Transcriptomic Insights into Metabolism-Dependent Biosynthesis of Bacterial Nanocellulose.

Bacterial nanocellulose (BNC) is an attractive green-synthesized biomaterial for biomedical applications and various other applications. However, effective engineering of BNC production has been limited by our poor knowledge of the related metabolic processes. In contrast to the traditional perception that genome critically determines biosynthesis behaviors, here we discover that the glucose metabolism could also drastically affect the BNC synthesis in .

[Bacterial Community Structure and Antibiotic Resistance Gene Changes in IFAS+Magnetic Coagulation Process Wastewater Treatment Plant in Cold Regions].

The main objective of this study was to explore the changes in bacterial communities and antibiotic resistance genes (ARGs) in an integrated fixed-film activated sludge (IFAS)+magnetic coagulation process wastewater treatment plant (WWTP) in Xinjiang. The bacterial communities and ARGs in the influent, suspended activated sludge, attached biofilm, and effluent were studied using 16S rRNA gene sequencing and metagenomic sequencing. The results showed that the average relative abundances of Chloroflexi and Nitrospirae in activated sludge were 3.

pH-adjustment strategy for volatile fatty acid production from high-strength wastewater for biological nutrient removal.

Volatile fatty acid (VFA) production from three types of high-strength organic wastewater (cassava thin stillage, starch wastewater and yellow-wine processing wastewater) were compared. The results showed that cassava thin stillage was the most suitable substrate, based on its high specific VFA production (0.68 g chemical oxygen demand (COD)/g initial soluble chemical oxygen demand (SCOD)) and yield (0.

[Kinetic simulation of enhanced biological phosphorus removal with fermentation broth as carbon source].

As a high-quality carbon source, fermentation broth could promote the phosphorus removal efficiency in enhanced biological phosphorus removal (EBPR). The transformation of substrates in EBPR fed with fermentation broth was well simulated using the modified activated sludge model No. 2 (ASM2) based on the carbon source metabolism.

[Mechanisms of the improvement in dewaterability of alkaline fermented sludge by simultaneous ammonium and phosphate recovery].

Simultaneous ammonium and phosphate recovery could notably improve the dewaterability of alkaline fermented sludge, the mechanisms of which, however, remains unclear at present. The influence of zeta potential, divalent ions, extracellular polymeric substances (EPS), dissolved polymers and struvite were studied in batch experiments. Under the optimal ammonium and phosphate recovery condition [i.

[Kinetic model of enhanced biological phosphorus removal with mixed acetic and propionic acids as carbon sources. (III): Model application].

The kinetic model based on SCFAs metabolism was applied for the prediction of phosphorus-and glycogen-accumulating organisms (PAO and GAO) competition with different carbon sources and m(P)/m(COD) ratios. When acetic acid was used as the sole carbon source, the biomass compositions were almost the same as those before cultivation, and neither PAO nor GAO could be out-competed from EBPR. However, increasing propionic acid in the influent helped PAO to be the predominance organism, and EBPR performance kept excellent when the ratio of propionate to mixed acids (acetate + propionate) was higher than 0.

[Kinetic model of enhanced biological phosphorus removal with mixed acetic and propionic acids as carbon sources. (II): Process simulation].

Two groups of sequencing batch reactors were used to study the metabolism substrate transformation of phosphorus-accumulating organisms (PAO) and glycogen-accumulating organisms (GAO) fed with mixed acetic and propionic acids. Seven stoichiometry parameters and 24 kinetic parameters were contained in the PAO and GAO kinetic model, and stoichiometry parameters were deduced from the stoichiometry models, while kinetic parameters were determined by experimental results. The kinetic model parameters of stoichiometry and kinetics were determined according the experiments and the literature.

[Kinetic model of enhanced biological phosphorus removal with mixed acetic and propionic acids as carbon sources. (I): Model constitution].

Based on activated sludge model No. 2 (ASM2), the anaerobic/aerobic kinetic model of phosphorus-accumulating organisms (PAO) was established with mixed short-chain fatty acids (SCFAs) as the base substance in enhanced biological phosphorus removal process. The characteristic of the PAO model was that the anaerobic metabolism rates of glycogen degradation, poly-beta-hydroxyalkanoates synthesis and polyphosphate hydrolysis were expressed by SCFAs uptake equation, and the effects of anaerobic maintenance on kinetics and stoichiometry were considered.

[Polyhydroxyalkanoate (PHA) synthesis by activated sludge microbes using acetic acid as carbon source].

Polyhydroxyalkanoate (PHA) is a type of biodegradable plastics. The synthesis of PHA by activated sludge has the advantage of easy operation. With acetic acid as the carbon source, the anaerobic synthesis of PHA in the anaerobic-aerobic activated sludge system was compared with the aerobic one in the aerobic sludge system.

[Effect of different ratios of propionic to acetic acids on long-term cultured active sludge for enhanced biological phosphorus removal].

With the long-term cultured enhanced biological phosphorus removal systems in sequencing batch reactors, the effect of different ratios of propionic acid to acetic acid on the transformations of phosphorus and polyhydoxyalkanoates (PHA), and the metabolism stoichiometry of PHA by phosphorus accumulating organisms were studied in this paper. Results showed that the phosphorus removal efficiency improved with the increase of propionic acid to acetic acid ratio, and the suitable C-mol ratio of propionic acid to acetic acid was 2:1. Stoichiometry study indicated that 0.

[Biological nitrogen and phosphorus removal in the anaerobic-aerobic-anoxic-aerobic-anoxic-aerobic sequencing batch reactors].

The biological nitrogen and phosphorus removal was investigated in two anaerobic-anoxic-aerobic sequencing batch reactors (SBRs), which were fed with synthetic and municipal wastewater, respectively. The operating cycle of (AO)3 SBR was 1.5 h anaerobic --> 1 h aerobic --> 1 h anoxic -->20 min aerobic --> l h anoxic --> 20 min aerobic.

[Long-term and short-term effects of propionic/acetic acid ratios on metabolism of glycogen-accumulating organisms].

Three activated sludges enriched with glycogen accumulating organisms (GAO) were acclimatized respectively with different ratios of propionic to acetic acid (i.e. biomass SBR-A, C and E) .

[Effect of SRT on denitrifying phosphorus removal in A/A/O process].

Based on a laboratory-scale anaerobic-anoxic-oxic process acclimated with municipal wastewater, effect of SRT on denitrifying phosphorus removal occurred in the system was investigated. The results indicate that the contribution of anoxic denitrifying phosphorus removal to total phosphorus removal becomes larger with prolonging the sludge retention time. DNPAOs' denitrification and P uptake capacities per anoxic PHAs utilized are quickly increased, while PAOs' P uptake capacity per aerobic PHAs utilized is rarely influenced by SRT.

[Addition of propionic acid on simultaneous biological phosphorus and nitrogen removal in anaerobic-low dissolved oxygen system].

Two lab-scale sequencing batch reactors (SBRs) were operated under conditions of anaerobic-low dissolved oxygen (DO) (0.15 - 0.45 mg x L(-1)), and the influences of addition of propionic acid on simultaneous biological nitrogen and phosphorus removal system were investigated.

[Influence of wastewater initial pH on enhanced biological phosphorus removal in sequencing batch reactor (SBR)].

Two laboratory-scale sequencing batch reactors (SBRs) were operated continuously to investigate the influence of wastewater initial pH on enhanced biological phosphorus removal (SBR1: pH = 6.8; SBR2: pH = 7.6).

[Research on substrate transformation mechanism in A2/O process].

Based on a laboratory-scale anaerobic-anoxic-oxic process acclimated with real wastewater, substrate transformation mechanism and the effect of nitrate on substrate transformations occurred in the system were investigated. The results indicated that under the anaerobic condition without nitrate, phosphorus-accumulating organisms (PAOs) could take up 51% of COD consumed and store them to PHAs; anoxic and aerobic specific phosphorus uptake rates were 3.87 mg/(g x h) and 6.

[Research on polyhydroxyalkanoate form a key aspect to enhanced biological phosphorus transformation].

To investigate the influence of PHB and PHV formed on phosphorus (P) release, uptake and removal during enhanced biological phosphorus removal (EBPR), anaerobic/aerobic batch experiments were conducted with biomass acclimated with propionic to acetic acid carbon molar ratios of 0.5 and 2 on two sequencing batch reactors (SBR1 and SBR2). Statistically significant correlations between polyhydroxyalkanoate (PHA) quantity and form and P release/uptake and removal were observed (R2 >0.

[Impact of pH on the generation of COD, phosphorous and ammonia-nitrogen during the anaerobic fermentation of excess activated sludge].

There are mainly two kinds of sludge in the municipal wastewater treatment plant, i. e. , primary and secondary sludge.