Added: 24.08.2010 14:27
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Phosphorus fertilizers from waste water

Phosphorus reserves are depleting in the world, one answer to this looming shortage can be extracting phosphorus from waste water

Phosphorus is an essential fertilizer for the agriculture industry. The demand for fertilizers is expected to grow in coming decades, especially because of growing fertilization in the developing countries. According to some experts, phosphate rock reserves in quarry sites around the world are depleted in roughly 50 years. Even before that the price of the phosphate extracted from this diminishing natural reserve will start to increase and make food production more expensive. This might cause a serious problem for the food supply of the world.
However, one solution to the problem might be closer than we think. Answer may lie in processing domestic sewage, that is, from the wastewater we (people) flush down the toilet every day. Sewage has traditionally been a nuisance because it triggers blooms of algae that deplete local waters of oxygen. In the future this waste could be a valuable raw material of the fertilizer industry.
Phosphorus can be collected from sewage at the wastewater treatment facilities. Once collected, it can be processed to pellets, which can be used as a fertilizer in agriculture just like phosphorus extracted form phosphate rock.
Especially in the future when the price of fertilizers is expected to grow, producing fertilizers form waste is a lucrative business. Even bigger returns than processing domestic sewage, might be gained from processing nutrients from dairy and pig waste (also methane for energy production could be collected in the process). The domestic wastewater industry has enormous potential, but the potential of the agricultural industry is considered even bigger.

Opportunity: conservation of a depleting natural resource, more effective waste water purification

Threat: (no threat?)

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Comments

Typical waste-water contains around 4mg of phosphorus per liter. The question is whether extraction of phosphorus would be practical, i.e. from economical point of view as well as energy consumption and amount of work. Perhaps the effort should be put into investigating if human and animal waste and waste water sludge are safe as fertilizer as such (as waste or byproduct). Several studies show that source separated human urine is good and safe fertilizer (tested at TAMK, Tampere, Finland on cabbage, potatoes and onion).
The problems so far are micropollutants in urine, feces or sludge. Such pollutants are pharmaceutical residues and personal care products that can persist in the environment and affect target or non-target organisms.