Rheology of Animal and Human Feces

The book entitled "Rheology of Animal and Human Feces" is structured into four chapters. Rheology is the scientific discipline that studies how materials flow or deform under the action of applied forces. In the context of animal feces and organic substances, rheology plays an important role in several fields, including environmental engineering (sludge management, biogas production, organic fertilizers), agricultural engineering (transport, storage, and field application), and the sanitation sector (wastewater and waste treatment). Animal feces and manure are complex suspensions composed of a solid phase, consisting of undigested plant fibers, cells, and mineral particles, and a liquid phase, consisting of water, fats, dissolved proteins, salts, and gases generated during fermentation processes. Their composition depends on several factors, including the animal species (cow, pig, poultry, etc.), the type of feed and hydration regime, and the stage of digestion and degree of fermentation. Typical rheological characteristics show that animal feces and manure behave as non-Newtonian fluids, often exhibiting pseudoplastic behavior with a yield stress and thixotropic properties.