de Oliveira Karine Goulart, Jokipii-Lukkari Soile, Luukkonen Tero
Fibre and Particle Engineering Research Unit, University of Oulu, Oulu, Northern Ostrobothnia, 90014, Finland.
Department of Chemical Engineering, Universidade Federal de Santa Catarina, Florianópolis, State of Santa Catarina, 88040-900, Brazil.
Open Res Eur. 2024 Feb 12;4:26. doi: 10.12688/openreseurope.17101.1. eCollection 2024.
Stone wool is commonly used as a plant substrate in soilless cultivation and discarded after one growing season. Stone wool waste is difficult to recycle, and thus it is typically landfilled. Alkali-activation of stone wool (i.e., milling and mixing with an alkaline solution) has been shown to be a feasible way to upcycle this waste fraction into, for example, construction products. In this study, the aim was to develop recycled plant substrate from stone wool waste from greenhouses via alkali activation.
Waste stone wool from greenhouses was characterized by X-ray fluorescence (XRF) and mixed with sodium silicate solution either directly or after ball milling. The alkali-activation process was combined with the addition of H O , pre-made foam, or granulation to obtain suitable porous material for the plant substrate application. Preliminary greenhouse cultivation experiments of pea ( ) were conducted with alkali-activated stone wool mixed with peat (a weight ratio of 1:1) and fertility analysis of the mixture were conducted.
The results indicated that the most feasible production method was to use ball-milled stone wool and to combine alkali activation with granulation. The obtained granules could reach 2.7 MPa as compressive strength while the other methods resulted in very fragile material. The preliminary greenhouse cultivation experiments revealed that there were significant levels of nutrients (Ca, P, K, and S) and alkalinity leached from the granules which hindered the growth of pea. The high P and S amounts were also confirmed by the XRF results of stone wool.
It can be concluded that the developed granules did not function well as a plant substrate for pea but could enable the re-utilization of the nutrients contained in the greenhouse stone wool waste. Moreover, their application to acidic sulfate soils could be feasible as it would utilize the alkalinity of granules.
岩棉通常用作无土栽培中的植物基质，在一个生长季节后被丢弃。岩棉废料难以回收利用，因此通常被填埋。岩棉的碱活化（即研磨并与碱性溶液混合）已被证明是将这种废料升级转化为例如建筑产品的可行方法。在本研究中，目的是通过碱活化从温室岩棉废料中开发出再生植物基质。
通过X射线荧光光谱法（XRF）对温室岩棉废料进行表征，并将其直接或在球磨后与硅酸钠溶液混合。碱活化过程与添加过氧化氢、预制泡沫或造粒相结合，以获得适用于植物基质应用的合适多孔材料。用碱活化岩棉与泥炭（重量比为1:1）混合进行豌豆的初步温室栽培实验，并对混合物进行肥力分析。
结果表明，最可行的生产方法是使用球磨后的岩棉，并将碱活化与造粒相结合。所获得的颗粒抗压强度可达2.7兆帕，而其他方法得到的材料非常易碎。初步温室栽培实验表明，从颗粒中浸出了大量的养分（钙、磷、钾和硫）和碱，这阻碍了豌豆的生长。岩棉的XRF结果也证实了磷和硫的含量很高。
可以得出结论，所开发的颗粒作为豌豆的植物基质效果不佳，但可以使温室岩棉废料中所含的养分得到再利用。此外，将它们应用于酸性硫酸盐土壤可能是可行的，因为这将利用颗粒的碱性。
