抄録
Though alkylphenol ethoxylates (APEOs) are hydrophilic, their biologicial degradation by-products, alkylphenols (APs), are hydrophobic and are known to affect the endocrine system. Therefore, it is necessary to decompose the aromatic ring of APs and APEOs before their load to the environment, as the biological decomposition of them is very difficult.
In this study, we focused on decomposition characteristics of nonylphenol ethxylates (NPEs) by ozonation (O3) and ozone/hydrogen peroxide process (O3/H2O2). Acetate, oxalate, and formate ions were detected as their oxidation by-products. The aromatic ring was easily broken down by O3 alone, however the higher decomposition ratio of NPEs to acetic acid was achieved by using smaller doses of ozone with hydrogen peroxide. For example, at ozone gas concentration of 1.9mg·l-1, the ozone dose required to degrade NPEs (10μM) to acetic acid of 154μM (i.e., 88% decomposition) was 70μM O3 with H2O2 dose of 76μM, while 392μM O3 without H2O2 (O3 alone).
It was confirmed that O3 and O3/H2O2 processes could be used to increase the biodegradability of recalcitrant; smaller doses of ozone can be sufficient to change the structure of the recalcitrant, making it more amenable to bacteriological breakdown.
