Hydrothermal treatment (HT) is an appropriate treatment method for organic hazardous wastes such as antibiotic fermentation residue (AR). However, there is no effective way to recycle hydrolysate with high nitrogen content. In this study, penicillin fermentation residue (PR, a type of AR) was used as raw material to study the release and redistribution of N during hydrothermal process. And the influences of pH, ion ratio and reaction time on the preparation of struvite were analyzed. The results showed that the nitrogen in PR consists of Inorganic-N and Amino-N. Most of N (~70%) that entered hydrolysate was converted into org-N, NH4+-N and NO3--N. At 260 °C, the NH4+-N concentration was 2842.78 mg/L, accounting for 45.2% of total nitrogen. The remaining amino-N in the hydrochar was gradually converted to pyridine-N, pyrrole-N and quaternary-N with the increasing of temperature. At pH = 9.5, Mg2+: NH4+: PO43- = 1.3: 1: 1.15, struvite was prepared by hydrolysate. And over 95% removal rate of NH4+-N could be achieved. XRD analysis showed that the main component of the product was struvite, which was further confirmed by SEM-EDX and FT-IR. It was found that there was trace amount of MgKPO4·H2O precipitation in the product. In addition, Mg3(PO4)2 precipitation might also be formed at pH = 10.
Keywords: Hydrolysate; Hydrothermal treatment; Penicillin fermentation residue; Struvite.
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