Quantification of polyhydroxyalkanoate accumulated in waste activated sludge

• Published in: Water research (Oxford) 2022-08, Vol.221, p.118795-118795, Article 118795
• Main Authors: Pei, Ruizhe, Vicente-Venegas, Gerard, Van Loosdrecht, Mark C.M., Kleerebezem, Robbert, Werker, Alan
• Format: Article
• Language: English
• Subjects: Activated sludge; Biopolymer; Image analysis; Polyhydroxyalkanoate (PHA); Staining; Thermogravimetric analysis (TGA)
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2022.118795

•Staining microscopy and image analysis can quantify PHA distribution in biomass.•Volume and mass ratios of stored PHA to non-PHA biomass were correlated.•Degree of enrichment for a PHA storing activated sludge (55%) was estimated.•Distribution of 16S rRNA levels was not specific to PHA accumulation activity. [Display omitted] Polyhydroxyalkanoate accumulation experiments at pilot scale were performed with fullscale municipal waste activated sludge. Development of biomass PHA content was quantified by thermogravimetric analysis. Over 48 h the biomass reached up to 0.49 ± 0.03 gPHA/gVSS (n=4). Samples were processed in parallel to characterise the distribution of PHA in the biomass. Selective staining methods and image analysis were performed by Confocal Laser Scanning Microscopy. The image analysis indicated that nominally 55% of this waste activated sludge was engaged in PHA storage activity. Thus even if the biomass PHA content reached 0.49gPHA/gVSS, the accumulating fraction of the biomass was estimated to have attained about 0.64gPHA/gVSS. The combination of quantitative microscopy and polymer mass assessment enabled to distinguish the effect of level of enrichment in PHA storing bacteria and the average PHA storage capacity of the accumulating bacteria. The distribution of microbial 16S rRNA levels did not follow a measurable trend during PHA accumulation.