Spreading sewage on land
Recently there have been discussions on the danger to human health and the environment in the spreading of sludge on land. The argument is that sewage sludge should not be spread on land because its contents are at any moment so vastly various and so constantly changing as to be far beyond the analysis adequate to establish safety.
Sludge is the residue created in the attempt to retrieve clean water from sewage. The water is to be made clean by extracting from it the vast array of pollutants which it is the very purpose of sewers, hence sewage, to receive. The more thorough going the attempt to clean the sewage, the more thoroughly noxious the residue— the sludge will be. This can create a problem. It is the very purpose of sewage treatment to make it so. And in this purpose, sewage treatment succeeds: it creates a mix so dense with the noxious as to be a very hazardous material. Indeed, given the certain presence in sewage of toxic materials on a vast scale, sludge properly understood should be classified as a hazardous waste.
In considering the argument one needs to bear in mind the overwhelming complexity and unpredictability of what enters the sewage stream, sludge is unmonitorable. Of the 80,000 known chemicals and the unknown number of biological organisms and agents that can go down the drain, what does enter the sewage stream is unpredictable from hour to hour, from day to day, from month to month. Today, the sludge may contain an unusually high dose of mercury or lead; tomorrow it may get a spike of dioxin as pentachlorophenol and other organic chemicals interact chemically when they happen to enter the wastewater stream at the same time; the day after tomorrow, because of heavy rains, it may be inundated with cadmium from non-point-source road run-off; and where the sewer receives hospital wastes, the sludge will contain virulent and resistant strains of disease organisms as well as synthetic pharmaceutical drugs of every kind. This is but a minute sample of what sludge can—and will—bring to the soil.
But more terrible, even, for the future than these disease organisms is that none of the 80,000 chemicals and their new, unknown, negatively synergistic combinations created in the highly active environment of the sludge—none of these will be eliminated by either composting, heating, or pelletizing. And so, with no records necessary, they pass untraced and untraceable into the soil to do untellable damage to life: if not this year, then in five, or ten, or fifty.
The disposal of sludge is the immediate problem with which we are faced. Sewers, and the treatment of sewage that must unceasingly produce sludge are the deep problem. Using water as a transportation medium for waste materials is the fundamental mistake that gave rise to so destructive and unfixable a sequence of mistaken technologies: sewers leading to vast water pollution; vast water pollution leading to sewage treatment; sewage treatment leading to the production of an unusable mix of all the pollutants that treatment could remove— sludge, the climax inherent in sewers and the water carriage of wastes. The spending of resources—time, energy, materials, money—on upgrading the level of wastewater treatment, on the construction of sewerage, or on efforts to “clean up” sludge, can be no more than a waste of all those resources. The time and energy and money should be spent instead on developing systems that do not cause the problems caused by sewers.