Effects of rice husk powder and thermal hydrolysis on sludge characteristics.

To reduce the water content and improve the incineration characteristics of sludge, rice husk and thermal hydrolysis were employed in this study. Effects of rice husk and thermal hydrolysis on the characteristics of the sludge were investigated. The results showed that synergistic thermal hydrolysis with rice husk could effectively destroy sludge particles and release more bound water. For rice husk with a particle size of 50-mesh and an additional amount of rice husk at 1:0.2, the solid content of the sludge was reduced from 17.4 to 16.2%, and the sludge particle size was reduced by 6%. Filtration time and specific resistance to filtrate (SRF) were shortened by 88.9 and 98.7%, respectively. The organic matter content of the filtration cake increased by 14%, compared with the sludge treated by thermal hydrolysis without rice husk. Furthermore, it could be shown that the most optimal conditions were rice husk of particle size 50-mesh and an additional amount of rice husk at 1:0.2, which could lead to effective thermal hydrolysis and higher organic matter content of the filtration cake.

Prognostic Value of Serum Cholinesterase Levels for In-Hospital Mortality among Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease.

Cholinesterase (ChE) is associated with the pathogenesis of chronic obstructive pulmonary disease (COPD), including chronic airway inflammation and oxidation/antioxidant imbalance. However, the relationship between serum ChE levels and survival outcomes of patients hospitalized with acute exacerbations of COPD (AECOPD) is unknown. In this retrospective single-center study, we investigated the ability of the serum ChE level to predict in-hospital death in patients hospitalized with AECOPD. The clinicopathological data, including serum ChE levels as well as clinical and biochemical indicators were extracted for 477 patients from the hospital records and analyzed. Our results demonstrated that AECOPD patients with lower serum ChE levels were associated with increased mortality, frequent hospitalization due to acute exacerbations (AE) in the past year, and longer hospital stay. The optimal cutoff value for the serum ChE level was 4323 U/L. The area under the ROC curve (AUC) values for predicting in-hospital mortality based on the serum ChE level was 0.79 (95% confidence interval (CI), 0.72-0.85). Multivariate logistic regression analysis demonstrated that serum ChE level ≤ 4323 U/L (odds ratio (OR) 9.09, 95% CI 3.43-28.3, p < 0.001), age-adjusted Charlson comorbidity index (aCCI), and the number of hospitalizations due to AE in the past year were independent risk factors for predicting the in-hospital mortality of AECOPD patients. In conclusion, our study demonstrated that low serum ChE levels were associated with significantly higher in-hospital mortality rates of patients hospitalized with AECOPD. Therefore, serum ChE level is a promising prognostic predictor of hospitalized AECOPD patients.

Establishment of the Permeability Model for Soft Solid Sludge Conditioned with Flocculants.

Permeability plays a decisive role in the dewatering process and reflects the difficulty of filtration, especially for soft solid material such as sludge. In this paper, the physicochemical properties and dewatering performance of sludge conditioned with different kinds of flocculants were investigated. Results showed that the flocculant could change the sludge microstructure such as floc morphology, specific surface area, and fractal dimension. Compared with filtration pressure, flocculants had a greater influence on sludge permeability which was a significant negative correlation with filtration pressure and was a positive correlation with flocculant dosage. In order to describe the fact that fluid flows through the porous voids for soft solid sludge, the improved Kozeny constant was corrected. Research showed that permeability was more significant in the dewatering process for the sludge conditioned with inorganic flocculants than that with organic flocculants. The Kozeny constant was not only relevant with suspension nature but also with filtration pressure. The range of the improved Kozeny constant was reasonably determined based on flocculant type, concentration, and filtration pressure, which was of great help to project applications. For raw sludge, the improved Kozeny constant was 958 times than that of the original value, and it decreased significantly for conditioned sludge.

Semi-solid rheology characterization of sludge conditioned with inorganic coagulants.

Rheology measurement, a state-of-the-art technology in a multitude of engineering disciplines, has often been used for computational fluid dynamic simulation of wastewater treatment processes, especially in anaerobic digestion and dewatering. In this work, rheological tests were used to study the semi-solid characteristics of sludge and a good result was obtained. The inorganic coagulants polyaluminum chloride (PAC) and ferric chloride (FC) both increased the floc strength of sludge, leading to higher rheology parameters such as elastic modulus, viscous modulus and specific thixotropy area. Curiously, the shape of all rheological curves exhibited little change with increasing coagulant dosage. The results indicated that various physical and chemical actions among coagulants and sludge flocs relate only to rigid structure, not to the nature of rheology behavior. Frequency sweep tests clearly showed that elastic modulus was a logarithmic function of frequency, suggesting that sludge could not properly be called a soft material due to its inorganic particles. An improved viscoelastic model was successfully developed to predict the experimental data of creep and recovery tests in the linear viscoelastic region. Furthermore, complicated viscoelastic behavior of sludge was also observed, and all the rheology tests could provide the optimum dosage of PAC but not the optimum dosage of FC.

Rheology characteristics of activated sludge and thermal treated sludge at different process temperature.

In this paper, flow behavior for activated sludge and thermal treated sludge at different process temperature and various solids content were analyzed. Results show viscosity of activated sludge and thermal treated sludge both decreased with increasing temperature, while temperature dependence of viscosity for both types of sludge were not same at the whole study range. The relationship between viscosity and temperature could be expressed by Arrhenius equation for activated sludge, and it was interesting that this law was only suitable when certain solid content (80 g/L) for thermal treated sludge. Moreover, the logistic model was certified to be accurate in describing the functionality for thermal treated sludge. As solid content was at range of 80-100 g/L, active energy of viscosity for both kinds of sludge were similar, indicating that physicochemical properties' change of sludge after thermal hydrolysis had little effect on viscosity sensibility. Arrhenius law was also suitable for describing the relationship between storage modulus and process temperature for activated sludge. However, for thermal treated sludge, Arrhenius law was invalid. Yield stress for activated sludge was prominent, while it could be ignored for thermal treated sludge.

Effects of thermal hydrolysis temperature on physical characteristics of municipal sludge.

Effects of thermal hydrolysis temperature on the physical properties of municipal sludge was further studied by a series of experiments. There was a decrease in bound water content with an increase in hydrolysis temperature, while there was an increase in pH at temperatures below 120 °C, and a decrease at temperatures exceeding 120 °C. An analysis of settleability, centrifugation and vacuum filtration of the treated sludge indicated that the threshold temperature was 120 °C, which was the same as the temperature for the bound water content and particle size. In addition, raw sludge with a solids content of 100 g/L, exhibited significant non-Newtonian fluid characteristics. At thermal hydrolysis temperatures exceeding 120 °C, non-Newtonian fluid characteristics including liquid and solid characteristics were significantly weakened. The consistency index (k) decreased from 5.90 Pa·s to 0.068 Pa·s, while the flow index (n) increased from 0.31 to 0.74, suggesting that thermal hydrolysis sludge was much closer to Newtonian fluids compared to raw sludge. Modification of bound water content, particle size and viscosity with hydrolysis temperature, revealed the nature of improved dewaterability by thermal hydrolysis. The fractal dimension of the sludge floc increased from 2.74 to 2.90, meaning that the floc became more compact after thermal hydrolysis.

STAT6 phosphorylation inhibitors block eotaxin-3 secretion in bronchial epithelial cells.

The STAT6 (signal transducer and activator of transcription 6) protein facilitates T-helper cell 2 (Th2) mediated responses that control IgE-mediated atopic diseases such as asthma. We have identified compounds that bind to STAT6 and inhibit STAT6 tyrosine phosphorylation induced by IL-4. In the bronchial epithelial cell line BEAS-2B, compound (R)-84 inhibits the secretion of eotaxin-3, a chemokine eliciting eosinophil infiltration. (R)-84 appears to prevent STAT6 from assuming the active dimer configuration by directly binding the protein and inhibiting tyrosine phosphorylation.