Saturday, January 05, 2008

When you flush, where do the solids go? What happens to the waste water? Q4 of the Big Here Quiz

Because my home is in the Riverfront Sanitary Drainage System (pdf), my educated guess is that the solids and wastewater make its way to the Lou Romano Water Reclamation Plant for treatment.

The facility, which discharges into the Detroit River, is believed to be the largest primary treatment plant discharging into the Great Lakes basin. The Detroit River Canadian Cleanup Committee, a community based organization working to improve the health of the Detroit River, recommended the treatment upgrade to local officials some time ago. The city is adding secondary treatment capability to produce cleaner effluent.

The biosolids "are heat dried and pelletized at a plant on Sandwich Street, operated by Prism Berlie Windsor Ltd. The finished pellets are used as a fertilizer and soil conditioner."

While the Windsor product is 3-5-0 on the N, P and K scale, it is also heavy in micronutrients and adds moisture retention characteristics to the soil. It's also a soil conditioner with high organic matter. Application rates vary from three to four tonnes per acre, based on the following crop and a soil tests.

The biosolids are roughly 65 per cent organic matter and take years to break down so the benefits are gradual, he says. Both active pathogens and cysts are killed in the pasteurizing heat treatment.

The Windsor sludge is of particular value because analysis shows it to be low in lead, cadmium and mercury, which have no place in the soil matrix. There is a decade of data backing claims about this product, he says. Bernie Calhoun cash crops more than 800 acres near Essex and says that over the years sewage sludge has helped his farm a lot by adding organic matter. He considers it a good substitute for cattle manure. He has used the pellets as well, but says "I like it for free, I don't want to pay for it," stressing that human biosolids have a pejorative sound, especially to non-farm rural neighbours.

1 comment:

kendallsc said...

Thanks for educating your readers re this largely invisible topic; worth noting that food scraps processed through a food waste disposer/garbage disposal also end up in biosolids (instead of landfills), and help to further improve the quality of biosolids - making disposers a compelling environmental management tool in completing the cycle of returning organic waste back to soil.