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回収した凝集剤を用いた化学強化一次処理における微小汚染物質の動態
Fate of micropollutants in chemically enhanced primary treatment using recovered coagulants.
PMID: 32561017 DOI: 10.1016/j.jenvman.2020.110815.
抄録
本研究では、新鮮なアルミニウムと鉄の凝集剤を用いて、凝集による廃水中の複数の微小汚染物質（MP）の運命を決定した。抗生物質、食品添加物、界面活性剤などの異なるグループから18種類のMPを選択し、地元の廃水処理場から回収した一次流入水に添加した。回収された凝集剤と凝集後の処理排水中のMPsの分布を、新鮮な凝集剤とリサイクルされた凝集剤の両方について測定した。凝集後の廃水にはlog Kが2.5未満のMPが多く存在し、log Kが2.5を超えるMPは凝集汚泥に吸着していた。対数Kが2.5以上のMP（ジクロフェナク,クラリスロマイシン等）について、凝集剤のリサイクルによる汚泥への蓄積の程度とともに、その分布比（K）を測定した。スルファメトキサゾール，エリスロマイシン，スルファチアゾールなどは，凝固時の除去率が低かった。テトラサイクリン系化合物は鉄やアルミニウムとのキレート化の可能性を示した。log K＞2.5のMPは10%未満であったが、回収された凝集剤と一緒にリサイクルされており、凝集剤のリサイクル時にMPが蓄積する懸念を軽減することができた。
In this study, the fate of several micropollutants (MPs) in wastewater due to coagulation using both fresh and recovered aluminum and iron coagulants was determined. 18 MPs from different groups such as antibiotics, food additives, and surfactants were selected and spiked into the primary influent collected from a local wastewater plant. The distribution of MPs in the recovered coagulant and treated effluent after coagulation was determined for both fresh and recycled coagulants. The distribution of MPs in wastewater and the removal during coagulation were compound specific; MPs with log K < 2.5 were predominantly present in the effluent after coagulation, while MPs with log K > 2.5 were sorbed on the coagulated sludge. The distribution ratio (K) of all the MPs (diclofenac, clarithromycin, etc.) with log K > 2.5 was determined along with their extent of accumulation in sludge due to the recycling of coagulants. Compounds such as sulfamethoxazole, erythromycin and sulfathiazole, showed low removal during coagulation. The tetracycline group of compounds showed possible chelation with iron and aluminum. Only <10% of the initially spiked MPs with log K > 2.5 was being recycled with the recovered coagulant, thus alleviating the concern of accumulation of the MPs during recycle of the coagulants.
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