Microbial community shifts in the oxic-settling-anoxic process in response to changes to sludge interchange ratio

Abstract

This particular study set out to demonstrate alterations on the microbial community of the oxic-settling-anaerobic/anoxic (OSA) process treating real domestic wastewater by changing interchange ratios (IRs). The sludge yield of systems operated at different IRs (1/13, 1/17 and 1/20) to assess sludge reduction was used to analyze microbial community composition variations. The highest IR (1/13) resulted in the highest sludge reduction (52.1%), while the OSA systems with IR of 1/17 and 1/20 reduced sludge production by 37.4% and 35.5%, respectively, in comparison to conventional systems. 16S rRNA gene amplicon sequencing analysis showed that the bacterial communities were composed of similar phylogenetic groups, Proteobacteria, Acidobacteria, and Bacteroidetes being dominant. The relative abundances differed due to the applied IRs. The highest abundance of Actinobacteria was determined at the highest IR (1/13) and increasing of the HRT to 1/20 caused a significant reduction in Actinobacteria species and the lowest abundance (6%) was determined in the OSA systems. The abundant of Thiothrix species that are boosted in the OSA trials may have a vital role in OSA systems, where its abundance was below the detection limits in the seed sludge sample. Therefore, they could be used as bioindicators in the OSA system.

A review on promising strategy to decrease sludge production: Oxic-settling-anoxic/anaerobic process

“…Similarly, using the DGGE fingerprint technique it was shown that Proteobacteria and Bacteroidetes species were the most abundant in the OSA process [66]. The finding is consistent with findings of the later study by [64] using Next Generation Sequencing (NGS) of bacterial 16S rRNA gene amplicons, which showed that Proteobacteria, Actinobacteria, Bacteroidetes, and Chloroflexi were also predominant phyla in OSA systems in which their proportions in the microbial community distinguished due to the different IRs applied during the operation period. But surprisingly, Thiotrichaceae (phylum: Proteobacteria) species were not detected in the seed sludge sample, the majority of the total sequences were represented by Thiotrichaceae at the family level in all OSA systems and the genus level, Thiothrix was the predominant one.…”

“…Various specific molecular methodologies have been applied to document and compare the microbial culture structure and population dynamics in control and OSA process systems [21], [26], [33] , [36], [64], [65]. Microbial communities can be strongly affected by diverse factors [66].…”

The future of aviation soars with HTL-based SAFs: exploring potential and overcoming challenges using organic wet feedstocks

“…Manure, food waste, and municipal sewage sludge (SS) are examples of water-rich biomass resources that HTL can eliminate without resorting to incineration, which is the most popular method of disposal in the US, Japan, and Europe. 101 According to estimates, SS is generated at a rate of 75–100 MLT of dry solids (DS) annually 102 and is expected to increase to 127.5 MLT DS by 2030 103 Additionally, 17% of the food produced worldwide is wasted annually, 104 amounting to roughly 1.3 billion tonnes (BLT), 105 and the annual production of manure is estimated to be between 15–20 MLT. 106 All of these biomasses produce constantly and have the potential to be used as feedstocks for the manufacturing of SAFs.…”

Evolution and Prospects in Managing Sewage Sludge Resulting from Municipal Wastewater Purification

“…Presently, the MSS as DS produced annually for more than 100,000 WWTPs operating worldwide amounts to a minimum of 45 [130], although a more realistic estimate is 75-100 million tons. According to Shanmugam et al [131], global sewage sludge production is predicted to reach 127.5 million tons as DS by 2030.…”