A new microalgal negative carbon technology for landfill leachate treatment: Simultaneous removal of nitrogen and phosphorus.

Replete with ammonia nitrogen and organic pollutants, landfill leachate typically undergoes treatment employing expensive and carbon-intensive integrated techniques. We propose a novel microalgae technology for efficient, low-carbon simultaneous treatment of carbon, nitrogen, and phosphorus in landfill leachate (LL). The microbial composition comprises a mixed microalgae culture with Chlorella accounting for 82.58 %. After seven days, the process with an N/P ratio of approximately 14:1 removed 98.81 % of NH4+-N, 88.62 % of TN, and 99.55 % of TP. Notably, the concentrations of NH4+-N and TP met the discharge standards, while the removal rate of NH4+-N was nearly three times higher than previously reported in relevant studies. The microalgae achieved a removal efficiency of 64.27 % for Total Organic Carbon (TOC) and 99.26 % for Inorganic Carbon (IC) under mixotrophic cultivation, yielding a biomass of 1.18 g/L. The treatment process employed in this study results in a carbon emissions equivalent of -8.25 kgCO2/kgNremoved, representing a reduction of 33.56 kgCO2 compared to the 2AO + MBR process. In addition, shake flask experiments were conducted to evaluate the biodegradability of leachate after microalgae treatment. After microalgae treatment, the TOCB (Biodegradable Total Organic Carbon)/TOC ratio decreased from 56.54 % to 27.71 %, with no significant improvement in biodegradability. It establishes a fundamental foundation for further applied research in microalgae treatment of leachate.

Differential expression of microRNAs in the intervertebral disc of hypoxia-inducible factor-1alpha deficient mice / 中国组织工程研究

BACKGROUND:It is confirmed that the absence of hypoxia-inducible factor-1α (HIF-1α) accelerates the degenerative process in the intervertebral discs, and microRNAs have an important role in degeneration of the intervertebral discs. OBJECTIVE:To evaluate the changes of microRNAs in the intervertebral discs of HIF-1α-deficient (HIF-1α-/-) mice which may mediate the signaling pathway of HIF-1α in the intervertebral discs. METHODS: As previously reported, HIF-1α-/- mice were established. HIF-1α-/- mice and HIF-1αflox/flox mice (control mice) aged 4 weeks were used. MRI and histological staining were used to evaluate the degeneration of the intervertebral discs. Total RNAs were extracted from the intervertebral discs tissues by Trizol, and the differential expression profile of microRNAs was harvested by significance analysis of microarrays and Cluster, based on microarray screening. Real-time quantitative reverse transcription-PCR was applied to verify the reliability of microRNA array results. RESULTS AND CONCLUSION:The number of nucleus pulposus cels in the intervertebral discs of HIF-1α-/- mice was decreased, the cels presented with smal size and the color deepened in the cytoplasm. Finaly, differential expression profile of microRNAs (n=10) was obtained, seven of which were upregulated and three were downregulated. In conclusion, the loss of HIF-1α may cause the imbalance of some important miRNAs, which may result in a large amount of dead nuclear pulposus cels and mediate disc degeneration in HIF-1α-/- mice.