From tissue to coagulant
Meftah and colleagues used the green outer part of the stem of Austrocylindropuntia subulata. Material was collected in the Settat region of Morocco. Cleaning, drying, grinding and sieving produced a powder from which an aqueous extract was prepared. The material's surface characteristics and ability to support coagulation and flocculation were studied [Meftah et al. 2024].
Coagulation means destabilisation of fine suspended particles, while flocculation means their aggregation into larger clusters. These flocs can settle faster than dispersed particles. Plant material properties are related to macromolecules and functional groups that can interact with the surfaces of suspension components. The study analysed these properties using methods including infrared spectroscopy [Meftah et al. 2024].
Experimental conditions and results
Trials concerned suspensions and wastewater rich in apatite material from the Khouribga region. Mixing tests were conducted in 1 l beakers. An initial rapid mixing phase was replaced by a slower phase, after which flocs were left to settle. The turbidity of liquid above the sediment and changes in the position of the sediment boundary were measured. Experiments were repeated three times [Meftah et al. 2024].
The authors achieved a strong reduction in turbidity and accelerated settling compared with a sample without added coagulant. The effect varied with suspension concentration and extract dose. The results describe phase separation in a particular mineral system. A full assessment of treated water quality would additionally include dissolved components and microbiology [Meftah et al. 2024].
Storage of powder and extract
Dry powder was stored for a year in a closed container in a dark place. It retained effectiveness in the tests after this time. The aqueous extract was also assessed after storage for six days and three months. Its ability to support sedimentation remained high, although the liquid changed colour and smell, which the authors linked to transformations of its organic components [Meftah et al. 2024].
The difference between the stability of dry biomass and an aqueous preparation matters for process design. It provides information on the form in which raw material can be stored. Reproducibility between plant harvests, extraction parameters and behaviour in other wastewater require separate investigation. Using succulent tissue properties in controlled particle separation is biologically interesting [Meftah et al. 2024].
Miller and colleagues’ work on Opuntia spp. supplies an independent reference. They combined dose changes with zeta-potential measurements and kaolin-floc images. Negative potential persisted during successful aggregation, while microscopy showed clay particles distributed along a thread-like matrix. Reduced activity after excessive material addition completed a pattern consistent with macromolecular bridging [Miller et al. 2008].
This coagulation-mechanism comparison distinguishes two levels of description. Infrared spectra identify chemical groups in a preparation, while particle behaviour and floc shape help establish how particles join. For Austrocylindropuntia subulata, combining these measurements with sedimentation would connect extract properties more closely with apatite-suspension separation. Wastewater composition and raw-material preparation remain part of the comparison [Miller et al. 2008] [Meftah et al. 2024].
The state of stored material adds another process variable. In the Opuntia experiments, intensive blending of fresh tissue and strong heating changed activity, which the authors related to changes in the mixture or its interactions. Comparison with dry powder and stored Austrocylindropuntia extract supports assessing each preparation under its own conditions. Settling-rate measurements can then be combined with liquid composition and the condition of the stored material [Miller et al. 2008] [Meftah et al. 2024].
Prepared from scientific publications. Accepted names were checked in POWO on 9 October 2026.
Extraction and optimization of Austrocylindropuntia subulata powder as a novel green coagulant
Meftah K., Meftah S., Lamkhanter H., Bouzid T., Rezzak Y., Touil S., Abid A., Extraction and optimization of Austrocylindropuntia subulata powder as a novel green coagulant, Desalination and Water Treatment, 2024, 318:100339, doi: 10.1016/j.dwt.2024.100339
Experiments on the use of powdered Austrocylindropuntia subulata chlorenchyma to coagulate and flocculate suspensions. They include material characterisation, sedimentation and turbidity removal tests, and the stability of dry powder and aqueous extract. The results concern specific mineral effluents and laboratory mixing conditions.
Toward Understanding the Efficacy and Mechanism of Opuntia spp. as a Natural Coagulant for Potential Application in Water Treatment
Miller S. M., Fugate E. J., Oyanedel Craver V., Smith J. A., Zimmerman J. B., Toward Understanding the Efficacy and Mechanism of Opuntia spp. as a Natural Coagulant for Potential Application in Water Treatment, Environmental Science & Technology, 2008, 42(12):4274-4279, doi: 10.1021/es7025054
A laboratory experiment on removing turbidity from a kaolin suspension using Opuntia spp. material. The authors compare doses, pH, electrolytes and processing of the raw material. Zeta potential measurements and TEM images support a mechanism of particle adsorption and bridging by polymer components.
