Leachate: An avoidable threat to human health and the environment.
Water is one of the most essential substances on Earth, with groundwater being its prime natural source, supporting all forms of life. Without water, human beings will cease to exist. The same can be said of all plants and animals, as well, since water forms one of the building blocks necessary for life to thrive. What happens when the primary source of water is continuously exposed to contamination due to indiscriminate heaping of biodegradable waste that in turn, forms leachate?
Underground water is the water present beneath the Earth’s surface, found in soil pore spaces and the crevices of rock formations. It is highly useful and usually an abundant resource, but overuse can cause depletion. One of the most evident problems, however, comes from natural or human induced contamination.
Amongst many pollutants that have the ability to contaminate our ground water and pose health risks to all the life form that consume it, one of the most harmful is leachate. Due to its liquid form and extremely high concentration, leachate can easily seep in through soil and very small amount can pollute a large volume of groundwater, leaving it unsuitable for domestic water use.
What is leachate?
According to the U.S. Geological Survey (USGS), “Landfills are the final repository for a heterogeneous mixture of liquid and solid waste from residential, industrial, and commercial sources, and thus, have the potential to produce leachate — a liquid waste product that consists of a diverse mixture of chemicals as precipitation or applied water which moves through the waste.”
When landfill waste degrades, rain rinses the resulting products out, forming leachate. Leachate is a by-product with high strength and toxicity. It presents as a liquid that has percolated through solid waste and contains extracted suspended materials in it. Leachates are a great danger to underground water, especially those that are built close to dumpsites, landfills and waste dumping areas.
Leachate is mostly formed through the:
1. Biological decay of organic materials, either aerobically or anaerobically.
2. Chemical oxidation of waste materials.
3. Escape of gases from landfills.
4. Dissolving and leaching of organic and inorganic wastes by water and leachate moving through the landfills.
5. The flow of dissolved materials by concentration gradients and osmosis.
Due to the formation process, leachate from dumpsites contain high concentrations of ammonia and Nitrogen (NH3-N), organic compounds, heavy metals, and inorganic compounds such as calcium, magnesium, sodium, potassium, ammonium, iron, sulfate and bicarbonate. Although its composition may vary from time to time, the effect on soil leads to bio-toxicity and ground water contamination.
Hazardous effects of leachates on underground water
Owing to its toxic composition, the hazardous effects of leachates cannot be overemphasized. Nothing is more critical to our natural resources than our water supply, which is why the lethal effects of leachates on underground water primarily affect human beings.
Groundwater is a source for boreholes, and boreholes are the main source of domestic water in many areas of Nigeria, most especially the South-South region. They depend on it for both local and commercial purposes; therefore, its contamination is a direct threat to the health of the residents of an affected community. Medical Literature tells us that some general health conditions caused by consuming leachate contaminated water can range from sweating, bleeding stomach disorders, to blood disorders, congenital disabilities and even cancer. However, based on the different hazardous components of these leachates, the effects vary.
Many landfills contain toxic wastes that could have a damaging effect on human health if ingested. Let us look at some of the health effects from acute exposure to certain chemicals and heavy metals found in leachates:
Lead = Abdominal pain, diarrhoea, vomiting, confusion, drowsiness, seizures.
Mercury = bloody diarrhoea, dehydration, renal failure.
Cadmium compounds = metallic taste, cough, chest pain, nausea, diarrhoea, skin irritation.
Nickel = skin irritation, dermatitis, diarrhoea, gum disease.
Toluene = tremors, convulsions, coma.
Phenols/cresols = burning pain in the mouth and throat, nausea, vomiting, diarrhoea, sweating, coma, shock.
The health effects from long term exposure to these chemical compounds and heavy metals include:
Lead = anorexia, abdominal pain, constipation, chronic nephropathy, hypertension.
Mercury = tremors, memory loss, seizures, coma, irritability, acute kidney failure, decrease in platelets, anaemia that follows gastrointestinal bleed.
Cadmium compounds = anaemia, kidney damage, possible prostate and lung problems.
Phenols and cresols = renal failure.
Benzene = blood-related disorders.
With these dangers posed by leachates due to poor disposal of waste, inadequate awareness only make situations worse. Ignorance will leave an unhealthy cycle of constructing boreholes and digging underground water wells close to dumpsites that have potentials of producing leachates that can contaminate the ground water.
How can you help?
Be aware: As individuals, we have to be accountable and practice proper waste management techniques — reuse, reduce and recycle; this will cut down the amount of waste that ends up in landfills. We also need to detest from constructing boreholes near dumpsites or waste disposal areas.
What can the government do?
- Create platforms to sensitize people on the dangers: Raising awareness about proper municipal solid waste management (MSWM) is a critical component of effective waste management. Key stakeholders need to be aware of a city’s waste management process and have a reliable system that can train people on the dangers of improper waste disposal methods.
- Provide sustainable waste disposal solutions: The Government needs to be committed to supporting the need for a universal, useful, long-term improvement and the proper management of medical waste in Nigeria. This solution should involve the provision of safer and environmentally friendly options of disposing of waste.
- Enforcement of safe borehole and Underground water well construction: The government needs to introduce a strategy with insights aimed at developing and implementing national and international standards on borehole and underground water well constructions away from dumpsites.
Pollution control for leachate is a world-wide concern, and there is still a big challenge in the source for methods of its reduction and total pollutant removals. However, the provision of a system that favours environmentally safe methods of waste disposal will go a long way to prevent the occurrence of leachate and thus groundwater pollution.
Furthermore, the government needs to commit to ensuring and enforcing adequate waste disposal practices. This includes proper treatment of leachate before its discharge into the water receivers.
Water is a scarce and valuable natural resource, we have a duty to protect and preserve it at all cost.
