Papers in 2026
Ormosil hybrid coatings as a sustainable antibiofouling solution for microalgae cultivation in tubular photobioreactors
This study demonstrated the potential of citric acid–APTES (Ormosil) coatings as an effective antifouling strategy to reduce biofilm formation in tubular photobioreactors used for microalgae cultivation. Among the tested coatings, CApTES2.7 exhibited superhydrophilic behavior in air and superoleophobic behavior underwater, significantly reducing the adhesion of Chlorella vulgaris compared to uncoated glass surfaces. Light transmission experiments and microscopic analyses showed that biofilm accumulation on coated surfaces decreased by more than 50 %, maintaining optical clarity within the reactor. Thermodynamic, DLVO, and XDLVO modeling supported these findings, indicating lower adhesion energies for algal cells on Ormosil-coated surfaces, consistent with their experimental antifouling performance. The application of CApTES2.7 coating in tubular PBR systems resulted in a 54.5 % increase in light transmittance compared to uncoated systems, thereby improving the photonic environment available for microalgal growth. Additionally, no chemical cleaning was required between cultivation cycles in coated reactors, demonstrating potential for reducing operational costs and water consumption in large-scale systems. In conclusion, this study presents an environmentally friendly and sustainable approach to overcoming biofilm-induced light attenuation—one of the main bottlenecks in industrial photobioreactors. Ormosil-based coatings not only extend the service life of PBRs but also enhance the economic feasibility of microalgae-based bioprocesses for biofuel, bioplastics, and high-value biomolecule production.
Effects of cultivation temperature on protein production of selected Spirulina strains under photobioreactor conditions
Spirulina is cultivated industrially for food supplement applications due to its high protein content and protein quality. This study assessed the influence of cultivation temperature on the productivity of widely accessible, protein-rich Spirulina strains under standardized bubble column photobioreactor conditions, with the goal of identifying strains with consistently high nutritional value across varying temperatures and culture age for outdoor applications. Five strains were first screened for protein content at 30 °C, and three with protein contents ≥60 % dry biomass were selected for cultivation at 25 °C, 35 °C, and 40 °C. Protein content was measured daily to determine variations, and protein quality was assessed at log and stationary growth phases. The metal content was analyzed to assess the toxic heavy metal bioaccumulation potential. At the optimum temperature of 35 °C, the strains had similar biomass productivities. However, the protein contents were highly temperature and strain-specific. Based on the strain, under identical process conditions, a relatively stable protein content of around 65 % or a content variation from 30 to 70 % was observed through the cultivation. Growth at 25 °C lowered the biomass productivity without affecting the protein contents, and growth at 40 °C lowered both parameters. S. platensis UTEX 2340 had consistently the highest protein quality, reflected by its higher cumulative essential amino acid contents and essential amino acid index scores. However, at 35 °C, the strain also had a mercury content exceeding the safety limits set for food supplements. These findings demonstrate the importance of strain selection and cultivation temperature in maintaining the nutritional value of Spirulina-based products.
Microplastic Pollution and Risk Evaluation in the Gediz River
Microplastics (MPs), particles less than 5 mm in diameter, enter the aquatic ecosystem through the degradation of larger plastics. They can accumulate in the environment for long periods due to their durability and buoyancy. In this study, a risk assessment of MPs was conducted at five different stations in the Gediz River via a Pollution Load Index (PLI) and a Polymer Hazard Index (PHI) calculated for dry and wet seasons to highlight the risks caused by seasonal variations of pollution levels for different types of MPs in an urban river discharging to Izmir Bay. The results showed that MPs were widespread in the area, with an average abundance of 13 211 units/L/L. During the dry season, the mean number of particles was 67±57; during the wet season, the mean number of particles decreased to 50±37. The most common type was polypropylene with 62.4%, followed by Polyethylene and Polyethylene Terephthalate (8.3% and 7.01%). The most abundant MP shapes are fragments and fibers, with 47.1% and 38.5%. During the dry season, PLI values ranged from 0.99 to 2.44, while in the wet period, they ranged from 1.08 to 2.11. Furthermore, PHI values for the MP species detected at each station ranged from 3.81 to 7.91. The results indicated that the Gediz River is a significant MPs source for Izmir Bay and demonstrates a major hazard for its overall ecological condition.