Good afternoon. Thanks to Carl and Fred for their posts. I agree with both of you. Fred's right that my intro telescoped human attitudes to their shit (I'll address the issue of why I don't like to say "waste" shortly) into the last two centuries or so. I should have been more specific. The rise of the unmentionability of excrement is, in the general sweep of history, recent. Three hundred years ago, it was still commonplace for the highest noblemen and women in Paris and London to use the corridors of palaces as their toilet, quite openly. On the one hand people had little choice but to be at close quarters with excrement, because it was everywhere, in overflowing cesspools; on the street; in the rivers. That meant that there was much more pragmatism about our bodily functions and products: The Wellcome Institute, a medical library in London, has a lovely engraving of a maidservant being handed a stool sample in a bedpan by a visiting doctor, and asking whether he'd like a fork. Doctors and medical men were much more at ease with examining stools, and also, like Paracelsus, in endeavouring to make use of it in medicine, either by recommending it be ingested or applied to the skin in one form or another. I don't know the medical grounds for that, but I was fascinated to learn that fecal transfusions are now used to treat severe cases of MRSA, a "superbug." A relative's feces can supply healthy bacteria that somehow defeats MRSA when conventional treatment didn't.

Which is why I don't like the word "waste." Human excrement can be and has been turned into snuff (in those filthy 17th century courts, it was dried, ground into powder, and sniffed as "poudrette"); bricks; fuel; jewellery; art, and - which brings me to Carl and Caroline's posts - fertilizer. Carl is right that human "waste" contains the exact nutrients - potassium, phosphorus and nitrogen - that farmers pay a fortune for in the form of artificial fertilizer. Biosolids people will say that that's why biosolids make sense (not least because phosphate reserves are finite and running out), to which one response is, but what about everything else that's in sewers? Fred's list of pharmaceuticals and unpleasant chemical compounds, for a start. And industrial waste, heavy metals, hospital waste. I remember meeting a manager at a huge London wastewater treatment plant who was baffled by how many hospital aprons he kept having to fish out of his filters. Anything goes down a toilet, drain or sewer, and much of it is not good, and some of it surely ends up in biosolids. Pure, safely composted human excrement is an excellent fertilizer. And Carl is right when he suggests that these nutrients - in the form of human excreta - should ideally be separated from technical/industrial waste in the sewage stream. I would love to see that happen. But - and this is where I diverge from Caroline and Carl and other eco-san people, possibly wrongly - I don't see yet how that is possible. The trouble with the flush toilet and the waterborne treatment paradigm is that at least for the user, it works brilliantly in that it requires very little input (aside from the obvious), little responsibility and not much upkeep. Also, the flush toilet can be located inside a house, doesn't smell and really is an extremely user-friendly waste disposal unit. I'm not saying there aren't huge problems further down the line, or that waterborne sewerage isn't to say the least odd and perhaps even ludicrous. But for the average Joe (plumber or no), the toilet is for now unbeatable. I have spoken to sanitation experts who have been attempting for years to persuade people in developing countries to invest in ecological sanitation such as composting toilets or latrines. They have enormous difficulty doing so, because people simply can't be bothered. That, as much as persuading wastewater treatment officials who think their system is unassailable, is a huge hurdle to overcome, no matter how much I may agree with Caroline's description of current sludge use as "pollution transfer." ( I wasn't "promoting" the use of Class A biosolids, by the way. As I don't know the answer to the million dollar question of whether sludge is indisputably safe or not, I preferred to simply ask the questions, and I described Class A from the perspective of the biosolids people who are proud of their product. I was neither promoting nor otherwise, but describing. I hope.)

That gloom aside, I am heartened by the fact that 20 years ago, perhaps it could have been thought that the general public would never dream of spending minutes or hours every week sorting through their rubbish and putting outside to be collected. But recycling is pervasive. So perhaps there is hope for the eco-san utopian future of people putting out their composted excreta after all. I agree with Fred that there is enormous enthusiasm and innovation from some professionals working in the field. But mostly what I've encountered, certainly in the rich world, is frustration rather than idealism.