Search Results (3)

Microalgae-based wastewater treatment can support sustainable crop production. This study evaluated whether ethanol supplementation improves swine wastewater (SW) treatment by Dictyosphaerium sp. and enhances algal biofertilizer production. Across the ethanol levels tested, 500 mg/L ethanol significantly promoted algal growth and enhanced liquid-phase net removal of total salts, carbonate/bicarbonate, ammonium, phosphate, and calcium. Ethanol supplementation also reduced apparent nitrogen loss, and no residual ethanol was detected at the end of the culture. In the biofertilizer production experiment, peak algal biomass, algal nitrogen, and algal phosphorus increased by 320.0–407.4%, 122.7–158.1%, and 100.0–170.0%, respectively. Metatranscriptomic analysis showed active transcription of adh, aldh/aldB, and acs in Dictyosphaerium sp. and some bacterial taxa, mainly Flavobacterium, Chryseobacterium, Comamonas, and Brevundimonas. Community and transcriptomic results indicate enhanced photosynthetic activity and taxon-specific N- and P-related transcriptional responses, consistent with altered nitrate/nitrite transformation potential and increased nitrogen retention in the algal–bacterial system. Under the tested conditions, ethanol supplementation shows promise for SW treatment and algal biofertilizer production. Full article

This study uses industrial wastewater from an aluminum factory to evaluate the phycoremediation efficiency of two green microalgal strains, Dictyosphaerium sp. and Tetradesmus obliquus. The industrial wastewater contained high levels of pollutants, including COD, ammonium, nitrate, phosphate, and heavy metal ions (Al³⁺, Cu²⁺, Cr³⁺, Zn²⁺, Mn²⁺, Cd²⁺). Four biomass conditions were tested: free-living cells (active living cells), immobilized cells (entrapped within alginate), dried biomass (non-living dried cells), and acid-treated dried biomass (chemically modified for enhanced adsorption). Both strains demonstrated significant pollutant removal, with living biomass (free and immobilized) achieving the highest nutrient and organic pollutant removal, and non-living biomass (dried and acid-treated) being more efficient for rapid heavy metal removal. Tetradesmus obliquus showed superior performance across most parameters, while Dictyosphaerium sp. exhibited the highest aluminum removal (99.4%, reducing Al from 481.2 mg/L to 10.2 mg/L). These findings highlight the potential of microalgae-based approaches and support species-specific strategies for cost-effective and sustainable phycoremediation of industrial wastewater. Full article

Sulfonamides (SAs) are the most common and bio-refractory antibiotics detected in surface water systems, which cause long-term toxic effects on aquatic organisms. This study used the combination of a BiVO₄ photocatalyst and freshwater micro-green alga (Dictyosphaerium sp.) to remove sulfadiazine (SD) and sulfamethazine (SM2) at an initial concentration of 5 mg/L (1:1 v/v) for 7 days. We set up three gradient concentrations of BiVO₄ (0.5, 1 and 2 g/L) combined with the same concentration (80 mg/L) of Dictyosphaerium sp. and then prepared corresponding concentrations of pure BiVO₄ and pure microalgae as controls. We evaluated the ability of BiVO₄ and Dictyosphaerium sp. combined technology to remove SAs by observing the removal efficiency of antibiotics and explained the degradation mechanism of antibiotics and the key role of microalgae by studying the changes of reactive oxygen species (ROS) and inorganic ions (nitrogen, sulfur). The results showed that the degradation rate of these two SAs in the 0.5 g/L BiVO₄–algae group could reach >96% within 7 d, which was higher than that in the 2 g/L BiVO₄ group (93%) and the algae group (28%). The increased degradation efficiency of SAs in BiVO₄ and microalgae systems was mainly due to the increased amount of ROS. Meanwhile, more SAs were degraded to inorganic compounds such as NH₄⁺-N, NO₃⁻-N and SO₄²⁻-S under ROS stress. It was found that microalgae can absorb the degradation products of antibiotics such as NH₄⁺-N for their own growth, thereby reducing the toxicity of antibiotic by-products. In addition, BiVO₄ had no damaging effect on the autofluorescence intensity of the microalgae. Our study provides an efficient and eco-economic approach to remove antibiotics using visible-light irradiation in aquatic environments and provides new insights into the biological removal of other antibiotic contaminants in aquatic environments. Full article