Control of sludge settleability based on organic load and ammonia nitrogen load under low dissolved oxygen.

Controlling dissolved oxygen (DO) at low level can save energy for wastewater treatment plants (WWTPs), but it is easy to induce filamentous sludge bulking. Through establishing the kinetic equation of sludge settleability, ammonia nitrogen (NH4 +-N) load and organic load (food-to-microbe ratio, F/M), the mechanism of the competitive relationship between filamentous and floccular bacteria under low DO was analyzed. The results showed when DO, NH4 +-N load and F/M were in the range of 0.15-0.35 mg/L, 0.035-0.15 d-1 and 0.12-0.42 d-1, respectively, the mass transfer limitation of organic matter was the main factor determining the dominant growth of filamentous bacteria. When DO, NH4 +-N load and F/M were in the range of 0.35-0.65 mg/L, 0.035-0.065 d-1 and 0.12-0.22 d-1, respectively, the mass transfer limitation of NH4 +-N was the main factor determining the dominant growth of filamentous bacteria. When DO was low, no matter how NH4 +-N load and F/M changed, the growth of filamentous bacteria was promoted. When DO and F/M were in the range of 0.35-0.65 mg/L and 0.22-0.42 d-1, respectively, no matter how NH4 +-N load and F/M changed, the growth of filamentous bacteria was inhibited. Therefore, in actual operation, ensuring relatively low DO and high F/M was beneficial for the sludge settleability improvement.

Ammonium removal by native microbes and activated sludge within the Jialu River basin and the associated microbial community structures.

To explore the availability of native microbes and activated sludge for ammonium removal, the native microbes and activated sludge in Jialu River basin were investigated in terms of ammonium-removing activities and their microbial communities using spectrophotometry and high-throughput sequencing. NH4+-N and total nitrogen (TN) in the targeted river ranged from 2.45 ± 1.76 to 8.56 ± 2.54 mg/L and from 3.42 ± 2.79 to 13.49 ± 5.06 mg/L, respectively. Both the native microbes and activated sludge had strong ammonium-removing activities with the removal efficiencies of more than 94%. High-throughput sequencing results indicated that, after five batches of operation, the class Gammaproteobacteria (28.55%), Alphaproteobacteria (14.55%), Betaproteobacteria (13.89%), Acidobacteria (8.82%) and Bacilli (7.04%) were dominated in native community, and there was a predominance of Gammaproteobacteria (21.57%), Betaproteobacteria (16.33%), Acidobacteria (12.41%), Alphaproteobacteria (10.01%), Sphingobacteriia (6.92%) and Bacilli (6.66%) in activated sludge. These two microbial sources were able to remove ammonium, while activated sludge was more cost-effective.

The influence of in situ purification system on pathogen in the river fed by the drainage of sewage plant.

An in situ integrated system, consisting of ecological floating islands (EFI), ecological riverbeds (ER), and ecological filter dams (EFD), was built in a ditch only receiving the effluent of sewage plant; the effect of in situ technologies on the distribution of aquatic pathogen was investigated. The results showed the aquatic pathogen decreased along the ditch. Specifically, the relative abundance of Legionella, Aeromonas, and Acinetobacter decreased from 0.032, 0.035, and 0.26 to 0.026%, 0.012%, and 0.08%, respectively. Sedimentation, filtration, and sorption (provided by plant roots and biofilms on substrates) were principal processes for the removal. The nitrogen removal bacteria to prevent the potential risk of eutrophication were also evaluated. The EFI and ER were the dominant sites for Nitrosomonas (34.96%, 32.84%) and Nitrospira (35.74%, 54.73%) enrichment, while EFI and EFD facilitated the enrichment of denitrification bacteria. Notably, the relative abundance of endogenous denitrifiers (DNB-en) (including Dechloromonas at 9.72%, Thermomonas at 0.58%, and Saccharibacteria at 2.55%) exceeded those of exogenous denitrifiers (DNB-ex) (Thauera at 0.20%, Staphylococcus at 0.005%, and Rhodobacter at 0.27%). This study demonstrated that the in situ integrated system was effective in reducing the abundance of pathogens in the drainage channel, and the deficiency of DNB-ex and carbon sources made nitrate removal difficult.

Comparison of agricultural wastes and synthetic macromolecules as solid carbon source in treating low carbon nitrogen wastewater.

This paper investigated the feasibility of using agricultural wastes and synthetic macromolecules as solid carbon sources and studied the effects of improvement of denitrification by the selected agricultural wastes. The carbon release capacity and denitrification performance of corncob (CC), peanut shell (PS), obsolescent rice (OR) and polycaprolactone (PCL), poly butylene succinate (PBS), polyvinyl alcohol sodium alginate (PVA-SA) were systematically analyzed. The results showed that for each carbon source, the first-order kinetic equation was basically followed during the carbon release process. PVA-SA, CC and PS had higher carbon release capacity with accumulative dissolved organic carbon (DOC) of 16.22-20.63 mg·g-1 and chemical oxygen demand (COD) of 100.86-134.10 mg·g-1. Correspondingly, they showed excellent denitrification performance with almost no residual NO3--N, and the denitrification process well followed the Monod equation. PCL, PBS and OR had lower carbon release capacity with accumulative DOC of 2.06-3.14 mg·g-1 and COD of 13.29-24.13 mg·g-1, respectively. Nevertheless, these materials can also improve the denitrification performance, with the residual NO3--N in the range of 6.02-6.36 mg·L-1, and the effluent DOC was in the range of 10-15 mg·L-1. Synthetic polymers are more suitable for nitrogen removal in groundwater treatment, while agricultural wastes are ideal carbon sources for secondary effluent treatment.

Biological denitrification using polycaprolactone-peanut shell as slow-release carbon source treating drainage of municipal WWTP.

The development of slow-release carbon source is an effective way to reduce the total nitrogen (TN) in low carbon to nitrogen ratio wastewater. In this study, a novel solid slow-release carbon source (PPP) was prepared using polycaprolactone (PCL) and peanut shell (PS) as carbon sources with polyvinyl alcohol-sodium alginate (PVA-SA) as hybrid scaffolds. The carbon release properties of PPP and each carbon source materials were compared. The performances of nitrogen removal and microbial community structure using PPP as external carbon source were investigated. The results showed that PPP had the best slow-release performance, and its release process followed the first-order release equation. The ratio of acetic acid, propionic acid and butyric acid in released organic matter was stable at (75.73 ±â€¯4.62)%:(17.22 ±â€¯4.53)%:(7.06 ±â€¯1.02)%. When using PPP as an external carbon source for denitrification, the relative abundance of Gammaproteobacteria increased from 39.32% to 46.66%, while the Shannon index decreased from 8.59 to 8.29. The utilization efficiency of PPP was determined by the ratio of the organic matter releasing rate to the released organic matter consumption rate. By optimizing the PPP dosage, both high nitrogen removal efficiency and low residual organic matter could be achieved.

3-Arylisoindolinone and sesquiterpene derivatives from the mangrove endophytic fungi Aspergillus versicolor SYSU-SKS025.

A pair of 3-arylisoindolinone enantiomers: (+)-asperglactam A (1), (-)-asperglactam A (1) and a pair of nor-bisabolane enantiomers: (+)-1-hydroxyboivinianic acid (2), (-)-1-hydroxyboivinianic acid (2), along with seven known compounds (3-8) were obtained from the mangrove endophytic fungus Aspergillus versicolor SYSU-SKS025. Their structures were determined on the basis of HRESIMS and NMR spectroscopic data, and X-ray diffraction. (+)-Asperglactam A (1) and (-)-asperglactam A (1) are the first optically pure examples in the 3-arylisoindolinone family, which are rarely found in natural sources. All isolated compounds were evaluated for α-glucosidase inhibitory activity. The enantiomers of 1-3 showed moderate inhibitory activity against α-glucosidase with IC50 values ranging from 50 to 190µM. Compound 7 exhibited significant inhibitory activity against α-glucosidase with IC50 value of 7.5µM. In addition, compound 7 was found to inhibit nitric oxide production in RAW 264.7 macrophages with IC50 value of 12.5µM.