Bioremediation of chlorinated ethenes in aquifer thermal energy storage
Ni, Z. - \ 2015
Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Tim Grotenhuis; P.F.M. van Gaans. - Wageningen : Wageningen University - ISBN 9789462575752 - 216
watervoerende lagen - thermische energie - verzwakking - grondwater - waterzuivering - duurzame energie - biogeochemie - aquifers - thermal energy - attenuation - groundwater - water treatment - sustainable energy - biogeochemistry
Subjects: bioremediation; biodegradation; environmental biotechnology, subsurface and groundwater contamination; biological processes; geochemistry; microbiology
The combination of enhanced natural attenuation (ENA) of chlorinated volatile organic compounds (CVOCs) and aquifer thermal energy storage (ATES) appears attractive because such integration provides a promising solution for redevelopment of urban areas in terms of improving the local environmental quality as well as achieving sustainable energy supply. It will reduce the current negative interference between groundwater contaminants and ATES systems that arises from the rapid increase of ATES system numbers and generally long duration of contaminated groundwater treatments. However, currently the implementation of the combined system is at an initial stage, and still requires comprehensive study before advancing to mature application. Studies should specifically focus on understanding of the basic biogeochemical processes in aquifer systems under conditions of ATES and enhanced bioremediation and their mutual impacts when combined in ATES-ENA. To this end, the research as reported in this thesis employed laboratory experiments and modeling approaches focused on finding the essential process factors involved in the combined system, revealing possible drawbacks, and providing a better understanding to design alternative options on better operation of the combined system.
Chapter 2 assessed the limiting factor for reductive dechlorination of PCE in an Fe(III) reducing aquifer, being the typical type of subsurface in the Netherlands. A step-wise batch study was performed which consisted of redox conditioning by lactate and ascorbic acid, followed by reductive dechlorination in different scenarios. For the sediment material sampled from the Fe(III) reducing aquifer, conditioning of the redox potential could stimulate PCE dechlorination. It was concluded that 75 µmol electron equivalents per gram dry mass of aquifer material was the threshold to obtain a redox potential of -450 mV, which is theoretically suitable for PCE reductive dechlorination. However, dechlorinating bacteria required for fully reductive dechlorination are generally lacking in Fe(III) reducing aquifers. Without bioaugmentation of dechlorinating bacteria, PCE could only be reduced to TCE or cis-DCE. The step-wise approach and findings obtained from different scenarios tested in this study are relevant for improving the cost-effectiveness of the design and operation of in situ bioremediation. The redox potential of an aquifer can be used as a general indicator to evaluate the potential for CVOCs reductive dechlorination. For achieving specific goals of in situ bioremediation projects at different CVOCs contaminated sites with various environmental conditions, the balance between cost, benefit, and potential risks (e.g. bio‑chemical well clogging due to bacteria growth and precipitation of metal-oxides) should be estimated before the design and operation of the ATES-ENA systems. This chapter provides insights into the essential factors that determine the feasibility of ATES-ENA.
In Chapter 3, the two most important impacts of ATES on enhanced bioremediation of CVOCs were investigated using batch experiments. Besides, another type of underground thermal energy storage system, the borehole thermal energy storage (BTES) was also studied as a comparison to ATES. Here cis-DCE was targeted as it is commonly found to accumulate in the subsurface due to incomplete dechlorination. Compared to a natural situation (NS) with sufficient electron donor and bioaugmentation at a constant temperature of 10 ˚C, we assessed the effect of ATES by exchanging liquid between bottles kept at 25 and 5 ˚C, and the effect of BTES by alternating temperature between 25 and 5 ˚C periodically. Under ATES warm condition, cis-DCE was dechlorinated to ethene and at an increasing rate with each liquid exchange, despite no biodegradation being observed under ATES cold condition. The overall removal rate under alternating ATES conditions reached 1.83 μmol cis‑DCE/day, which was over 1.5 and 13 times faster than those in BTES and NS conditions. Most probably growth of biomass occurred under ATES warm condition, leading to an autocatalytic increase in conversion rates due to higher biomass concentration. Comparison between batches with or without Dehalococcoides inoculum revealed that their initial presence is a determining factor for the dechlorination process. Temperature then became the dominant factor when Dehalococcoides concentration was sufficient. The results also indicated that Dehalococcoides was preferentially attached to the soil matrix. This chapter highlights the importance of the dynamic temperature regimes in ATES on the bioremediation of CVOCs and recommends to implement biostimulation actions in the ATES warm well.
Further impacts of ATES related to change in redox condition on bioremediation of CVOCs, with focus on microbial responses of Dehalococcoides, were explored in Chapter 4. In this chapter, we adopted a recirculating column experiment with a flow rate of 10 mL/min (representing the flow velocity at a distance of 1.3 m from the center of a typical ATES well) to simulate the ATES system. To mimic potential periodic redox fluctuations that accompany ATES, serial additions of lactate and nitrate were performed. Firstly, also at the relatively high liquid velocity (compared to normal bioremediation conditions) complete reductive dechlorination from cis-DCE to ethene was achieved in the column system. However, dechlorination was immediately terminated by subsequent nitrate addition due to direct interruption of Dehalococcoides retention to the soil matrix. In our column system, which was much more homogeneous than subsurface in reality, repeated interruption of dechlorination via Dehalococcoides was extremely severe. Such repeated interruption by nitrate dosing eventually led to less easily reversible while requiring more efforts for recovering dechlorination. In addition, the hypothesis of the immobility of Dehalococcoides was further confirmed by the microbial analysis of microorganism in the liquid phase where only less than 0.1% of the Dehalococcoides inoculum could be found back. Although some field studies demonstrated easier regeneration of Dehalococcoides in the subsurface after suffering oxidant, results from this chapter emphasized the sensitive resilience of Dehalococcoides which needs careful consideration in biostimulated ATES condition, and a functional combined system requires dedicated ATES operation and monitoring on the aquifer geochemical conditions.
The major concern on possible negative impact of enhanced bioremediation on ATES is biological clogging attributed to biomass growth. As chemical clogging due to Fe(III) precipitates is a common problem in the functioning of ATES, the clogging issues (both biological and chemical) should be addressed before practical application. The potential clogging issues in the combined system were then researched in Chapter 5 using the same recirculating column system as in the previous chapter. For this purpose, two flow rates, 10 and 50 mL/min, were implemented. In the two columns, enhanced biological activity and chemically promoted Fe-oxide precipitation were studied by addition of lactate and nitrate respectively. Pressure drop (∆P) between the influent and effluent of the columns was monitored to indicate clogging of the system. The results showed no increase in ∆P during the period of enhanced biological activity, with large amount of lactate and active inoculum being added, even when the concentration of total bacteria in the liquid phase increased by four orders of magnitude. Nitrate addition, however, caused significant increase of ∆P. Remarkably, in the column with higher flow rate (50 mL/min), an unforeseen blow-up occurred at the end of experiment, as the buildup of pressure in the system was higher than the strength of the glass column. However, in the column with flow rate of 10 mL/min, high pressure buildup caused by nitrate addition could be alleviated by lactate addition. Such finding indicates that the risk of biological clogging related to biostimulation is relatively small, because by maintaining a low redox condition biostimulation itself may counter chemical clogging in ATES. Nevertheless, acknowledging that a column system cannot fully mimic real ATES conditions, additional tests are necessary to further investigate the clogging issues in the combined system.
In Chapter 6, we performed a simulation of ATES-ENA with a reactive transport model, using ATES as the engineering tool for lactate injection in a hypothetical TCE contaminated aquifer which is assumed to be homogeneous. Many relevant processes in the combined system were simulated, such as TCE, cis-DCE and VC dechlorination, sulphate and Fe(III) reduction, organic acid fermentation and oxidation and growth of different biomass. In total 15 scenarios are considered in the model, including variations in lactate dosage (three concentration levels: 3.8, 1.9 and 0.38 mmol/L), temperature (three pairs for the ATES cold/warm well: 5/15 ˚C, 10/10 ˚C, 5/25 ˚C), biomass mobility (purely mobile or immobile), and pH limitation on Fe(III) reduction (absence and presence of such an effect). In the five years’ simulation by the model, complete dechlorination to ethene was achieved within 1 year, in the influence zone of the ATES wells, for the reference scenario with 3.8 mmol/L lactate, 5/15 ˚C ATES well temperatures and mobile biomass. Scenarios with lower dosage of lactate gave results with less dechlorination progress. Growth of biomass, especially iron reducer and lactate fermenter, was significant also in the first year (for both mobile and immobile biomass scenarios). Biomass also spread throughout the influence volume of ATES for both warm and cold wells. However, scenarios with different well-temperature pairs did not noteworthy differ in dechlorination progress. This could probably be due to biomass concentration being the limiting factor in this model setup, while temperature was not. Such situation was quite different than that in Chapter 3, of which experiment with bioaugmentation in the beginning. Besides, the model here could not include the important autocatalytic process (Chapter 3) which generated much faster dechlorination than just could be realized by only temperature increase in this chapter. In general, the modeling in this chapter suggests that applying ATES as engineering tool for biostimulation (substrate injection and bioaugmentation) can be a cost-effective approach to support the combined system.
Eventually in Chapter 7, overall discussions upon results gained from previous chapters were integrated and the research questions as presented in the introduction are reiterated. In addition, recommendation upon future study, and wider implications with future perspective for practical application are also discussed. We concluded that redox condition is the most essential factor in the ATES-ENA system. The mutual impacts of ATES and ENA were revealed to be quite positive. Elevated temperature in the ATES warm well synergizing with groundwater transport can provide “1 + 1 > 2” effect. Besides, ENA can probably reduce risk of chemical clogging in ATES, instead of causing biological clogging. The further investigation was recommended to perform with larger scale pilot tests. Finally, a brief review of possible applications was given for two countries, the Netherlands and China, which both have dense groundwater and subsurface contaminations around urban areas. The ATES technology is much more mature in the Netherlands, whereas in China, the advantage is the more flexible usage of subsurface. For both countries, ATES-ENA can provide cost‑effective outcomes on both energy production and groundwater management.
Low-resolution modeling of dense drainage networks in confining layers
Pauw, P.S. ; Zee, S.E.A.T.M. van der; Leijnse, A. ; Delsman, J.R. ; Louw, P.G.B. de; Lange, W.J. de; Oude Essink, G.H.P. - \ 2015
Groundwater 53 (2015)5. - ISSN 0017-467X - p. 771 - 781.
grondwaterstroming - watervoerende lagen - modellen - klimaatverandering - groundwater flow - aquifers - models - climatic change - aquifer - simulation - intrusion - seepage - florida - system - field - flow
Groundwater-surface water (GW-SW) interaction in numerical groundwater flow models is generally simulated using a Cauchy boundary condition, which relates the flow between the surface water and the groundwater to the product of the head difference between the node and the surface water level, and a coefficient, often referred to as the “conductance.” Previous studies have shown that in models with a low grid resolution, the resistance to GW-SW interaction below the surface water bed should often be accounted for in the parameterization of the conductance, in addition to the resistance across the surface water bed. Three conductance expressions that take this resistance into account were investigated: two that were presented by Mehl and Hill (2010) and the one that was presented by De Lange (1999). Their accuracy in low-resolution models regarding salt and water fluxes to a dense drainage network in a confined aquifer system was determined. For a wide range of hydrogeological conditions, the influence of (1) variable groundwater density; (2) vertical grid discretization; and (3) simulation of both ditches and tile drains in a single model cell was investigated. The results indicate that the conductance expression of De Lange (1999) should be used in similar hydrogeological conditions as considered in this paper, as it is better taking into account the resistance to flow below the surface water bed. For the cases that were considered, the influence of variable groundwater density and vertical grid discretization on the accuracy of the conductance expression of De Lange (1999) is small.
Modelling and monitoring of Aquifer Thermal Energy Storage : impacts of soil heterogeneity, thermal interference and bioremediation
Sommer, W.T. - \ 2015
Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Tim Grotenhuis; J. Valstar. - Wageningen : Wageningen University - ISBN 9789462572942 - 204
watervoerende lagen - thermische energie - opslag - energieterugwinning - economische impact - milieueffect - bodemsanering - grondwaterverontreiniging - aquifers - thermal energy - storage - energy recovery - economic impact - environmental impact - soil remediation - groundwater pollution
Modelling and monitoring of Aquifer Thermal Energy Storage
Impacts of heterogeneity, thermal interference and bioremediation
Aquifer thermal energy storage (ATES) is applied world-wide to provide heating and cooling to buildings. Application of ATES, instead of traditional heating and cooling installations, reduces primary energy consumption and related CO2 emissions. Intensified use of the subsurface for thermal applications requires more accurate methods to measure and predict the development of thermal plumes in the subsurface related to thermal interference between systems and address issues concerning subsurface urban planning and wide spread presence of contaminants in urban groundwater systems.
In this thesis, subsurface heat transport in ATES and the associated influence on storage performance for thermal energy was assessed. Detailed monitoring of subsurface temperature development around the wells of an existing system was achieved by a unique application of Distributed Temperature Sensing (DTS) using glass fibre optical cables. The measurements reveal unequal distribution of flow rate over different parts of the well screen and preferential flow due to aquifer heterogeneity. Heat transport modelling shows that heterogeneity causes preferential flow paths that can affect thermal interference between systems, mainly depending on well-to-well distance and hydrogeological conditions.
At present, design rules are applied in such way that all negative interference is avoided. However, this limits the number of ATES systems that can be realized in a specific area, especially as these systems generally use only 60% of their permitted capacity. To optimize the use of available aquifer volume, the amount of thermal interference that is acceptable from an economical and environmental perspective was studied for different zonation patterns and well-to-well distances. Selecting the hydrogeological conditions of Amsterdam, the Netherlands, as a case study, this method shows that it is cost-effective to allow a limited amount of thermal interference, such that 30–40% more energy can be provided than compared to the case in which all negative thermal interference is avoided.
Because many urbanized areas deal with contaminated soil and groundwater, ambitions to increase the number of ATES systems are confronted with the presence of groundwater contaminants. This is of concern, because groundwater movement induced by the ATES system can result in increased mobility and spreading of these contaminants. However, the combination between ATES and soil and groundwater remediation could be a promising integrated technique, both for improving groundwater quality and development of ATES. Opportunities to use ATES as a continuous biostimulation tool for enhanced reductive dechlorination (ERD) have been explored with a reactive transport model.
Regional scale impact of tidal forcing on groundwater flow in unconfined coastal aquifers
Pauw, P.S. ; Oude Essink, G.H.P. ; Leijnse, A. ; Vandenbohede, A. ; Groen, J. ; Zee, S.E.A.T.M. van der - \ 2014
Journal of Hydrology 517 (2014). - ISSN 0022-1694 - p. 269 - 283.
grondwaterstroming - kustgebieden - watervoerende lagen - groundwater flow - coastal areas - aquifers - sea-water intrusion - saline groundwater - fresh - beaches - discharge - dynamics - lenses - table - zone
This paper considers the impact of tidal forcing on regional groundwater flow in an unconfined coastal aquifer. Numerical models are used to quantify this impact for a wide range of hydrogeological conditions. Both a shallow and a deep aquifer are investigated with regard to three dimensionless parameter groups that determine the groundwater flow to a large extent. Analytical expressions are presented that allow for a quick estimate of the regional scale effect of tidal forcing under the same conditions as used in the numerical models. Quantitatively, the results in this paper are complementary to previous studies by taking into account variable density groundwater flow, dispersive salt transport and a seepage face in the intertidal area. Qualitatively, the results are in line with previous investigations. The time-averaged hydraulic head at the high tide mark increases upon a decrease of each of the three considered dimensionless parameter groups: R (including the ratio of the hydraulic conductivity and the precipitation excess), a (the slope of the intertidal area) and AL (the ratio of the width of the fresh water lens and the tidal amplitude). The relative change of the location and the hydraulic head of the groundwater divide, which together characterize regional groundwater flow, increase as a and AL decrease, but decrease as R decreases. The difference between the analytical solutions and numerical results is small. Therefore, the presented analytical solutions can be used to estimate the bias that is introduced in a numerical model if tidal forcing is neglected. The results should be used with caution in case of significant wave forcing, as this was not considered.
Methode voor het bepalen van de potentie voor het toepassen van lokale zoetwateroplossingen : Fresh Water Options Optimizer - fase 1
Bakel, J. van; Louw, P. de; Stuyt, L.C.P.M. ; Tolk, L. ; Velstra, J. ; Hoogvliet, M. - \ 2014
Utrecht : Programmabureau Kennis voor Klimaat (Rapport / STOWA 2014-16) - ISBN 9789490070847 - 82
zoet water - watervoorziening - drainage - infiltratie - sloten - wateropslag - watervoerende lagen - maatregelen - inventarisaties - fresh water - water supply - drainage - infiltration - ditches - water storage - aquifers - measures - inventories
Binnen Kennis voor Klimaat worden kleinschalige maatregelen ontwikkeld om de zoetwatervoorziening te verbeteren. In deze studie zijn methoden ontwikkeld waarmee de potentie van dergelijke maatregelen op het schaalniveau van een groter gebied, voor hoog en laag Nederland, kan worden verkend. In deze studie zijn de opschalingsmogelijkheden bekeken voor de volgende lokale zoetwateroplossingen: (1) drains2buffer, (2) regelbare en klimaatadaptieve drainage, (3) kreekruginfiltratie, (4) Freshmaker, (5) verticale ASR, (6) waterconservering door stuwen en (7) waterconservering door slootbodemverhoging.
Response to recharge variation of thin rainwater lenses and their mixing zone with underlying saline groundwater
Eeman, S. ; Zee, S.E.A.T.M. van der; Leijnse, A. ; Louw, P.G.B. de; Maas, C. - \ 2012
Hydrology and Earth System Sciences 16 (2012). - ISSN 1027-5606 - p. 3535 - 3549.
grondwater - watervoerende lagen - zoet water - neerslag - zoutwaterindringing - kustgebieden - groundwater - aquifers - fresh water - precipitation - salt water intrusion - coastal areas - sea-level rise - climate-change - coastal aquifer - water interface - fresh - transport - dispersion - discharge - islands - surface
In coastal zones with saline groundwater, fresh groundwater lenses may form due to infiltration of rain water. The thickness of both the lens and the mixing zone, determines fresh water availability for plant growth. Due to recharge variation, the thickness of the lens and the mixing zone are not constant, which may adversely affect agricultural and natural vegetation if saline water reaches the root zone during the growing season. In this paper, we study the response of thin lenses and their mixing zone to variation of recharge. The recharge is varied using sinusoids with a range of amplitudes and frequencies. We vary lens characteristics by varying the Rayleigh number and Mass flux ratio of saline and fresh water, as these dominantly influence the thickness of thin lenses and their mixing zone. Numerical results show a linear relation between the normalised lens volume and the main lens and recharge characteristics, enabling an empirical approximation of the variation of lens thickness. Increase of the recharge amplitude causes increase and the increase of recharge frequency causes a decrease in the variation of lens thickness. The average lens thickness is not significantly influenced by these variations in recharge, contrary to the mixing zone thickness. The mixing zone thickness is compared to that of a Fickian mixing regime. A simple relation between the travelled distance of the centre of the mixing zone position due to variations in recharge and the mixing zone thickness is shown to be valid for both a sinusoidal recharge variation and actual records of daily recharge data. Starting from a step response function, convolution can be used to determine the effect of variable recharge in time. For a sinusoidal curve, we can determine delay of lens movement compared to the recharge curve as well as the lens amplitude, derived from the convolution integral. Together the proposed equations provide us with a first order approximation of lens characteristics using basic lens and recharge parameters without the use of numerical models. This enables the assessment of the vulnerability of any thin fresh water lens on saline, upward seeping groundwater to salinity stress in the root zone.
Analysis of the thickness of a fresh water lens and of the transition zone
Eeman, S. ; Leijnse, A. ; Raats, P.A.C. ; Zee, S.E.A.T.M. van der - \ 2011
Advances in Water Resources 34 (2011)2. - ISSN 0309-1708 - p. 291 - 302.
geohydrologie - watervoerende lagen - zoet water - zout water - delta's - geohydrology - aquifers - fresh water - saline water - deltas - submarine groundwater discharge - porous-media - coastal aquifer - brine transport - barrier-island - interface - flow - infiltration - dispersion - intrusion
In regions with saline groundwater, fresh water lenses may develop due to rainwater infiltration. The amount of fresh water that is available for e.g. agricultural crops depends on the thickness of the lens and the extent of mixing between fresh and saline water. In this paper, we consider the mixing of fresh water and upward moving saline ground water in low-lying deltaic areas. The parameters that dominate the flow and transport problem are investigated using dimensionless groups and scaled sensitivities. We characterize the numerically simulated thicknesses of the lens and of the mixing zone by spatial moments. Rayleigh number and mass flux ratio, which is the ratio of the salt water seepage and the precipitation, determine the thickness of the fresh water lens. The local thickness of the mixing zone is mainly influenced by the dispersive/diffusive groups and the mass flux ratio. In addition, convergence of streamlines towards an outflow boundary affects the thickness, particularly in the vicinity of this boundary. Analytical and numerical steady state solutions for lens thickness are compared, taking into account upward seepage, for the two cases with and without a density difference between lens and underlying groundwater. Agreement between the numerical and analytical solutions for the lens thickness is good except when the mass flux ratio becomes small. For zero mass flux ratio, it is implicitly assumed in the analytical solution that salt water is stagnant, and that is unrealistic. Relative contributions of longitudinal and transversal hydrodynamic dispersion and diffusion to the thickness of the mixing zone are quantified numerically for different phases of lens formation. Longitudinal dispersion dominates in the early stages of lens formation, while diffusion and transversal dispersion dominate at steady state
Developing an environmentally appropriate, socially acceptable and gender-sensitive technology for safe-water supply to households in arsenic affected areas in rural Bangladesh
Amin, N. - \ 2010
Wageningen University. Promotor(en): Anke Niehof; Wim Rulkens, co-promotor(en): Harry Bruning. - [S.l. : S.n. - ISBN 9789085858164 - 243
plattelandsontwikkeling - platteland - ontwikkeling - ontwikkelingsstudies - watervoorziening - milieubescherming - grondwater - grondwaterverontreiniging - watervoerende lagen - pijpleidingen - arsenicum - maatschappelijke betrokkenheid - landbouwhuishoudens - waterfilters - drinkwater - sociologie - bangladesh - zuid-azië - rural development - rural areas - development - development studies - water supply - environmental protection - groundwater - groundwater pollution - aquifers - pipelines - arsenic - community involvement - agricultural households - water filters - drinking water - sociology - bangladesh - south asia
To confront the arsenic crisis in Bangladesh, several options for a safe water supply in the rural As-affected areas are available. Most of these options have shown a minimum scope to mitigate arsenic-related risks because of their poor performance and non-acceptability by the rural households. In this research, therefore, the development of an appropriate technology for an As-free, safe drinking water supply is considered from a local perspective and a societal context. To achieve the goal and objectives of this research, four research questions were formulated (Chapter 1). The first research question is about the technological and socio-economic performance of community-based pipeline water supply systems that use deep aquifers. The second question deals with available and currently implemented household-level arsenic removal technologies in rural Bangladesh. The third addresses the weaknesses, limitations, strengths and advantages of the technologies in terms of a number of technological, social, economic and gender indicators. Fourth, the question is posed of the most promising arsenic removal option for rural house¬holds in terms of its techno¬logical performance and social acceptability and suitability from a gender perspective. The occurrence of As in the Delta region is of geochemical origin and its distribution in the groundwater has distinct regional patterns and depth trends. An overview of the arsenic problem in Bangladesh is given in Chapter 2.
The overall objective of the research was to develop a socially appropriate and gender-sensitive household-level As removal filter. Technical, socio-economic and cultural aspects were incorporated in this research to assess the development of a sustainable innovation through multi- and interdisciplinary approaches. The technical validation of the systems was carried out through laboratory-based research, to address the efficiency, robustness, operational and maintenance convenience, safety and viability of the technology. For the social research, the model by Spaargaren and Van Vliet (2000) was adjusted to address the filter’s suitability in terms of lifestyle, domestic time-space structures, affordability, standards of comfort, cleanliness, convenience and modes of provision. In addition, I also considered the household resource-based affordability during the operation and maintenance phase, in terms of a socio-technological and gender perspective. A conceptual model was developed to guide the research and to answer the research questions (Chapter 1). The socio-economic data on the main concepts of this research work were collected through a survey (Appendix 2).
In this research, a synthesis of knowledge resulting from disciplinary, open-ended collaboration and local perspectives is achieved. Such a transdisciplinary research approach ensures an integration of knowledge through the participation of a variety of stakeholders, including end users, and mutual learning between the different stakeholders, such as users of the Modified Garnet Homemade Filter (MGH Filter), caretakers, village committees, implementing organizations and donors, users of water, households, and women.
The community–based piped water supply in Bangladesh
There are several alternative sources to get safe and As-free drinking water in Bangladesh. A community-based piped water supply system using deep aquifers is one of them. In this research, three community-based piped water supply systems were compared to evaluate their technological and economic sustainability, the sustainability of using deep aquifers for the long term, and the social and gender appropriateness of the systems, based on the users’ perspective (Chapter 4). The technical performance of the three systems in different geological conditions was found satisfactory in terms of their efficacy, water quality, adequacy of the water supply, and operations and maintenance. The water is As- and Fe-free and is of good taste. The concentration of As is below the limiting range of drinking water in Bangladesh (50µgL-1As), as well as within the WHO and new EPA standards (10µgL-1As). The sustainable use of deep aquifers for a longer period is a serious issue. To address the sustainability, hydro-geological factors need to be well understood. Overextraction of water from deep aquifers could induce a downward migration of dissolved As and permanently destroy the deep resource. Only one system is practicing chlorination to disinfect the water in the overhead tank, while the other two systems do not have such a provision. However, the field data reveal that the three systems are technologically acceptable and do not require disposal of contaminated sludge.
The women who are using one of the three water supply systems are satisfied about the water supply systems. They think the systems reliable in their delivery of adequate water and convenient and comfortable for the women users. Women can get water close to their house, which saves collection time and a physical burden. The appointed caretakers are operating the systems efficiently, including maintenance and the collection of the monthly bill from the beneficiaries. The economical sustainability seems to be satisfactory, provided the initial costs are subsidized by external financial assistance with only a little contribution from the communities, which varies from five to seven percent of the total capital cost. The community participation in sharing the installation cost for the system and the monthly bill are fixed, based on the economical condition of the households. However, a drawback of the community-based piped water system is disruption of the system due to its sensitivity to power failure, which is a big problem in Bangladesh. Other shortcomings are the limitations to extend the system to meet the increasing demand of the village people. On the long term, economical sustainability factors need to be considered, such as the availability of funds and the participation of the users in the system’s management, which were absent in all three systems.
Currently available and implemented household-level arsenic removal technologies
The application of arsenic removal technologies to provide safe drinking water in rural areas plays a vital role where other, alternative options and safe aquifers are not easily available and where community-based pipeline water supply systems are not feasible. In this research, physico-chemical and biological as well as conventional techniques for the removal of arsenic were reviewed (Chapter 5). Based on literature, an inventory was carried out of 40 available and currently implemented technologies at the household level in terms of their arsenic removal efficiency, cost and users’ acceptance. All the technologies remove As from the water to a limited extent. Therefore, there is scope for further development of these technologies. A multiple-criteria analysis (MCA) approach was applied to select a technology for the further development of an appropriate arsenic removal filter for household-level use. In the research, based on the integrated assessments, the MCA-GARNET technology was selected for further development.
An assessment of the performances of the three governmentally certified arsenic removal technologies for rural household use was carried out (Chapter 5). This research concludes that the government’s investments in an improved water supply so far have failed to meet the needs of the poor villagers, because they are not able to buy the costly Alcan and Read-F filters. Even the relatively cheap Sono filter proved to be unaffordable for the poorest. Furthermore, assessing the As removal efficiency and life span of these filters is difficult at this preliminary stage, and so is predicting how the disposal of the spent filter materials will be carried out by the users. The As leaching from the sludge/waste generated by the three treatment processes is dependent on the type of removal mechanism and the ultimate sludge disposal methods.
Development of a chemical-free arsenic removal technology for household use
In this research, by the active participation of potential end users and other stakeholders, I have included local knowledge and social and gender perspectives in the process of the development of an innovative As removal filter (MGH filter) (Chapter 6). The MGH filter efficiency and breakthrough point were studied at different operational variables, such as filter bed thickness, types of filter media and flow rate. The toxicity of the spent material was addressed by a TCLP test. The developed filter meets the Bangladesh standard for arsenic in drinking water (50µgL-1). It can reduce the arsenic concentrations of the shallow tube well water samples from 160-959µgL-1 to 0-50µgL-1. It can also remove bacteriological contamination in terms of total coliform and fecal coliform counts from >500 to 0 cfu/100 mL-1 . The filter consists of two-bucket filters in series, each with three filter material layers of 14 cm thickness each, containing sand, brick chip and sand (Figure 7.1). The first-class brick chips of 1.3 cm size and Sylhet coarse sands were found to be the most efficient. The major advantage of this unit is that it does not require any daily addition of chemicals and can be operated at a high flow rate. It needs to be cleaned regularly to prevent bacterial contamination, while its maintenance requires treatment with bleaching powder at 15-day intervals. The filter is cost–effective and viable; the investments and operational cost are about € 10.8-13.4 and € 0.11-0.14 per 100 liters of treated water, respectively.
In this research, a multi-perspective and participatory socio-technological assessment of the filter’s performance during the field level application was carried out in two phases: the trial phase during March 2008 and the evaluation phase during July 2008 (Chapter 7). Eight MGH filters were distributed among eight households in the research area in Kumarbhog. In this research, the multi-perspective assessment comprised interdisciplinary and transdisciplinary approaches to evaluate the performance of the filters for household use. Both quantitative and qualitative methods of data collection and analysis were used. The suitability and acceptability of the filters were evaluated through systematic observation, interviewing, FGDs and eight case studies of the filter users. The compatibility and appropriate¬ness of the filter were viewed from a gender pers¬pective, since access to safe water is an important practical gender need of women, directly related to their domestic and reproductive role.
Women of the selected eight rural households adopted the technology and ran the filters successfully during the trial phase. As elsewhere in developing countries, in Bangladesh too, rural women are the managers of water for household use. They hardly participate in income generation. The male household head controls the allocation of household income and expenditures, which caused problems when women wanted to re-install their filter. The household survey revealed that sometimes, women cannot be bothered to fetch safe water from far away and, instead, drink the con¬taminated water from their own shallow tube wells. Having the appliance inside the house complied well with the social norms and religious restrictions (purdah) that women have to abide by. In these circumstances, the MGH filter was eagerly accepted by the eight households, because it reduced women’s social and physical burden to fetch As-free, safe water far from their home. In the evaluation phase, some filters were unused because the women could not persuade their husbands to purchase the necessary filter bed materials. During the evaluation phase, the performance of the filters declined compared to the trial phase, because not all users followed the instructions on its operation and maintenance, such as proper chlorination and clean¬liness of the appliance. Disposal of spent filter material was carried out in different ways by the MGH filter users, but more investigation is needed to enable an environmentally friendly disposal of the As-rich sludge.
A new filter system has been developed that can be used by women at the household level. In terms of the simplicity of construction, operation and maintenance, As removal efficiency, and bacterial removal efficiency, its technical performance is good. It is also very cost-effective. However, because such a system always needs to be completely safe for producing drinking water, on the long term as well as under local and household conditions other than those investigated in this research project, further evaluation and additional research will be necessary. In this research, the filter was field-tested under controlled conditions for a month and evaluated after three months. Considering the need for arsenic treatment options in Bangladesh and other developing countries, further research on the performance of the MGH technology could have important positive implications for a safe water supply. Therefore, to allow for seasonality, the MGH filter should be pilot-tested and properly developed over a period of at least a year, in different geographical conditions. A social, economic and technical validation of the MGH filter should be included in the pilot-testing in different parts of the country by applying interdisciplinary and transdisciplinary approaches. Because women are the collectors and managers of drinking water, doing the validation in different parts of the country allows for variation in women’s roles and position and the local socio-cultural context. The MGH filter should be submitted for certification by the government of Bangladesh after further testing and development. The technological principle of the MGH filter may be used to research and develop a community-based low-cost arsenic removal water supply system in rural areas. The results of this research testify to the feasibility of a gender-sensitive, socially acceptable and technologically sound, sustainable solution to the problem of the As contamination of water for household use in rural areas in Bangladesh.
Incentives to reduce groundwater extraction in Yemen
Hellegers, P.J.G.J. ; Perry, J.N. ; Al-Aulaqi, N. ; Al-Eryani, A.R. ; Al-Hebshi, M. - \ 2008
The Hague : LEI Wageningen UR (Report / LEI : Research area 1, International policy ) - ISBN 9789086152704 - 131
stimulansen - grondwater - grondwaterwinning - grondwaterstand - watervoerende lagen - welpijpen - duurzaamheid (sustainability) - irrigatie - hulpbronnengebruik - watergebruik - landbouw - waterbescherming - boeren - houding van boeren - sociale economie - waterbeleid - regering - jemen - verdroging (milieu) - economische verandering - incentives - groundwater - groundwater extraction - groundwater level - aquifers - tube wells - sustainability - irrigation - resource utilization - water use - agriculture - water conservation - farmers - farmers' attitudes - socioeconomics - water policy - government - yemen - groundwater depletion - economic change
This report describes the results of the study on options for changing the eco-nomic incentive structure for groundwater extraction in Yemen. The study aims to evaluate the potential role of economic incentives to reduce unsustainable ir-rigation water consumption and to make recommendations for implementing water conservation incentives. It first identifies factors that have triggered groundwater overdraft, then studies farmers' behaviour regarding groundwater extraction on the basis of in-depth interviews with farmers in each of the follow-ing three basins - in the Sana'a Basin, the Taiz Basin and Wadi Hadramout. Fi-nally, a number of changes in the incentive structure are evaluated, among others incentives that decrease the profitability of irrigation water use and sub-sidies on improved irrigation technology. The study shows that although the lit-erature and economic theory suggest that the range of possible interventions is wide (water pricing, metering, water rights, water markets, taxes, subsidies, in-formation, participatory management, et cetera), the range of potentially effec-tive interventions in the Yemeni political context is more limited. The Yemeni case is unique, as there is a close linkage between water and a central socio-economic issue: qat. This adds to the difficulties of implementing or enforcing change.
Variation in space and time of water flow and solute transport in heterogeneous soils and aquifers : a new multi-compartment percolation sampler and a new parameterization of the spatio-temporal solute distribution
Bloem, E. - \ 2008
Wageningen University. Promotor(en): Reinder Feddes, co-promotor(en): G.H. de Rooij. - S.l. : S.n. - ISBN 9789085049227 - 153
grondwaterstroming - opgeloste stof - transportprocessen - watervoerende lagen - variatie in de tijd - bemonsteren - distributie - grondwaterverontreiniging - ruimtelijke variatie - groundwater flow - solutes - transport processes - aquifers - temporal variation - sampling - distribution - groundwater pollution - spatial variation
Het experimentele en theoretische onderzoek gepresenteerd in dit proefschrift heeft geleid tot een verbetering van de mogelijkheden om stoffentransport in de ondergrond beneden een onverzadigde bodem te observeren. De lange termijn prestaties van de nieuwe multi-compartement samplers onder de ruwe omstandigheden van het open veld waren overtuigend. De samplers bleken geschikt voor een grotere verscheidenheid aan toepassingen
Solubility of arsenic in multi-component systems : from the microscopic to macroscopic scale
Stachowicz, M. - \ 2007
Wageningen University. Promotor(en): Willem van Riemsdijk. - [S.l.] : S.n. - ISBN 9789085047650 - 207
bodemchemie - arsenicum - oplosbaarheid - grondwaterverontreiniging - grondwaterwinning - drinkwater - watervoerende lagen - soil chemistry - arsenic - solubility - groundwater pollution - groundwater extraction - drinking water - aquifers
Arsenic in groundwater has generated one of the most important problems with respect to the quality of drinking water in the modern world. The aim of this thesis has been to assess, as good as possible for the present state of the art, the factors and processes that govern the arsenic behavior in contaminated aquifers. The research tactics have included 3 sequential steps: (1) obtaining adsorption datasets for systems simulating relevant groundwater field situations; (2) interpretation of these data with a molecular based adsorption model and the model application to predict the adsorption behavior of arsenic for a range of compositions relevant in the field; (3) providing quantitative understanding of the behavior of arsenic in natural waters. This knowledge may contribute to a better understanding of the problem, the long-term solutions, such as an optimization of treatment techniques for drinking water as well as a methodology to guide the positioning of new arsenic-free wells
Decentrale voorziening in energie, water en andere nutsfuncties
Mels, A.R. ; Andel, N. van; Kristinsson, J. ; Wortman, E. ; Oei, P. ; Wilt, J. de; Lettinga, G. ; Zeeman, G. - \ 2006
Spil 5 (2006)229-230. - ISSN 0165-6252 - p. 12 - 18.
tuinbouw - energiebehoeften - energie - recycling - woonwijken - verwarming - innovaties - watervoerende lagen - huisvesting - glastuinbouw - energiebesparing - horticulture - energy requirements - energy - recycling - housing - residential areas - heating - innovations - aquifers - greenhouse horticulture - energy saving
Presentatie van een nieuw ontwerp van een tuinbouwkas met een daaraan gekoppelde woonwijk. Het ontwerp, Zonneterp genaamd, is o.a. gebaseerd op een kas, die tijdens de zomer overtollige warmte opslaat in aquifers en deze warmte kan gebruiken voor het verwarmen van de kas en de woningen tijdens de nacht of gedurende de winter
De doorlatendheid van de bodem voor infiltratiedoeleinden; een gebiedsdekkende inventarisatie voor het Waterschap Peel en Maasvallei
Massop, H.T.L. ; Gaast, J.W.J. van der; Kiestra, E. - \ 2005
Wageningen : Alterra (Alterra-rapport 1212) - 95
permeabiliteit - infiltratie - hydraulisch geleidingsvermogen - kwel - watervoerende lagen - grondwaterstroming - fysische bodemeigenschappen - grondwater - geohydrologie - limburg - permeability - infiltration - hydraulic conductivity - groundwater - mapping - seepage - aquifers - groundwater flow - geohydrology - limburg
In opdracht van waterschap Peel en Maasvallei is een onderzoek uitgevoerd naar de geohydrologische eigenschappen van het topsysteem. Het waterschap gebruikt deze informatie bij de beoordeling en advisering ten behoeve van infiltratievoorzieningen. Voor de beoordeling van deze voorziening zijn de doorlatendheid en de dikte van de deklaag van belang alsook het doorlaatvermogen van het onderliggende watervoerende pakket. Voor het gebiedsdekkend vaststellen van de eigenschappen is het gebied geschematiseerd in 60 eenheden op basis van bodemeigenschappen en opbouw diepere ondergrond. Aan deze eenheden is een k-waardetabel gekoppeld. Deze tabel is gebaseerd op beschikbare metingen en schattingen en aangevuld met metingen die in het kader van dit onderzoek zijn uitgevoerd. Naast k-waarden is een diktekaart van de deklaag vervaardigd op basis van bruikbare boringen. Het doorlaatvermogen van het eerste watervoerend pakket is afgeleid uit verschillende bronnen, waaronder pompproeven. Een belangrijk punt bij gebruik van de geïnventariseerde gegevens is de anisotropie van de deklaag als gevolg van het voorkomen van klei, leem of veenlagen
Praktijkexperiment duurzame energieverzameling door middel van daksproeiers
Zwart, H.F. de - \ 2004
onbekend : Agrotechnology & Food Sciences Group (Report / Wageningen UR, Agrotechnology & Food Innovations 233) - ISBN 9789067548083 - 49
energiegebruik - duurzaamheid (sustainability) - zonne-energie - warmteopslag - watervoerende lagen - koelsystemen - warmteoverdracht - meting - binnenklimaat - glastuinbouw - energy consumption - sustainability - solar energy - heat retention - aquifers - cooling systems - heat transfer - measurement - indoor climate - greenhouse horticulture
Kassen hebben in de zomer veel warmte over en komen in de winter warmte tekort. Wanneer de overtollige warmte in de zomer verzameld en opgeslagen kan worden zou de kas in de winter met duurzame energie verwarmd kunnen worden. Omdat het om grote hoeveelheden warmte gaat kunnen de zomerse overschotten niet in bovengrondse buffers worden opgeslagen, maar moeten hier ondergrondse watervoerende lagen worden gebruikt (aquifers, zie KADER 3). Warmteopslag in aquifers kan door water tussen twee putten heen en weer te pompen, waarbij de ene put zo’n 5 °C kouder dan de gemiddelde bodemteperatuur is en de andere zo’n 5 °C warmer. De warmte en koudeverliezen blijven hierdoor beperkt. Het zal duidelijk zijn dat voor de toepassing van warmte met een temperatuur van rond de 15 °C een warmtepomp gebruikt moet worden (Zie KADER 1). Deze warmtepomp koelt het water uit de warme put af naar zo’n 5 °C en maakt hiermee een bron met koud water. Om in de winter van het volgende jaar opnieuw van de warmtepomp gebruik te kunnen maken moet dit koude water weer worden opgewarmd. A&F in Wageningen heeft onderzoek gedaan naar de mogelijkheid om deze opwarming te realiseren met standaard dekbesproeiingssystemen. Dit zijn relatief goedkope systemen die ook nu al op veel kassen gebruikt worden. Het belangrijkste verschil tussen het nu onderzochte systeem in de bestaande systemen is dat bij gangbare sproeiers kaskoeling plaatsvindt door verdamping van water, en in het voorgestelde nieuwe systeem de lage temperatuur van het opgespoten water koeling aan de kas geeft. Zo worden drie vliegen in één klap geslagen namelijk: 1. de sproeiers geven een groter koelvermogen 2. er wordt duurzame energie verzameld, waarmee in de winter gas kan worden bespaard 3. het verdampingsverlies wordt beperkt.
In-situ metal precipitation in a zinc-aerobic, sandy aquifer by means of biological sulfate reduction
Janssen, G.M.C.M. ; Temminghoff, E.J.M. - \ 2004
Environmental Science and Technology 38 (2004)14. - ISSN 0013-936X - p. 4002 - 4011.
terugwinning - sulfaten - neerslag - kooldioxide - decontaminatie - waterverontreiniging - watervoerende lagen - biologische behandeling - zware metalen - zink - recovery - sulfates - precipitation - carbon dioxide - decontamination - water pollution - aquifers - biological treatment - heavy metals - zinc - acid-mine drainage - reducing bacteria - removal - carbon - water - reactor - effluent - ethanol - energy - growth
The applicability of in situ metal precipitation (ISMP) based on bacterial sulfate reduction (BSR) with molasses as carbon source was tested for the immobilization of a zinc plume in an aquifer with highly unsuitable initial conditions (high Eh, low pH, low organic matter content, and low sulfate concentrations), using deep wells for substrate injection
The applicability of in situ metal precipitation (ISMP) based on bacterial sulfate reduction (BSR) with molasses as carbon source was tested for the immobilization of a zinc plume in an aquifer with highly unsuitable initial conditions (high E-h, low pH, low organic matter content, and low sulfate concentrations), using deep wells for substrate injection. Batch experiments revealed an optimal molasses concentration range of 1-5 g/L and demonstrated the necessity of adding a specific growth medium to the groundwater. Without this growth medium, even sulfate, nitrogen, phosphorus, and potassium addition combined with pH optimization could not trigger biological sulfate reduction. In column experiments, precipitation of ZnS(s) was induced biologically as well as chemically (by adding Na2S). In both systems, zinc concentrations dropped from about 30 mg/L to below 0.02 mg/L. After termination of substrate addition the biological system showed continuation of BSR for at least 2 months, suggesting the insensitivity of the sulfate reducing system for short stagnations of nutrient supply, whereas in the chemical system an immediate increase of Zn concentrations was observed. A pilot experiment conducted in situ at the zinc-contaminated site showed a reduction of zinc concentrations from around 40 mg/L to below 0.01 mg/L. Termination of substrate supply did not result in an immediate stagnation of the BSR process, but continuation of BSR was observed for at least 5 weeks.
Praktijkmeting aan een ondergronds energieopslagsysteem en validatie van een dynamisch simulatiemodel
Campen, J.B. ; Zwart, H.F. de - \ 2004
Wageningen : Agrotechnology & Food Innovations (Rapport / Agrotechnology and Food Innovations 058) - ISBN 9789067547437 - 31
watervoerende lagen - thermische energie - simulatiemodellen - kassen - ondergrondse opslag - glastuinbouw - aquifers - thermal energy - simulation models - greenhouses - underground storage - greenhouse horticulture
Well clogging by particles in Dutch well fields
Timmer, H. ; Verdel, J.D. ; Jongmans, A.G. - \ 2003
Journal American Water Works Association 95 (2003)8. - ISSN 0003-150X - p. 112 - 118.
grondwaterwinning - blokkering - watervoerende lagen - putten - watervoorziening - nederland - groundwater extraction - blockage - aquifers - wells - water supply - netherlands
For the water supply company Hydran South Holland in the Netherlands, clogged wells constituted a significant problem that lowered production capacity of the well field, disrupted the purification process at the treatment plant, and decreased overall revenues. This study was undertaken to develop a better understanding of the dogging process, the nature of the clogging materials, and the exact position of these materials in the well. The Hydron South Holland wells pump anaerobic groundwater from aquifers consisting of Pleistocene, sandy, and fluvial sediments, Samples were collected from a number of wells with a reduced specific capacity. Light microscopy and electron microscopy were performed on undisturbed samples, and particle size distribution and chemical analyses were conducted on bulk samples. On the basis of study results, a new two-pronged rehabilitation procedure was developed for seriously clogged wells. Initial findings indicate that the procedure offers both good immediate results and a significantly lower clogging rate over the long term. Hydron South Holland is conducting further research to prevent initial clogging and fine-tune well drilling techniques and well design. Utilities experiencing well clogging in similar aquifer conditions can use these findings to optimize their own rehabilitation procedures or as a jumping-off point for new research on well clogging and well design. - MPM.
Energie in balans; Evaluatie van warmteterugwinning uit een aquifer met elektrische warmtepompen op een glastuinbouwbedrijf met grondkoeling in 2002
Ravensbergen, P. ; Vernooy, C.J.M. - \ 2003
Den Haag : LEI (Rapport / LEI : Domein 3, Natuurlijke hulpbronnen en milieu ) - ISBN 9789052428710 - 60
glastuinbouw - evaluatie - watervoerende lagen - warmteterugwinning - warmtepompen - thermische energie - nederland - warmteopslag - greenhouse horticulture - evaluation - aquifers - heat recovery - heat pumps - thermal energy - netherlands - heat retention
Dit rapport is een beschrijving van een energetische, technische en economische evaluatie van warmteterugwinning uit een aquifer met elektrische warmtepompen op een vermeerde-ringsbedrijf van 3,5 ha glas in de praktijk, gedurende de periode van december 2001 tot december 2002. Aan de hand van de bevindingen van deze praktijkevaluatie, is een rendementsbere-kening gemaakt voor een normaal glastuinbouwproductiebedrijf met grondkoeling, waar al elektrische aangedreven koelmachines aanwezig zijn. Het rapport besluit met een aantal praktische aanbevelingen waarop te letten, indien een ondernemer warmteterugwinning met een aquifer overweegt.
Analytical Solution for Transient Water Table Heights and Outflows from Inclined Ditch-Drained Terrains
Verhoest, N.E.C. ; Pauwels, V.R.N. ; Troch, P.A. ; Troch, F.P. De - \ 2002
Journal of Irrigation and Drainage Engineering-Asce 128 (2002)6. - ISSN 0733-9437 - p. 358 - 364.
watervoerende lagen - grondwaterstroming - grondwateraanvulling - modellen - aquifers - groundwater flow - groundwater recharge - models
This paper presents two analytical solutions of the linearized Boussinesq equation for an inclined aquifer, drained by ditches, subjected to a constant recharge rate. These solutions are based on different initial conditions. First, the transient solution is obtained for an initially fully saturated aquifer. Then, an analytical expression is derived for the steady state solution by allowing time to approach infinity. As this solution represents the groundwater table shape more realistically, this water table profile is used as an initial condition in the derivation of the second analytical solution for the groundwater table height, and the in- and outflow into the ditches. The solutions allow the calculation of the transient behavior of the groundwater table, and its ouflow, due to changing percolation rates or water level heights in both ditches.
Toepasbaarheid van aquifers in de glastuinbouw voor aardwarmtewinning en warmteopslag
Braak, N.J. van de - \ 2001
Wageningen : IMAG [etc.] (IMAG nota P 2001-120) - 77
watervoerende lagen - geothermische energie - warmteterugwinning - warmtebehoud - glastuinbouw - aquifers - geothermal energy - heat recovery - heat conservation - greenhouse horticulture