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This study investigated the effect of light intensity on the growth and nutrient uptake of Chlorella sorokiniana cultivated in nitrogen-rich anaerobic digestion wastewater. Three light intensities (20, 68, and 162 µmol m⁻2 s⁻1) were applied over a 30-day period with a 16:8 h light–dark photoperiod. The goal was to understand how light affects biomass productivity, nutrient assimilation, and biochemical composition under varying nitrogen concentrations originating from biogas plant digestate, up to 5 g L⁻1. The results showed that higher light intensities significantly boosted biomass production, achieving a five-fold increase at 162 µmol m⁻2 s⁻1 compared to 20 µmol m⁻2 s⁻1. Nutrient uptake followed a similar pattern, with 94% of ammonium nitrogen removed in 7 days under high light, compared to 55% after 30 days under low light. Phosphorus content was also completely removed after 7 days under light intensities of 68 and 162 µmol m⁻2 s⁻1. Additionally, elevated light intensity led to increased lipid accumulation (from 29.7% to 34%) and reduced protein content (from 30.9% to 26.1%), with carbohydrate content not being affected by light intensity. These findings highlight light intensity as a critical factor for optimizing microalgae cultivation in nitrogen-rich biogas digestate, promoting both effective nutrient removal and biomass production for potential bioenergy applications. [ABSTRACT FROM AUTHOR]

Featured Application: Potential application of the outcomes of the present study is feasible, for wastewater bioremediation with concurrent cost-efficient biofuel production, along with value-added health product and biofuel development, while also reducing the carbon footprint, certainly after implementation of the necessary regulation sandboxes, to promote environmental and human health protection and also job creation and economy strengthening. In the current study, the cultivation of microalgae on wastewater-based substrates is investigated for an effective natural wastewater treatment that also generates biofuels and value-added products beneficial to human health. Additionally, the health of ecosystems can be evaluated via microalgae. The utilization of microalgae as bioindicators, biofuel producers, and wastewater treatment providers, under the biorefinery concept, is covered in this article. In fact, bioremediation is feasible, and microalgae culture can be used to efficiently process a variety of effluents. Along with wastewater processing and the creation of value-added substances, bioconversion concurrently offers a viable and promising alternative for reducing CO2 greenhouse gas emissions to contribute to climate change mitigation. The microalgal biorefinery being considered as the third generation is unique in that it addresses all the aforementioned problems, in contrast to lignocellulosic biomass from agricultural waste in second-generation biorefineries and edible crops in first-generation biorefineries. In particular, one of the most promising natural resources for the manufacture of biofuel, including biodiesel, bioethanol, biomethane, and biohydrogen, is found to be microalgae. Furthermore, products of high value, like fatty acid methyl esters, astaxanthin, β-carotene, DHA, and EPA can be made. Hence, microalgal biomass offers a substitute for the development of biofertilizers, bioplastics, pharmaceuticals, cosmetics, animal and aquatic feeds, and human nutrition products, thus promoting human and environmental health. [ABSTRACT FROM AUTHOR]

The current study investigated the performance of a moving bed biofilm reactor (MBBR), when adding 3D-printed biocarriers fabricated with 13X and bentonite (MBBR 3D), when using K1 commercial biocarriers (MBBR K1) and when not adding biocarriers at all (control MBBR). For the evaluation of the MBBR efficiency, various physicochemical parameters were measured, while biofilm extracted from the biocarriers was evaluated. The findings suggest that there is an optimal biodegradation of the organic load in all MBBR units. The nitrification and denitrification processes were improved in MBBR 3D as compared to the control MBBR and MBBR K1. The dry mass of the biofilm in the 3D-printed biocarriers was two orders of magnitude larger than in the K1 biocarriers. Moreover, in the K1 biocarriers the mass of the biofilm varied in relation to time, since it could not be protected inside the holes, something that did not happen with the 3D-printed biocarriers. Finally, it was found, mostly in MBBR 3D and less in MBBR K1, that the growth of nitrifying bacteria and heterotrophs inside the units increased the biomass production in the form of soluble microbial products, which in turn favored the adhesion of biomass on the surface of biocarriers. [ABSTRACT FROM AUTHOR]

Thirteen bacterial isolates from a bioreactor treating a mixture of municipal and molasses wastewater were investigated for their potential to degrade and decolorize melanoidins. All isolates were initially screened for manganese peroxidase activity and growth potential in the presence of four synthetic melanoidins solutions at concentrations ranging from 3 to 7 g/L/L. Three isolates of potential manganese peroxidase‐producing bacteria two Klebsiella sp. (B2–B3) and Escherichia coli (B4) and one strain of Lactobacillus kefiri (B1) showed high synthetic melanoidin tolerance. The 16S rDNA sequence showed that they were closely related to E. coli and Klebsiella sp. The most significant degree of decolorization was observed on day 1, reaching 60–67%. Furthermore, the tested strains reduced the chemical oxygen demand by more than 50% or more than 70% of the initial value with or without additional supplementation of the reaction mixture, respectively. All tested isolates showed increased ability for reducing the organic matter content of a raw melanoidin solution exceeding 65%, favouring, therefore, the utilization potential of the isolated strains for the biological processing of molasses wastewaters. Thus, microbial decolorization could be an innovative wastewater treatment for environmental protection purposes. [ABSTRACT FROM AUTHOR]