What happens to waste when they get to the landfill

Not far from your house - maybe in a couple of tens of kilometers, and can be, and is much closer - it operates a large-scale chemical reactor, where every day is charged with new portions of ingredients, the composition of which no one knows for sure, and the output of the reactor itself is not quite predictable. this reactor is called a dump, or in terms of bureaucratic language, landfill solid waste. All that emit urban residents, is here eventually. N + 1 and Layfhaker decided to find out what happens to waste when he is in a landfill.

In 2015, in Russia, according to Frost & Sullivan industry analyst firm, produced 57 million tons of solid waste, it is only slightly less than the volume of steel production (71 million tonnes). In Moscow and in the field of household trashWhat is waste? (About 11 million tons per year) consists essentially of food waste (22 percent), paper and paperboard (17 percent), glass (16 percent) and plastic (13 percent), textile, metal and wood accounts for 3 percent, even 20 percent - all rest.

In Russia landfills falls to 94 per cent of the garbage, only 4 per cent is recycled, 2 per cent - is burned.

For comparison: in the EU there is a 45 per cent recycling of garbage, 28 percent - goes to landfill and 27 percent - is burned.

Russian dumps per year into the atmosphere emit 1.5 million tons of methane and 21.5 million tons of CO₂. Total in Russia in 2015 was 13.9 thousands of existing landfills, including in the Moscow region - 14. Only one in the Moscow Chekhov district dump (landfill "Kulakovo") issued for the yearPolygon TKO IN MOSCOW REGION: CURRENT ENVIRONMENTAL SITUATION
RECLAMATION AND PROSPECTS in an atmosphere of methane 2.4 tons, 39,4 tons of carbon dioxide, 1.8 tons of ammonia and 0,028 tons of hydrogen sulfide.

Properly organized landfill - a sophisticated high-tech construction. Before it is ready to receive debris must prepare fundus: put it clay layer about one meter thick, over the lay watertight geomembrane layer geotextiles, 30-cm layer of gravel, in which to put a system of pipes for collecting filtrate - liquid that will be collected from the garbage, and the top will be more protective permeable membrane. The bottom of the landfill must be at least two feet above the water table.

Near the dump require pumping and treatment plant for pumping and neutralization of the filtrate, which is saturated with organic acids and other organic matter, heavy metal compounds. In addition, debris layer when it starts to accumulate need to install a piping system for collecting and disposing of the landfill gas, the station for cleaning and incineration.

When the dump is full (usually takes 20-30 years old landfill waste), it is necessary to close the top of the landfill more one protective layer, keeping the landfill gas collection system - it will have to work more ten years.

The life of the landfill

Chemical life garbage in a landfill can be dividedLandfill Gas Basics into four main phases. During the first phase aerobic bacteria - bacteria that can live and grow in the presence of oxygen - all long cleave molecular chains of carbohydrates, proteins, lipids, of which the organic waste, i.e. mainly edible waste.

The main product of this process - carbon dioxide, and nitrogen (the amount of which is gradually reduced during the life of the landfill). The first phase lasts as long as the trash is still enough oxygen, and it can take months or even days until the garbage relatively fresh. The oxygen content varies greatly depending on the degree of debris spressovanoy and how deeply it is buried.

The second phase It begins when all the oxygen in the trash has already been used. Now, the main role is played by the anaerobic bacteria which convert substances by their aerobic counterparts to acetic, formic and lactic acid, and also in alcohols - ethyl and methyl.

Environment in the landfill becomes very acidic. As the acid are mixed with moisture, it releases the nutrients nitrogen and phosphorous making available to the multi-faceted community of bacteria, which in turn rapidly produce carbon dioxide and hydrogen. If a landfill is disturbed or the thickness of debris somehow penetrate oxygen, everything goes back to the first phase.

The third phase landfill life begins with the fact that certain varieties of anaerobic bacteria begin to process organic acids and to form acetates. This process makes the environment more neutral, which creates conditions for the bacteria that produce methane. Bacteria and bacteria-methanogens, which produce acids, form a mutually beneficial relationship: "acid" bacteria produce a substance that consume methanogens, - carbon dioxide and acetates, which in large quantities are harmful to themselves acidogenic bacteria.

The fourth phase - the longest - begins when the composition and the level of gas production in a landfill becomes relatively stable. At this stage, the landfill gas contains from 45 to 60 percent methane (by volume), from 40 to 60 percent - of carbon dioxide, and from 2 to 9 percent of other gases, such as sulfur compounds. This phase can last about 20 years, but even after 50 years after the landfill ceased to bring the trash, it continues to allocate gas.

Methane and carbon dioxide - the main products of the decomposition of garbage, but not the only ones. In the "repertoire" landfills includes hundreds of different volatile organic compounds. Scientists who examined the seven landfill sites in the UK, foundTrace Organic Compounds in Landfill Gas at Seven U.K. Waste Disposal Sites composed LFG about 140 different compounds, including alkanes, aromatic hydrocarbons, cycloalkanes, terpenes, alcohols, ketones, chlorine compounds including organochlorine compounds such as chloroethylene.

What could go wrong

head of the department of environmental monitoring and forecasting RUDN Marianne Kharlamov explains that the exact composition of landfill gas depends on many factors: the time year of compliance technologies in the construction and operation of the landfill, the age of the landfill of waste composition on the climatic zone, the air temperature and humidity.

"If it is valid polygon if continued receipt of organic matter, the composition of the gas may be very different. There may be, for example, the process of methane fermentation, i.e. falls into the atmosphere, mainly methane, then carbon dioxide, ammonia, hydrogen sulfide, mercaptans may be, sulfur-containing organic compounds ", - he said Kharlamov.

Most toxic emissions of the main components are hydrogen sulphide and methane - that they are in high concentrations can cause poisoning.

However, notes Kharlamov, a person is able to feel the hydrogen sulphide in very low concentrations, which are more very far from dangerous, so if a person feels the smell of hydrogen sulfide, it does not mean that he immediately threatens poisoning. In addition, when burning debris may form dioxins - much more toxic substances, which, however, do not have immediate effect.

Technology landfills operation assumes that the landfill gas is collected via degassing system, and then it is purified from impurities and combusted in a flare or used as fuel. Kharlamov said that the burning of the raw landfill gas, as doneDegassing "Kutchino". As landfill gas eliminates the landfill BalashikhaFor example, at the site "Kuchino," can create many new problems with toxic products of combustion.

In this case formed, for example, sulfur dioxide (combustion with hydrogen sulfide) and other toxic sulfur compounds. In normal gas utilization must first purify it from sulfur compounds.

Marianne Kharlamov

Another danger arises when in the thick debris begins to warm up, the fire without air, like peat. In this case, the dump abruptly changes its repertoire in emissions in large numbers appear aldehydes, polycyclic aromatic hydrocarbons, chlorinated poliaromatika. "At the same time there is a characteristic smell. The usual smell of dump - it is the smell of decay, which give hydrogen sulfide and mercaptans. In case of fire starts to smell fries - the smell of hydrogen fluoride, which is formed during combustion ", - Harlamova explained.

According to her, sometimes they try to stop the flow of the atmosphere of landfill gas, landfill covering top film, and then a layer of earth. But this creates additional problems: "When rotting voids and gaps arise soil, in addition, the film does not pass water, which means that the top will occur swamp", - she says.

The main source of problems with landfills, said Kharlamov - food and organic waste. They basically create the conditions for the "production" of methane and hydrogen sulfide. Without food waste trash much better amenable to sorting and recycling. "If we were able to organize waste collection system so that organic matter does not flow in landfills, it would solve most of the problems with landfills that emerge today", - said the scientist.