Anaerobic Municipal Wastewater Treatment: Comparison and Assessment of Different Design Approaches for UASB-Reactors (PDF)

Inhaltsangabe:Introduction:
It is well known that freshwater is finite and an indispensable resource for any living organism on Earth. Inappropriately, during the last decades, anthropogenic activities expansion, in parallel with population growth, has been the main cause of the deterioration of water quality.
According to UNESCO the world¿s population is growing nearby 80 million people each year, which suggests an increasing of freshwater demand of about 64 billion m³ a year. Likewise, the demographic estimations indicate that 90% of the 3 billion people, who are expected to be added to the world population in 2050, will be living in developing countries, mainly in regions that are already by this time in water stress.
However, in order to relate the increasing demand for water, not only the demographic aspect should be taken into account but also economic and social aspects must be considered. The economic expansion affects water since there is an increase in the number of consumers as well as modifications in their consumption habits, in a way that services are offered, goods are produced and transported. The social aspect points out to individual rather than collective actions mainly considering poverty, education, culture, lifestyle and consumption patterns. Obviously the demand and the importance for satisfactory sanitation conditions become indispensable. The World Health Organization (WHO) and The United Nations Children's Fund (UNICEF) report that 2.5 billion people still have a lack of access to improved sanitation, including 1.2 billion people who have no facilities at all. While in developed areas the sanitation coverage achieves 99%, in developing regions this number is around 53%. Furthermore, in Latin America and the Caribbean the coverage sanitation is approximately 79%. In Brazil, target area of this study, only 55.2% of the municipalities are covered by a sewage collection system.
In this manner, coverage sanitation does not mean necessarily that the wastewater is treated. Hence, the wastewater must be followed by a treatment system (removal of physical, chemical and biological compounds) in order to achieve pollution mitigation targets for the environmental quality and human health and welfare. According to UNESCO more than 80% of the domestic wastewater in developing countries is discharged untreated, polluting rivers, lakes and coastal areas. Therefore, a large number of technologies have been developed with the intention [...]