What advantages are provided to developing rural areas by building and using an anaerobic digester?

why does nitrogen have to be “fixed”? what organisms are responsible for nitrogen fixation?

the transformation and transport of substances though earth’s systems are known as biogeochemical cycles. what is included in these?

1. Anaerobic digesters offer numerous environmental and public health advantages to the developing rural regions. Some of the functions of anaerobic digesters are odor reduction, greenhouse gas reduction, organic waste reduction, and destruction of pathogens. Anaerobic digestion refers to a carbon-neutral technique that generates biogas, which can be utilized for generating electricity, heating, for supplementing the natural gas supply, and mechanical energy.  

2. The fixation of nitrogen takes place in the form of N2, which further gets converted to ammonia, nitrate, or another nitrous oxide. So, that it can be utilized as a nutrient by the living species. One of the key constituents of the nitrogen cycle is nitrogen fixation. The process of nitrogen fixation is performed by the microbes occurring naturally in the soil known as diazotrophs. This comprises bacteria like archaea and Azotobacter.  

3. A model of the Earth system has been adopted in the form of associating spheres, that is, the hydrosphere, atmosphere, lithosphere, and biosphere. As open systems, the mass and energy are cycled spontaneously between them. The transformation and conduction of substances via the Earth system are collectively termed as biogeochemical cycles. These comprise the nitrogen, carbon, water, and oxygen cycles.  

the correct option is option d