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Additional macro benefits

When the country is facing decreasing forest plantations and soil degradation, biogas technologies can prevent these problems and fully substitute firewood in the rural areas. Daily firewood demand per person is around 3 kg and for their substitution will be necessary around 2,3 m3 of biogas. [8].
Well functioning biogas plants can replace the entire consumption of firewood or charcoal of an individual household by biogas. In macro-economic cost-benefit analyses the amount of firewood or charcoal saved is often directly translated into hectares of forest lost. The monetary benefit of biogas would then be reflected in re-afforestation costs. This simplistic approach is questionable because rural populations use, as much as possible, dry firewood. Live trees are only harvested, if no dead wood is available and deforestation effect manifests itself very slowly and up to a certain stage the forest can self-restore. At the same time afforestation sites or firewood plantations can not re-establish the bio-diversity of a natural forest and between the destruction of a natural forest and the re-establishment of some form of tree cover lies a time gap with negative, often irreversible effects on soils, river beds, fauna and flora. Deforestation decrease and soil degradation is one of the main arguments in favor of implementation of biogas technologies.
Animal waste also negatively influence sanitary living conditions by pollution of water resources. Manure sewage constitute a favorable environment for development of different microorganisms, including pathogenic, and have a high content of helminthes eggs. A unique distinctive feature of implementation of biogas technologies is simultaneous decrease in firewood demand and improvement of soil quality that substantially decreases the danger of their degradation, and also decrease in greenhouse gas emissions in the atmosphere, preventing climate change.

Biogas plants provide utilization of waste and sewage and directly improve sanitary conditions in individual households and in the country as a whole. Digesting of the substrate also excludes open storage of manure and faeces. Moreover, pathogenic micro flora is actively destroyed during the fermentation process. Therefore, implementation of biogas technologies increases average life expectancy of the population, frees the population from expenditures for medicines and treatment of intestinal diseases.

Reduction of pathogenic capacity
The processing of animal and human excrement in biogas systems obviously improves sanitary conditions for the plant owners, their families and the entire village community. The initial pathogenic capacity of the starting materials is greatly reduced by the fermentation process. Each new biogas system eliminates the need for one or more waste/manure/latrine pits, thereby substantially improving the hygiene conditions in the village concerned. Direct connection of toilets to digesters id especially beneficial from the point of view of sanitary conditions and eliminated noxious odors.

Reduction of disease transmission
Since biogas slurry does not attract flies or other vermin, the vectors for contagious diseases, for humans and animals alike, are reduced. Furthermore, eye infections and respiratory problems, attributable to soot and smoke from the burning of dried cow dung and firewood, are mitigated. [8].

Gastrointestinal diseases
Many of the gastrointestinal diseases are spread by the pathogenic bacteria contained in fecal matter. Contagion is pre-programmed by the farmers themselves when they use night soil or liquid manure to fertilize their fields. The anaerobic digestion of human, animal and organic wastes and effluents extensively detoxifies such material by killing most of the ova and pathogenic bacteria. It is not surprising, that the widespread popularization of biogas in China has had immediate beneficial effects on the sanitary conditions of the areas. Schistosomiasis, previously a widespread, menacing disease in rural China, was reduced by 99% through the introduction of biogas technology and the number of tapeworm infections has been reduced to 13% of the pre-biogas level [14].

Economic value of disease reduction
For the user of biogas technology, health effects are tangible with regards to the smoke reduction in the kitchen. The reduction of parasitic diseases can only be felt if the numbers of biogas systems in an area reaches a critical threshold.

Construction of biogas plants creates additional work places and possibilities for creating commercial enterprises as it increases the quantity of produced energy thereby developing rural areas of the country which leads to decrease in migration and improvement of overall living conditions.

Local enterprises
The construction phase of biogas systems provides short-term employment and income due to the need for excavation, metal-work, masonry and plumbing. The subsequent operation and maintenance of the finished systems can have long-term beneficial effects on regional employment and income as skilled craftsmen can be recruited not only for construction, but for service and repair. Community plants require a permanent staff for plant administration, raw material procurement, plant operation and maintenance, distribution of the gas yield and disposal of the effluent sludge. In China, the construction of biogas systems encouraged local industries to manufacture the requisite building materials and accessories for biogas plants[8].

To the extent that the introduction of biogas technology generates jobs and higher income while improving living conditions, it may be assumed that fewer rural inhabitants will be drawn away to urban centers in search of employment [8].

Biogas technology not only supports national economies and the environmental protection, but as its main outcome for the local population it provides for a wide range of improvements in overall living conditions. Sanitary and health conditions improve and the quality of nutrition is enhanced by an improved energy availability. Through the provision of lighting and the reduction of time-consuming fuel gathering cultural and educational activities are supported. Establishing community-level biogas systems is recommended to ensure that the technology reduces the gap between the levels of income of rural households.

Successful wide dissemination of biogas technologies requires taking into account interfering relationships between existing climate, social, economical and ecological conditions, increasing public and political awareness and state support.