【地域資源開発学科】熱処理された汚泥からのリン抽出とアルミニウムの分離

Hiroyuki Harada, Endar Hidayat, Seigo Uemoto & Keiko Fujita

Because global phosphorus (P) resources are limited, the continued supply of this element is a concern, and the recovery of P from waste is desirable. Carbonized sludge contains aluminum (Al) and iron (Fe) as a result of the addition of coagulants added during dewatering, which hinders the effective use of recovered P. Therefore, it is necessary to develop recovery methods that extract P but not Al or Fe. Zirconium was loaded onto orange waste, a cheap and available agricultural waste in Japan, to investigate the feasibility of its utilization for phosphorus recovery. In the present study, a biomass adsorbent was applied to the selective adsorption of P following extraction using 0.25 mol/l sulfuric acid. This process, based on a batch adsorption system employing a solid-to-liquid ratio of 50 mg/ml or more, was found to adsorb close to 100% of the P but less than 6% of the Al. When the adsorbent was separated and treated with a 0.25 mol/l sulfuric acid solution at a solid-to-liquid ratio of 20 mg/ml, about 75% of the Al was removed but none of the P. Immersion in a NaOH solution was able to strip the P from the adsorbent, giving P and Al concentrations in the desorption solution of 800 and 3 mg/l, respectively.

　リン資源は有限であり、枯渇が見込まれている。そのため環境に排出すされた固形物などから回収技術を確立させることが重要である．下水汚泥の炭化物は凝集剤に起因するアルミニウムや鉄を含むのでリサイクルを促進するためにはこれらの成分を分離することが求められる。ミカンジュース搾りかすにジルコニウムを担持し、リンを吸着する。この吸着剤を0.25mol/lの硫酸溶液で洗浄することで同時に吸着したアルミニウムの75%を効率的に分離できることを明らかにした。