Purpose

The study aimed to determine the effect of the addition of innovative combinations of organic-mineral mixtures obtained from biochar (BC), zeolite (Z), soil (S), poultry litter (PL), and slurry (SL) to post-flotation sediment (PFS) on (i) heavy metal mobility, (ii) heavy metal accumulation in willow, and (iii) PFS respiratory activity.

Materials and methods

The tests were carried out under laboratory conditions in containers with 500 g of PFS, to which 1% (w/w) of organic-mineral mixtures were added. Willow was grown for 90 days on substrates with the addition of organic and mineral mixtures.

Results and discussion

The addition of mixtures BC + Z + S + PL and BC + Z + S + SL to PFS significantly reduced the pH to, respectively, 7.12 and 7.02. This can be attributed to the release of the hydrogen load combined with organic anions deriving from the mineralisation of organic materials and the nitrification process. The addition of BC + Z and BC + Z + S mixtures to PFS reduced the content of Zn-H₂O by 65%, Cd-H₂O by 48%, and Ni-H₂O by 30%. The addition of BC + Z + S + PL and BC + Z + S + PL mixtures to PFS increased the content of water-extracted Pb, respectively, 40 and over 60 times. The content of bioavailable heavy metals (extraction with 1 M NH₄NO₃) in PFS was comparable in all treatments to which mixtures were added. Altered mobility of heavy metal ions may be associated with a change of substrate properties, including redox potential, pH value, as well as the introduction into the soil of materials with significantly developed sorption surfaces. In the first 2 weeks of incubation of mixtures with PFS, respiratory activity was very low, except for that in BC + Z + S + PL and BC + Z + S + SL treatments. In these treatments, oxygen consumption was more than 50 times higher compared to the control treatment and more than 10 times higher in relation to BC + Z and BC + Z + S treatments.

Conclusions

The mixtures of BC + Z and BC + Z + S effectively reduced the content of water-extracted heavy metals in PFS. BC + Z + S + PL and BC + Z + S + PL mixtures were not effective in reducing water-extracted mobile heavy metals in PFS. The introduction into PFS of mixtures partially composed of biologically unstable materials (PL, SL) increased the biochemical activity measured by respiratory activity and reduced biomass increment of willow aerial parts. The adverse response of willow to the introduction of mixtures with poultry litter or slurry into PFS indicates the need to verify the amount of these materials in the mixtures or to stabilise them by biological or thermal processes.

Graphical abstract

中文翻译：

---

浮选后沉积物废物的植物稳定作用：重金属的迁移和矿物-有机混合物对生化过程的刺激

目的

该研究旨在确定在浮选后添加从生物炭（BC），沸石（Z），土壤（S），家禽垃圾（PL）和浆液（SL）获得的有机矿物混合物的创新组合的效果（i）重金属迁移率，（ii）柳树中的重金属积累和（iii）PFS呼吸活动的沉积物（PFS）。

材料和方法

在实验室条件下，在装有500 g PFS的容器中进行测试，向其中添加1％（w / w）的有机矿物质混合物。在添加有机和矿物混合物的基础上，柳树生长了90天。

结果和讨论

向PFS中添加BC + Z + S + PL和BC + Z + S + SL混合物将pH值分别显着降低至7.12和7.02。这可以归因于释放的氢负荷与源自有机材料矿化和硝化过程的有机阴离子相结合。在PFS中添加BC + Z和BC + Z + S混合物可将Zn-H ₂ O的含量降低65％，将Cd-H ₂ O的含量降低48％，将Ni-H ₂ O的含量降低30％。向PFS中添加BC + Z + S + PL和BC + Z + S + PL混合物分别将水提取Pb的含量提高了40倍和60倍以上。可生物利用的重金属含量（用1 M NH ₄ NO ₃萃取在添加了混合物的所有处理中，PFS中的）是可比的。重金属离子迁移率的变化可能与底物性质的变化有关，包括氧化还原电势，pH值，以及将具有明显发展的吸附表面的材料引入土壤。在与PFS孵育混合物的前两周中，除BC + Z + S + PL和BC + Z + S + SL处理外，呼吸活动非常低。在这些处理中，与对照处理相比，耗氧量高出50倍以上，与BC + Z和BC + Z + S处理相比，耗氧量高出10倍以上。

结论

BC + Z和BC + Z + S的混合物有效地降低了PFS中水提取的重金属的含量。BC + Z + S + PL和BC + Z + S + PL混合物不能有效减少PFS中水提取的移动重金属。将部分由生物不稳定材料（PL，SL）组成的混合物引入PFS，可以提高通过呼吸活动测得的生化活性，并减少柳树空中部分的生物量增量。杨柳对将带有家禽垫料或泥浆的混合物引入PFS的不良反应表明，需要验证混合物中这些物质的量或通过生物或热过程稳定它们。

图形概要