processed and purified by a wastewater treatment plant.
In any case, the most suitable treatment technologies must be carefully reviewed to select the most feasible and efficient process for the leachate characteristics.
Chemical Composition and Contaminants of Leachate from Municipal Solid Waste
Landfill leachate from municipal solid waste is characterized by high chemical and biological oxygen demand and its contaminants generally consists of undesirable substances such as organic and inorganic contaminants.
Landfill leachate may differ in the chemical composition and age of landfill contents, the degradation procedure, climate and hydrological conditions.
The most important parameters to consider in landfill leachate wastewater treatment are:
Chemical Oxygen Demand (COD): in landfill leachate wastewaters this value can easily surpass 100,000 mg/L; (What Is Chemical Oxygen Demand (COD))
Biological Oxygen Demand (BOD): leachates normally contain a wide biological matter, usually up to 75,000 mg/L (What Is BOD ?)
Total Dissolved Solids (TDS): leachate wastewaters typically show a value range of 20,000 to 60,000 ppm (What Are Total Dissolved Solids (TDS) ? )
The landfill leachate chemical composition can be affected by the age of the leachate itself as shown in the graph below:
The variability of landfill leachate wastewaters needs to be carefully considered when choosing a treatment method. Also, depending on the country, the discharge limits for landfill leachate wastewaters can vary. For instance, in China the BOD levels must be below 60 mg/L, among the strictest limits worldwide.
The chemical content analysis is the first step in designing a wastewater treatment system for surface cleaning wastewaters. The chemical analysis service is performed in our laboratory, you can get in touch with us to book a test for any wastewater.
Landfill Leachate Wastewater Treatment Options and Solutions
Landfill leachate wastewater treatment options include biological and physicochemical processes, such as membrane filtration solutions.
How to Treat Wastewater from Landfill Leachate?
Wastewater from landfill leachate can be treated by various technologies, but some are more effective than others.
The most common treatment technologies for leachate are:
Aerobic and Anaerobic processes;
Coagulation- flocculation, also by electrocoagulation;
As we can understand, an appropriate treatment system for landfill leachate wastewaters can cut down discharge volumes and cost for enterprises, while at the same time reducing environmental pollution.
Aerobic and Anaerobic Processes for The Treatment of Landfill Leachate
Both aerobic and anaerobic processes are goo technologies for the treatment of leachates from solid waste landfills.
Aerobic Treatment Processes for Leachate Wastewater Treatment
Aerobic treatment processes should allow to treat biodegradable organics and nutrients. Unlike anaerobic processes, nitrification (oxidizing ammonium to nitrate) is available in the aerobic processes.
The aerobic processes that are based on suspended growth (i.e., activated sludge) have been widely studied and adopted.
The integration of aerobic processes and membrane separation technology which is termed membrane bioreactor (MBR) has also led to new focus on treatment of leachate.
Anaerobic Treatment Processes for Leachate Wastewater Treatment
Anaerobic treatment processes for leachate wastewater treatment are commonly applied and are suitable for dealing with high strength wastewater.
Anaerobic digestion conserves energy and produces less sludge compared to aerobic processes with suspended growth. However, anaerobic digestion suffers from low reaction rates. In addition to anaerobic digestion, there are other processes such as up-flow anaerobic sludge blanket (UASB) reactor and anaerobic filter (AF).
Oxidized ammonium and nitrate, can be denitrified to nitrogen gas in anaerobic condition, therefore, aerobic processes and anaerobic processes can be combined for completely treating nitrogen as nutrients.
Membrane Filtration for Landfill Leachate Wastewater Treatment
The use of different membrane technology, such as Disk Tube Reverse Osmosis (DTRO), to treat wastewater has gained considerable attention for the treatment of landfill leachate wastewater.
Membrane separation involves the selective filtration of influent through different-sized pores.
Microfiltration (MF), dynamic membranes (DMs), nanofiltration (NF), ultrafiltration (UF) and reverse osmosis (RO) are the main membrane processes employed in landfill leachate treatment. The advantages of using membranes include low overall energy requirements, simplicity and high efficiency.
Among the new procedures for landfill leachate treatment, DTRO is one of the most promising and effective techniques. The DTRO process separates contaminants into two streams, namely, permeate (filtrate) and highly polluted concentrates, which are often recirculated into the waste body.
The picture above shows one of the DTRO systems that YASA ET installed in a container for a landfill leachate treatment project in China. These kinds of systems are easily installed and the treatment process can be monitored remotely thanks to a smart PLC and internet connection.
For more information about our containerized solutions you can get in touch with us for a free consultation.
Further Treatment of Leachate Wastewater by Vacuum Evaporators
Wastewater evaporation by vacuum evaporators has become an effective method for removing contaminants and concentrating waste from the treatment processes of leachate wastewater, such as membrane filtration.
A vacuum evaporation equipment, such as EVADEST, uses almost no chemicals for cleaning wastewater and thanks to its MVR technology it has much lower energy consumption when compared to other types of products on the market. In some cases, a multiple effect evaporator is required, especially is the wastewater volume is high.
This technology can further concentrate salts, heavy metals, and hazardous materials, reducing COD, BOD and TSS very effectively for DTRO concentrate. In this application evaporators can further reduce sludge by 90% with the correct pre-treatment set up.
The last improvement brought by MVR evaporators make this technology the preferred choice for large volumes of RO concentrates.
New Methods: Electrocoagulation for Landfill Leachate Wastewater Treatment
In recent years new technologies were studied for the treatment of landfill leachate wastewaters.
In this case, electrocoagulation has been proven very effective in the reduction and removal of most of the leachate contaminants, especially ammonia nitrogen (NH3-N) and the levels of chemical oxygen demand (COD).
Landfill leachate treatment with Electrocoagulation is one of those applications, where this electrochemical technology has been utilized as part of an integrated treatment solution. With its reactions that cause both sedimentation and flocculation, it can remove or reduce multiple contaminants in a single process. It is even capable of precipitating out smaller particles that chemical treatment methods can miss.
Though there would be further steps required to treat the landfill leachate so that the resulting water would be clean enough to discharge or reuse. This specialized EC process can be an effective process in an integrated process system to treat the leachate. The lower lifecycle cost of this electrochemical process, performance, along with its relatively easy operation render the EC process as a primary candidate for landfill leachate wastewater treatment.
Combined with Electro-oxidation, EC can effectively separate the pollutants and coagulate them from the water body as shown in the video below.
These methods can separate the most resistant contaminants by using electrochemical reactions. In case the organic content of painting wastewaters is too high, the Electrooxidation technology should be preferred since it can breakdown and remove those elements.
The contained costs of this technology, combined with the minimal use of chemicals, make it a good choice for these wastewater pre-treatment applications. More information about this technology can be found here: Electrocoagulation System for Water and Wastewater Treatment (yasa.ltd)
Now you can also test these technologies with our test equipment, click here for more info.
What Is The Best Treatment Technology for Landfill Leachate Wastewaters?
The best system for the treatment of wastewaters from landfill leachate combines electro-chemical, evaporative, and membrane filtration technologies.
For more information about our solutions, you can get in touch with us at:
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