Improvement of phosphorus release from sludge by combined electrochemical-EDTA treatment.

In this paper, combined with the addition of ethylenediaminetetraacetic acid (EDTA), the electrochemical treatment of waste activated sludge (WAS) was investigated to explore its effect on the release of phosphorus (P) from WAS. The results showed that during the electrochemical treatment, the addition of EDTA could significantly promote the release of P from the WAS to the supernatant, the optimal amount of EDTA was 0.4 g/g total suspended solids (TSS), when the release of total dissolved phosphorus (TDP), organic phosphorus (OP) and molybdate reactive phosphorus (PO43--P) were 187.30, 173.84 and 13.46 mg/L, respectively. OP was the most likely form of P to be released during this process. Moreover, combined electrochemical-EDTA treatment could promote the release of P and metal ions from extracellular polymeric substances (EPSs) to the supernatant, and increase the solubility and disintegration of sludge. EDTA chelated the metal ions of sludge flocs and phosphate precipitates to cause sludge floc decomposition, thereby promoting the release of P from WAS.

Interaction energy and detachment of magnetic nanoparticles-algae.

Magnetic separation, a promising bioseparation technology, is confronted with the challenges in recovery and recycle of magnetic matters during algae harvesting for biofuel extraction. The thermodynamic method was used to characterize the surface interactions between MNPs and algae cells. Three methods were adopted to detach magnetic nanoparticles-algae (Microcystis aeruginosa, Synechocystis sp., Nannochloropsis maritima and Stigeoclonium sp.) and recover magnetic nanoparticles (MNPs) in this study. The thermodynamic method indicated that the greatest adhesion strength was expected for Stigeoclonium sp. on MNPs. High detachment efficiency of MNP-algae was achieved by ultrasonic-extracting, which got above 90% after 5 recycles. Moreover, the harvesting efficiencies of these four algae cells could remain more than 90% after 5 recycles using a mixture of the regenerated and the raw MNPs.

Characterization of 19 polymorphic SSR markers in Spirodela polyrhiza (Lemnaceae) and cross-amplification in Lemna perpusilla.

PREMISE OF THE STUDY: Polymorphic microsatellite primers were developed for greater duckweed, Spirodela polyrhiza (Lemnaceae), to investigate genetic diversity and structure for application in a bioremediation program. METHODS AND RESULTS: A total of 401 publicly available S. polyrhiza whole-genome shotgun sequences were searched for simple sequence repeat loci of two or more nucleotides. Of these, 60 primer pairs were selected to analyze 68 individuals of S. polyrhiza from three populations. Nineteen polymorphic microsatellite loci were developed. A total of 108 alleles were detected with an average of 5.7 alleles per locus. The levels of expected and observed heterozygosity were 0.0511-0.8669 and 0-0.8750, respectively. Ten loci also successfully amplified in 16 individuals of Lemna perpusilla. CONCLUSIONS: The results demonstrate the broad utility of these microsatellite loci for studying population genetics in S. polyrhiza.