图文导读
P
形态调控方法设计
Fig.
1
.
Schemes of P recovery from sewage sludge and the design principle of our technical route.
(a)
Conventional technical route (Conv-Tech);
(b)
Our technical route (HyperPhos
℗
);
(c)
The upper part shows the dominant pH intervals of the solubility of Fe-P, Al-P, Ca-P, and Mg-P. The wider with of the band shows the smaller solubility of the P species. The lower part shows the pH of the pretreated sludges.
(d)
Thermodynamic analysis of the formation reactions of different P species under different reaction temperatures. lgK > 5 means the reaction is complete in a thermodynamically spontaneous manner.
(e)
P species transformation in the pretreated sludges.
研究团队通过反应热力学分析，发现
Fe/Al-P
在
pH
为
3~6
、反应温度为
150~250 ℃
存在特异性生成反应窗口。基于小组前期开发的碳基骨架辅助水热预处理技术，在实现污泥脱水性能优化与燃料特性改善的基础上，通过木质纤维素类组分自分解产酸精准调控体系
pH
至目标区间，在无需外源
Fe/Al
投加的情况下实现水热环境下有机
P
向
Fe/Al-P
的转化，并采用全国多批次污泥验证了预处理技术的适用性。
焚烧灰
P
回收路线：
P
的强化富集、靶向溶出及高值产物回收
Fig.
2
.
Phosphorus footprint during P-enrichment process
.
(a)
Distribution of phosphorus in dewatering products.
(b)
Distribution of phosphorus
in the incineration products.
(c)
Comparative analysis of the phosphorus resource grades between the incineration ashes and the commercially mined raw P-ores worldwide.
灰中
P
的强化富集：
通过液体核磁、
P
结合形态分析等手段，发现预处理过程中有机磷、磷酸单酯、焦磷酸盐等不稳定态
P
均被转化为高热稳定性的
Fe/Al
正磷酸盐，
1000 ℃
下
P
的挥发损失仅为原泥的
60%
，所得富磷焚烧灰资源品位与当前不同国家典型商业开采磷矿的产品品级相当，灰中
Fe/Al-P
占比始终高于
72%
。
Fig.
3
.
Selective phosphorus leaching with ultra-low solvent concentration.
Phosphorus leaching efficiency of Conv-Tech using
(a)
acid leaching and
(b)
alkali leaching. Phosphorus leaching efficiency of HyperPhos
℗
using
(c)
acid leaching and
(d)
alkali leaching. C
omparison of the phosphorus leaching efficiency and the solvent concentrations between HyperPhos
℗
and the literature using
(e)
acid leaching
and
(f)
alkali leaching.
Note that the number of theoretically ionizable H
+
and OH
-
varies with the acid or alkali (e.g., H
2
SO
4
has two H
+
but HCl has only one H
+
), we use the total theoretically ionizable H
+
and OH
-
as the functioning component contents to measure the strength of the leaching reagents.
C
omparison of the heavy metal co-dissolution rates between HyperPhos
℗
and the literature using
(g)
acid leaching
and
(h)
alkali leaching.
Fe/Al-P
的强化浸出：
发现
H
2
C
2
O
4
与
NaOH
适用于富
Fe/AlPO
4
焚烧灰中
P
的溶出，
C
2
O
4
2-
/OH
-
通过与
Fe/AlPO
4
发生还原反应及螯合置换等协同作用促进
P
的释放，此时
P
浸出率最高达到
99.5%
（酸浸）与
85.0%
（碱浸），所需浸出液浓度远低于文献平均水平，重金属等杂质的共溶率也显著降低。
Fig.
4
.
High-grade P-rich product recovery without CER purification and pH adjustment.
(a-d)
The different leachates and the recovered products of Conv-Tech and
HyperPhos
℗
.
Note that the CER purification process is applied to Conv-Tech
whether using acid or alkali leaching.
(e-h)
XRD patterns comparison between the recovered products and the commercial products.
(i-l)
SEM images of the recovered products.
(o-p)
Assessment of whether the products meet the relevant application standards.
(q-t)
The global phosphorus mass flow and the overall P-recovery rates.
浸出液中
P
的高效回收：
通过热力学平衡分析确定
P
产物的单独沉淀区间，开发了热诱导等高值
P
产物的选择性回收方法。在省略
CER
净化、
pH
调节的前提下，利用浸出液中的共溶金属离子直接回收得到了
FePO
4
、
AlPO
4
和羟基磷灰石，产物纯度满足土地利用标准和工业应用要求。
直接土地利用路线：
P
生物有效性的系统评价
