Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Anaerobic treatment of municipal wastewater in a UASB-Digester system : temperature effect on system performance, hydrolysis and methanogenesis
    Zhang, Lei - \ 2016
    Wageningen University. Promotor(en): Grietje Zeeman; Huub Rijnaarts, co-promotor(en): Tim Hendrickx. - Wageningen : Wageningen University - ISBN 9789462579798 - 165
    municipal wastewater - anaerobic digesters - hydrolysis - temperature - water treatment sludge - sludges - water treatment - sewage sludge - sewage - stedelijk afvalwater - anaërobe verteerders - hydrolyse - temperatuur - waterzuiveringsslib - slib - waterzuivering - rioolslib - rioolwater

    A novel treatment chain for low strength domestic sewage includes low temperature anaerobic treatment as the main process. It can improve the energy efficiency of sewage treatment compared with conventional aerobic sewage treatment. A combination of an Upflow Anaerobic Sludge Blanket reactor and a sludge digester, a UASB-digester system, was proven to be one of the successful anaerobic systems to challenge temperatures as low as 10°C and organic matter concentrations in the range of 382 and 1054 mg chemical oxygen demand (COD)/l. The UASB is operated at low sewage temperature (10°C) and high loading rate. The produced non-stabilised sludge in the UASB is recirculated over the mesophilic digester (35°C) to convert organic solids to methane gas and produce anaerobic biomass fed back into the UASB reactor, where it converts dissolved COD at the low temperature of the waste water.

    The effect of sludge recirculation rate and sludge transfer point on the performance of a UASB-digester treating domestic sewage at 15 ˚C was studied in this research. The results show increased total COD removal efficiency when increasing the sludge recirculation rate from 1% to 2.6% of the influent flow rate. Methane gas production increases with the sludge recirculation rate, in the range of 1 to 12.5% of the influent flow rate. A higher sludge transfer point results in an increased suspended COD removal efficiency and a higher VSS concentration of the UASB sludge bed.

    Co-digestion was applied for improving soluble COD removal efficiency of a UASB-digester system, operated at low temperatures and treating domestic sewage with a high dissolved/suspended COD ratio. Glucose was chosen as a model co-substrate and added to the sludge digester to produce additional methanogenic biomass, which was continuously recycled to inoculate the UASB reactor. Methane production in the UASB reactor almost doubles and soluble COD removal efficiency equals the biodegradability of the influent dissolved COD, due to a twofold increase in methanogenic capacity, when applying co-digestion 16% of influent organic loading rate. Therefore, co-digestion is a suitable approach to support a UASB-digester for treatment of low temperature domestic sewage.

    A pilot scale UASB-digester (130 + 50 L) was studied to treat domestic wastewater at temperatures of 10-20°C at an HRT of 6 h in the UASB reactor and 15 h in the digester. The results show a stable COD removal efficiency of 60 ± 4.6% during the operation at 12.5 to 20°C. COD removal efficiency decreases to 51.5 ± 5.5% at 10°C. The decreased COD removal efficiency is attributed to an increased influent COD load, leading to insufficient methanogenic capacity of the UASB reactor at such low temperature. Suspended COD removal efficiency was 76.0 ± 9.1% at 10-20°C. The effluent COD concentration is 90 ± 23 mg/L at temperatures between 12.5 and 20°C, while soluble COD removal efficiency fluctuates due to variation in the influent COD concentration. 80% of the influent biodegradable COD is recovered as methane gas (including dissolved methane).

    Low temperature (10-25°C) hydrolysis after applying a short pre-hydrolysis at 35°C was studied compared with those without the pre-hydrolysis. Batch experiments were executed using cellulose and tributyrin as model substrates for carbohydrates and lipids. Low temperature anaerobic hydrolysis rate constants increase by a factor 1.5 - 10 after applying a short anaerobic pre-hydrolysis at 35°C. The hydrolytic activity of the supernatant collected from the digestate after batch digestion of cellulose and tributyrin at 35°C was higher than that of the supernatants collected from the low temperature (≤ 25°C) digestates. The observed hydrolysis in the UASB of a UASB-digester system, treating domestic sewage at low temperatures (10-20°C) is in line with the elevated hydrolytic activity of mesophilic supernatant.

    Effects of temperature and temperature shocks on specific methanogenic activity (SMA), and acetate affinity of the digester sludge were studied. Digester sludge from a UASB (12.5°C)-digester (35°C) system, was fed with acetate at constant temperatures of 10-35°C and at varying temperatures from 35°C to 25, to 15 to 10°C. The results show no lag phase in methane production rate when applying temperature shocks of 35°C to 25, 15, and 10°C. The temperature dependency of the SMA of the digester sludge after the temperature shocks was similar to the one at constant temperatures. Acetate affinity of the digester sludge was high at the applied temperatures (10-35°C). Latter is consistent with the finding of no VFA in the effluent of the UASB-digester, treating low strength, and low temperature (12.5°C) domestic wastewater.

    The UASB-digester system to treat low strength, low temperature domestic sewage was provided with a proof-of-principle, and its essential underlying anaerobic processes were sufficiently elucidated to make the technology ready for further scaling up and demonstration in practice.

    New wastewater treatment concepts towards energy saving and resource recovery
    Khiewwijit, R. - \ 2016
    Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Karel Keesman; Hardy Temmink. - Wageningen : Wageningen University - ISBN 9789462576407 - 148
    waste water treatment - energy saving - recovery - municipal wastewater - nutrients - volatile fatty acids - afvalwaterbehandeling - energiebesparing - terugwinning - stedelijk afvalwater - voedingsstoffen - vluchtige vetzuren
    At present, conventional activated sludge (CAS) systems are widely applied to treat municipal wastewater. The main advantages of CAS systems are that they are robust and generally produce an effluent quality that meets the discharge guidelines. However, CAS systems cannot be considered sustainable because they consume large amounts of energy (mainly for aeration and sludge treatment), have a high CO2 emission and do no recover a potential resource of water, energy and nutrients nitrogen (N) and phosphorus (P). Therefore, in this thesis new municipal wastewater treatment concepts that combine treatment with recovery of valuable resources and can save considerable amounts of energy were investigated by modelling and experiments.

    Quantitative numerical results showed that the feasibility of two novel wastewater treatment configurations, including combined bioflocculation and anaerobic digestion but with different nutrient removal technologies, i.e. (cold) partial nitritation/Anammox or microalgae treatment, is location dependent. Using Dutch municipal wastewater and climate conditions, the configuration with cold partial nitritation/Anammox is the most promising wastewater treatment concept, because it can: 1) treat wastewater year round; 2) produce an effluent at a quality that meets the discharge guidelines; 3) reduce CO2 emission by 35% compared to the CAS system; 4) achieve a net energy yield up to 0.24 kWh per m3 of wastewater compared to a negative net energy yield of -0.08 kWh per m3 of wastewater for the CAS system; and 5) recover 80% of the sewage P. Additionally, the feasibility of the two configurations was investigated for 16 locations around the globe. The results quantitatively support the pre-assumption that the configuration with (cold) partial nitritation/Anammox is applicable in tropical regions and some locations in temperate regions. The configuration with microalgae treatment is only applicable the whole year round in tropical regions that are close to the equator line. The results also showed that the configuration employing microalgae treatment has an advantage over the configuration employing partial nitritation/Anammox with respect to consumption of aeration energy and recovery of nutrients, but not with respect to area requirements. For a tropical climate country like Thailand, the net energy yield of both configurations is at least a factor 10 higher than the CAS system, while CO2 emission is at least 22% lower.

    In CAS systems energy recovery from wastewater is accomplished by anaerobic digestion of the organic solids in primary and secondary sludge into methane. However, volatile fatty acids (VFA), which are intermediate digestion products, may be preferred over methane, because VFA can be used as starting compounds for a wide range of higher value products. In this thesis the experimental results showed that a combined process with bioflocculation, using a high-loaded membrane bioreactor (HL-MBR) to concentrate sewage organic matter, and anaerobic fermentation, using a sequencing batch reactor to produce VFA is technologically feasible. An HL-MBR operated at a hydraulic retention time (HRT) of 1 hour and a sludge retention time (SRT) of 1 day resulted in very good performance, because as high as 75.5% of the sewage COD (chemical oxygen demand) was diverted to the concentrate and only 7.5% was mineralized into CO2. It was also found that 90% of the sewage NH4-N and PO4-P were conserved in the HL-MBR permeate, which can be reused as irrigation water as it is free from solids and pathogens.

    During anaerobic fermentation of the HL-MBR concentrate at an SRT of 5 days, 35°C and without pH control, methane production was inhibited, but incomplete solids degradation mainly limited the VFA production as only 15% of the sewage COD was converted to VFA. Thus, the VFA yield needed to be increased. It was hypothesized that high pH (pH 8–10) fermentation combined with a long SRT, allowing for sufficient solubilization of solids and colloidal COD, can improve the VFA yield. In the current study, it was found that application of a pH shock of 9 in the first 3.5 hours of a sequencing batch cycle followed by a pH uncontrolled phase for 7 days gave the highest VFA yield of 440 mg VFA-COD/g VSS and this was equivalent to 26% of the sewage COD. This yield was much higher than at fermentation without pH control or at a constant pH between 8 and 10. The high yield in the pH 9 shock fermentation could be explained by: 1) a reduction of methanogenic activity; or 2) a high degree of solids degradation; or 3) an enhanced protein hydrolysis and fermentation. This study also demonstrated that the VFA yield can still be further optimized by fine-tuning pH levels and longer operation, possibly with fermentative microorganisms adapted to a high pH that are commonly found in nature. This would further increase VFA yield to 33% of the sewage COD.
    Removal of micropollutants in source separated sanitation
    Butkovskyi, A. - \ 2015
    Wageningen University. Promotor(en): Huub Rijnaarts; Grietje Zeeman, co-promotor(en): L. Hernández Leal. - Wageningen : Wageningen University - ISBN 9789462574168 - 189
    verontreinigende stoffen - verontreiniging - waterverontreiniging - afvalwater - stedelijk afvalwater - volksgezondheidsbevordering - waterzuivering - verwijdering - geneesmiddelen - farmaceutische producten - antibioticumresiduen - residuen - pollutants - pollution - water pollution - waste water - municipal wastewater - sanitation - water treatment - removal - drugs - pharmaceutical products - antibiotic residues - residues
    Source separated sanitation is an innovative sanitation method designed for minimizing use of energy and clean drinking water, and maximizing reuse of water, organics and nutrients from waste water. This approach is based on separate collection and treatment of toilet wastewater (black water) and the rest of the domestic wastewater (grey water). Different characteristics of wastewater streams facilitate recovery of energy, nutrients and fresh water. To ensure agricultural or ecological reuse of liquid and solid products of source separated sanitation, the quality of these materials has to meet (future) standards, i.e. for micropollutant concentrations. Therefore the objectives of this thesis included assessment of micropollutant content of source separated sanitation products intended for resource recovery and examination of post-treatment technologies for micropollutant mitigation within source separated sanitation
    Bacterial battery chargers
    Versluis, K. ; Heijne, A. ter - \ 2015
    stedelijk afvalwater - afvalwaterbehandeling - elektriciteit - elektronen - bacteriën - bio-energie - biobased economy - biotechnologie - waterzuivering - municipal wastewater - waste water treatment - electricity - electrons - bacteria - bioenergy - biotechnology - water treatment
    Annemiek ter Heijne investigates a new method to produce electricity from waste water. She uses bacteria as battery chargers.
    Waterschap maakt goudmijn van zuiveringsinstallaties
    Crielaard, J.P. - \ 2013
    stedelijk afvalwater - nieuwe sanitatie - recycling - innovaties - waterschappen - municipal wastewater - new sanitation - innovations - polder boards
    “Wist je dat wij 10 procent van onze energierekening door het toilet spoelen? Dat is toch zonde”, zegt Jack Crielaard, van The Social Innovation Foundation (TSIF). Als we sommige dingen anders organiseren en anders gaan denken ligt dat allemaal voor het oprapen.” TSIF helpt bedrijven en organisaties om die kansen ook echt op te rapen en is op dit moment nauw betrokken bij de ontwikkeling van “groene hubs” door Waterschap Rijn en IJssel.
    Experimental and modeling studies of horizontal subsurface flow constructed wetlands treating domestic wastewater
    Mburu, N. - \ 2013
    Wageningen University. Promotor(en): Piet Lens, co-promotor(en): D.P.L. Rousseau; J.J.A. van Bruggen. - Leiden : CRC Press/Balkema - ISBN 9781138015524 - 183
    afvalwaterbehandeling - afvalwater - stedelijk afvalwater - helofytenfilters - wetlands - cyperus papyrus - horizontale stroming - kenya - waste water treatment - waste water - municipal wastewater - artificial wetlands - wetlands - cyperus papyrus - horizontal flow - kenya
    Sanitation in unsewered urban poor areas: technology section, quantitative microbial risk assessment and grey water treatment
    Katukiza, A.Y. - \ 2013
    Wageningen University. Promotor(en): Piet Lens, co-promotor(en): M. Ronteltap. - Leiden : CRC Press/Balkema - ISBN 9781138015555 - 256
    afvalwaterbehandeling - waterzuivering - volksgezondheidsbevordering - stedelijke gebieden - stedelijk afvalwater - risicoschatting - volksgezondheid - waste water treatment - water treatment - sanitation - urban areas - municipal wastewater - risk assessment - public health
    Cost-effective solutions for water quality improvement in the Dommel river supported by sewer-WWTP-river integrated modelling
    Benedetti, L. ; Langeveld, J. ; Nieuwenhuijzen, A.F. van; Jonge, J. de; Weijers, S. ; Klein, J.J.M. de; Nopens, I. ; Flameling, T. ; Zanten, O. van - \ 2013
    Water Science and Technology 68 (2013)5. - ISSN 0273-1223 - p. 965 - 973.
    stedelijk afvalwater - afvalwaterbehandeling - oppervlaktewaterkwaliteit - rivieren - aquatische ecologie - controle - infrastructuur - onzekerheidsanalyse - kaderrichtlijn water - noord-brabant - municipal wastewater - waste water treatment - surface water quality - rivers - aquatic ecology - control - infrastructure - uncertainty analysis - water framework directive - noord-brabant - urban drainage systems - real-time control - treatment-plant - simulation - management - pollution
    This project aims at finding cost-efficient sets of measures to meet the Water Framework Directive (WFD) derived goals for the Dommel River (The Netherlands). Within the project, both acute and long-term impacts of the urban wastewater system on the chemical and ecological quality of the river are studied with a monitoring campaign in the urban wastewater system (wastewater treatment plant and sewers) and in the receiving surface water system. An integrated model, which proved to be a powerful tool to analyse the interactions within the integrated urban wastewater system, was first used to evaluate measures in the urban wastewater system using the existing infrastructure and new real-time control strategies. As the latter resulted to be beneficial but not sufficient, this paper investigated the use of additional infrastructural measures to improve the system cost-effectively and have it meet the Directive's goals. Finally, an uncertainty analysis was conducted to investigate the impact of uncertainty in the main model assumptions and model parameters on the performance robustness of the selected set of measures. Apart from some extreme worst-case scenarios, the proposed set of measures turned out to be sufficiently robust. Due to the substantial savings obtained with the results of this project, the pay-back time of the whole monitoring and modelling work proved to be less than 5 months. This illustrates the power of mathematical modelling for decision support in the context of complex urban water systems
    The removal of faecal coliforms in waste stabilization pond systems and eutrophic lakes
    Ansa, E.D.O. - \ 2013
    Wageningen University. Promotor(en): H.J. Gijzen, co-promotor(en): H.J. Lubberding. - Leiden : CRC/Balkema - ISBN 9789461735362 - 114
    fecale coliformen - afvalwater - afvalwaterbehandeling - hergebruik van water - algen - stedelijk afvalwater - faecal coliforms - waste water - waste water treatment - water reuse - algae - municipal wastewater

    The reuse of domestic wastewater presents many challenges including the risk of pathogen infection; hence the removal of pathogens from domestic wastewater is very relevant. It is known that algae play a crucial role in the process of their removal by raising the pH and dissolved oxygen concentration which tend to be injurious to bacteria. It is however not known how algal disinfection ability is affected by biomass changes in sewage of varying strengths and whether algae contribute in sedimenting faecal coliforms (FC) from the water column through attachment to their surfaces. Experiments were conducted to investigate the importance of FC attachment to algae, the effect of varying concentration of algae in sewage of different strengths on FC removal and the effect of algae on FC removal in a tropical eutrophic lake. The effect of reducing algal densities in a pilot-scale hybrid algae-duckweed pond system on FC removal was also investigated with the aim of understanding the importance of FC attachment in such a treatment system in relation to pure algal and duckweed treatment lines. Algae helped in sedimenting FC to the bottom of reactors. It was shown by experimentation under laboratory conditions that in domestic wastewater treatment an optimum algal density exists at which maximum FC removal is achieved. Algae were also important in significantly reducing Escherichia coli contamination in a eutrophic lake through increased oxygenation and pH elevation. At algal density ≤0.08mgL-1 in the Weija Lake, decay rate of E. coli was directly proportional to the chlorophyll a concentration of the lake. The strength of domestic wastewater undergoing treatment may also affect the rate of decay of FC, particularly as algal concentration changes. In darkness, higher algal biomass (or chlorophyll a concentration) resulted in higher inactivation of FC although dissolved oxygen concentration and pH were low suggesting a role by another factor in the inactivation of FC. At algal densities ≥ 13.9mg L-1 higher removal of FC occurred in MSW (medium strength wastewater) compared with LSW (low strength wastewater) whether in light or in darkness. The highest rate of decay in LSW occurred at 3.2mgL-1 chlorophyll a concentration in light while that of the MSW occurred at 20.0mgL-1 in light. Addition of raw wastewater to an ongoing wastewater treatment process lowered the rate of FC removal for a wide range of algal densities (0.6 – 19.6mgL-1 chlorophyll a concentration), under light conditions. The hybrid pond system performed well in FC (4.3 log units) and Biochemical Oxygen Demand (BOD) (89%) removal and these parameters in addition to total phosphorus were not affected by seasonal changes. FC attachment to suspended matter was important only in the first two ponds of the duckweed, algal and hybrid pond systems. Little variation of FC decay with depth was observed. FC decay rates in the mornings were usually lower than in the afternoons in algal ponds but not in the duckweed ponds. High densities of macro-invertebrates belonging to the class Ostracoda were associated mainly with the surface and bottom of duckweed ponds and these were much higher than that of algal ponds at similar locations. FC numbers in duckweed ponds correlated strongly and positively with mean ostracod numbers in ponds. FC numbers also correlated well with Shannon-Wiener diversity index of macro-invertebrates in all the three pond systems. Integrating a hybrid pond system such as this for aquaculture would be a big boost economically and health-wise for communities in developing countries with warm tropical conditions.

    Autotrophic nitrogen removal from low strength waste water at low temperature
    Hendrickx, T.L.G. ; Wang, Y. ; Kampman, C. ; Zeeman, G. ; Temmink, B.G. ; Buisman, C.J.N. - \ 2012
    Water Research 46 (2012)7. - ISSN 0043-1354 - p. 2187 - 2193.
    afvalwaterbehandeling - afvalwaterbehandelingsinstallaties - stikstof - verwijdering - denitrificatie - temperatuur - anaërobe behandeling - ammonium - oxidatie - energiebesparing - stedelijk afvalwater - waste water treatment - waste water treatment plants - nitrogen - removal - denitrification - temperature - anaerobic treatment - ammonium - oxidation - energy saving - municipal wastewater - anaerobic ammonium oxidation - treat sewage - reactor - system
    Direct anaerobic treatment of municipal waste waters allows for energy recovery in the form of biogas. A further decrease in the energy requirement for waste water treatment can be achieved by removing the ammonium in the anaerobic effluent with an autotrophic process, such as anammox. Until now, anammox has mainly been used for treating warm (>30 °C) and concentrated (>500 mg N/L) waste streams. Application in the water line of municipal waste water treatment poses the challenges of a lower nitrogen concentration (
    Assessing sanitary mixtures in East African cities
    Letema, S.C. - \ 2012
    Wageningen University. Promotor(en): Jules van Lier, co-promotor(en): Bas van Vliet. - S.l. : s.n. - ISBN 9789461734136 - 167
    volksgezondheidsbevordering - sanitaire voorzieningen - oost-afrika - riolering - anaërobe afbraak - stedelijk afvalwater - afvalwaterbehandeling - afvalwaterbehandelingsinstallaties - sanitation - sanitary facilities - east africa - sewerage - anaerobic digestion - municipal wastewater - waste water treatment - waste water treatment plants

    The urbanisation of poverty and informality in East African cities poses a threat to environmental
    health, perpetuates social exclusion and inequalities, and creates service gaps (UN-Habitat, 2008).
    This makes conventional sanitation provision untenable citywide, giving rise to the emergence
    of sanitation mixtures. Sanitation mixtures have different scales, institutional arrangements, user
    groups, and rationalities for their establishment, location, and management. For assessing the
    performance of both the mixtures as a whole and the different sanitation approaches constituting
    these mixtures, novel approaches for analyses are required. This thesis, therefore, departs from
    the centralised-decentralised approaches to a modernised mixtures (MM) approach in seeking a
    more inclusive assessment of sanitary configurations taking into account public and environmental
    health, accessibility and flexibility of sanitation systems as sustainability criteria. To achieve this,
    the four objectives formulated for this thesis are to:
    1. Make an inventory of sanitary systems in Kampala and Kisumu.
    2. Assess and map sanitary systems along MM dimensions in Kampala and Kisumu.
    3. Assess sustainability of sanitary systems on defined MM criteria in Kampala and Kisumu.
    4. Enhance insights on the applicability of MM criteria as conceptual model, assessment and
    prescriptive tool for sanitary mixtures in East African cities.
    Case study cities were chosen from a typology of primary and secondary cities that have urban
    sewer systems since colonial times. The two cities were deemed to offer rich cases that would give
    a general outlook of other East Africa cities, thus can offer possibilities for generalization. The
    thesis utilised a multi-method and multi-level approach in data collection and analysis. A multicriteria
    analysis is used in sustainability performance assessment of sanitation systems based on
    defined MM criteria.
    Firstly, modernisation debates and resultant modernities in sanitation provision were reviewed
    in Chapter 2. The review shows that Western modernisation and resultant modernities and their
    structures of service provision have not resonated well in developing countries. Consequently,
    alternative theories that dispute a universal approach to modernity emerged to offer alternatives
    to modernisation. Alternative options are characterised by multiple rationalities, diversity and
    multiplicity. Modernities in terms of sanitation provision are further operationalized as competition
    between the proponents of centralised versus decentralised solutions. A third way of looking at
    sanitation modernisation that is more inclusive is advanced through the introduction of the MM
    In Chapter 3, the presence of urban sewer systems in Kampala and Kisumu cities is assessed. The
    results show that urban systems are of medium scale and serve about 10% of the city population.
    They are publicly owned and managed by public enterprises under new public management.
    Besides, they are conventionally designed, constructed and operated without the involvement
    of end-users. Treatment plants are either overloaded, underutilised or treatment stages are
    mismatched. Consequently, about 30-70% of the treatment stages are not operational. Effluent
    discharge standards and bio-solids reuse requirements are not met, and the adopted treatment
    technologies are inappropriate for the investigated conditions. Sewer networks are supported by
    pumping stations and siphons that are only partially operational due to high operational costs and
    mechanical failures. Public sewerage is further plagued by urban informality and multiplicity of
    city spatial structures. Planned city core, and to a limited extent peri-urban areas, are served by
    public sewers, while sewer trunk lines pass through informal slum settlements without connections.
    In Chapter 4, satellite systems are analysed and configurations mapped. Satellite systems are
    intermediate semi-collective decentralised sewerage and treatment systems developed parallel to
    urban and onsite systems. They are provided by multiple actors, serve planned middle and high
    income residential, industrial complexes, endowed public and private universities, and government
    facilities. In terms of scale, they are community, neighbourhood and small-urban sanitation
    solutions. Besides, satellite systems are private sewerage systems that utilise gravity sewers and
    localised mechanised or non-mechanised treatment. The flows are based on land use or facility
    specific and are treated close to the point of generation. They are based on conventional designs
    and construction protocols without end-user involvement.
    Onsite systems in Kampala and Kisumu cities are examined in Chapter 5. Planning forecast
    indicates that onsite systems will dominate sewer (urban and satellite) systems beyond the next
    two decades. They are small-scale, highly decentralised and use simple technologies. Pit latrines
    dominate septic tanks in number, with eco-san on pilot scales and bio-latrine being a new
    sanitation option. Faecal sludge collection, treatment and safe disposal is dismal. The private
    sector dominates over local authorities in provision of faecal sludge services, but public sewerage
    agencies receive and co-treat faecal sludge with sewage although sewage works are not designed to
    receive faecal sludge. They are regulated by the Ministry of Health, enforced by the city councils
    and are provided by multiple actors solely or in partnership. Onsite sanitation can be a transient
    or permanent solution depending on mass flows and spatial requirements. However, for better
    sanitation provision, a permanent solution, with room for amendments to anticipate changes in
    space and mass flow is imperative.
    In Chapter 6, sustainability performance of sanitation systems are assessed following the defined
    three MM criteria. The performance shows that there is no sanitation system that is completely
    outcompeted in performance, neither are there systems with a very good performance. Sanitation
    system choices, consequently, are made among imperfect options, which call for balancing the
    various elements of sanitation provision to suit different policy and local contexts. Varying the
    assigned relative weight of the various criteria used in the overall MCA assessment indicates
    that generally, any slight increase in weight has an impact on systems that already have a high
    performance whereas in the case of systems with low performance the change is dismal or even
    negative. Therefore, programmes for improvement of sanitation systems might be directed to
    improvement options where systems already have a relatively high performance. However, those
    with a low performance may need comprehensive or even system reconfigurations for significant
    impacts to be realised.
    In conclusion, sanitation mixtures are theorised as the co-existence of different phases of
    modernity in tandem with local context variables. Thus, there is no one-fit-all paradigmatic way
    to sanitation provision if the local contexts are apparently different even within the same city.
    However, a shift of the centralised-decentralised dichotomy to modernised mixtures paradigm
    offers better impetus as it can utilise the advantages of both centralised and decentralised
    approaches without jeopardising existing provision pathways. The MM approach is helpful in assessing, mapping and describing sanitation systems in cities where sanitation mixtures are the
    norm rather than the exception.
    One way to modernise sanitation mixtures is by shifting the centralised-decentralised paradigm
    in order to modernise the mixed sanitation landscape. This is premised on the notion that such
    a shift will result in merging the strengths of centralised approach, e.g. economies of scale,
    efficiency, and convenience, with strengths of decentralised approach, e.g. accessibility, flexibility,
    participation, and reuse and recovery in development of intermediate systems configuration. This
    can be achieved through, among others, avoiding use of pumping stations, adoption of multiple
    service levels, involvement of private sector, servicing households at intermediate scale, and
    establishing sanitation suitability and management zones.
    The MM approach is also very helpful as a conceptual model for organising a research
    agenda which can be set along the four assessment dimensions of scale, management, flows
    and participation, as well as in searching for appropriate intervention measures along one or
    more of these dimensions. As an assessment and decision making tool, it is helpful in finding
    out which elements highlighted in the sustainability assessment need to be restructured and
    which need improvement in order to enhance their sustainability. However, translation of the
    proposed conceptual MM model into a mathematical model is a challenge yet to be explored.
    Considering its intrinsic dynamic character in dependence to varying spaces, flows, and scales
    along city development, a mathematical MM model would provide a regulatory design tool
    for city planners for adopting amendments to existing sanitation solutions. Obviously, up to
    date monitoring and inventory records are a pre-requisite for applying such a model, requiring
    institutional upgrading. Although the current results described in this thesis provide the basis
    for a more structured assessment and generalisation of sanitation mixtures, more research and
    contextualisation is needed in other regions, for further elaboration of MM model, and for the
    refinement of the assessment tool.

    Assessing sanitary mixtures in East African cities
    Letema, S.C. - \ 2012
    Wageningen : Wageningen Academic Publishers (Environmental policy series vol. 6) - ISBN 9789086867691 - 161
    volksgezondheidsbevordering - sanitaire voorzieningen - riolering - anaërobe afbraak - stedelijk afvalwater - afvalwaterbehandeling - afvalwaterbehandelingsinstallaties - oost-afrika - sanitation - sanitary facilities - sewerage - anaerobic digestion - municipal wastewater - waste water treatment - waste water treatment plants - east africa
    SANitation CHoice Involving Stakeholders : a participatory multi-criteria method for drainage and sanitation system selection in developing cities applied in Ho Chi Minh City, Vietnam
    Buuren, J.C.L. van - \ 2010
    Wageningen University. Promotor(en): Wim Rulkens, co-promotor(en): Katarzyna Kujawa. - [S.l. : S.n. - ISBN 9789085858263 - 424
    afvalverwerking - volksgezondheidsbevordering - drainage - vietnam - stedelijk afvalwater - waste treatment - sanitation - drainage - vietnam - municipal wastewater
    Keywords: sanitation; drainage; planning; multi-criteria decision analysis; stakeholder dialogues, developing countries

    The poor living in slums and other unplanned urban areas in developing countries have no access to adequate drainage and sanitation provisions with grave consequences to their health and living conditions. This thesis takes an analysis of the causes and consequences of that provision deficit as point of departure and seeks more effective mechanisms for inclusive and environmentally sustainable drainage and sanitation implementation. This occurs at two levels. Firstly, there is the level of the developing cities in general, and secondly the level of Ho Chi Minh City, Vietnam.
    Despite political will for improvement and many ongoing urban upgrading projects, environmental agencies in Ho Chi Minh City appeared unable to meet the demand for adequate infrastructure. New fast-growing residential areas demonstrated a replication of the flooding and wastewater disposal problems, that are addressed in economically more important areas. The main cause seemed insufficient capacity in land and housing management. Small wastewater-treatment plants of hospitals, hotels, markets and residential projects, meant to reduce pollution in the absence of large-scale treatment works, showed serious shortcomings due to inadequate design and operation.
    As the mentioned provision deficit is analyzed as rooted in a top-down approach, with a too limited involvement of the users of systems, a more effective approach is sought in a bigger contribution of communities and private parties to project planning, implementation and operation, without denying the important role of government.
    The contribution of this thesis to a multi-stakeholder approach drainage and sanitation planning is SANCHIS (Sanitation Choice Involving Stakeholders). This planning methodology brings about a learning process in which experts and non-experts are enabled to connect local experience with systemic knowledge, in order to generate, assess and select sustainable drainage and sanitation solutions. The method is supported by a data-base which describes assessment criteria and 58 drainage and sanitation system options clustered into 12 groups. Subsequently, detailed descriptions of toilet, on-site treatment, transport, treatment, reuse and disposal technologies are presented. These enable the distinction between feasible and non-feasible system options in a situation under study and a comparison of performances of options. SANCHIS enables the application of material flow analysis of water, organic matter, nitrogen and phosphorus to identify the repartition of these substances over the gaseous, liquid and solid products of drainage and sanitation systems. SANCHIS also facilitates a quantitative analysis of methane emissions, energy consumption and capacity-cost relationships.
    In an application to three different types of residential areas in Ho Chi Minh City SANCHIS has proven its worth to systematically evaluate the strengths and weaknesses of drainage and sanitation system options.
    Through application during workshops in Ho Chi Minh City insight was gained in the possibilities of the method and in items to be improved. It was concluded, that the SANCHIS method led to a shared and deepened view of the addressed problem and its solutions and a strengthened commitment among stakeholders to realize the new infrastructure. The participation of stakeholders from a wide range of practices has likely delivered more specific options to choose from than if only provider-related experts had been offering options. The experiences confirmed the author’s expectation that multi-criteria decision methods are an essential element in a participatory approach in infrastructure development and that they can be tools in the transformation of infrastructure to environmental sustainability and increased involvement of a variety of public, community and private formal and informal actors.
    Kosteneffectieve oplossingen zijn noodzakelijk en mogelijk : geïntegreerd agrarisch hergebruik van gezuiverde effluenten : kosteneffectieve oplossingen voor zuivering en hergebruik van afvalwater
    Lier, J.B. van - \ 2007
    Spil 239-240 (2007)4. - ISSN 0165-6252 - p. 25 - 28.
    afvalwater - afvalhergebruik - recycling - irrigatiewater - landbouw met irrigatie - ontwikkelingslanden - stedelijk afvalwater - waste water - waste utilization - irrigation water - irrigated farming - developing countries - municipal wastewater
    In de geïrrigeerde landbouw wordt op grote schaal gedeeltelijk of helemaal niet gezuiverd water gebruikt. Ingegaan wordt op de vraag hoe via voorlichting en zuiveringstechnieken kostenbewust hergebruik van water voor de landbouw kan plaatsvinden zonder dat pathogene organismen terechtkomen bij de consument, de omwonenden of de boeren
    Microbial community analysis in sludge of anaerobic wastewater treatment systems : integrated culture-dependent and culture-independent approaches
    Roest, C. - \ 2007
    Wageningen University. Promotor(en): Willem de Vos; Fons Stams, co-promotor(en): A.D.L. Akkermans; Hauke Smidt. - [S.l.] : S.n. - ISBN 9789085048398 - 159
    rioolslib - micro-organismen - anaërobe omstandigheden - afvalwaterbehandeling - anaërobe behandeling - stedelijk afvalwater - sewage sludge - microorganisms - anaerobic conditions - waste water treatment - anaerobic treatment - municipal wastewater
    The need for clean water is increasing and anaerobic wastewater treatment can be used as a cost-effective solution for purification of organically polluted industrial waste streams. This thesis presents results from microbiological investigations of several full-scale and lab-scale anaerobic wastewater treatments systems. Anaerobic wastewater treatment has gained popularity and is now one of the key technologies in environmental biotechnology. However, knowledge of the microbial community structure – function relationships is limited. A combination of cultivation-dependent and cultivation-independent techniques can be used to improve this knowledge. In this thesis, batch serial dilution incubations from a methanol-fed lab-scale thermophilic (55°C) methanogenic bioreactor indicated that syntrophic interspecies hydrogen transfer-dependent methanol conversion is at least equally important as direct methanogenesis in this lab-scale reactor. A direct methanol-utilizing Methanomethylovorans hollandica-related strain was detected up to a 108-fold dilution, while Thermodesulfovibrio relatives and Methanothermobacter thermoautotrophicus strains were found till 109–fold dilutions in the presence of H2/CO2. Microbial diversity was further evaluated in two expanded granular sludge bed reactors fed with increasing oleic acid loading rates. The archaeal community in the reactor inoculated with granular sludge stayed quite stable and active, whereas the relative abundance of Methanosaeta-like organisms gradually decreased in the reactor inoculated with suspended sludge when oleate loads were increased to 8 kg of chemical oxygen demand m-3 day-1. Desulfomicrobium and Methanobacterium were found to dominate the start-up of a full-scale synthesis gas fed gas-lift reactor treating metal and sulphate rich wastewater. Most Probable Number (MPN) counts confirmed that heterotrophic sulphate reducing bacteria (SRB) were dominant (1011-1012 cells/g VSS) compared to homoacetogens (105-106 cells/g VSS) and methanogens (108-109cells/g VSS). Methanogens can still persist in sulphate-reducing bioreactors with short sludge retention time, since competition for hydrogen is determined by Monod kinetics and not by hydrogen threshold values. The microbial community in a full-scale upflow anaerobic sludge blanket reactor treating paper mill wastewater operated at 37°C was relatively stable over a period of 3 years as indicated by a high similarity (>75%) of denaturing gradient gel electrophoresis profiles of 16S ribosomal RNA gene fragments. Batch incubations at different temperatures resulted in microbial community changes. While the archaeal community composition differed significantly between incubations at 45 and 55°C, the bacterial composition changed between 37 and 45°C. Overall the bacterial community was dominated by Firmicutes (68% of the clones) and Delta-Proteobacteria (17% of the clones). A sequential degradation of first butyrate and then propionate at 37°C was linked to strong presence of Syntrophomonas sp. and Desulfobulbus propionicus, respectively. MPN series allowed estimating the number of micro-organisms per ml sludge that could use propionate without sulphate (109), propionate and sulphate (105), butyrate without sulphate (108), butyrate with sulphate (105), glucose (109) and H2/CO2 (1010). Archaea were mainly dominated by Methanosaeta, but also Crenarchaeota-relatives were identified. Bacterial clone sequences were related to a variety of different known species, with expected functions in anaerobic digestion like fermentative bacteria, syntrophic short chain fatty acids oxidisers and SRB. However, about 80% of the clones was similar to sequences in the database without close cultured relatives, but many of these appeared to be present in anaerobic environments. It is important to improve knowledge of these unknown micro-organisms and fast accurate monitoring and identification could be instrumental in realising this. Therefore, a pilot macro-array was developed and tested. It appeared that combining probes generated by PCR amplification of the V1 and V6 variable regions of the 16S rRNA gene provided accurate differentiation of closely related organisms. The integrated application of molecular and cultivation dependent analyses of microbiota structure and function of a broad variety of anaerobic wastewater treatment systems described in this thesis has been used to improve insight of the ecophysiology in such reactors. Some general commonalities of anaerobic systems have been found, but also system-specific characteristics. This provides potential identification of general and system-specific indicator populations, allowing improved diagnostics and reactor predictability.
    Greening sanitary systems: and end-user perspectives
    Hegger, D.L.T. - \ 2007
    Wageningen University. Promotor(en): Arthur Mol; Gert Spaargaren, co-promotor(en): Bas van Vliet. - [S.l.] : S.n. - ISBN 9789085047117 - 266
    afvalbeheer - afvalwaterbehandeling - milieubeleid - innovaties - duurzaamheid (sustainability) - nieuwe sanitatie - modernisering - hedendaagse samenleving - verzamelen - urine - stedelijk afvalwater - waste management - waste water treatment - environmental policy - innovations - sustainability - new sanitation - modernization - contemporary society - collection - urine - municipal wastewater
    The central aim of the thesis is to contribute to a transition towards sustainable sanitation and wastewater systems and practices in Western society by developing a social science perspective on sanitation and wastewater management. The empirical core of this study comprises a comparative case study analysis of Dutch, German and Swedish pilot projects in which wastewater management technologies are experimented with in a domestic setting. Desk research, participatory observation and interviews with consumers and providers have been used to analyze these projects in detail
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