Biofilm in reverse osmosis (RO) membranes is a common problem in water treatment at haemodialysis facilities. Bacteria adhere and proliferate on RO membranes, forming biofilms, obstructing and damaging the membranes and allowing the transfer of bacteria and/or cellular components potentially harmful to the health of haemodialysis patients. Our aim was to characterize the bacterial community associated to biofilm of RO membranes and to identify potentially pathogenic bacteria present in the haemodialysis systems of two dialysis centres in Chile. The diversity of the bacterial communities present on RO membranes and potable and osmosed water samples was evaluated using Illumina sequencing. Additionally, bacteria from potable water, osmosed water and RO membrane samples were isolated, characterized and identified by Sanger’s sequencing. The molecular analyses of metagenomics showed that the phyla having a greater relative abundance in both dialysis centres were Proteobacteria and Planctomycetes. Pseudomonas, Stenotrophomonas, Agrobacterium, Pigmentiphaga, Ralstonia, Arthrobacter, Bacteroides and Staphylococcus were bacterial genera isolated from the different samples obtained at both haemodialysis centres. Pseudomonas spp. was a bacterial genus with greater frequency in all samples. Pseudomonas and Staphylococcus showed higher levels of resistance to the antibiotics tested. Results demonstrated the presence of potentially pathogenic bacteria, showing resistance to antimicrobials on RO membranes and in osmosed water in both dialysis centres studied.

Water infiltration into soil is a key process in regulating the hydrological cycle and sustaining ecosystem services in high-Andean environments. However, limited information is available regarding its dynamics in these ecosystems. This study evaluated the influence of three types of vegetation cover and soil properties on water infiltration in a high-Andean environment. A double-ring infiltrometer, the Water Drop Penetration Time (WDPT, s) method, and laboratory physicochemical characterization were employed. Soils under forest cover exhibited significantly higher quasi-steady infiltration rates (i_s, 0.248 ± 0.028 cm·min⁻¹) compared to grazing areas (0.051 ± 0.016 cm·min⁻¹) and agricultural lands (0.032 ± 0.013 cm·min⁻¹). Soil organic matter content was positively correlated with i_s. The modified Kostiakov infiltration model provided the best overall fit, while the Horton model better described infiltration rates approaching i_s. Sand and clay fractions, along with K⁺, Ca²⁺, and Mg²⁺, were particularly significant during the soil’s wet stages. In drier stages, increased Na⁺ concentrations and decreased silt content were associated with higher water repellency. Based on WDPT, agricultural soils exhibited persistent hydrophilic behavior even after drying (median [IQR] from 0.61 [0.38] s to 1.24 [0.46] s), whereas forest (from 2.84 [3.73] s to 3.53 [24.17] s) and grazing soils (from 4.37 [1.95] s to 19.83 [109.33] s) transitioned to weakly or moderately hydrophobic patterns. These findings demonstrate that native Andean forest soils exhibit a higher infiltration capacity than soils under anthropogenic management (agriculture and grazing), highlighting the need to conserve and restore native vegetation cover to strengthen water resilience and mitigate the impacts of land-use change.

The use of amendments in combination with Bacillus subtilis has been understudied as a strategy for rehabilitating acid soils and improving cropping systems. This study aimed to evaluate the effects of amendments and B. subtilis on the development, yield, and nutritional quality of the hard yellow maize Marginal 28 T variety. A randomized complete block design with a factorial arrangement was employed, considering five amendments, including biochar, alongside the application of B. subtilis. The combination of biochar and B. subtilis significantly increased plant and ear height (p < 0.01), achieved a grain yield of 4.11 t ha⁻¹, and reduced flowering time by seven days. Strong correlations were observed between male and female flowering (r = 0.99) and between stem diameter and leaf area (r = 0.95), indicating improved vegetative development. Soil pH and nutrient availability, such as phosphorus, were also enhanced. The combined use of amendments and B. subtilis optimizes yield and improves soil chemical properties. Thus, applying biochar and B. subtilis improves growth, yield, and soil quality, consolidating a promising strategy for sustainable agriculture in acid soils.

Arsenate As(V) is a toxic contaminant commonly found in aquifers and groundwater that poses significant risks to human health. The effective treatment of arsenic-contaminated water is therefore crucial for safeguarding public health. This study investigates removing As(V) using iron oxide-coated ignimbrite in batch experiments by varying the adsorbent dosage, initial As(V) concentration, contact time, and system temperature. The adsorption experiments revealed that the Langmuir isotherm model better fit the data (R² = 0.99) than the Freundlich model (R² = 0.73). According to the Langmuir model, the maximum adsorption capacity of As(V) on the iron oxide-coated ignimbrite was 4.84 mg·g⁻¹ ± 0.12 mg·g⁻¹ of As(V), with a standard deviation of ±0.05 mg·g⁻¹ after 2 h of exposure with 0.15 g/50 mL iron oxide-coated ignimbrite adsorbent concentration. In the kinetic analysis, the pseudo-first-order model best described the adsorption process at 283 K, 293 K, and 303 K, although the pseudo-second-order model also showed an adequate fit, particularly at 293 K. This indicates that, while the pseudo-first-order model is generally more suitable under these conditions, the pseudo-second-order model may also apply under certain circumstances. The results of the batch experiments demonstrate that iron oxide-coated ignimbrite is a promising adsorbent for effectively reducing high concentrations of As(V) in contaminated water.

Background. The morphological quality of cocoa (Theobroma cacao L.) seedlings in the nursery is essential for the success of commercial plantations. Bioferments represent a sustainable alternative to improve the morphology and quality of seedlings. Objective. To evaluate the effect of bioferments on the morphology and quality of cocoa seedlings in the nursery. Methodology. Four treatments were used with different combinations of substrates and solid and liquid bioferments. A completely randomized design with four repetitions was used, measuring morphological and quality variables. Results. The traditional substrate treatment with the addition of solid and liquid bioferments (ST+BS+BL) showed the highest values in height, stem diameter, dry biomass and Dickson quality, surpassing the traditional substrate by 51%. Implications. Bioferments improve the availability of nutrients and the structure of the substrate, favoring the development of vigorous and better quality seedlings. Conclusions. The combination of solid and liquid bioferments represents an agroecological strategy to optimize the morphological attributes and quality of cocoa seedlings in the nursery.