Jeon SK  Shin HA  Kim DJ

Vol. 24,  No. 2, pp. 87-98, Jun.  2018
10.7464/ksct.2018.24.2.087

Bioavailability Heavy metals Phosphorus recovery Sewage sludge ash Thermochemical treatment

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Phosphorus (P) is an essential and irreplaceable element for all living organisms, and it is widely used as a fertilizer. Unfortunately, it is estimated that phosphate reservoir is depleted within about 100 years. Sewage sludge ash (SSA) is an alternative resource for P recovery because of its high P content. However, SSA cannot be directly used as a fertilizer due to heavy metals in it and low P bioavailability. Thermochemical treatment with Cl donor is known to reduce heavy metal contents and increase P bioavailability of SSA. Literature review on thermochemical technologies of SSA for the reduction of heavy metals and bioavailability enhancement has been carried out to estimate the status of current P recovery technology and to develop strategic future research plan for P recovery. The review showed that CaCl2 and MgCl2 were the most effective Cl donors and reaction temperature (<1000 ℃) was the critical operation condition for the reduction. The removal efficiency depends on the species of heavy metals. Thermochemical technology of SSA for P recovery showed the possibility of commercial application in the near future to overcome the coming crisis of human sustainability by P depletion, but it needs cost effectiveness and more ecofriendly process to reduce energy consumption.