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1

Cadmium Removal from Contaminated Soil by Electro-Kinetic Method

Hawal Laith Hamdan, Al-Sulttani Ali Omran, Hamza Jinan N.

Journal of Ecological Engineering

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2023

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Vol. 24, nr 1

79--86

EN

For this study, an electro kinetic method used to eliminate cadmium from the polluted soil. This method is useful at low permeability medium. Several experiments were conducted with variable operating circumstances, using different pH purging solutions. Rice husks were used in this work as an adsorbent medium available and free of charge to counteract the reverse osmosis process that occurs and affects the work efficiency. The final results after the end of the practical experiments of this process showed that the percentages of the removal process began to increase after the pH gradually decreases. The pH of the solution for the three experiments conducted was 3, 6 and 9, respectively. The best removal rate was 68% in this process at pH 3 ; when compared with the second and third tests at pH 6 and 9, the removal ratios were 58% and 51.5%, respectively. It was discovered that the cadmium removal rate began to decrease along with voltage. At 30 volts the removal rates were 68%, whereas 20 volts they were 66%. Rice husks have been shown to be an effective adsorbent for counteracting reverse osmosis. Therefore, it can be successfully used as an adsorbent medium.

2

Research on the embossment phenomenon of disc grinding by workpiece's removal rate

Sun Cong, Xiu Shichao, Li Qingliang, Wang Jingyu, Zhao Yu

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 3

739--755

EN

The disc grinding has become a widely used technology in the precision-manufacturing process for plate stainless steel. However, embossment phenomenon occurs on the ground workpiece's surface. Moreover, the workpiece's removal rate can be applied to measure the embossment. In most studies, the researches on the disc grinding technology mainly focus on the trajectory distributions, which might be not appropriate enough to capture the workpiece's removal rate. To this end, this paper has presented a multiple grits-discretized (MGD) model on the workpiece's removal rate to identify the formation mechanism of the embossment phenomenon. Meanwhile, the current model is established based on the grits' distributions, the grits' size and the kinematic multiple grits' trajectory. The theoretical prediction for the distribution of workpiece's removal rate shows a reasonable agreement with the experimental validation. It shows that the removal rate is non-uniformly distributed on the workpiece's surface, which results in the workpiece's embossment. Furthermore, the workpiece's removal rate is greatly affected by the speed ratio. Therefore, the proposed model is not only anticipated to be meaningful for improving the uniformity of the machined workpiece by adjusting the speed ratio, but also expected to be useful for enhancing the understanding on the disc grinding enterprises.

3

Analysis of the start-up of natural bio-film colonization of constructed rapid infiltration system

Xu W., Yang J., Wang J., Jian Y., Tang M.

Polish Maritime Research

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2016

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S 1

32--35

EN

Abstract: this paper studied the start-up of natural bio-film colonization under the conditions where wet-to-dry ratio was 1:6, hydraulic load was 0.8m3/m2·d, and water temperature was 100C-150C, it took 25d in total to become mature, after the success of bio-film colonization, the removal rate of COD and NH4+-N can be stabilized at 80%, and the removal rate of NH4+-N can reach 90% above. The microorganism was divided into the following stages during bio-film colonization:1. Reversible adhesion of cell on the surface of the carrier, 2.Irreversible adhesion of cell on the surface of the carrier, 3.Division of cell adhering to the surface of the carrier and formation of microcolony adhering to the surface of the carrier, 4.Growth of microcolony adhering to the surface of the carrier to be mature bio-film with three-dimensional structure. The process of natural bio-film colonization can be judged comprehensively according to removal rate of NH4+-N and COD, effluent pH as well as color of microbial film.

4

Effect of Stubble Heights and Treatment Duration Time on the Performance of Water Dropwort Floating Treatment Wetlands (FTWS)

Xin Z., Li X., Nielsen S., Yan Z., Zhou Y., Tang Y., Guo W., Sun Y.

Ecological Chemistry and Engineering. S

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2012

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Vol. 19, nr 3

315-330

EN

Floating treatment wetlands (FTWs) with Water Dropwort (Oenanthe javanica) were established in winter to investigate their potential role in the purification of eutrophicated water, and to identify the effects of different stubble heights of the Water Dropwort on the performance of the FTWs. The results of the experiments demonstrated: The Water Dropwort FTWs were effective in buffering the pH of the experimental water. The Water Dropwort FTWs were efficient in purifying eutrophicated water, with removal rate for total nitrogen (TN), total phosphorus (TP), ammonium nitrogen ( NH N 4 + - ), and nitrate nitrogen ( NO N 3 - - ) at 91.3, 58.0, 94.6, and 95.5% in the 15-day experiment, respectively. No significant difference in the purification effect was found among different stubble heights of Water Dropwort FTWs. Significant differences between the zero control and the FTWs were found for the removal of TP in the first 11 days; and for the removal of NH N 4 + - in the first 4 days. No significant difference was found between the zero control and the FTWs for NO N 3 - - in the first 4 days, but significant difference was detected after day 4. The optimum treatment duration time for the FTWs with Water Dropwort will depend on the nutrients to be removed. These results will provide basis for further application of the FTWs at large scale, as well as for future studies on the mechanism of nutrient removal process.

PL

Badano proces oczyszczania wód z wykorzystaniem ruchomych mokradeł (FTW) obsadzonych Oenanthe javanica. Celem prowadzonych w zimie badań była ocena ich potencjalnej roli w oczyszczaniu wód zeutrofizowanych oraz określenie wpływu różnych wysokości ściernisk roślinnych na wydajność procesu. Wyniki eksperymentów wykazały, że systemy FTW skutecznie buforowały pH badanej wody. Za pomocą FTW ze zeutrofizowanej wody usunięto azot ogólny (TN), fosfor ogólny (TP), azot amonowy (NH N) 4 + - i azot azotanowy (NO N) 3 - - odpowiednio w ilościach: 91,3, 58,0, 94,6 i 95,5%, w czasie trwania 15-dniowego eksperymentu. Nie wykazano istotnych różnic w efekcie oczyszczania przy stosowaniu różnych wysokości ściernisk roślinnych. Stwierdzono wpływ czasu prowadzenia eksperymentu na usuwanie TP, którego usunięto najwięcej w pierwszych 11 dniach, a NH N 4 + - w ciągu pierwszych 4 dni trwania procesu. Nie stwierdzono istotnej różnicy między kontrolą i FTW dla NO N 3 - - w ciągu pierwszych kilku dni, ale znacząca różnica pojawiła się po 4 dniu. Optymalny czas trwania procesu z wykorzystaniem FTW zależy od składników odżywczych, które mają być usunięte. Opisane wyniki stanowią podstawę zarówno do rozwinięcia zastosowania FTW na dużą skalę, jak i dla przyszłych badań nad mechanizmem procesu usuwania składników odżywczych.

5

Decomposition of hydrogen sulfide in organic materials

Pawłowska M., Zdeb M., Montusiewicz A., Lebiocka M.

Environment Protection Engineering

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2009

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Vol. 35, nr 3

157-165

EN

Organic materials (mainly composts, bark and shavings, heather twigs) are the substances most often used as packing beds in biofilters. The aim of the study was to evaluate the rate of hydrogen sulfide removal in pine bark. The initial concentration of hydrogen sulfide was up to 58% v/v. The removal rates of this gas, using the pine bark bed, ranged from 0.003 cm3 g -1 min-1 (115.64 g m-3 h-1) to 0.040 cm3 g-1 min-1 (1541.85 g m-3 h -1). The results of a preliminary test suggest that the process is abiotic. In order to eliminate biotic pathways of hydrogen sulfide removal, the samples were sterilized.