Degradation data report of Suzhou landfill leachate

The Challenges and Treatment of Landfill Leachate

Leachate generated from municipal solid waste landfills contains hazardous contaminants that threaten the environment if released untreated.

The complex and variable composition of leachate poses difficulties for effective and sustainable treatment.

Leachate pollutants include:

High levels of biodegradable and bio-refractory organic matter measured as biological/chemical oxygen demand.

Toxic organics are also present.

Strong coloration from humic and fulvic acids formed during waste decomposition.

Heavy metals such as lead, nickel, zinc and copper that leach from waste and endanger public health and ecosystems.

High ammonia measured as total Kjeldahl nitrogen that reduces dissolved oxygen in water bodies, impacting aquatic life.

Chlorides from plastics and waste that cause salinization of groundwater and surface water.

Additional contaminants such as sulfides, phosphates, pathogens, microplastics, pharmaceuticals, and volatile organics at varying concentrations between landfills based on accepted waste types.

Treating this complex and variable waste stream presents challenges:

No single process effectively removes all pollutants, requiring multiple treatment stages and increased costs.

Bio-refractory and toxic organics cannot be fully treated biologically, necessitating physico-chemical processes.

Heavy metals need specialized removal through precipitation, ion exchange, membrane filtration, etc.

Varying leachate composition requires flexibility to adapt treatment intensity and types.

A fixed approach will not suit all landfill:

Large volumes of leachate at major sites demand high-throughput, low-cost treatment for sustainability. Simple, low-maintenance systems are advantageous.

Residual pollutants may remain after treatment, requiring advanced final polishing before discharge due to strict regulations.

A combination of biological, chemical and physical treatment tailored to leachate composition based on waste inputs and monitoring provides the best outcomes environmentally and economically.

Boron-doped diamond electrochemical oxidation can degrade bio-refractory organics and ammonia while avoiding the generation of hazardous byproducts. Leachate from municipal solid waste landfills contains an array of contaminants at varying and often hazardous levels that present challenges for effective and sustainable treatment. Multiple processes are typically required to remove pollutants to regulated levels for discharge or reuse. Boron-doped diamond electrochemical oxidation shows promise as an advanced method for leachate treatment, enabling massive reductions in ammonia, nitrogen, organic matter and color while limiting unwanted byproducts.

1.Experimental principle
This experiment uses the principle of electrochemical catalytic oxidation and uses BDD electrodes as the core reaction device to finally convert the organic matter in the water sample into CO2 and H2O.

2.Electrodes
2.1 Anode: Two BDD electrodes with a single crystal silicon substrate, the surface area of the film is 200cm2.
2.2 Cathode: Three titanium sheets.

3．Experimental operation
Take 1L of water sample into the beaker, put the BDD electrode module (the actual utilization area of the anode is 140cm2, the area ratio of the cathode and anode plate is 2 to 1), connect the power supply, adjust the current intensity to 8A, the duty cycle to 80%, and the frequency 4000Hz; start to degrade. During the degradation process, the water sample is stirred with a magnetic stirrer to make it uniform. Take samples at regular intervals, record current and voltage values, and measure temperature and pH.

4．Experimental phenomenon
The original water sample is dark brown, turbid, and has a strong odor; more foam is produced during the degradation process, and a small amount of brown precipitate is produced; after degradation, the water sample becomes clear and the pH value increases slightly.

5．Results and analysis