Combination of microalgae cultivation and piggery wastewater treatment has become a hot topic in recent years. Nutrient removal from aerated piggery wastewater (APW) by Desmodesmus sp. CHX1 and the optimization of cultivation conditions were investigated in this study. Results indicated that Desmodesmus sp. CHX1 showed an efficient growth in APW, with specific growth rate of 0.26–0.56 d⁻¹. The biomass yield based on nutrient consumption was 9.65 g biomass/g NH₄–N and 209.15 g biomass/g total phosphorus (TP) respectively. Desmodesmus sp. CHX1 performed well in nutrient removal from APW, with ammonium nitrogen (NH₄–N) and TP removal efficiency (RE) of 78.46% and 91.66% respectively after 7 days of culture. Nutrient removal process fitted the pseudo-first-order kinetic equations well, with removal rate (RR) constant of 0.24 d⁻¹ for NH₄–N and 0.28 d⁻¹ for TP. The optimum conditions for nutrient removal from APW by Desmodesmus sp. CHX1 were light intensity of 150 μmol photons m⁻² s⁻¹ in the photoperiod for 24 h when the temperature was set at 35°C with alga cell inoculation concentration of 30%. The removal efficiencies of NH₄–N and TP were 88.26% and 95.06% respectively under the optimal conditions after 7 days of culture. Our results can be a good reference for enhancement of microalga production and the nutrient RE and further extend the application of the large-scale piggery wastewater treatment under a controlled environment.

The aim of this study was to explore the effects of temperature and light on microalgal growth and nutrient removal in turtle aquaculture wastewater using a single-factor experiment method. Results showed that the growth process of Desmodesmus sp. CHX1 in turtle aquaculture wastewater exhibited three stages, namely adaptation, logarithmic, and stable periods. Temperature and light significantly influenced the growth and protein and lipid accumulation of Desmodesmus sp. CHX1. The optimal conditions for the growth and biomass accumulation of Desmodesmus sp. CHX1 included a temperature of 30 °C, a photoperiod of 24L:0D, and a light intensity of 180 μmol photon/(m²·s). Increased temperature, photoperiod, and light intensity enhanced nutrient removal efficiency. Maximum nitrogen removal was achieved at a temperature of 30 °C, a photoperiod of 24L:0D, and a light intensity of 180 μmol photon/(m²·s), with the removal efficiency of 86.53%, 97.94%, 99.57%, and 99.15% for ammonia, nitrate, nitrite, and total phosphorus (TP), respectively. Temperature did not significantly affect TP removal, but increased photoperiod and light intensity improved the removal efficiency of TP. The development of microalgae biomass as a feed rich in protein and lipids could address feed shortages and meet the nutritional needs of turtles, offering a feasible solution for large-scale production.

This study aims to optimize the self-flocculation ability of microalgae Desmodesmus sp. CHX1 by the response surface methodology (RSM). Key parameters (i.e. pH, temperature and flocculation time) that significantly affected the Desmodesmus sp.CHX1 flocculation were determined. Results show that the flocculation efficiency of Desmodesmus sp.CHX1 increased in response to the prolonged settling time, particularly within the first 6 h, given the secretion of extracellular polymers. The RSM result suggested that both temperature and time exerted more significant effects on flocculation efficiency than solution pH. In specific, the maximum flocculation efficiency could reach 94.0% under the optimal conditions with the temperature, time and pH of 12.37°C, 6.96 h and 7.98, respectively. Validation experiments further indicated the reliability of the optimal parameter conditions. GRAPHICAL ABSTRACT

Microplastics (MPs) have been proven to be one of the major threats to the wastewater treatment system. However, the impact of MPs on microalgae-based wastewater treatment technology are still unknown. In this study, effects of polyvinyl chloride (PVC), polypropylene (PP), and polyethylene (PE) on the removal of nitrogen and phosphorus from synthetic piggery digestate by microalgae were investigated. Results show that the effect of PVC particle size on the growth of microalgae was significant. The effects of PVC content, PP particle size and content, PET particle size and content on the growth of microalgae were all not significant. The removal of ammonia nitrogen by microalgae was influenced significantly by PVC particle size and content, PP particle size and content, the effects of PET particle size and content on the removal of ammonia nitrogen were all not significant. The effects of particle size and content for three MPs on the removal of total phosphorus were all significant. Microalgae cells were bound together after being adsorbed by MPs, which increased the secretion of extracellular polymers and influenced the removal of ammonia nitrogen and total phosphorus.

The process of mining is invariably associated with ecological and environmental challenges within the mining region, making ecological restoration efforts in these areas especially crucial. Bryophytes, acting as key pioneer species, exhibit distinctive advantages and potential for application in the ecological restoration of mining sites. This study offered a concise overview of the fundamental traits of bryophytes, as well as their classification and distribution in mining regions across China using literature synthesis and field surveys. It primarily explored the role bryophytes played in the ecological restoration of such areas, the selection of appropriate bryophyte species, and cultivation techniques through systematic analysis. Additionally, the case studies of bryophytes’ applications in ecological restoration within mining regions were analyzed. Results indicated that bryophytes in China’s mining areas were diverse and widely distributed. Notably, bryophytes contributed to soil improvement, vegetation recovery, and the monitoring and indication of heavy metal pollution, with most demonstrating a robust tolerance to these contaminants. Future research should focus on screening suitable bryophytes, refining cultivation methods, and investigating their interactions with soil microorganisms.