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Options Abound For Improving Phosphorus Management

“The underlying problem leading to food waste stems in part from consumer behaviours supported by an economic system built to produce more than we need.”

Anew report by the International Institute for Sustainable Development outlines several avenues that could be explored to improve phosphorus management:

Another case for local food networks: “Cycling phosphorus exported in food products back to the land requires effort. This can be challenging due to the distances between food production and consumption. In North America, for example, a meal generally travels 1,500 kilometres from origin to plate. Facilitating the recovery and recycling of phosphorus sources is therefore imperative.”

Phosphorus recovery from waste water treatment: The report’s authors say this is one of the most promising areas of research worldwide. There are several pilot programs underway.

Struvite extraction from waste water: Phosphorus and ammonium can be recovered from waste water in the form of struvite, a magnesium-ammonium-phosphorus precipitate. Ostara, a Vancouver-based corporation, has invented a technology used to recover phosphorus from waste water using struvite so that it can be converted into a slow-release fertilizer, magnesium ammonium phosphate or MAP.

The report says these developments present a huge opportunity for the City of Winnipeg looking to recoup some of the billion or so dollars it must spend to upgrade its waste water treatment. A struvite recovery system would prevent waste water return pipes from clogging and produce a substantial amount of fertilizer (potentially more than 500 tonnes per year), which could be sold to the agricultural sector.

Controlling food waste and recapturing phosphorus through composting: “Food waste must be reduced and disposed of in a manner that recycles phosphorus back to the land to support further plant growth. This includes finding alternatives to landfills for disposal of organic substances.”

It is estimated that up to 40 per cent of all food is wasted worldwide. “The world’s hungry could be fed more than seven times over with food waste originating from Europe and the United States alone,” the report said. “Other studies point out that large amounts of all fruits and vegetables produced never see the inside of a supermarket, since they don’t meet size and structure regulations.”

“The underlying problem leading to food waste stems in part from consumer behaviours supported by an economic system built to produce more than we need.”

Treatment of sewage sludge: Sewage sludge that contains more than 300 organic pollutants and pathogens, including hormones, antibiotics, and heavy metals such as cadmium and zinc, can be treated using monocombustion that concentrates phosphorus and heavy metals through mass loss. The report says the ash offers less-favourable phosphorus availability than biosolids but the final product surpasses most European environmental standards for fertilizers in terms of permissible heavy-metal content.

Improved agricultural practices: Within the Lake Winnipeg Basin opportunities abound to better use, recover and recycle phosphorus, the report says. Livestock in the basin emit approximately 166,283 tonnes of phosphorus per year, and potential non-point emissions originating from croplands range from 1,851 to 33,191 tonnes of phosphorus per year, and point sources (from industrial and municipal waste water) emit approximately 1,635 tonnes of phosphorus per year. Recovering and recycling this phosphorus could potentially displace costly mineral fertilizers.

As well, the report noted practices such as no till promote the growth of mycorrhizal fungi, which are central to phosphorus absorption by many crops. “In 2006, approximately 33,000 farms reported using conventional tillage on 5.33 million hectares of land. There are clearly many opportunities in the Lake Winnipeg Basin to lessen our dependence on rock phosphate-derived mineral fertilizers.” [email protected]

About the author

Vice-President of Content

Laura Rance

Laura Rance is vice-president of content for Glacier FarmMedia. She can be reached at [email protected]

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