_Wastewater treatment in middle-income countries._ In middle-income countries, particularly uppermiddle-income countries, wastewater management is becoming an increasingly important concern, and more complex regulatory structures are being developed, along with the political will and the financial resources to implement them. Wastewater treatment has advanced, but both operational deficiencies and difficulties in mobilizing needed investments and operating funds still persist. An example of the wastewater treatment experience of Latin America and the Caribbean (LAC) region, a predominantly middle-income region, is provided in Box 2.3. Statistics about wastewater treatment capacity can be misleading since they usually refer to installed capacity rather than real capacity, as is exemplified by a survey of LAC countries (Egocheaga and Moscoso 2004) and a study from China (Xie _et al_ ., 2009).

_Wastewater treatment in high-income countries._ Wastewater is generally, but not always, treated in high-income countries. The OECD countries have made major investments over the past 40-50 years to achieve high treatment levels. In North America, over 90 percent of wastewater is treated, generally to secondary, and in many cases, tertiary levels (WHO/UNICEF, 2000). Progress in the United States has largely been the result of a subsidy program in which US$56 billion in federal construction grants were provided to local governments from 1972–1989 to build mandated secondary treatment facilities, but these grants were eliminated and subsequently replaced by state revolving funds for loans to municipalities (Bartone, 1997).

In Europe, driven by the 1991 European Union (EU) Directive on Urban Waste Water Treatment, over 68 percent of wastewater is treated (CEC, 2004). However, performance varies greatly across EU countries and in 2003 only Austria, Denmark, Germany, and the Netherlands fully complied with the directive. In other countries significant amounts of wastewater—from 40 to 60 percent—were still not being treated adequately before being discharged into the surface waters of the Member States. According to the European Commission, the directive represents the most cost intensive European legislation in the environmental sector. The EU estimates that €152 billion were to be invested in wastewater treatment from 1990 to 2010. The EU provides support for the implementation of the directive in the order of €5 billion per year.

The industrialized countries are now placing more focus on how to improve the management of wastewater sludge and biosolids (UN-HABITAT, 2008). Much of this progress in wastewater treatment has been driven by the desire to protect the aquatic environment and amenity values, and to control toxic substances such as trace chemicals, heavy metals, and newly perceived problems of endocrine-disrupting compounds (EDCs), and pharmaceuticals and personal care products (PPCPs).

Many of the non-OECD high-income countries have made substantial investments in wastewater treatment over the past two decades and have implemented more complex and comprehensive regulatory frameworks. Advance treatment systems have been built, particularly in the high-income Mediterranean Basin and Middle Eastern Countries where the investments have been driven by severe water scarcity.

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