Waste stabilization pond use in Central America: The experiences of El Salvador, Guatemala, Honduras and Nicaragua

Within the last 15 years 34 waste stabilization pond systems have been buil t in Central America in the countries of El Salvador (8 systems), Honduras (12 systems), Guatemala (9 systems), and Nicaragua (8 systems); these syste ms were built for municipalities with populations ranging from 5,000 to 80, 000 persons. There are 14 additional systems in the final design phase or u nder construction in the region, including the first designs for large citi es: a 162 hectare facultative system for Managua, Nicaragua (population ( 1 ,000,000); and a 168 hectare system for San Pedro Sula, Honduras (populatio n (640,000). Monitoring data from Honduras and Nicaragua show that treatmen t efficiency is generally comparable to tropical pond systems cited in the literature in other parts of the world, although fecal coliform removal has not been as good as theoretically predicted and the desludging of facultat ive ponds has been a significant operational cost. While waste stabilizatio n ponds are generally considered the technology of choice for municipal was tewater treatment within Central America. theta are, nevertheless, problem areas that need to be addressed if waste stabilization pond use is to have continued acceptance and longterm sustainability. These areas of concern at the regional level are: i) design guidelines using parameters from data de veloped in Central America; ii) effluent guidelines that are realistic for pond effluents for reuse or surface water discharge; iii) monitoring progra ms focusing specifically on pathogen removal; iv) cost-effective grit remov al and sludge removal from facultative ponds; v) improving designs for path ogen removal; vi) the need for centralized (El Salvador and Nicaragua) vers us decentralized (Guatemala and Honduras) mechanisms for financing and oper ation and maintenance; vii) the development of comparative cost data for co nstruction, operation and maintenance, pond desludging, and microbiological monitoring; and viii) the development of training programs for design, ope ration and maintenance, and monitoring.