Wyniki wyszukiwania - BazTech

1

Effect of polyacrylamide on the process of removing impurities in the rare earth leachate

Wu Xiaoyan, Zhou Fang, Liu Chufan, Feng Jian, Zhang Zhenyue, Chi Ruan

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 1

182--191

EN

The impurity removal process of the rare earth (RE) leachate is usually accompanied by the formation of flocs, and a certain amount of polyacrylamide flocculant needs to be added in this process. However, few studies have investigated the effect of the flocculant on the impurity removal process. Therefore, this paper compares the influence on the process of removing impurities with or without the adding of polyacrylamide (PAM). The results showed that the addition of PAM had little effect on the removal rate of impurities, but it was conducive to the recovery of RE. When ammonium bicarbonate was firstly adopted to regulate the solution pH to 5.0, and then sodium sulfide was used to adjust the pH to 5.2, and 0.5 mL/100 mL of PAM was added to the leachate, 96% Al3+ and 98% Zn2+ were removed from the leachate, while 95% RE was maintained. In addition, PAM could accelerate the settlement of flocs and then shorten the production cycle. The increase in RE recovery rate may be due to the addition of PAM to shorten the settling time of the flocs, thereby reducing the RE ions adsorbed during the flocculation process and increasing the recovery rate of the RE.

2

Generalized modeling of the sludge volume index and suspended solids to monitor activated sludge bioflocculation using image analysis

Khan Muhammad Burhan, Nisar Humaira, Ng Choon Aun

Environment Protection Engineering

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2020

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Vol. 46, nr 3

17--37

EN

The performance of an activated sludge wastewater treatment plant depends on bioflocculation that is monitored by physical measurements such as the sludge volume index (SVI) and mixed liquor suspended solids (MLSS). The estimation of SVI and MLSS has been proposed using image analysis based modeling which is time-efficient and valid for multiple plants operating in different states. The methodology includes the sequence of image acquisition using bright-field microscopy, a robust segmentation of flocs, partitioning of flocs based on different ranges of their equivalent diameters, extraction of morphological features, and modeling of SVI and MLSS using the features. It is proposed that bright-field microscopy at lower magnification to capture the flocs is sufficient to model SVI and MLSS. A robust approach for image segmentation is adopted by integrating state-of-the-art image segmentation algorithms. It is hypothesized that flocs in different ranges of equivalent diameter respond differently to the variation in the operating state. Hence, flocs and their respective image analysis features are categorized based on the range of equivalent diameter. Finally, stepwise regression is used for feature selection and model identification to explore the feasibility of generalization of models to multiple plants in different states regarding SVI and MLSS.

3

Zmiana ilości wprowadzonej energii ultradźwięków do osadów ściekowych w zależności od zawartości w nich suchej masy

Parkitna K., Kowalczyk M., Krzemińska D.

Rocznik Ochrona Środowiska

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2013

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Tom 15, cz. 3

2039--2053

EN

Despite of many studies on the use of ultrasonic disintegration for sewage sludge conditioning, have not yet been generally accepted indicators to choose the best parameters of used ultrasound to assist in the process of dewatering sludge. Still the most important issue is to adjust proper quantities of introduced energy depending on the characteristic parameters of sewage sludge. The publication presents the results of studies which purpose was to determine the relation of ultrasound energy introduced during sonification of sewage sludge with variable contents of their dry mass. Based on the survey and after analysis of the results, we can conclude that the amount of ultrasound energy introduced into the sewage sludge depends strictly on the content of their dry mass. Together with the increase of dry matter content, grows the amount of energy introduced into sludge. Regardless of the used disintegrator’s power for sonification, for each analyzed amplitude, together with increasing exposure time, density of energy increased nonlinearly. For sludge treated sonification at a specific time, value of this parameter was also changing nonlinearly to the size of used amplitude. The greater the value of the amplitude, the quantity of energy introduced had higher values.

4

Analysis of post-coagulation properties of flocs in terms of coagulant choice

Gumińska J., Kłos M.

Environment Protection Engineering

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2012

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Vol. 38, nr 1

103-114

EN

The knowledge of properties of floes produced in coagulation may enable one to reduce effects of their breakage in a treatment system. This is particularly important in treatment of water contaminated mainly with natural organic matter; produced floes are fragile and susceptible to rupture. The purpose of the research was to determine the influence of a coagulant type on postcoagulation suspension strength. The results show that floes produced based on prehydrolyzed coagulants are more resistant to breakage than those produced by a hydrolyzing coagulant. Strength of post-coagulation suspension increased with the increase of polynuclear Al species (Alb species).

5

Identyfikacja i modelowanie rozkładów wielkości cząstek dla ustalonych warunków procesu flokulacji

Dyląg M., Kamieński J., Rosiński J., Szatko W.

Inżynieria i Aparatura Chemiczna

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2010

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Nr 4

22-23

PL

Przedstawiono wyniki badań stężenia cząstek pierwotnych na rozkłady wielkości flokuł. W oparciu o porównanie z rozkładami rzeczywistymi uzyskanymi eksperymentalnie potwierdzono zadowalające odwzorowanie układu wielkości flokuł wyznaczonego z modelu opartego o równania bilansu populacji. Powyższe stwierdzenie dotyczy warunków stacjonarnych dla przepływów w zakresie liczb Reynoldsa 104

EN

Investigation results of primary particles concentration influence on floe size distributions are presented in the paper. A comparison between empirical size distributions and floe sizes obtained from the population balance model equations gave a satisfactory representation. Abovementioned observations concerned steady state flow conditions in the Reynolds number range of 104

6

Nowe kierunki w rozwoju maszyn mielacych

Tyralski T., Biel-Tyralska A.

Przegląd Papierniczy

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2004

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R. 60, nr 5

253-261

EN

The article evaluates an influence of construction and parameters of refiners (conical, disc and the newest cylindrical refiners of Andritz AG) on the effectiveness of refining process. For this purpose the following criteria have been considered: hydraulic efficiency, homogeneity of refining represented by a number of refining impacts and capacity of a particular refiner for pulp dispersing, The last criterion determines the size and consistency of flocs or, what is the most needed, a complete dispersion of flocs. Authors analyze an impact of dispersion degree of fibre suspension (deflocculating) alongside the whole refining area on the size of space between bars and forces affecting fibres. It has been proved that with the complete dispersion of fibre suspension (flocks) in entire refining area, the intensity of refining (SEL) should be strictly adjusted to the fibre morphology which is significantly different for fibres of earlywood and latewood. This is possible with the use of fractionation prior to refining, e.g. with application of AM80-F hydrocyclones made by NOSS AB, that is the cross section fractionation. It has been also showed that with a certain intensity of refining, the hydraulic effectiveness of refining depends on the value of relation between idle running of refiner and cutting edge length. Analysis cover value changes of this relation as a function of the rotor velocity and its diameter in different hydrodynamic and rheological conditions. Calculations proved that construction and parameters of Andritz cylindrical refiners enable treatment of short-fibre hardwood pulp in dispersed form of pulp suspension in the entire area of refining.