## **Box  2.3  Wastewater treatment in the LAC region**

The Latin America and the Caribbean (LAC) region has the highest rate of sanitation coverage among the developing regions. According to the 2000 global assessment conducted by WHO and UNICEF, 49 percent of the LAC population was connected to a sewer system in 2000 compared to 42 percent in 1990: 68 million people had gained access to a sewer connection over a single decade. Most of this increase had occurred in urban areas; 63 percent of the urban population was connected to sewers. However, less than 14 percent of the urban wastewater collected through sewerage systems is reported to receive some kind of treatment, often by inadequate and poorly operated treatment plants, and the rest is all discharged raw. Of a total of 600 m<sup>3</sup> /s of urban wastewater that is collected, it is estimated that only 36 m<sup>3</sup> /s (6 percent) receives adequate treatment.

To gain better insight into wastewater treatment in LAC, in 2003 the Pan American Center for Sanitary Engineering and Environmental Sciences (CEPIS) carried out a regional inventory of urban sewerage and treatment in 11 participating countries,<sup>7</sup> with some 2,333 cities responding to the survey. These cities, with a total population of 43.6 million, reported that 72.5 percent of their population was connected to sewerage networks, and 140.5 m<sup>3</sup> /s of wastewater was collected, of which 40 percent received treatment. A total of 1,251 treatment plants were reported by the cities, treating a total of 55.4 m<sup>3</sup> /s (see table). The quality of treated effluent was only reported for 114 of the 1,251 plants surveyed (9.1 percent), of which only 27 plants (24 percent) achieved an effluent quality of less than 1,000 fecal coliforms per 100 ml (the WHO 1989 guideline for unrestricted irrigation).

|Type of treatment plant|Number of WWTPs|Total volume treated (l/s)|
|---|---|---|
|Activated sludge|233|25,031|
|Aerated lagoon|40|3,849|
|Stabilization pond|553|10,365|
|Anaerobic pond|15|120|
|Combined pond system|29|4,117|
|Primary treatment|370|11,672|
|Other|11|215|
|Total|1,251|55,368|

_Sources:_ WHO/UNICEF, 2000; PAHO, 2001; Egocheaga and Moscoso, 2004.

# _2.2.2 Levels of economic development and wastewater irrigation issues_

The different wastewater treatment characteristics discussed above are a significant determinant of the key issues in wastewater use in agriculture, again classified along the four types of countries. Again countries tend to progress from unplanned to planned wastewater irrigation as per capita incomes increase (Table 2.4). But a number of constraints need to be addressed during this progression. They include not only technical issues (e.g., the emerging need to increase wastewater treatment), but also institutional (e.g., coordination among stakeholders), regulatory (e.g., wastewater use guidelines), economic/financial (problems of water pricing), and social issues (e.g., perceptions of safety of wastewater use).

> 7 The countries participating in the survey included: Argentina, Bolivia, Chile, Colombia, Costa Rica, Ecuador, Mexico, Nicaragua, Paraguay, Peru and the Dominican Republic.

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