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Content of Heavy Metals and Their Fractions in Organic Soils of Podlasie

Wiater Józefa

Journal of Ecological Engineering

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2019

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Vol. 20, nr 3

179--184

EN

The purpose of this study was to determine the total content of cadmium, lead, nickel, copper, zinc and their fractions in organic soils of Podlasie used as permanent grassland. The research material were samples taken from 30 soils of the Podlasie province in 2011-2013. The samples were taken from the determined layer to depth of 0-30 cm. Basic physicochemical properties were determined in the taken soil samples: organic carbon content, pH in 1 M KCl potentiometrically. The total content of metals after mineralization in aqua regia was determined, and cadmium fractions were determined with a modified BCR method. The measurements were conducted by means of atomic absorption spectroscopy with electrothermal atomization using Varian AA-100 spectrometer. It was found that only 2 soils can be included in the soils with first pollution degree due to the cadmium content. The content of other metals was at geochemical background level. The distribution of investigated metals in the fractions in studied organic soils was different comparing to mineral soils. Most of the analyzed elements were present in the fraction associated with organic substance, which limited their mobility, as evidenced by their low share in the available and potentially available fraction. The proportion of metals in the residual fraction was low, which is typical for organic soils. The share of studied metals in particular fractions varied depending on the sampling date, which may be related to the climatic conditions course in the study period and the treatments performed on these soils.

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Changes of the Content of Heavy Metals and PAH’s in Sewage Sludge Treated with Reed Bed Lagoons

Boruszko D.

Journal of Ecological Engineering

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2018

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Vol. 19, nr 4

75--87

EN

In Poland, low-input methods such as composting, vermicomposting, reed beds, willow energy and solar driers are increasingly often being used in the processing of sewage sludge. The northeastern part of Poland has operated successfully for years using these methods. This paper presents the results of using low-cost methods of sludge treatment in the wastewater treatment plant located in Zambrow, Podlaskie Province. The results of sewage sludge studies on the PAHs and heavy metals content after treatment in a reed bed system are presented. Among the 16 examined PAHs, the lowest concentration was obtained for the dibenz (a,h)anthracene. Not a single sample exceeded a concentration of 100 μg/kg d.m. The highest concentration was exhibited by fluoranthene, benzo(g,h,i)perylene and indeno(1,2,3-c,d)pyrene. The concentration of these compounds exceeded 1000 μg/kg d.m. The obtained results for the PAHs in sewage sludge from the reed lagoon at the treatment plant in Zambrow showed that the average content of PAHs studied was approximately 8300 μg/kg d.m. The lowest concentration, below 1.3 mg/kg d.m. of the seven heavy metals examined was obtained for mercury (Hg). On the other hand, the highest concentration, exceeding 1300 mg/kg d.m. was found in the case of zinc (Zn). The obtained results for the heavy metals in sewage sludge from the reed bed lagoons in Zambrow show that the average content of heavy metals studied is approximately 1620 mg/kg d.m. The results of the study demonstrate a high efficiency of the low-cost methods used in the Zambrów WWTP in terms of the quality of processed sludge. The sewage sludge from the lowest layer of the reed lagoon (13–14 years of dewatering and transformation) are characterized by the lowest PAHs and heavy metals content. The higher a sediment layer lies, i.e. the shorter the time of processing, the higher are the PAHs and content of heavy metals content. This indicates a great role of reeds in the accumulation of these compounds.

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Specjacja metali ciężkich w kondycjonowanych osadach ściekowych stabilizowanych w procesie fermentacji metanowej

Dąbrowska L., Papis D.

Inżynieria i Ochrona Środowiska

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2006

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T. 9, nr 4

365-377

PL

Prezentowane w artykule badania prowadzono w kierunku określenia przydatności kondycjonowania osadów ściekowych metodą termiczną do upłynnienia substratu organicznego i intensyfikacji procesu fermentacji. Podjęto próbę wykazania, na ile kondycjonowanie przyczynia się do przechodzenia jonów metali ciężkich z osadów do cieczy osadowych i wpływa na zmianę form ich występowania w osadach po fermentacji. Stwierdzono korzystny wpływ 6-godzinnego termicznego kondycjonowania osadów na fermentację metanową, o czym świadczy uzyskanie w procesie fermentacji osadu kondycjonowanego większej o ok. 12% sumarycznej ilości biogazu w porównaniu do osadu niekondycjonowanego. Kondycjonowanie termiczne osadu spowodowało przechodzenie jonów cynku, miedzi i niklu do cieczy osadowej, przy czym najwyższy wzrost stężenia uzyskano dla niklu. Kondycjonowanie osadów nie przyczyniło się do istotnych zmian form występowania metali ciężkich w osadach po procesie fermentacji. W przypadku miedzi 85% całkowitej zawartości było związane z frakcją organiczną. Cynk występował głównie w połączeniu z uwodnionymi tlenkami żelaza i manganu (33 ÷ 41%) oraz materią organiczną (29 ÷ 32), odpowiednio w kondycjonowanych i niekondycjonowanych osadach. Nikiel występował w osadzie kontrolnym w podobnych ilościach we wszystkich frakcjach (po ok. 18 ÷ 22% w każdej frakcji), natomiast w osadzie kondycjonowanym głównie w połączeniach z tlenkami żelaza i manganu (24%) oraz materią organiczną (26%). We frakcji związków trudno rozpuszczalnych wyższą zawartość cynku i niklu stwierdzono po fermentacji w osadzie niepoddawanym kondycjonowaniu, co może świadczyć o tym, że intensyfikacja fermentacji poprzez kondycjonowanie termiczne osadów powoduje uwalnianie metali ze stabilnych połączeń.

EN

The research presented in this paper was aimed at determining the influence of thermal pre-treatment of sewage sludge on liquefaction of organic substrates and intensification of the fermentation process. The attempt was also made to evaluate the degree, in which thermal pre-treatment may cause a release of heavy metals (Zn, Cu and Ni) from sludge to the liquid phase, and may affect changes of their forms of occurrence (speciation) in sludge after fermentation. The samples of sludge (primary, excess and fermenting) were obtained from the municipal wastewater treatment plant in Czestochowa. Mesophilic fermentation was carried out in bioreactors (V = 0.55 dm³) with the mixture of primary and excess sludge pre-treated thermally (T = 70°C, t = 6 h) and inoculated with the fermenting sludge. As a control, a bioreactor with non-treated sludge mixture was used. For quantitative determination of heavy metals speciation in sludge the sequential extraction was done according to the modified Tessier's procedure. The profitable effect of 6-hour thermal pre-treatment on methanogenic fermentation was observed due to improved hydrolysis of organic substrates, as indicated by double increase of organic carbon content in the liquid phase, as well as by generation of 12% more biogas (in volume), as compared to the control. Thermal pre-treatment of sludge resulted in a release of all Zn, Cu and Ni ions to the liquid phase, and the highest increase of concentration was observed for Ni ions. However, after fermentation the decrease of heavy metals concentration in the liquid phase and their accumulation in sludge were found in both: test and control reactors. Thermal pre-treatment did not cause any significant changes of heavy metals speciation in sludge after fermentation. In the case of Cu ions, ca. 85% of their total amounts present, were connected with organic matter. Zn ions were mainly bound with hydrated Fe and Mn oxides (33 ÷ 41%) and organic matter (29 ÷ 32%) for pre-treated and non-treated sludge mixtures, respectively. Ni ions were present in the non-treated sludge mixtures in similar amounts in all forms of occurrence (each fraction of ca. 18 ÷ 22%), whereas in the pre-treated sludge they were mainly bound with Fe and Mn oxides (24%) and organic matter (26%). Higher contents of Zn and Ni found in the fraction of non-dissolved compounds after fermentation of non-treated sludge may indicate that intensification of the fermentation process by thermal pre-treatment causes the release of heavy metals from the stable complexes.