Metal and metalloid sequestration in a constructed wetland system for treatment of landfill leachate during 2003-2012

Landfill leachate treatment can be expensive and energy consuming when carried out in wastewater treatment plants. However, there can be several possible solutions for reducing cost and energy requirements and one of them is on-site biological treatment of polluted landfill leachate in constructed wetland systems. This paper evaluates the sequestration of 15 metals and 2 metalloids in a free water surface flow constructed wetland consisting of 10 ponds at Atleverket near Örebro during a period of ten years. The operation and maintenance of treatment wetland is minimal and the retention time is highly variable but generally between 6-12 months. The water flows by gravity from one pond to another. The system which was designed for removal of nitrogen and organic material shows a good retention efficiency of these elements. The analyte concentrations in the effluent and influent were compared by using statistical software. The variations in inlet concentration were significantly higher than in the ones in the outlet. The removal efficiency for all elements but three (magnesium, sulfur and boron) was above 50%. Some elements were retained to a certain level during all years; these elements are Al, As, Ba, Ca, Cr, Cu, Pb, Fe, V, Zn and Mn. Long-term analysis of the operation has shown that the constructed wetland continues to perform well and it retains its ability to remove the metals studied

Metal and Metalloid Sequestration in a Constructed Wetland System for Treatment of Landfill Leachate During 2003–2012

The treatment of landfill leachate in constructed wetland systems is a common practice in Europe. However, very few studies were made to evaluate their performance over a long period of time. A free surface constructed wetland system consisting of sediment traps followed by 10 ponds connected with overflows was built at Atleverket near Örebro, Sweden in 2001. It receives pre-treated leachate from the municipal landfill. As part of the wetland monitoring programme a large data set on the surface concentrations of 15 metals and 2 metalloids has been collected from different sampling sites within the wetland during the operation period. In this study, the data from inlet and outlet of the wetland were compiled and analysed. The aim of this paper is therefore to estimate the removal efficiency of metals and metalloids using data on concentrations and flow and investigate the effect of wetland age on removal pattern. The elements with the highest removal efficiency were Al, As, Ba, Ca, Cr, Cu, Fe, Mn, Pb, V and Zn ranging from 95% for Pb to 65 % for Ca. The elements with the lowest reduction were B, Co K, Mg, Ni and S ranging from Co 56 % to 40 % for S. It was found that the removal efficiency was not related to inlet concentrations of the elements as the elements with high and low inlet concentrations were found in both groups. Analysis of reduction pattern also revealed that the group with higher removal efficiency showed fairly constant outlet concentrations during the study period, while the elements with lower removal efficiency demonstrated variable outlet concentrations. No statistical difference in removal due to age of the wetland was found. The study results showed that the wetland system has high removal efficiency of metals and metalloids and the removal pattern is not affected by age of the wetland. The influence on reduction due to leachate characteristics, wetland design and retention time will be discussed

Cellular uptake of quercetin and luteolin and their effects on monoamine oxidase-A in human neuroblastoma SH-SY5Y cells

Monoamine oxidase-A (MAO-A) is the main enzyme in the metabolism of the neurotransmitter serotonin (5-hydroxytryptamine). Elevated activity of MAO-A in the brain may contribute to the pathogenesis of depressive disorders. Plant flavonoids, such as flavonol quercetin and flavone luteolin, have been suggested to be potential antidepressant compounds because they exert a suppressive effect on the MAO-A reaction. We evaluated the effects of these flavonoids on MAO-A activity and protein level using SH-SY5Y as model serotoninergic nerve cells. Quercetin and luteolin were incorporated into SH-SY5Y cells rapidly and converted to O-methylated derivatives. Luteolin accumulated in cells after 24-h incubation, whereas quercetin disappeared completely from cell fractions and culture medium. Addition of ascorbic acid prevented the disappearance of quercetin and allowed it to exert its cytotoxicity (similar to luteolin) at >10 μM. Luteolin and quercetin were incorporated into mitochondria fractions within 1-h incubation and attenuated MAO-A activity slightly but significantly. After 24-h incubation, luteolin attenuated MAO-A activity, but quercetin needed ascorbic acid for its attenuation. Neither luteolin nor quercetin significantly affected MAO-A protein level. These data suggest that luteolin and quercetin can be direct inhibitors of MAO-A in nerve cells by targeting mitochondria