Toward efficient sludge processing using novel rheological parameters: dynamic rheological testing.

Materials known as complex fluids exhibit a transitional behaviour between their solid and liquid states. Sludges produced at different treatment stages of wastewater treatment are examples of these materials, since they exhibit solid behaviour within shorter time frames and liquid behaviour over longer durations. These sludges can also change from solid-like to liquid-like, or vice versa, when subjected to even a slight deformation; this stems from their complex makeup, which includes both particulate materials and polymeric gels, including both biopolymers and the synthetic polymers used in conditioning them. This paper focuses on two means of quantifying dynamic rheological test results: (1) the linear viscoelastic behaviour (LVE) of sludge samples, as measured by the strain sweep analysis storage (G') and loss moduli (G"); and (2) the flow curve, which presents the relationship between the shear viscosity and shear rate and determines the yield stress values of samples using the strain sweep test mode. With these methods, sludges can be more accurately characterised, allowing better prediction of their behaviour in treatment and transport processes.     

Fate and Effects of Fry-Drying Application on Municipal Dewatered Sludge

The present experimental investigation examined the applicability of fry-drying technology for municipal dewatered sludge by using waste engine oil for frying. The process was studied in a 100–180°C temperature range for 2 to 20 min frying times. The cakes were shaped in a diameter range of 1 to 3 cm with 3-cm-length prior to the frying. Experimental points were determined by the Box–Wilson experimental method. Statistical analysis was employed for determining the response function coefficients for variables. The response functions were as dry solids content (DS), volatile solids content (VS), and low heating value (LHV). Experimental and predicted results indicated good agreement with high correlation coefficients. The results showed that fry-drying is an alternative, fast process for sludge drying. In addition, it makes fry-dried sludge as a product with noteworthy LHV. This study provides further insight into the fry-drying of municipal dewatered sludges.     

Dual Polymer Conditioning of Water Treatment Residuals

Conditioning of either wastewater biosolids or water treatment residuals conventionally utilizes a single polymer to improve subsequent dewatering. The sequential addition of two polymers has been reported to enhance biosolids dewaterability, but comparable benefits have not been demonstrated for water treatment residuals. This paper evaluated the use of cationic and nonionic polymers, singly and in combination (dual), to investigate whether dual polymer conditioning of residuals offers any advantages, and to determine whether the results could be accommodated by current mechanistic understandings. For this purpose, lab-scale tests used capillary suction time (CST), supernatant viscosity, zeta potential, streaming current, turbidity, floc size, and rheometric analyses. Comparisons of CST and viscosity results for single and dual polymer additions indicated that dual polymer use gave moderately improved dewaterability, possibly due to the increased mixing utilized for dual polymer addition. Using a cationic polymer produced a less turbid supernatant. Zeta potential and streaming current were not good indicators of conditioning efficacy when a nonionic polymer was used. Rheometric analyses were only meaningful in one selected method for treatment of the data: the area under the rheogram up to a shear rate of 30?inverse?s. Overall, implementation of dual polymer use does not appear warranted.     

Consumption of green coffee and the risk of chronic diseases

ABSTRACT

Green coffee contains macro nutrients such as carbohydrates, protein, fat, as well as minor components such as caffeine, trigonelin and chlorogenic acid. Phenolics, chlorogenic acids and brown pigments are sources of natural antixodants. High polypehonic materials found in green coffee and especially chlorogenic acid in it have an important place. It is considered that; green coffee has effects on body mass, blood glucose and lipid levels, blood pressure, prevention from cardiovascular diseases which is based on chlorogenic acid consisting antioxidant activity. However, many topics like toxicological effects, doses, amounts, usage in the body, advantages and disadvantages, etc. of these active molecules need to be examined. For these reasons this article was rewieved to evaluate health effects of green coffee.     

A Comprehensive Numerical Study on Thermohydraulic Performance of Fluid Flow in Triangular Ducts with Delta-Winglet Vortex Generators

Triangular ducts fitted with various kinds of delta-winglet type vortex generators (VGs) are commonly used to achieve compactness and heat transfer enhancement in many industries. Successive locations of VGs on the inner surfaces of the ducts can be arranged in Common Flow Up (CFU) and Common Flow Down (CFD) orientations. In the present numerical study simultaneous effects of orientation and streamwise distance between VGs on triangular fin performance is carried out considering both global and local flow and heat transfer fields. With the configurations considered in this study, a CFD–CFU orientation and a nondimensional streamwise distance of 0.5 is determined as the best configuration. “RNG k-?” turbulence model with “Enhanced wall treatment” option is determined as the best turbulence model to predict the flow fields inside the triangular duct with built-in VGs, for Reynolds number of 5000.     

Green synthesis of Ce2 O3 NPs and determination of its antioxidant activity

In this study, the authors presented synthesis of ceria nanoparticles (NPs) by the bio‐reduction method and their antioxidative activity. Aqueous extract of Euphorbia (Euphorbia amygdaloides) was used as reducing and stabilising agents. They used aqueous extract of Euphorbia (E. amygdaloides) as reducing and stabilising agent. Ultraviolet–visible (UV–vis) absorption spectroscopy was used to monitor the quantitative formation of ceria NPs. They also addressed the characteristics of the obtained ceria NPs using scanning electron microscopy (SEM), X‐ray diffraction (XRD) and transmitting electron microscope (TEM). The synthesised cerium (III) oxide (Ce₂ O₃) NPs were initially noted through visual colour change from colourless pale yellow cerium (III) to light yellow cerium (IV) and further confirmed the band at 345 nm employing UV–vis spectroscopy. The average diameter of the prepared NPs was about 8.6–10.5 nm. In addition, the synthesised Ce₂ O₃ NPs were tested for antioxidant and anti‐bacterial activities using ferric reducing antioxidant power, cupric reducing antioxidant capacity, ferrous ions chelating activity, superoxide the anion radical scavenging and 2, 2′‐azinobis 3‐ethylbenzothiazol to‐6‐sulphonic acid scavenging activity. It could be concluded that Euphorbia (E. amygdaloides) extract can be used efficiently in the production of potential antioxidant and anti‐bacterial Ce₂ O₃ NPs for commercial applications.Inspec keywords: cerium compounds, nanoparticles, nanofabrication, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet spectra, visible spectraOther keywords: Ce₂ O₃ , α‐tocopherol, butylated hydroxytoluene, anion radical scavenging, ferrous ions chelating activity, 2, 2''‐azinobis 3‐ethylbenzothiazol to‐6‐sulphonic acid scavenging activity, UV‐vis spectroscopy, light yellow cerium, ultraviolet‐visible absorption spectroscopy, SEM, XRD, green synthesis, transmitting electron microscopy, X‐ray diffraction, scanning electron microscopy, aqueous extract Euphorbia amygdaloides, antioxidative activity, bio‐reduction method, ceria nanoparticles, antioxidant activity     

Use of drainability and filterability simulations for evaluation of oxidative treatment and polymer conditioning of sludge.

In the traditional view of sludge structure, a two-phase system is visualized. The solid phase is often illustrated as consisting of uniform, spherical, negatively charged particles. This simplistic picture limits the understanding of both conditioning and dewatering. Specifically, it limits us to only two strategies for destabiiization: charge neutralization (using cationic coagulant species with either uniform or patch effects), and bridging (using polymeric flocculants). In fact, the situation is more complex in many respects. In this paper, we compared chemical conditioning of anaerobically digested biosolids using (1) conventional polymeric flocculation, and (2) treatment by chemical oxidants. Since these strategies may alter dewatering behavior by very different mechanisms, we report comparisons using a lab-scale simulator of belt press dewatering, including separate steps for the drainage and filtration processes. This allows greater insight into the effects of these conditioning methods and how they might be properly employed.     

Response Surface Methodological Approach for the Assessment of Thermal Drying of Dewatered Municipal Sludge

Thermal drying of dewatered municipal sludge was studied in the temperature range 50–180°C for different times from 10 to 120 min. The Box–Wilson response surface experimental method was used to investigate the effects of temperature and time on sludge drying. Statistical analysis using the methodology was employed to determine the response function coefficients for each variable: temperature and time. The response functions of the study were dry solids (DS) content, volatile solids (VS) content, and low heating value (LHV). Experimental and predicted results from the model indicated excellent agreements. Higher drying temperatures and time led to higher DS content. Higher temperatures increase the drying kinetics and longer drying times allow more time for water to evaporate. The elevated temperatures and time did not drastically change the VS content values. Only small-scale changes were observed regarding the increases in temperature and time. Higher shrinkage percentages were achieved via increased temperature and time. The drying kinetics exhibited increased drying rates depending on the decrease in water content. This study showed that the response surface methodology could be used as a tool for drying process optimization.     

Physical characteristics of a waste activated sludge: conditioning responses and correlations with a synthetic surrogate.

The efficient and economic management of waste activated sludge (WAS) requires a proper understanding of the sludge's material properties. Though there has been much study of WAS, an adequate linkage between its physical and chemical properties has been elusive. In particular, the conditioning and dewatering of WAS are expensive operations, and the addition of polymer to WAS leads to even more complex material behavior that is difficult to optimize. This paper reports on an extensive characterization of WAS, both with and without polymer conditioning. We combined the classical "jar test" approach with less conventional rheometric and electrokinetic measurements. In addition to the use of sampled WAS, a synthetic surrogate sludge was formulated, attempting to duplicate properties of WAS and allow more extensive characterization of a reproducible surrogate to WAS. Results with both the synthetic surrogate and WAS indicated that the traditional, electrokinetic, and rheological properties were related. However, the dose optima by rheometry were somewhat higher in both cases.