Bacterial and Microfauna Mechanisms for Sludge Reduction in Carrier-Enhanced Anaerobic Side-Stream Reactors Revealed by Metagenomic Sequencing Analysis

Abstract

Packing carriers into the anaerobic side-stream reactor (ASSR) can enhance sludge reduction and save footprint by investigating ASSR-coupled membrane bioreactors (AP-MBRs) under different hydraulic residence times of the ASSR (HRT SR ). Three AP-MBRs and an anoxic-aerobic MBR (AO-MBR) showed efficient chemical oxygen demand (>94.2%) and ammonium nitrogen removal (>99.3%). AP-MBRs have higher (p < 0.05) total nitrogen (61.4−67.7%) and total phosphorus (57.5−63.8%) removal than AO-MBRs (47.8 and 47.7%). AP-MBRs achieved sludge reduction efficiencies of 11.8, 31.8, and 36.2% at HRT SR values of 2.5, 5.0, and 6.7 h. Packing carriers greatly improved sludge reduction under low HRT SR and is promising for accelerating sludge reduction in compact space. Metagenomic sequencing analysis showed that genes responsible for metabolism were enriched in AO-MBRs, while genes related to cellular motility and cell signaling were more abundant in the AP-MBRs. A longevity-regulating pathway showed that long lifespan provided more opportunities for worms to prey bacteria. Microscopic examination revealed that some specific protozoa (Arcella, Clathrulina, Aspidisca, Litonotus, Chiloclonella, and Vorticella) and metazoa (Rotaria and Aeolosoma hemprichi) were enriched in ASSRs. Aeolosoma hemprichi was only detected in ASSRs, and unique Cylops appeared on carriers. These results contribute to growing understanding of micrometabolic mechanisms including functional genes and microfauna-driving sludge reduction.

Applications of Genomics, Metabolomics, Fourier Transform Infrared in the Evaluation of Spoilage Targets of Shewanella putrefaciens from Spoiled Bigeye Tuna

“…COG 1506 in S. putrefaciens XY 07 was primarily associated with peptidases. Besides, COG 0308 (aminopeptidase) is one of the peptidases that can hydrolysis proteins . COG0814 (amino acid transport) and COG0697 (membrane) in S. putrefaciens XY 07 were involved in amino acid transport and metabolism; such ion transporters and a great variety of other highly specific transporters and permeases also play a vital role in marine bacteria .…”

“…Besides, COG 0308 (aminopeptidase) is one of the peptidases that can hydrolysis proteins. 24 COG0814 (amino acid transport) and COG0697 (membrane) in S. putrefaciens XY 07 were involved in amino acid transport and metabolism; such ion transporters and a great variety of other highly specific transporters and permeases also play a vital role in marine bacteria. 25 A total of 226 genes were found in the S. putrefaciens XY 07 and annotated into energy production and conversion, of which the most abundant COGs were COG1053 (succinate dehydrogenase), COG1012 (dehydrogenase), COG0348 (4Fe-4S ferredoxin iron−sulfur binding domain protein), COG0243 (molybdopterin oxidoreductase), COG1301 (sodium dicarboxylate symporter), and COG0479 (succinate dehydrogenase).…”

Microfauna in the activated sludge treatment of the effluent from a soybean processing industry: a form of evaluation and control of the process

“…Small amounts of pedunculated or fixed ciliates were also identified (Figure 3). Among them, it was possible to identify the protozoan similar to Vorticella, which occurs in systems with good efficiency and well-oxygenated sludge (LEE et al, 2004;PAYANDEH;MEHRDADI;DADGAR, 2017;PONCE-ROBLES et al, 2018;JIANG et al, 2021).…”

Highly Enriched Anammox Bacteria with a Novel Granulation Model Regulated by Epistylis spp. in Domestic Wastewater Treatment

“…Protozoa are known to play an essential role in filtering water and acting as potential bioindicators in wastewater treatment systems. − However, many studies have reported that protozoa were observed in granules with bacteria and extracellular polymeric substances. The protozoa involved in these studies include ciliates, amoebae, and flagellates. − Additionally, protozoa can attach to larger granules and be retained in systems with high settleability .…”