分享一篇文献：利用富铁污泥制得的生物炭从厌氧消化液中回收磷：一种潜在的磷肥

通讯作者：杨家宽

第一作者：Wang hui

通讯单位：华中科技大学环境科学与工程学院

论文DOI：10.1016/j.watres.2020.115629

https://doi.org/10.1016/j.watres.2020.115629

亮点

·利用富铁污泥制得的生物炭可以回收厌氧消化液中的磷；

·Fe−300生物炭对磷的最大吸附量为1.843 mg/g；

·化学沉淀吸附70%磷，物理吸附30%磷；

·化学沉淀吸附的磷可由Pseudomonas aeruginosa释放；

·Fe−300生物炭提高了种子发芽率，增加了草茎长度。

摘要

    本文研究了一种利用富铁污泥(经Fenton试剂处理的脱水污泥)制得的生物炭从厌氧消化液中回收磷的新技术。富铁污泥经过低温300℃热解后制得的生物炭(简称Fe-300生物炭)对磷(大部分为正磷酸盐和焦磷酸盐)的吸附能力优于高温500 ~ 900℃热解后的生物炭的吸附能力，对厌氧消化液中磷的最大吸附量为1.843 mg/g (Fig. 1)。吸附等温线采用二元Langmuir-Langmuir模型，以磷酸二氢钾(KH2PO4)为模型溶液进行模拟，结果表明70%的磷是通过与Fe元素发生化学反应沉淀去除的，其余30%的磷是通过Fe−300生物炭表面的物理吸附去除的(Fig. 2)。添加吸附了大量磷元素后的Fe−300生物炭能使种子发芽率提高至92%，而未添加生物炭的种子发芽率为66% (Fig. 5)。此外，Pseudomonas aeruginosa能促进Fe−300生物炭表面沉淀的磷酸氢铁分解释放磷，培养20 d后磷的总释放量为3.045 mg/g (Fig. 6)。本研究表明，利用富铁污泥制得的生物炭可以作为一种新型的有益功能材料用于厌氧消化液中磷的回收。生物炭回收的磷能作为磷肥在园林土壤中重新利用，从而提高厌氧消化液和富铁污泥的附加值。

Fig. 1. Comparison of TP removal efficiencies of biochar (300–900 °C) samples derived from the RS and the Fe−rich sludge for the adsorption of (a) the KH2PO4 solution, and (b) the liquid phase of anaerobic digestate. (c) Desorption efficiency and P adsorption capability of the Fe−300 biochar in the KH2PO4 solution during five successive adsorption−desorption cycles.

Fig. 2. (a) Adsorption kinetics, (b) adsorption isotherm using Langmuir and Freundlich models, and (c) adsorption isotherm using a dual Langmuir-Langmuir model of the Fe−300 biochar for phosphorus adsorption in the KH2PO4 solution. Symbols represent the experimental data, and lines represent the modelled results.

Fig. 3. XRD patterns of Fe−300 biochar (Fe−300) (a) before and (b) after phosphorus adsorption for the KH2PO4 solution (Fe−300−KH2PO4) with the Fe−300 biochar dose of 1 g/ L.

Fig. 4. XPS Fe 2p spectra of (a) Fe−300 biochar (Fe−300) before, (b) after P adsorption for the KH2PO4 solution (Fe−300−KH2PO4), and (c) Fe−300 biochar after P adsorption for the liquid phase of anaerobic digestate (Fe−300−AD); XPS P 2p spectra of (d) Fe−300 biochar (Fe−300) before, (e) after P adsorption for the KH2PO4 solution (Fe−300−KH2PO4), and (f) Fe−300 biochar after P adsorption for the liquid phase of anaerobic digestate (Fe−300−AD). CPS denotes the counts per second.

Fig. 5. Comparison of (a) grass seed germination rate, (b) the shoot length of grass seedlings loaded with different biochars, and (c) the photo of grass seedlings laden with different biochars.

Fig. 6. The content of P released from the Fe−300 biochar after P adsorption for the liquid phase of anaerobic digestate (Fe−300−AD) while incubated with P. aeruginosa for 20 days.

Fig. 7. A sustainable sludge recycling strategy to develop a potential P fertilizer recovered from waste activated sludge and anaerobic digestate.