Tertiary treatment of municipal wastewater in an IBFR dominated by PD/A with unique niche

To explore the feasibility of biofilter reactor to treat municipal secondary effluent deeply without extra carbon source, this paper proposed an integrated biofilter reactor (IBFR) coupling partial denitrification (PD) with anammox (A) to treat the secondary effluent and raw sewage with the flow ratio of 3:1 together. The results show that the effluent concentration of TN and COD in IBFR could be reduced to 10 mg/L and 15 mg/L, respectively, under hydraulic retention time of 1.5 h and nitrogen loading rate of 0.55 kg/(m3·d). The highest specific anammox activity (19.2 mg N/(g TVS·d)) and the maximum extracellular polymeric substance (EPS) content (107.21 mg/g TVS) occurred at the 25-50 cm section of IBFR, where Thauera, Candidatus Anammoximicrobium and Candidatus Brocadia were the dominant denitrifiers and anammox bacteria. Furthermore, the cyclic self-stratification occurred along the reactor height, where the utilization, decomposition, transformation and cross-feeding of EPS enhanced the performance stability of nitrogen and carbon removal, strengthened the niche structure and promoted the synergistic symbiosis. In conclusion, IBFR coupling PD and A demonstrated the possibility to treat secondary effluent without additional carbon sources, which is expected as an alternative approach for tertiary treatment of municipal wastewater.

[Impact of water body environments on the microbial community of Oncomelania hupensis snails in marshlands around the eastern Dongting Lake]

OBJECTIVE

To evaluate the effects of water body environments on the microbial community of Oncomelania hupensis snails in marshlands of the eastern Dongting Lake where natural extinction of O. hupensis snails are found, so as to explore the correlation between the natural extinction of O. hupensis snails and the microbial community in snails.

METHODS

Snails were caged water bodies in the Qianliang Lake marshland (Qianliang Lake regions) where natural extinction of snails was found and in the Junshan Park marshland (Junshan Park regions) in the eastern Dongting Lake for 30 days, and then all snails were collected and identified for survival or death. DNA sequencing of the fungi and bacteria was performed in snails before and after immersion in waters, and the biodiversity and abundance were analyzed.

RESULTS

The survival rates of O. hupensis snails were 28.0% (70/250) and 64.8% (162/250) in Qianliang Lake regions and Junshan Park regions 30 days after immersion in waters, respectively (χ² = 81.365, P < 0.01). The number of the fungal community and the biodiversity of the bacterial community were both greater in snails caged in Qianliang Lake regions post-immersion than pre-immersion, and there was a significant difference in the structure of the fungal and bacterial communities. The microbial community with a significant difference included Flavobacteriaceae,which was harmful to O. hupensis snails.

CONCLUSIONS

The water body environment affects the composition of the microbial community in O. hupensis snails in marshlands with natural snail distinction around the eastern Dongting Lake; however, further studies are required to investigate whether the natural distinction of snails is caused by water body environments-induced changes of the microbial spectrum in O. hupensis snails.

Comparative experiments of fibril formation from whey protein concentrate with homogeneous and secondary nuclei

Two types of special structures, homogeneous and secondary nuclei, form during fibril formation. The structural and functional properties of amyloid fibrils in whey protein concentrate (WPC) with different ratios of added homogeneous nuclei to secondary nuclei were investigated. Thioflavin T fluorescence analysis and kinetic equations indicated that two types of nuclei could accelerate WPC fibrillation compared with WPC self-assembling into amyloid fibrils, thereby reducing the lag time and increasing the number of fibrils. However, there were considerable differences in the nucleation-inducing capability of WPC fibrillation between homogeneous and secondary nuclei. The number of fibrils formed by adding homogeneous nuclei was higher than that obtained with secondary nuclei, the increase in the Th T fluorescence intensity induced by homogeneous nuclei was 1.83-fold much than secondary nuclei. Meanwhile, secondary nuclei yielded a 2.71-fold faster aggregation rate of WPC than homogeneous nuclei, particularly during the first hour of thermal treatment (protein mass ratio of nuclei to WPC 1:1). The gelation time of WPC after secondary nuclei addition was shorter, from 10 h (WPC (2.0/6.5)) to 4 h (WPC + HN) to 2 h (WPC + SN); however, the gel microstructure of WPC after the addition of homogeneous nuclei was denser, yielding a preferred water holding capacity.

The structure and amphipathy characteristics of modified γ-zeins by SDS or alkali in conjunction with heating treatment

γ-Zein was modified by SDS or alkali combined with heating treatments in water and in 70% ethanol to change its amphipathic properties and explore the relationship between amphipathic characteristic and structure. γ-Zein water-dispersibility was dramatically increased via alkali or SDS combined with heating treatments, but their ethanol-dispersibilities were significantly different during ethanol evaporation. High both water-dispersibility and ethanol-dispersibility were found from alkali modified γ-zein while high water-dispersibility but low ethanol-dispersibility were obtained from SDS modified γ-zein, indicating that alkali modified γ-zein had better amphipathic characteristic compared with SDS modified γ-zein. Alkali modified γ-zein with higher amphipathic characteristic possessed higher structural inversion ability since it was easy to recover its native state as solvent changing from water to ethanol, contrary to SDS modified γ-zeins whose amphipathic characteristic was not improved. Moreover, the higher structural inversion ability of alkali modified γ-zein depended on the recovery capability of α-helix structure as solvent altering.

Acid-responsive properties of fibrils from heat-induced whey protein concentrate

The heat-induced fibrils of whey protein concentrate (WPC) have demonstrated an acid-responsive property; that is, the fibrils went through formation-depolymerization-reformation as pH was adjusted to 1.8, 6.5, and back to 1.8. We investigated the microstructure, driving force, and thermal stability of 3.0% (wt) WPC nanofibrils adjusted between pH 6.5 and 1.8 twice. The results showed that the nanofibrils had acid-responsive properties and good thermal stability after reheating for 10h at 90°C and adjusting pH from 1.8 to 6.5 to 1.8. The content of WPC fibril aggregates was not much different with the prolongation of heating times during pH variation. Although the nanofibrils' structure could be destroyed only by changing the pH, the essence of this destruction might only form fiber fragments, polymers that would restore a fibrous structure upon returning to pH 1.8. A described model for the acid-responsive assembly of fibrils of WPC was proposed. The fibrils went through formation-depolymerization-reformation by weaker noncovalent interactions (surface hydrophobicity) as pH changed from 1.8 to 6.5 back to 1.8. However, the fibrils lost the acid-responsive properties because much more S-S (disulfide) formation occurred when the solution was adjusted to pH 6.5 and reheated. Meanwhile, fibrils still possessed acid-responsive properties when reheated at pH 1.8, and the content of fibrils slightly increased with a further reduction of α-helix structure.

Laparoscopic esophageal myotomy and anterior partial fundoplication for the treatment of achalasia

BACKGROUND

The purpose of this study was to determine the initial results of laparoscopic esophageal myotomy and anterior fundoplication in the treatment of 26 patients with achalasia.

METHODS

Operative time, complications, and length of hospitalization were recorded for each patient. Postoperative outcomes were assessed by a standardized patient questionnaire, 24-hour esophageal pH studies, and esophageal transit studies.

RESULTS

Twenty-six consecutive patients with class IV dysphagia underwent a laparoscopic esophageal myotomy and anterior partial fundoplication, with a single incidence of intraoperative esophageal perforation. The mean operative time was 3.5 hours. The median length of hospitalization was 5 days. Of the 21 patients for whom follow-up was available (median follow-up, 4 months), 19 (90%) were satisfied and 2 (10%) were somewhat satisfied with their surgery. After operation, 14 of the 21 patients (67%) reported no dysphagia (class I), whereas 6 (28%) had class II dysphagia (less than once per week) and only 1 (5%) had class III dysphagia (greater than once per week). Liquid-phase esophageal transit studies (n = 14) revealed a significant improvement in esophageal clearance in the supine position from 18% before operation to 44% after operation (p = 0.006). Distal esophageal acid exposure was normal in 6 of 7 patients.

CONCLUSIONS

These early results suggest that laparoscopic esophageal myotomy and anterior partial fundoplication provides efficacious treatment of achalasia.