Photo/Illutration Nagoya city authorities are set to begin marketing fertilizer generated from sewage sludge. (Provided by the Nagoya city government)

NAGOYA--Sludge generated through sewage treatment is set to be marketed by city officials here as the perfect fertilizer rich in nitrogen and phosphorus.

Nitrogen is an indispensable ingredient to the growth of plants. As for phosphorus, Japan relies mostly on imports, but its prices are continuing to soar.

Officials are hoping to market 1,000 tons of sludge-derived fertilizer annually.

Sewage sludge is mostly comprised of dead bodies of microorganisms that have ingested and decomposed  human waste.

Around 20,000 tons of sewage sludge is generated in Nagoya every day.

City authorities also incinerate sludge. The ash that is left can be used as a raw material to make cement. In addition, sludge can be dried out for reuse, among other things, as solid fuel.

In the past, sewage sludge seldom featured as fertilizer though it was recognized as containing key ingredients that promote plant growth.

The central government, however, changed course last year and initiated an aggressive campaign to promote the use of sewage sludge as fertilizer.

This was due to a sharp rise in the price of phosphorus and other raw materials stemming partly from the crisis in Ukraine and a global rise in demand for grain.

Fertilizer derived from sewage sludge is now permitted on condition its product quality is guaranteed through regular ingredient analysis.

Nagoya city officials decided that the solid fuel they are already producing can be repurposed, just as it is, for use as fertilizer.

Plans are afoot to produce around 7 tons of fertilizer a day at a special-purpose treatment plant in the city’s Minato Ward.

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