12/29/10

A Call for More Use of Human Excreta

Goal is to Address Peak Phosphorus Concerns....

A December 2010 report from the UK Soil Association urges mining P from wastewater.... Learn more about the report and see NEBRA's comments....

In a recently released report, the Soil Association, Great Britain's leading organic certification organization, has called for "a change to EU organic regulations to allow the use of human sewage – rich in ‘natural’ phosphate - on agricultural land to ensure phosphate levels are maintained. Globally only 10% of human waste is returned to agricultural soils."
 
Dr. Isobel Tomlinson, the author of the report "A rock and a hard place: Peak phosphorus and the threat to our food security," said: "A radical rethink of how we farm, what we eat and how we deal with human excreta, so that adequate phosphorus levels can be maintained without reliance on mined phosphate, is crucial for ensuring our future food supplies."
 
The Soil Association presents a vision of "ecological sanitation," involving capture of human excreta at the home level, without mixing it with grey water or other wastwater.  This, the report notes, reduces "the risk of potential contamination form heavy metals and organic compounds from industrial sources and domestic greywater."
 
See the Soil Association's news release about decreasing phosphorus reserves.  The full report can be downloaded here.
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NEBRA Comment:

by Ned Beecher, Executive Director

Many in the biosolids management profession welcome the Soil Association's encouragement of the use of human waste on agricultural soils - even for organic crops.  But, the fact is, the Association's vision of human excreta recycling is not the same as modern biosolids/treated sewage sludge recycling.
 
While the approach proposed by the Soil Association is laudable and effective for capturing phosphorus - a critical goal – it would require considerable additional infrastructure at the household and regional level to collect, treat, and utilize the resulting resources.  At the same time, existing domestic and industrial wastewater would continue to require treatment -  but separately.
 
Still, the Soil Association's report does represent  common ground with current biosolids recycling.  Human excreta is a resource.  Ecological sanitation should be pursued and applied widely where appropriate and cost-effective. But there will still need to be centralized wastewater management.  All approaches should strive to maximize the use of the resource.
 
And there is certainly agreement that peak phosphorus is a true and increasingly pressing concern.  It just so happens this concern dovetails positively with increasing concerns in some areas regarding excessive levels of phosphorus in agricultural soils due to repeated applications of animal manures and biosolids.
 
A solution coming from the biosolids management field is to harvest phosphorus from sewage sludge as part of the treatment process, which, for example, the Ostara process does now, for example, in York, PA (see Philadelphia Inquirer article).

So we are heading in the same direction, focused on sustainable soils and wise resource management.  And to further the common ground between the organic food movement and ecological sanitation  and modern biosolids recycling programs, biosolids managers can continue to strive for even higher quality biosolids through efforts to further reduce contaminants upstream.  More industrial pretreatment, pollution prevention, and product stewardship initiatives can address the concerns about trace contaminants in biosolids that keep organizations like the Soil Association from whole-heartedly embracing today's numerous successful biosolids recycling programs.

Oh, and by the way, the Soil Association included in their report, as an appendix, a "response from a water and sewage practioner, Thames Water," which states:

"We welcome this initiative from the Soil Association which will further raise the profile of the issue of limited phosphorus availability, and so generate debate on possible solutions. What is evident is that further research is warranted to understand better the flux of phosphorus in the environment, how much is needed to sustain productive agriculture, and the extent to which phosphorus recovered from domestic sources might contribute to this. Similarly, it would be helpful to understand the practicability, public acceptability and full environmental cost of ecological sanitation – particularly for densely populated urban areas. Further research might also help address the unanswered question regarding the fate of the greywaters generated in domestic dwellings. We can take some comfort that in the UK, a large proportion of domestic phosphorus is already recycled to agricultural land as biosolids (treated sewage sludge) and we have long promoted this as being the best environmental option where land availability and transport costs permit. If this material were to regain approval as suitable for organic farming then this would be a very positive step towards securing this valuable recycling route for phosphorus in the medium and longer term, pending the adoption and deployment of ecological sanitation systems."