An overview on the key advantages and limitations of batch and dynamic modes of biosorption of metal ions.

Water purification using adsorption is a crucial process for maintaining human life and preserving the environment. Batch and dynamic adsorption modes are two types of water purification processes that are commonly used in various countries due to their simplicity and feasibility on an industrial scale. However, it is important to understand the advantages and limitations of these two adsorption modes in industrial applications. Also, the possibility of using batch mode in industrial scale was scrutinized, along with the necessity of using dynamic mode in such applications. In addition, the reasons for the necessity of performing batch adsorption studies before starting the treatment on an industrial scale were mentioned and discussed. In fact, this review article attempts to throw light on these subjects by comparing the biosorption efficiency of some metals on utilized biosorbents, using both batch and fixed-bed (column) adsorption modes. The comparison is based on the effectiveness of the two processes and the mechanisms involved in the treatment. Parameters such as biosorption capacity, percentage removal, and isotherm models for both batch and column (fixed bed) studies are compared. The article also explains thermodynamic and kinetic models for batch adsorption and discusses breakthrough evaluations in adsorptive column systems. The review highlights the benefits of using convenient batch-wise biosorption in lab-scale studies and the key advantages of column biosorption in industrial applications.

Effectiveness of Opuntia ficus indica (cactus) fruit juice for sludge conditioning.

The possibility of using Opuntia ficus indica fruit juice (OFIFJ) as a bioflocculant for conditioning the synthetic kaolin sludge and sewage sludge (region Oran, Algeria, and Pau, France) was studied. Turbidity of the supernatant, dryness of the sludge cake, and total time of filtration (TTF) were examined parameters. Using vacuum filtration, lime was also tested as a chemical conditioner and gives good results on Lescar (France) sewage sludge in terms of cake's dryness, filtrate quality, turbidity (13.54%), and total time of filtration (TTF = 85.29%), comparing to the industrial polymer (Sedifloc 408C; turbidity; 8.33% and TTF: 2.94%). For the sewage sludge of Oran (Algeria), the results obtained with OFIFJ were compared to those obtained with the cladodes juice of the same plant OFIC, and also with a cationic polymer (Superfloc 8396). For an optimum dosage, it showed that OFIFJ has a flocculation activity as same as the cladodes juice OFIC for sludge conditioning and gives better results in terms of turbidity (dosage of 22.4 g/kg DM: 3.7 NTU for OFIC, dosage of 8.36: 3.63 NTU for OFIFJ. Dryness was enhanced from 14.91 to 22.93% (OFIC 16 g/kg DM) and to 24.48% (OFIF 20.9 g/kg DM) but for TTF, we found the opposite. In fact, this plant showed to be an available, biodegradable, and non-toxic flocculant. For kaolin synthetic sludge (30%), the optimum dosages of those conditioners were found to be 0.066 g kg-1 for OFIC, comparing between vacuum filtration and filtration compression; turbidity was enhanced for both techniques, contrary to dryness. Concerning the Oran city sewage sludge, both turbidity and dryness were optimized. Same thing for the France sewage sludge, all the studied parameters were enhanced with the two studied bioflocculants.