Wastewater Are Not Wastes

Abstract More than one billion people lack access to safe water worldwide. In particular, in deve10ping countries 80% of diseases and 30% of deaths are water related [UNDP (2007) Human Development Report, Industrial and agricultural activities are major sources of water pollution, but wastewater from houses (i.e., sewage or municipal wastewater containing urine, feces, and kitchen and washing wastes) is by far the main source of water contamination causing health problems. Proper sewage treatment is therefore a priority. Wastewater treatment generally consists of physical separation (solids from water-soluble compounds) followed by biological steps to decompose and reduce the amount of organic matter and remove compounds containing inorganic nitrogen and phosphorus. FinalIy, chemical processes can be used to disinfect the effluent water stream. This end-product is then discharged into surface waters if its quality meets local and national requirements to protect the environment from pollution. These principles for treating municipal wastewater have remained unchanged for more than a century. However, increasing demand for water and energy and dwindling global resources necessitate a serious reassessment of conventional wastewater treatment, especially as wastewater contains many valuable resources, such as reusable treated water, energy, nitrogen, and phosphorus (Watanabe 1999: Research needs to optimize wastewater resource utilization. Water Environment Research Foundation, Alexandria, VA, USA). The major constituent of wastewater (i.e., water) could well be recovered for industrial use (recycling), for use in agriculture (reuse), and even for use as drinking water so long as safety measures are in pIace and the practice is accepted. So far, innovations in wastewater treatment have generally been aimed at reducing costs, saving energy, and lowering the environmental impact. New technologies are emerging that provide tools to extract and profit from the constituent elements of wastewater streams. This chapter introduces the problems dealing with various wastewaters, including the actions taken to tackle associated problems in human health and the environment. Diminishing resources now pose new challenges lo finding ways to reuse the water, nutrients, and energy retrieved from wastewater streams. Several European research projects have actively engaged with different aspects of these technologies. This chapter provides background information to aid in understanding and interpreting their results.