Home composting is one of the preferred measures included in municipal programs for waste management activities in relation to biodegradable municipal waste. Home composting is often considered the most environmentally friendly way to deal with household biodegradable waste, as it reduces emissions and costs associated with the transport of compost, ensures careful control of the materials used and increases consumer awareness of the problems of environment. In sparsely populated areas, separate waste collection may be too expensive and home composting may be a better solution.

1.1.1. What is composting?

Home composting offers the opportunity to households to utilize a large part of their household waste (food residues and garden “green” waste). Almost two thirds of the waste generated in homes consists of organic components (flowers, old fruits and vegetables, coffee grounds, tea bags, egg shells, straw, sawdust, hay, grass clippings, wooden twigs, etc.) which degrade naturally.

The organic part suitable for composting consists of raw food and vegetable waste mixed at a certain ratio. Paper and cardboard can also be composted. In the process of composting, they become sources of organic carbon. Composting is a process of decomposition of organic waste in the presence of oxygen, which produces a homogeneous brownish-black crumbly material suitable for fertilizing crops and for restoring organic matter in soils. The process is carried out thanks to different types of microorganisms acting in an aerobic environment: bacteria, fungi, actinomycetes, algae, protozoa, which are naturally present in the organic part of household waste or can be added artificially to speed up the process. The most important factors that affect the process are: the presence of oxygen, moisture, the ratio of carbon to nitrogen, particle size, acidity and temperature.

Table 2 179 Optimal conditions for composting

1.1.2 What can we compost?
The waste that subject to composting are divided into food waste, “green” waste containing nitrogen (N) and “brown” waste containing carbon (C). Greens are those that are fresh and moist, and browns are dry and contain more carbon (C).

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Table 2 180 The waste for composing

In order to obtain quality compost, it is necessary for the “green” and “brown” waste to be mixed and to be in the ratio C: N = 30: 1 or to 4 parts C – carbon we add 1 part N – nitrogen.
Because of that “green” waste decomposes quickly and “brown” waste slowly, the composting process slows down when there is not enough “green” waste. When their amount increases a lot compared to the “brown” waste, the amount of ammonia – gas with an unpleasant odor increases. Much of the kitchen and garden waste can be composted, but there are some that we should not compost.

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Table 2 181 Types of waste

First of all, the paper and cardboard must be torn into small pieces, moistened and then mixed with the other materials. To speed up the composting process, used kitchen and garden waste should be crushed, ground, shredded or chopped, as particle size is one of the main factors (material, moisture, air and particle size) that affect the process.

1.1.3 How does the composting process work?
The composting process goes through two phases: the decomposition phase of organic matter and ripening phase.
• First phase
It starts as soon as kitchen and garden waste accumulates on pile or placed in a composter. It is carried out by aerobic microorganisms, which consume oxygen, release carbon dioxide and produce energy, which raises the temperature of the compost pile. The temperature is rising very quickly in the first 12-48 hours and can rise to 55-60 degrees. Its possible the temperature rises further and leads to a decrease in the activity of microorganisms. Therefore, it is necessary to turn the compost pile over provide cooling of the material and also to supply oxygen. This phase may take several weeks. At the end of the first phase it is already fresh compost.
• Second phase
In this phase, the temperature reaches 40-45 degrees and begins to decline progressively reaching a temperature slightly above room temperature. This phase can last several months. At the end of the ripening phase, stabilized, mature compost is obtained..

1.1.4. Composting in the form of a pile and in containers
Composting can be done by making a compost pile. She is prepares easily and does not require special equipment. You can choose constantly place in the garden where to compost in a pile. The place should be dry and equal. The pile should not be exposed to direct sunlight and should not be in a windy place. When you choose the place, separate the top layer of soil. Dig up and moisten the area. A pile of compost is made in layers because it is easier to make get a good mixture of materials and even distribution of moisture in each layer.
Therefore, never mix all the waste at once, but gradually on layers, step by step.
• Step 1
Collect enough material to create one cubic meter-pile. The material must be in the correct ratio in a ratio of 30: 1 carbon-kumaz. Crush all the rough materials to have more space. Get started the pile with 10-15 cm layer of straw, paper, leaves or sawdust. It is layer of high carbon materials.
• Step 2
Add 10-15 cm. layer of manure, freshly cut grass, peels of vegetables and fruits, coffee grounds tea bags, fresh hay. This is a layer of materials with a high nitrogen content. Add 5-6 cm layer of kitchen waste. Be sure to add an extra thin layer of soil or sawdust, leaves, or old compost to prevent bad odors. Check for porosity of the mixture. If dense materials such as fertilizer or wet leaves are used, sawdust, straw or other dry bulky material should be added to improve porosity.
• Step 3
Mix the layers rich in nitrogen and carbon. Stirring the pile will deliver the necessary oxygen, will provide faster composting and better quality compost. If the necessary conditions are met, composting can take up to 3-4 months, if the process is not observed, the required time will be 1 year.
• Step 4
Add water. In order to obtain quality compost it is necessary to pile up keeps moist. The compost pile should be designed to dissipate precipitation (rainwater drainage can occur when the pile has a rounded tip) and retain heat. On hot summer days and on rainy days, cover the pile with impermeable material. Perform a test to measure the moisture content of the compost by taking part of it in your hand and squeezing it with your palms. In order for the humidity to be good during compression, a few drops of water must fall. If necessary, add water, but remember that too much water is also not good for compost because the water washes away the nutrients.
• Step 5
Continue alternating layers until you complete the stack or fill the container in which you compost. The recommended pile dimensions should be 1.2 m width, 1.2 m height and 1.2 m length. Composters are most commonly used in households because it is more convenient, faster and more hygienic. It is easier to regulate temperature, humidity and oxygen flow and eliminates bad odor. It is not necessary to give extra means for composters. Everyone can make their own composter from available materials at home.
Suitable vessels are:
• Ordinary wooden box
• In a beehive
• Old barrel
• Wire mesh equipment
A composter can also be made of recycled plastic or damaged wooden pallets. They are placed directly on the ground and in a shady place. Wooden branches are placed at the bottom of the composter to provide air access. Then there are successively “green” and “brown” materials and food waste. After loading the composter, the material should be stirred and moistened periodically.
The material to be placed must be in small pieces to allow it to flow faster process. Large quantities of the same material should not accumulate. The compost should be neither too wet nor too dry. If it is too dry, more “green” materials or water should be added, and if it is too wet, “brown” materials should be added and mixed. The leaves can be added to the rest of the composting material, but when there are many, they can be composted separately. Composting can also take place in a simple network facility. It is good to wet the leaves well when placed in the pot. The resulting compost can be used to improve the physical structure of the soil and increase its fertility. Leaf compost is also used as mulch. Mulch is an organic material – peat, compost, straw, bark, etc., which is located around the stems of plants as a cover layer. It is used to suppress the development of weeds and retain moisture, when plowing, it can be spread over the meadow or over the seeds, it can be added to flower pots.
1.1.5. What factors influence the composting process?
• Oxygen
Oxygen is required for the composting process to take place. This stimulates the process of decomposition of materials by microorganisms. The greater the amount of oxygen, the faster the composting will take place. This is achieved by importing bulky materials into the compost pile, such as branches, which create the possibility of ventilation. In addition to providing more oxygen, periodic stirring of the compost is recommended. If you stir the compost more often during the first two weeks, it will become faster. The composting process can take place without oxygen, but it is very slow – anaerobic composting, which emits an unpleasant odor.

• Organisms
The composting process is done thanks to different types microorganisms that break down organic materials in an aerobic environment. Bacteria, actinomycetes and fungi are the most active in composting and the most important organisms are bacteria. Actinomycetes are especially important for the formation of humus. They turn dead matter into peat-like material. Other organisms that affect the composting process are: fungi, snails, beetles, ants and worms.

• Moisture
Humidity should be between 40-70% At higher humidity the process of composting is faster. If the humidity is very high, an opportunity arises for anaerobic / oxygen-free / conditions. Low humidity should also be avoided. Straw and fibrous materials provide the optimal amount of moisture needed. for good composting.

• Temperature

Temperature is an important factor in the composting process. Microorganisms, when they decompose organic matter they produce heat. Composting at temperature 50-60 degrees is most suitable. High temperatures destroy pathogens microorganisms and weed seeds. Reducing the temperature in the pile before the material has stabilized means that it reduces oxygen and must stir to add air.

• Composting accelerators
Ready-made compost can be added as a natural composting accelerator.
If there are undecomposed pieces in the finished compost, they can be returned to the composter. The composting process can be speeded up if fresh is added mowed grass. To speed up the composting process, activators can also be used, which can also be found on the Bulgarian market.