Degradation of BTEX by anaerobic bacteria: physiology and application

Pollution of the environment with aromatic hydrocarbons, such as benzene, toluene, ethylbenzene and xylene (so-called BTEX) is often observed. The cleanup of these toxic compounds has gained much attention in the last decades. In situ bioremediation of aromatic hydrocarbons contaminated soils and groundwater by naturally occurring microorganisms or microorganisms that are introduced is possible. Anaerobic bioremediation is an attractive technology as these compounds are often present in the anoxic zones of the environment. The bottleneck in the application of anaerobic techniques is the lack of knowledge about the anaerobic biodegradation of benzene and the bacteria involved in anaerobic benzene degradation. Here, we review the existing knowledge on the degradation of benzene and other aromatic hydrocarbons by anaerobic bacteria, in particular the physiology and application, including results on the (per)chlorate stimulated degradation of these compounds, which is an interesting new alternative option for bioremediatio

Towards a better estimation of prevalence of female genital mutilation in the European Union : a situation analysis

Background:Female genital mutilation (FGM) is a harmful cultural practice that is predominantly documented inAfrica, but also occurs in other parts of the world. Due to migration, women who have undergone FGM can also befound in the European Union (EU). Due to a lack of systematic representative surveys on the topic in EU, theprevalence of FGM and the number of women and children subjected to the practice remains unknown. However,information on the magnitude of the problem in the EU is necessary for policy makers to design and trackpreventive measures and to determine resource allocation.Methods:Between March 2015 and May 2015, we performed a situation analysis consisting of a critical interpretivesynthesis and SWOT-analysis of available at the time peer reviewed and grey literature document on nationalprevalence studies on FGM in the EU. Studies estimating the prevalence of FGM and the number of girls and womensubjected to the practice in the EU were mapped to analyse their methodologies and identify their Strengths,Weakness, Opportunities and Threats (SWOT). Distinction was made between direct and indirect estimation methods.Results:Thirteen publications matched the prioritized inclusion criteria. The situation analysis showed that both directand indirect methodologies were used to estimate FGM prevalence and the number of girls and women subjected toFGM in the EU. The SWOT-analysis indicated that due to the large variations in the targeted population and the availablesecondary information in EU Member States, one single estimation method is not applicable in all Member States.Conclusions:We suggest a twofold method for estimating the number of girls and women who have undergoneFGMinthe EU. For countries with a low expected prevalence of women who have undergoneFGM, the indirect method will providea good enough estimation of the FGM prevalence. The extrapolation-of-FGM-countries-prevalence-data-method, based on thedocumented FGM prevalence numbers in DHS and MICS surveys, can be used for indirect estimations of girls and womensubjected to FGM in theEU. For countries with a high expected prevalence of FGM in the EU Member State, we recommendto combine both a direct estimation method (e.g. in the form ofa survey conducted in the target population) and an indirectestimation method and to use a sample design as developed bythe FGM-PREV project. The choice for a direct or indirectmethod will ultimately depend on available financial means and the purpose for the estimation

Debating medicalization of Female Genital Mutilation/Cutting (FGM/C) : learning from (policy) experiences across countries

Background: Although Female Genital Mutilation/Cutting (FGM/C) is internationally considered a harmful practice, it is increasingly being medicalized allegedly to reduce its negative health effects, and is thus suggested as a harm reduction strategy in response to these perceived health risks. In many countries where FGM/C is traditionally practiced, the prevalence rates of medicalization are increasing, and in countries of migration, such as the United Kingdom, the United States of America or Sweden, court cases or the repeated issuing of statements in favor of presumed minimal forms of FGM/C to replace more invasive forms, has raised the debate between the medical harm reduction arguments and the human rights approach. Main body: The purpose of this paper is to discuss the arguments associated with the medicalization of FGM/C, a trend that could undermine the achievement of Sustainable Development Goal 5.3. The paper uses four country case studies, Egypt, Indonesia, Kenya and UK, to discuss the reasons for engaging in medicalized forms of FGM/C, or not, and explores the ongoing public discourse in those countries concerning harm reduction versus human rights, and the contradiction between medical ethics, national criminal justice systems and international conventions. The discussion is structured around four key hotly contested ethical dilemmas. Firstly, that the WHO definition of medicalized FGM/C is too narrow allowing medicalized FGM to be justified by many healthcare professionals as a form of harm reduction which contradicts the medical oath of do no harm. Secondly, that medicalized FGM/C is a human rights abuse with lifelong consequences, no matter who performs it. Thirdly, that health care professionals who perform medicalized FGM/C are sustaining cultural norms that they themselves support and are also gaining financially. Fourthly, the contradiction between protecting traditional cultural rights in legal constitutions versus human rights legislation, which criminalizes FGM/C. Conclusion: More research needs to be done in order to understand the complexities that are facilitating the medicalization of FGM/C as well as how policy strategies can be strengthened to have a greater de-medicalization impact. Tackling medicalization of FGM/C will accelerate the achievement of the Sustainable Development Goal of ending FGM by 2030

Transformation of chlorinated compounds by methanogenic granular sludge

Chlorinated compounds are an important group of contaminants often found in sediments, groundwater, soils, wastewaters, and off-gasses. Many of these pollutants are found on the EPA list of Priority Pollutants indicating their potential hazard for the environment. Initial degradation can occur via dechlorination reactions which are carried out by specific halorespiring bacteria or by acetogenic and/or methanogenic bacteria which dechlorinate via aspecific reactions. The dechlorination rates of halorespiring bacteria are generally high, due to the high degree of substrate specificity. However, these bacteria are limited in the number of chlorinated compounds they can degrade. This may be a disadvantage when they are put in to use for the remediation of environments with a mixture of chlorinated compounds. In those cases, a better strategy is the application of acetogenic and methanogenic bacteria which have a broad substrate specificity.This research has evaluated the aspecific dechlorinating ability of unadapted acetogenic and methanogenic bacteria in methanogenic granular sludge. The long-term goal of the research is the evaluation of the applicability of unadapted methanogenic consortia in the bioremediation of wastestreams contaminated with mixtures of pollutants.Chlorinated alkanes and cycloalkanes were completely or substantially degraded to lower- or non-chlorinated compounds by methanogenic (granular) sludge without prior adaptation. Different dechlorination reactions were observed. Chlorinated methanes were degraded mainly via oxidative and substitutive reactions to non-halogenated compounds like CO 2 , while chloroethanes were dechlorinated via dichloroelimination and reductive hydrogenolysis to lower chlorinated ethenes and ethanes. The cycloalkanes,α- andβ-HCH, were degraded via different reactions to a mixture of benzene and chlorobenzene. The degradation of chlorinated alkenes (tetrachloroethene and lower chlorinated ethenes) and aromatic compounds (hexachlorobenzene, and pentachlorophenol) by unadapted consortia takes place at low rates. This dechlorination of chloroethenes and pentachlorophenol is much slower compared to (cyclo)alkanes. Sometimes a long lag phase is required (lower chlorinated benzenes). PCBs were not degraded. All the degradation products, lower chlorinated alkanes and alkenes, and (chloro)benzene in case of HCH, are biodegradable under aerobic conditions.Contaminated soils often contain many bacteria, which are able to perform remediation provided that the environmental conditions are favorable. In that case, the addition of granular sludge does not seem to be necessary for the degradation the chlorinated compounds. However, the presence of a methanogenic bacterial consortium can lead to e.g., a decrease of the redox-potential, thus favoring the environmental conditions for other, more specialized dechlorinating bacteria. Another application of granular sludge may be the use of the facultative anaerobic or microaerophilic bacteria in the sludge. These bacteria can degrade the persistent dechlorination products under higher redox-conditions. Altogether, the broad spectrum applicability of the unadapted methanogenic granular sludge may make it a useful first "tool" in the (in situ) bioremediation of contaminated environments.</p

Optimaliseren van mestvergisting

In het onderzoek is in batchtesten de biogasopbrengst en hydrolyseconstante bepaald van een aantal soorten varkensmest en van gehygiëniseerde varkensmest. Vervolgens is in 4 (semi-)continu bedreven reactoren een aantal behandelingen getest, waarvan verwacht werd dat deze een verhogend effect hebben op het rendement van vergisting van varkensmes

The medicalisation of female genital cutting : harm reduction or social norm?

Today, female genital cutting is increasingly practised by trained healthcare providers. While opposition to medicalised female genital cutting (FGC) is strong, little is known about the underlying motivation for this medicalisation trend in practising communities. We formulated three hypotheses based on medicalisation theories. The medicalisation of FGC: (i) is stratified and functions as a status symbol, (ii) functions as a harm-reduction strategy to conform to social norms while reducing health risks and (iii) functions as a social norm itself. Conducting multilevel multinomial regressions using the 2005, 2008 and 2014 waves of the Egyptian Demographic Health Survey, we examined the relationship between the mother's social position, the normative context in which she lives and her decision to medicalise her daughter's cut, compared to the choice of a traditional or no cut. We found that an individual woman's social position, as well as the FGC prevalence and percentage of medicalisation at the governorate level, was associated with a mother's choice to medicalise her daughter's cut. Further research on factors involved in decision-making on the medicalisation of FGC is recommended, as an in-depth understanding of why the decision is made to medicalise the FGC procedure is relevant to both the scientific field and the broader policy debate

Mestvergisting bij korte verblijftijden

In four CSTR laboratory reactors research has been conducted into the effect of reduction of the retention time on the biogas production from pig and cattle slurry and the volatile fatty acid content in the digester. Further, the effect of adding a small amount of glycerine on the retention time and the volatile fatty acid content in the digester has been researched