Sludge conditioning, thickening and dewatering optimization in a screw centrifuge decanter: Which means for which result?

Sludge conditioning, thickening and dewatering optimization in a screw centrifuge decanter: Which means for which result?

Centrifuges are common machines used for sludge thickening and dehydration in wastewater treatment plants, but optimal performance and adjustment parameters are often difficult to predict and optimize, due to complex mechanisms occurring. separation and high shear stresses suffered by flocs. Laboratory tests are needed to assess performance and to evaluate chemicals and dosage to reduce the full-scale optimization time. They include the characterization of volatile materials, drainage and tests of the CST vs mixing time, basket rotation tests with shear, determination of the drought limit. The ability of these tests, to evaluate the dehydration of sludge and / or select the polymer and dosage, is discussed and is compared to the performance obtained in a screw centrifuge decanter in the laboratory and ongoing scale.

As a smart laboratory application tool, digital microfluidic (DMF) technology is widely used in DNA-based applications, clinical diagnosis, chemical synthesis and other areas. Additional components (such as heaters, centrifuges, blenders, etc.) are needed in practical applications on DMF devices. In this article, an interconnection method of DMF chips based on the electro-system-over-dielectric (EWOD) has been proposed. A slippery porous surface membrane (slips) with corrugated and open surface was used as a dielectric-hydrophobic layer material, composed of polytetrafluoroethylene membrane (PTFE) and silicone oil. Indium pewter oxide glass (ITO) was used to make the DMF chip. In order to test the relationship between the splicing deviation and the movement of the droplets, the effect of the different activation / stop electrodes on the minimum operating voltage when the drop has gone through a splice interval has been studied.

Separation and high efficiency collection and plasma collection of total blood using passive filtration

Side flow tests and hand analyzers facilitate diagnostic tests in the limited resource settings and the support point. However, many of these devices require sample preparation such as plasma separation to remove cells and isolate the liquid portion of the blood. More specifically, the separation of blood plasma is needed for routine health care assessments such as complete metabolic panels and chronic monitoring of the HIV viral load.

Laboratories, this type of treatment was treated with unconventional and hand-ruffled centrifuge devices (high volume) or plasma separation membranes (PSM) coupled with lateral flow tests (low volume). In this document, we describe a device that separates and stores undiluted blood plasma using only passive filtration in less than 10 min. The integration of a PSM with a prefilter and an absorbent material gives an increase of 3 times from the efficiency of the separation compared to the similar devices using a passive filtration. We demonstrate the reproducibility of our device through the physiological range of hematocrits (20 to 50%) with an average recovered plasma volume of 61.7 ± 2.6 μl

Maximum separation efficiency was obtained for a total blood sample (30% hematocrit) in 10 min. We evaluate the purity of our plasma sample as to the quantification of hemoglobin and reports a hemolysis as a minimum (≤ 5%) or undetectable (≤1%). The specific recovery of the human IgG, IFN-γ and HIV-1 RNA indicates that the diagnostic utility of the plasma obtained from our apparatus is unchanged with the plasma obtained via centrifugation. Finally, we demonstrate the use of recovered plasma, applied via “stamping”, to successfully perform an immunochromatographic dosage of commercial lateral feed for tetanus antibodies. This device platform is capable of producing pure plasma samples from blood to facilitate tests in limited resource settings to improve access to health care.

 Sludge conditioning, thickening and dewatering optimization in a screw centrifuge decanter: Which means for which result?

Insaturated zone flow process and aquifer response time in the chalk aquifer, Brighton, Southeast of England

The aquifer of chalk is one of the main sources of water in Southeast England. The unsaturated zone of the aquifer plays an important role controlling the time and magnitude of the recharge and constitutes a major way for the transport contaminant towards the water table. A range of previous work has addressed flow processes in the unsaturated area of ​​chalk, but physical understanding is always incomplete. Here we present the results of a study on the flow mechanism in the unsaturated area of ​​chalk using a combination of statistical analyzes and new laboratory methods. The study was undertaken on three sites (Barn North Heath, Pyecombe East and Preston Park) on the chalk of Bloc Brighton, Southeast England. Data from the daily hourly series and groundwater schedule and precipitation have been correlated. The results show that a slower response from the groundwater level to precipitation occurs during dry seasons (summer and autumn) when the amount of precipitation effective is less than 4 mm / day, with an insaturated zone thicker and drier.

A faster response occurs during wet seasons (winter and spring) when daily efficient precipitation exceed 4 mm / day with a thinner and wet unsaturated area. Very fast response periods (within 15 hours) were observed during the wet seasons of the North barn and Pyecombian East sites, with an unsaturated hydraulic conductivity (KU) deduced from 839 mm / day. A slower response was observed on an urbanized site (Preston Park) as a result of the reduction of direct refill due to reduced infiltration, due to impervious infrastructure attendance covering the area around Preston Park Borehole drilling. KU laboratory measurements of the chalk matrix using a geotechnical centrifuge display a variant of 4.27 to 0.07 mm / day, depending on the saturation level.

Thus, the quick responses can only be linked to the matrix flow, but indicate the contribution of karst fracture and flow processes in the water pipe. This article is protected by copyright. All rights reserved.

Gabriel Gonzalez

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