Technical Abstract: Throughout the long period of human expansion across the earth, the atmosphere and the earth’s natural waters have been used as low cost sinks or dumps for our human, agricultural and industrial wastes. Despite significant investment, the methods employed for the last half century have largely failed to achieve the needed nutrient reductions. Not only are surface waters in many watersheds increasingly eutrophic, but large semi-enclosed coastal water bodies, such as the Chesapeake Bay and the Gulf of Mexico have also become hypoxic over large areas. Algal Turf Scrubbing (ATS) is an engineered system for growing attached, lawn-like, filamentous algae on sloping surfaces over which wastewaters of many types can be pulsed. During the last decade, ATS has been demonstrated for tertiary sewage treatment and nutrient removal from farm wastes and streams and lakes; treatment rates of 40-80 million liters per day (lpd) are routine and entire river cleaning systems of 12 billion lpd are under design. Since the algal biomass is quite amenable to fermentation processes, several laboratories are now engaged in research & development on the potential of producing biofuels such as ethanol and butanol. Unlike the algal photobioreactor systems currently under development, the costs for producing a biofuel from the cleaning of wastewaters by ATS could be very low, essentially that of the refining cost.