Marion Martienssen

Biological treatment of leachate from solid waste landfill sites-alterations in the bacterial community during the denitrification process

Abstract Nitrite accumulation is frequently observed in leachate treatment plants. Generally, it has been attributed to unfavourable process conditions during the nitrification process. Production and utilization of nitrite during leachate treatment were investigated in an activated sludge bioreactor and an aerobic packed bed/anoxic activated sludge reactor. Under the conditions used, nitrite was accumulated by incomplete nitrification during the start-up period of the treatment only. On the other hand, high amounts of nitrite were built-up within the denitrification step. These high nitrite concentrations (more than 200 mg l−1 NO−2) were measured during the start-up period of the denitrification process and at TOC N-ratios less than 1.5. Nitrite accumulation and nitrite utilization could be correlated with changes in the microbial community present. During the start-up period (about 20 days), most of the bacteria isolated from the denitrification tank were able to reduce both nitrate and nitrite. Later at a TOC N-ratio of 3.5, a significant shift in the activated sludge biocommunity was observed. After 40 days, less than 0.1% of the isolated bacteria were capable to reduce nitrite. From the results obtained, it is concluded that the composition of the biocommunity plays a more important role in denitrification of leachate than previously considered.

Nitrogen transforming community in a horizontal subsurface-flow constructed wetland

Constructed wetlands are important ecosystems with respect to nitrogen cycling. Here we studied the activity and abundance of nitrogen transforming bacteria as well as the spatial distribution of nitrification, anaerobic ammonium oxidation (anammox), and denitrification processes in a horizontal subsurface-flow constructed wetland. The functional genes of the nitrogen cycle were evenly distributed in a linear way along the flow path with prevalence at the superficial points. The same trend was observed for the nitrification and denitrification turnover rates using isotope labeling techniques. It was also shown that only short-term incubations should be used to measure denitrification turnover rates. Significant nitrate consumption under aerobic conditions diminishes nitrification rates and should therefore be taken into account when estimating nitrification turnover rates. This nitrate consumption was due to aerobic denitrification, the rate of which was comparable to that for anaerobic denitrification. Consequently, denitrification should not be considered as an exclusively anaerobic process. Phylogenetic analysis of hydrazine synthase (hzsA) gene clones indicated the presence of Brocadia and Kuenenia anammox species in the constructed wetland. Although anammox bacteria were detected by molecular methods, anammox activity could not be measured and hence this process appears to be of low importance in nitrogen transformations in these freshwater ecosystems.

Investigation of sewer exfiltration using integral pumping tests and wastewater indicators.

Leaky sewers affect urban groundwater by the exfiltration of untreated wastewater. However, the impact of sewer exfiltration on the groundwater is poorly understood. Most studies on sewer exfiltration focus on water exfiltration, but not on the impact on groundwater quality. In this paper we present a new monitoring approach to estimate mass flow rates M(ex) of different wastewater indicators (WWIs) from leaky sewers by applying integral pumping tests (IPTs). The problem of detecting and assessing heterogeneous concentrations in the vicinity of leaky sewers can be overcome with the IPT approach by the investigation of large groundwater volumes up- and downstream of leaky sewers. The increase in concentrations downstream of a leaky sewer section can be used to calculate M(ex) with a numerical groundwater model. The new monitoring approach was first applied using four IPT wells in Leipzig (Germany). Over a pumping period of five days we sampled five inorganic WWIs: B , Cl(-), K+, NO3(-), NH4+ and three xenobiotics: bisphenol-a, caffeine and tonalide. The resulting concentration-time series indicated an influence of wastewater at one IPT well downstream of the leaky sewer. We defined ranges of M(ex) by implementing the uncertainty of chemical analyses. The results showed a M(ex) of 0-10.9 g m(-1) d(-1). The combination of M(ex) with wastewater concentrations from the target sewer yielded an exfiltration rate Q(ex) of 28.0-63.9 Lm(-1)d(-1) for the conservative ion Cl(-). Most non-conservative WWIs showed reduced mass flow rates in the groundwater downstream of the leaky sewer that indicate a mass depletion during their passage from the sewer to the pumping well. Application of the IPT methodology at other field sites is possible. The IPT monitoring approach provides reliable M(ex) values that can help to assess the impact of leaky sewers on groundwater.

Decolorization and Degradation of Erioglaucine (Acid Blue 9) Dye in Wastewater

Erioglaucine (CAS No. 3844-45-9) is a widely used acid aminotriphenylmethane dye of an intense blue color. Erioglaucine containing wastewater streams are not affected by activated sludge treatment plants. Therefore, pretreatment is necessary before discharging. In the industry the standard procedure is to use NaOCl for this purpose. Experiments showed that wastewater treated with this method could contain between 100 and 200 mg l−1 of adsorbable organic chlorine (AOX) compounds of a questionable ecotoxicological relevance. Alternative treatment methods with reagents containing H2O2 have been investigated. The experimental results are assessed in terms of color and DOC reduction, H2O2 consumption, and enhancement of biodegradability. A combination of activated carbon and H2O2 proved not to be a viable alternative. Treatment with Fentons reagent (H2O2 and Fe2+) was found to be effective in terms of color removal as well as enhanced biodegradability. In the optimum operating range of pH and H2O2/Fe2+ ratio 5...

Comparison of ten different DNA extraction procedures with respect to their suitability for environmental samples

DNA extraction for molecular biological applications usually requires target optimized extraction procedures depending on the origin of the samples. For environmental samples, a range of different procedures has been developed. We compared the applicability and efficiency of ten selected DNA extraction methods published in recent literature using four different environmental samples namely: activated sludge from a domestic wastewater treatment plant, river sediment, anaerobic digestion sludge and nitrifying enrichment culture. We assessed the suitability of the extraction procedures based on both DNA yield and quality. DNA quantification was performed by both ultra violet (UV) spectrophotometry and fluorescence spectrophotometry after staining with PicoGreen. In our study, DNA yields based on UV measurement were overestimated in most cases while DNA yields from fluorescence measurements correlated well with the sample load on agarose gels of crude DNA. The quality of the DNA extracts was determined by gel electrophoresis of crude DNA and PCR products from 16S rDNA with the universal primer set 27f/1525r. It was observed that gel electrophoresis of crude DNA was not always suitable to evaluate DNA integrity and purity since interfering background substances (e.g. humic substances) were not visible. Therefore, we strongly recommend examining the DNA quality of both crude DNA and 16S rDNA PCR products by gel electrophoresis when a new extraction method is established. Summarizing, we found four out of ten extraction procedures being applicable to all tested samples without noticeable restrictions. The procedure G (according to the standard method 432_10401 of the Lower Saxony State Office for Consumer Protection and Food Safety) had the broadest application range over procedure J (published by Wilson, 2001). These were followed by procedures F (Singka et al., 2012) and A (Bourrain et al., 1999). All four extraction procedures delivered reliable and reproducible crude DNA and PCR products. From an economical point of view, all procedures tested during this study were cheaper compared to commercial DNA extraction kits.

Comment on Schriks, M., Heringa, M.B., van der Kooi, M.M.E., de Voogt, P., van Wezel, A.P., 2010. Toxicological relevance of emerging contaminants for drinking water quality. Water Research 44, 461-476

Mario Schirmer *, Marion Martienssen , Kristin Schirmer c Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water, Uberlandstr. 133, 8600 Dubendorf, Switzerland Brandenburg University of Technology Cottbus, Institute for Environmental Technology, Chair Biotechnology of Water Treatment, Siemens-Halske-Ring 8, 03046 Cottbus, Germany Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Uberlandstr. 133, 8600 Dubendorf, Switzerland

Enhanced Natural Attenuation of MTBE

MTBE contamination in groundwater is an increasing environmental problem and treatment costs using conventional remediation technologies will increase if water is contaminated by MTBE. Generally, natural attenuation (NA) and enhanced natural attenuation (ENA) are possible low-cost alternatives to conventional techniques. Since biodegradation of MTBE is comparably slow under field conditions and often limited by the environmental conditions, optimizing these conditions within the framework of an ENA approach can be a useful means to enhance the natural degradation process.

The precision of bacterial quantification techniques on different kinds of environmental samples and the effect of ultrasonic treatment.

The precision of cell number quantification in environmental samples depends on the complexity of the sample and on the applied technique. We compared fluorescence microscopy after filtration, quantification of gene copies and the cultivation based most probable number technique for their precision. We further analyzed the effect of increasing complexity of the sample material on the precision of the different methods by using pure cultures of Pseudomonas aeruginosa, fresh water samples and sediment slurries with and without ultrasonic treatment for analyses. Microscopy reached the highest precision, which was similar between pure cultures and water samples, but lower for sediment samples due to a higher percentage of cells in clusters and flocks. The PCR based quantification was most precise for pure cultures. Water and sediment samples were similar but less precise, which might be caused by the applied DNA extraction techniques. MPN measurements were equally precise for pure cultures and water samples. For sediment slurries the precision was slightly lower. The applied ultrasonic treatment of the slurries dispersed the cell clusters and flocks, increased the precision of microscopical and MPN measurements and also increased the number of potential colony forming units. However, the culturable cell number decreased by half. For MPN quantification of viable cells in samples with a high proportion of clustered cells we therefore recommend an optimization of ultrasonic treatment and a confirmation by microscopy and cultivation to reach highest possible dispersion of the cells with a minimum of inactivation. As a result of these observations we suggest a correction factor for MPN measurements to consider the effect of sonication on complex samples. The results are most likely applicable to other complex samples such as soil or biofilms.

Effect of increasing salinity to adapted and non-adapted Anammox biofilms

ABSTRACT The Anammox process is an efficient low energy alternative for the elimination of nitrogen from wastewater. The process is already in use for side stream applications. However, some industrial wastewaters, e.g. from textile industry are highly saline. This may be a limit for the application of the Anammox process. The aim of this study was to evaluate the effects of different NaCl concentrations on the efficiency of adapted and non-adapted Anammox biofilms. The tested NaCl concentrations ranged from 0 to 50 g NaCl*L−1. Concentrations below 30 g NaCl*L−1 did not significantly result in different nitrogen removal rates between adapted and non-adapted bacteria. However, adapted bacteria were significantly more resilient to salt at higher concentrations (40 and 50 g NaCl*L−1). The IC50 for adapted and non-adapted Anammox bacteria were 19.99 and 20.30 g NaCl*L−1, respectively. Whereas adapted biomass depletes the nitrogen in ratios of / around 1.20 indicating a mainly Anammox-driven consumption of the nitrogen, the ratio increases to 2.21 at 40 g NaCl*L−1 for non-adapted biomass. This indicates an increase of other processes like denitrification. At lower NaCL concentrations up to 10 g NaCl*L−1, a stimulating effect of NaCl to the Anammox process has been observed. GRAPHICAL ABSTRACT

Data on DNA gel sample load, gel electrophoresis, PCR and cost analysis

The data presented in this article provide supporting information to the related research article “Comparison of ten different DNA extraction procedures with respect to their suitability for environmental samples” (Kuhn et al., 2017) [1]. In that article, we compared the suitability of ten selected DNA extraction methods based on DNA quality, purity, quantity and applicability to universal PCR. Here we provide the data on the specific DNA gel sample load, all unreported gel images of crude DNA and PCR results, and the complete cost analysis for all tested extraction procedures and in addition two commercial DNA extraction kits for soil and water.