American Scientist

To the Editors:

Vaclav Smil's article, "Water News: Bad, Good and Virtual" (August–September), left unmentioned the mishandling of sewage and organic wastes that pollute waters and increase ocean dead zones. The biggest global problem unaddressed by environmentalists and scientists working on global sustainability is the ever-expanding, never-ending organic waste mess. It is appalling that Group of Eight officials (representing the eight largest industrial market economies) in July talked up world health problems without mentioning any connection to water contamination by germs, toxics and drugs from organic wastes. The EPA  has announced conference plans concerning risks of drugs in drinking water indicating the need to eliminate unwanted hazards released from organic wastes.

Major elimination of those hazards in wastes and separated sewage solids could be obtainable by a pyrolysis system. Pyrolysis would destroy hazards while stopping waste bulk from re-emitting greenhouse gases via biodegradation as now occurs in dumps, sewage processing and composting. The process would produce charcoal for burial (or maybe soft coal could be substituted), gaseous hot distillates to produce refined organic chemicals to sell and big cost reductions for new dumps not needing to handle the organic wastes. Hot charcoal used in such a process could be passed through heat exchangers to produce steam to generate electricity. Yes, some energy whose production resulted in greenhouse gas emissions may be required. But gained would be the benefit of minimizing major water pollution sources potentially causing many health problems, reduced dump costs and the reduction of some greenhouse gas emissions.

James Singmaster, III
Fremont, CA

To the Editors:

Regarding Vaclav Smil's article, the author eloquently points out the amount of water used in U.S. agriculture. He mentions that rainfall needed to grow grains may be transpired, formed into clouds and then rain again some hundreds of miles away. That may be, but much agricultural water will carry off excess fertilizer and agricultural waste, especially the water used in meat and dairy production. We need to take account of the "wear and tear" on the water and to differentiate water "use" from water "consumption." I propose that the tallies of water used include the typical number of kilowatt-hours needed to clean the water and pump it back to the source reservoir.

Harriet Griesinger
Cambridge, MA

Dr. Smil responds:

Compared to virtual water or desalination, the two topics I developed in some detail, wastewater treatment has been receiving an enormous amount of attention in specialized professional publications. There were other important water matters that were not even briefly noted in my American Scientist article. That we need to do a much better job in dealing with the organics, toxics and metabolites has been obvious for decades. I readily agree with the call to view this challenge more urgently. New approaches should always be explored, but we could do a much better job even with the already well-established techniques. In either case, we must first be willing to pay for it: The real cost of water is inevitably higher than what we are paying now.