Miriam H A van Eekert

Wageningen University & Research | WUR · Environmental Technology

Source Segregation (SS) is a novel strategy in dairy housing that can reduce emissions and separate organic matter and nutrients more efficiently than traditional slurry solid-liquid separation. The anaerobic digestion (AD) methane yield of the SS fractions, however, is unknown. We aimed at unveiling the biomethane yield of these fractions by condu...

Soil organic carbon (SOC) is essential for most soil functions. Changes in land use from natural land to cropland disrupt long-established SOC balances and reduce SOC levels. The intensive use of chemical fertilisers in modern agriculture accelerates the rate of SOC depletion. Domestic organic residues (DOR) are a valuable source of SOC replenishme...

Extensive agricultural activities have been shown to degrade soils, promoting research into improving soil quality. One such method is to increase the amount of organic matter in the soil, and domestic organic residues (DOR) are commonly used for this purpose. The environmental impact of DOR-derived products, from production to agricultural applica...

This book comprises six chapters prepared by the COST Action Circular City (https://circular-city.eu/). The Action aims to establish a network of researchers and stakeholders testing the hypothesis that: ‘A circular flow system that implements nature-based solutions (NBS) for managing nutrients and resources within the urban biosphere will lead to...

Pit latrines are used by billions of people globally, often in developing countries where they provide a low-tech and low-cost sanitation method. However, health and social problems can arise from a lack of emptying or maintenance of these facilities. A better understanding of the biological and environmental parameters within pit latrines could in...

Organic amendments (OAs) produced via composting, anaerobic digestion, or lactic acid fermentation, can be used to replenish soil carbon. Not all OAs production technologies preserve C and nutrients in the same way. In this study, we compared the influence of these technologies (i.e., treatments) on C and nutrient preservation and OAs chemical comp...

This study aimed to assess the effect of carbohydrates on protein hydrolysis and potential implications for the design of anaerobic reactors for treatment of protein-rich wastewaters. Batch experiments were carried out with dissolved starch (Sta) and gelatine (Gel) at different chemical oxygen demand (COD) ratios ranging from 0 to 5.5 under methano...

Source separated toilet water (black water; BW) is an important alternative nutrient source for agriculture. However, reuse and recovery of nutrients from BW is limited by the presence of pollutants, such as pathogens and micropollutants. In this study, the fate of micropollutants during thermophilic and hyper-thermophilic anaerobic digestion (AD)...

Anaerobic conversion can be used to recover volatile fatty acids (VFA) from high-strength wastewaters and organic wastes. However, many waste(waters) contain considerable concentrations of proteins and knowledge about anaerobic conversion of protein into VFAs is limited. In this study the effect of the solids retention time (SRT) and pH on dissolve...

Cities are producers of high quantities of secondary liquid and solid streams that are still poorly utilized within urban systems. In order to tackle this issue, there has been an ever-growing push for more efficient resource management and waste prevention in urban areas, following the concept of a circular economy. This review paper provides a ch...

Anaerobic digestion is an attractive treatment technology for concentrated waste streams. However, high ammonia concentrations cause inhibition of methanogenesis, especially when operated at elevated temperatures like (hyper-)thermophilic (55 and 70 °C) anaerobic digestion. These emerging (hyper-)thermophilic technologies are beneficial due to high...

Vacuum toilets have gained increasing attention in circular urban development projects, because of their marked water saving qualities compared to conventional flush toilets and the increased resource recovery potential for energy in the form of biogas and phosphorous as, e.g., struvite from the resulting concentrated wastewater. A further reductio...

Thermophilic and hyper-thermophilic anaerobic digestion (AD) are promising techniques for the treatment of concentrated black water (toilet fraction of domestic wastewater collected by low flush volume toilets; BW), recovery of nutrients and simultaneous pathogen removal for safe recovery and reuse of those nutrients. This study showed that thermop...

The performance of the biodegradable plastic materials polyhydroxyalkanoate (PHA), polybutylene sebacate (PBSe) and polybutylene sebacate co-terephthalate (PBSeT), and of polyethylene (LDPE) was assessed under marine environmental conditions in a three-tier approach. Biodegradation lab tests (20 °C) were complemented by mesocosm tests (20 °C) with...

Source separated toilet water is a valuable resource for energy and fertilizers as it has a high concentration of organics and nutrients, which can be reused in agriculture. Recovery of nutrients such as nitrogen, phosphorous, and potassium (NPK) decreases the dependency on energy-intensive processes or processes that rely on depleting natural reso...

Our modern cities are resource sinks designed on the current linear economic model which recovers very little of the original input. As the current model is not sustainable, a viable solution is to recover and reuse parts of the input. In this context, resource recovery using nature-based solutions (NBS) is gaining popularity worldwide. In this spe...

Background: Many kinds of wastewaters contain appreciable quantities of protein. Anaerobic processes are suitable for the treatment of wastewater high in organics to achieve pollution control and recovery of energy as methane and hydrogen, or intermediates for production of biofuels and valuable biochemicals. A distinction between protein hydrolys...

Source separation and decentralised treatment of domestic wastewaters for resource recovery have matured into a viable alternative for large-scale centralised treatment. The separate collection of toilet wastewater facilitates optimised treatment of the separate flows for efficient resource recovery. Practical examples are set at the four demonstra...

In vitro methods were used to assess the full potential for decomposition (measured as biogas formation) from pit latrine samples taken from the top layer of 15 Tanzanian latrines. We found considerable variability in the decomposition rate and extent. This was compared with decomposition in the same latrines, measured by comparing top layer compos...

Production of biogas from different organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. A workshop was held in June 2015 in Leysin Switzerland to agree on common solutions to the conundrum of inconsiste...

The Open-Bio project and background of this deliverable: Open-Bio was a research project funded by the European Commission within FP7. The goal was to investigate how bio-based products can be integrated into the market, using standardisation, labelling and procurement. One part of the project was research on the biodegradability of bio-based poly...

A model of the rate at which pit latrines fill was developed and compared with actual fill rates measured in latrines in Ifakara, Tanzania. Model parameters were derived primarily from data collected during the field study in Tanzania, with one fitted parameter. Although the model did not accurately simulate the fill rate of individual pits, it pro...

Anaerobic digestion of manure is a widely accepted technology for energy production. However, only a minimal portion of the manure production in the EU is anaerobically digested and occurs predominantly in codigestion plants. There is substantial potential for biogas plants that primarily operate on manure (> 90%), however, the methane yields of ma...

In vier (semi-)continu bedreven laboratorium reactoren is onderzoek gedaan naar het effect van het verkorten van de verblijftijd op de biogasproductie van varkens- en rundveemest en het gehalte aan vluchtige vetzuren in de vergister. Tevens is onderzocht wat het effect is van het toevoegen van een kleine hoeveelheid glycerine op de verblijftijd en...

Vergisting van mest bij verblijftijden van korter dan 15 dagen is haalbaar, maar mestsoort en mestkwaliteit blijken een groot effect te hebben op de biogasproductie bij deze korte verblijftijden. Het is mogelijk om bij deze korte verblijftijd een kleine hoeveelheid (< 5%) glycerine toe te voegen waardoor de biogasproductie sterk toeneemt, zodat er...

This report comprises the results of an explorative study on innovative nitrogen recovery from side streams of wastewater treatment plants (WWTPs) in the Netherlands. The main objective of the study was to identify promising new technologies for recovery of nitrogen which can be subsequently used as an artificial fertilizer. This shortcircuits the...

The diffuse pollution by chlorinated organic compounds in river basins is a concern, due to their potential adverse effects on human health and the environment. Organohalides, like hexachlorobenzene (HCB), are recalcitrant to aerobic microbial degradation, and “Dehalococcoides” spp. are the only known microorganisms capable of anaerobic transformat...

Grondsmaak is wereldwijd een van de belangrijkste beperkende factoren voor de afzet van kweekvis afkomstig uit vijvers en recirculatiesystemen. Dit wordt vooral veroorzaakt door de lage waardering van consumenten voor kweekvis met grondsmaak. Marktprijs en marktvolume komen daardoor onder druk te staan. Daarnaast brengt de bestrijding van grondsmaa...

Grondsmaak is wereldwijd een van de belangrijkste beperkende factoren voor de afzet van kweekvis afkomstig uit vijvers en recirculatiesystemen. Dit wordt vooral veroorzaakt door de lage waardering van consumenten voor kweekvis met grondsmaak. Marktprijs en marktvolume komen daardoor onder druk te staan. Daarnaast brengt de bestrijding van grondsmaa...

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...

The ability of Dehalococcoides spp. to reduce chlorinated compounds offers a great potential for bioremediation and/or bioaugmentation of contaminated environments. So far, however, our knowledge of the activity of Dehalococcoides spp. in situ is limited to only a few subsurface environments. The aim of this study was to broaden this knowledge to o...

The fate and persistence of chlorinated organics in the environment have been a concern for the past 50 years. Industrialization and extensive agricultural activities have led to the accumulation of these pollutants in the environment, while their adverse impact on various ecosystems and human health also became evident. This review provides an upd...

A novel anaerobic, thermophilic, Gram-positive, spore-forming, and sugar-fermenting bacterium (strain TLO) was isolated from a geothermal spring in Ayaş, Turkey. The cells were straight to curved rods, 0.4-0.6 microm in diameter and 3.5-10 microm in length. Spores were terminal and round. The temperature range for growth was 40-80 degrees C, with a...

Hexachlorobenzene (HCB) has been widely used in chemical manufacturing processes and as a pesticide. Due to its resistance to biological degradation, HCB has mainly accumulated in freshwater bodies and agricultural soils. “Dehalococcoides” spp., anaerobic dechlorinating bacteria that are capable of degrading HCB, were previously isolated from river...

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 varkensmest

Momenteel leven ongeveer 2,4 miljard mensen zonder adequate sanitataire voorzieningen. Eén van de Millenium Development Goals richt zich dan ook op de halvering van dit aantal voor 2015. Mede daarom is 2008 door de Verenigde Naties uitgeroepen tot het Internationale jaar van de Sanitatie. Dit vormde de aanleiding voor de leerstoelgroepen Milieubele...

Zero valent iron (ZVI; Fe(0)) has been successfully employed for the transformation and subsequent detoxification of a wide range of environmental contaminants, including chlorinated organics, heavy metals, nitroaromatics and, to some degree, perchlorate. The combined use of ZVI plus controlled release carbon has been shown to generate environmenta...

Exocellular electron transfer plays an important role in anaerobic microbial communities that degrade organic matter. Interspecies hydrogen transfer between microorganisms is the driving force for complete biodegradation in methanogenic environments. Many organic compounds are degraded by obligatory syntrophic consortia of proton-reducing acetogeni...

An anaerobic coculture was enriched from a hexachlorocyclohexane (HCH) polluted soil. The coculture reductively dechlorinates the beta-HCH isomer to benzene and chlorobenzene in a ratio of 0.5-2 depending on the amount of beta-HCH degraded. The culture grows with H(2) as electron donor and beta-HCH as electron acceptor, indicating that dechlorinati...

Halorespiring microorganisms have been detected in soils that were not polluted with chlorinated compounds. In this study, we describe alternative electron acceptor utilization by some halorespiring bacteria and phylogenetically related bacteria. It appears that oxidized metals like selenate, arsenate and manganese are rather common electron accept...

Recent studies have focused on using vapor-phase bioreactors for the treatment of volatile organic compounds from contaminated air streams. Although high removal capacities have been achieved in many studies, long-term operation is often unstable at high pollutant loadings due to biomass accumulation and drying of the packing medium. In this study,...

The effects of relative humidity, temperature, pH and vapor-phase toluene concentration on Tyrophagus putrescentiae growth on Cladophialophora sp. were tested in controlled environmental chambers. It was observed that the mites were able to reproduce readily at relative humidities between 90% and 97% as well as on porous perlite support material pr...

Metal has been degreased since the late forties at the Brabant site in The Netherlands, located along a canal. These activities have resulted in soil contamination with trichloroethene (TCE) and trichloroethane (TCA). Within the framework of the Dutch research programme NOBIS, the contamination and soil conditions were thoroughly investigated, and...

The ability of granular methanogenic sludge to dechlorinate chloroethenes was investigated with unadapted sludge from an upflow anaerobic sludge blanket (UASB) reactor fed with methanol. The sludge degraded chlorinated ethenes, but the degradation rates were low. The addition of primary substrate was necessary to sustain dechlorination. The dechlor...

Chlorinated ethenes and chlorinated aromatics are often found as pollutants in sediments, groundwater, and wastewater. These compounds were long considered to be recalcitrant under anaerobic conditions. In the past years however, dechlorination of these compounds has been found to occur under anaerobic conditions at contaminated sites and in wastew...

The current knowledge on microbial reductive dechlorination of chlorinated ethenes (CEs) and its application are discussed. Physiological studies on CEs dechlorinating microorganisms indicate that a distinction can be made between cometabolic dechlorination and halorespiration. Whereas cometabolic dechlorination is a coincidental and nonspecific si...

The dechlorinating activity of a methanogenic granular sludge from a methanol-fed upflow anaerobic sludge blanket reactor was investigated with chlorinated ethanes. This unadapted methanogenic consortium degraded all chloroethanes tested. The product formation rates decreased with the number of chlorine substituents. The more highly chlorinated eth...

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 s...

β-Hexachlorocyclohexane (β-HCH) was microbiologically transformed under anaerobic conditions by methanogenic granular sludges from upflow anaerobic sludge blanket (UASB) reactors fed with methanol, volatile fatty acids (VFA), or sucrose as substrates. These sludges, which had not priorily been exposed to β-HCH transformed β-HCH to benzene and chlor...

The potential of granular sludge from upflow anaerobic sludge blanket (UASB) reactors for bioremediation of chlorinated pollutants was evaluated by using carbon tetrachloride (CT) as a model compound. Granular sludges cultivated in UASB reactors on methanol, a volatile fatty acid mixture, or sucrose readily degraded CT supplied at a concentration o...

The objective of this study was to evaluate the effect of various pulping conditions and different lignocellulosic feedstocks on the anaerobic treatability of pulping wastewaters. Wastewaters were prepared from lignocellulosic feedstocks commonly used in the forest industry, namely, pine, spruce and birch wood, and wheat straw. The pulping conditio...

Van 19 tot en met 21 mei vond in Wageningen de `Sanitation Challenge: an international conference on new sanitation concepts and models of governance¿ plaats. Het voornaamste doel was om de verschillende groepen die betrokken zijn bij onderzoek, ontwikkeling en implementatie van (nieuwe) sanitatie in een wetenschappelijke omgeving bij elkaar te bre...