The U.S. Wastewater Market : A Global Perspective

The 21st century will continue to be characterized by increasingly stringent standards for effluent quality, sludge composition and nonpoint discharges. Treatment facilities will be built within urban settings and must operate as good neighbors to dense living and working communities. In the past, the main pollution control effort was focused on the removal of organic carbon matter (COD, BOD, SS). Since the eighties, in order to protect sensitive receiving waters nitrogen and phosphorus removal also have been required in many areas. Since the guaranteed protection of water bodies is becoming an even stronger element behind the setting of standards, the concept of operational reliability and flexibility has become an imperative basis for new and reconditioned facilities. This means, for example, the necessity to treat the wastewater with a high level of efficiency all year long, including during both dry and wet weather flow periods.Illustration of this tendency is given by the European Directive (1991) defining new specifications for the protection of the water environment, and the USEPA rules governing the final application of biosolids (class A and B) with more sanitation protection and the rules governing stormwater and combined sewer overflow discharges.This new trend has had many consequences in the evolution of the design concept of plants (plant location, smaller footprint, integration of esthetic landscape, odor treatment …), the treatment line (parallel lines for more flexibility, standby equipment …), the treatment technology (new technologies such as biofilters, membranes, alternatives to chlorine disinfection …) and the plant operation (automation, smart sensors for maintenance, specific devices for on-line measurement of aeration and sludge control management …). These issues have an effect on all new plants and must be taken into consideration for existing ones when they are retrofitted to comply with new local standards and growth in the service area.To meet this need, technologies such as biofilters have been developed and perfected for large facilities, (OSLO IN NORWAY DALHIAN IN CHINA, LIVERPOOL IN THE UK, ROANOKE IN VIRGINIA, …). In the future, membranes, already used for industrial treatment, will be extended to small municipal wastewater plants though these must overcome the present limitation of capital cost and clogging control.