Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

Current refinement(s):

Records 1 - 20 / 230

  • help
  • print

    Print search results

  • export

    Export search results

  • alert
    We will mail you new results for this query: keywords==waste water
Check title to add to marked list
AQUAFARM van zuiveren naar oogsten
Verdonschot, P.F.M. - \ 2017
Aquafarm NL
afvalwater - waterzuivering - industriële grondstoffen - biobased economy - afvalwaterbehandeling - aquacultuur - biomassa productie - waste water - water treatment - feedstocks - waste water treatment - aquaculture - biomass production
Aquafarm ziet afvalwater als basis voor het produceren van hoogwaardige bouwstoffen, waarmee tegelijkertijd het water gezuiverd wordt.
Perspectieven voor de afzet van (fosfaat-verarmd) zuiveringsslib naar de landbouw
Regelink, Inge ; Ehlert, Phillip ; Römkens, Paul - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2819) - 75
afvalwater - rioolslib - besmetters - zware metalen - mest - fosfaten - landbouw - afvalhergebruik - waste water - sewage sludge - contaminants - heavy metals - manures - phosphates - agriculture - waste utilization
Het project heeft als doel om nieuwe afzetroutes te formuleren waarbij zuiveringsslib op een duurzame wijze wordt verwerkt tot meststoffen en bodemverbeteraars zodat waardevolle nutriënten en organische stof worden hergebruikt.
Mobiele waterzuivering glastuinbouw
Ruijven, Jim van; Os, Erik van; Vermeulen, Peter - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport GTB 1424) - 54
kassen - glastuinbouw - afvalwaterbehandeling - afvalwater - waterverontreiniging - afvoer - zuiveren - waterzuivering - oppervlaktewater - oppervlaktewaterkwaliteit - gewasbescherming - pesticiden - substraten - cultuur zonder grond - mobiele uitrusting - greenhouses - greenhouse horticulture - waste water treatment - waste water - water pollution - discharge - purification - water treatment - surface water - surface water quality - plant protection - pesticides - substrates - soilless culture - mobile equipment
Application of a mobile unit for discharge water purification is one of four options to apply to the purification obligation per 1-1-2018. Depending on the amount of discharge, future water strategy and investment options, mobile purification can be an interesting option. The amount of discharge water varies with crop, irrigation strategy and quality of the irrigation water and is between 122 and 3.340 m3/ha/year for surveyed companies. About 65% of greenhouse companies discharges
Groen proceswater: zuivering brouwerijprocesafvalwater met microalgen
Dijk, W. van; Weide, R.Y. van der; Kroon, A. - \ 2016
Lelystad : ACRRES - Wageningen UR (PPO 721) - 42 p.
brouwerij-industrie - brouwerijafvalwater - afvalwater - afvalwaterbehandeling - waterzuivering - algen - biomassa - biomassa productie - afvoerwater - flotatie - algenteelt - brewing industry - brewery effluent - waste water - waste water treatment - water treatment - algae - biomass - biomass production - effluents - flotation - algae culture
In 2012 is het project Groen Proceswater gestart. Hierin worden de mogelijkheden van zuivering van brouwerijprocesafvalwater met behulp van microalgen onderzocht. Dit is gedaan in een samenwerkingsverband van Heineken Nederland BV, Algae Food & Fuel en WUR-ACRRES. De resultaten behaald in 2012 en 2013 zijn beschreven in afzonderlijke rapporten. In dit rapport zijn de resultaten van 2014 en 2015 beschreven. In 2014 is onderzocht of een voorbehandeling van het proceswater via cavitatie-flotatie het zuiveringsresultaat kan verbeteren en in 2015 of de energie-input van de LEDbelichting kan worden verminderd door te flashen (afwisselende licht-donker periodes op microseconde tijdschaal). Verder is in 2015 en 2016 via een literatuurstudie gekeken naar de verwaarding van de geproduceerde algenbiomassa en zijn de conclusies van het gehele project samengevat.
Onderzoek Waterkringloopsluiting Tulpenbroeierij : overzicht huidige en toekomstige technieken om waterkringloopsluiting mogelijk te maken
Os, E.A. van; Feenstra, L. ; Ruijven, J. van; Stijger, C.C.M.M. ; Koeman-Stein, N. ; Appelman, W. - \ 2016
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1394) - 38
tulpen - forceren van planten - glastuinbouw - kasgewassen - afvalwaterbehandeling - afvalwater - recirculatiesystemen - drainagewater - pathogenen - pathogeen eliminatie - gewasbescherming - voedingsstoffen - fenolen - tulips - forcing - greenhouse horticulture - greenhouse crops - waste water treatment - waste water - recirculating systems - drainage water - pathogens - pathogen elimination - plant protection - nutrients - phenols
Closing of the water cycle is required in the forcing of tulips. For growers it is important to know if and how they can eliminate pathogens at an adequate way and which equipment is most suitable to break down plant protection products from waste water. Now participating growers have various equipment for full or partly disinfection. It is recommended to start with good pre-filtration methods to eliminate pathogens which can be fully achieved with UV and ozone, while products such as hydrogen peroxide with additives or chlorite products can be used for an after-effect in the pipe work. Phenolic compounds, released by the roots, can be eliminated with oxidising methods. However efficacy has not been investigated. Purification of discharge water, before entering the waste ditch, will be obliged. New, certified, equipment will come on the market soon. Reuse of discharge water, after pre-fi ltration and disinfection, is also an option.
Fosfaat uit afvalwater vissen
Smet, Louis de - \ 2016
phosphate - waste water treatment - waste water - fertilizers - phosphorus fertilizers - waste utilization - biobased economy - recovery
Evaluatie zuiveringstechniek voor verwijdering gewasbeschermingsmiddelen III
Ruijven, J.P.M. van; Beerling, E.A.M. ; Staaij, M. van der; Os, E.A. van - \ 2016
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1414) - 30
afvalwaterbehandeling - waterzuivering - afvalwater - waterverontreiniging - glastuinbouw - kassen - cultuur zonder grond - gewasbescherming - pesticiden - ozon - verwijdering - filtratie - technieken - waste water treatment - water treatment - waste water - water pollution - greenhouse horticulture - greenhouses - soilless culture - plant protection - pesticides - ozone - removal - filtration - techniques
Dutch greenhouse horticulture has to treat all discharged water from soilless cultivations for the removal of plant protection products, to meet the new Dutch Directive Hoofdlijnenakkoord (2015). Building on previous research, (1) the life span of activated carbon filters, (2) the effect of increasing concentrations of plant protection products on the removal efficacy of ozone and the removal efficacy of (3) multimedia filtration and (4) ultrasonic water treatment have been investigated. It turned out to be difficult to design an active carbon based water treatment system capable of durable treatment of greenhouse discharge water: organic and mineral material in the water blocked the pores, thereby clogging the filter system and causing leakage by pressure build-up. Activated carbon filtration (granular activated carbon, 48 min contact time, 50 μm prefiltration with sand filter) achieved a removal efficacy of >95% for up to 430 bed volumes treated. Combination with advanced oxidation improved the removal efficacy, but the removal time of the filter could not be determined due to leakage. The removal efficacy of ozone oxidation remained >98%, even at increased concentrations (factor 10 and 100) of plant protection products in the untreated water. The multimedia filter removed 75% of the plant protection products by adsorption, biological breakdown within the filter was not determined. Treatment of the water with ultrasonic waves hardly had any effect (maximum 30% efficacy) on the breakdown.
Opname van struviet als categorie in het Uitvoeringsbesluit Meststoffenwet : advies
Ehlert, P.A.I. ; Dijk, T.A. van; Oenema, O. - \ 2016
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 69) - 92
magnesiumammoniumfosfaat - kunstmeststoffen - wetgeving - afvalwater - fosfaten - besmetters - afvalwaterbehandelingsinstallaties - magnesium ammonium phosphate - fertilizers - legislation - waste water - phosphates - contaminants - waste water treatment plants
Only products, wastes and by-products designated by the Fertiliser Act can be freely traded as fertiliser in theNetherlands. Permitted fertilisers are listed in Regulation (EC) No 2003/2003 and wastes and by-products that canbe traded as fertiliser or as secondary raw material for fertiliser production are listed in Annex Aa of the implementingregulation of the Fertiliser Act. Wastes and by-products can be used as a fertiliser or a secondary raw materialif the criteria given in the Protocol for assessing the value and risks of waste used as fertiliser are met. Struvite is amagnesium ammonium phosphate (NH4MgPO4.6H2O) and is one of the forms in which phosphate can be recoveredfrom wastewater or process water. This origin means that struvite is classified as a waste, and as it is not listed inAnnex Aa the Fertiliser Act prohibits its use as a fertiliser. This publication reports on a study to formulate criteriafor lifting this waste status in accordance with the protocol. Depending on its quality, struvite acts as a fast-releaseor slow-release fertiliser. Due to the different techniques that are available for struvite formation, the differentwaste streams – municipal wastewater, effluent from manure processing, process water from the food manufacturingindustry – and different chemical polishing treatment processes, struvite can come in a range of qualities withdifferent concentrations of contaminants and may possibly contain pathogens. For the Ministry of Economic Affairs,the Scientific Committee on the Nutrient Management Policy has prepared an advice on including struvite in theFertiliser Act, with criteria. The study was based on literature research and consultation with stakeholders. Struviteis often co-precipitated with other phosphate minerals, such as phosphates of calcium, magnesium and iron, and anumber of these phosphates are present in struvite products. The advice covers this range of recovered phosphates
Slimmer omgaan met poep
Zeeman, Grietje - \ 2016
new sanitation - water treatment - waste water - urine - recovery - anaerobic treatment - separation
Goed Gietwater Werkpakket 3, taak 2 Industrieelonderzoek naar waterkringloopsluiting in opkweekbedrijven
Appelman, W.A.J. ; Brouwer, J.G.H. ; Blok, C. ; Maas, A.A. van der; Staaij, M. van der; Beerling, E.A.M. ; Meeuwsen, B. - \ 2016
Zeist : TNO - 61 p.
waterverontreiniging - emissie - emissiereductie - glastuinbouw - voedingsstoffen - waterbeheer - afvalwater - hergebruik van water - water pollution - emission - emission reduction - greenhouse horticulture - nutrients - water management - waste water - water reuse
Efficiënt omgaan met water speelt voor biologische en niet-biologische opkweekbedrijven van plantmateriaal een steeds grotere rol. Toenemende en strengere eisen met betrekking tot lozing van water en de emissie van nutriënten en gewasbeschermingsmiddelen naar het oppervlaktewater vragen nieuwe maatregelen. Overheden en de glastuinbouwsector hebben als doelstelling om de emissies van de glastuinbouwsector via het waterspoor in 2027 nagenoeg tot nul te reduceren waarbij er in 2018 al maatregelen moeten worden genomen met betrekking tot gewasbeschermingsmiddelen. Het doel van het Goed Gietwater project is om middels industrieel onderzoek te komen tot een vergaande waterkringloopsluiting in de opkweeksector. Met een geoptimaliseerd watermanagement en behandeling van het overtollige gietwater kunnen water en nutriënten worden teruggewonnen en emissies van nutriënten en gewasbeschermingsmiddelen naar het oppervlaktewater worden voorkomen.
Achtergronddocument vergunningenbeleid voor lozingen van afvalwater uit mestverwerkingsinstallaties
Voorthuizen, Ellen van; Overgoor, Ceciel ; Buisonjé, F.E. de; Verdoes, N. ; Hoeksma, P. ; Herpen, Frank ; Leeuwis-Tolboom., Janine - \ 2016
Nijmegen : Royal Haskoning - 99 p.
afvalwater - lozing - mestverwerking - vergunningen - waterbeheer - afvoerwater - waste water - disposal - manure treatment - permits - water management - effluents
Waterbeheerders in Nederland krijgen de laatste jaren steeds vaker te maken met vergunningaanvragen voor het lozen van afvalwater afkomstig uit mestverwerkingsinstallaties (MVI’s). Dit achtergronddocument biedt inzicht in het beleidskader voor en de technieken van mestverwerking, de afvalwaterstromen die daarbij vrij komen en technieken om dat afvalwater te behandelen. Daarnaast beschrijft het document het beleidskader voor lozingen van afvalwater, ervaringen uit de praktijk en uiteindelijk een eenduidig afwegingskader voor vergunningverleners. Het rapport eindigt met een aantal aanbevelingen voor het gebruik van dit rapport door vergunningverleners, voor het vervolgtraject dat onder regie van het Ministerie van I&M en bevat een aantal aanbevelingen om resterende kennisleemten te vullen. Het doel van dit achtergronddocument is inzicht te geven in de stand der techniek bij de behandeling van vrijkomende afvalwaterstromen uit mestverwerkingsinstallaties (MVI’s). Bij voldoende behandeling kan het afvalwater geloosd worden op de riolering (rioolwaterzuivering) of direct op oppervlaktewater. Het document heeft als nevendoel om de vergunningverlening te harmoniseren en het lozingenbeleid te onderbouwen.
Recirculatie bij snij-amaryllis (Hippeastrum) in drie teeltjaren (2013-2015) : Behoud plantgezondheid en voorkomen groeiremming bij hergebruik drainwater
Kromwijk, J.A.M. ; Burg, R. van der; Nijs, L. ; Overkleeft, J. ; Eveleens-Clark, B.A. ; Blok, C. ; Os, E.A. van; Baar, P.H. van; Grootscholten, M. ; Woets, F. - \ 2016
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1398) - 88 p.
amaryllis - glastuinbouw - kasgewassen - kasproeven - teelt onder bescherming - emissie - hergebruik van water - afvalwaterbehandeling - afvalwater - recirculatiesystemen - lycorine - stikstof - voedingsstoffen - kunstmeststoffen - greenhouse horticulture - greenhouse crops - greenhouse experiments - protected cultivation - emission - water reuse - waste water treatment - waste water - recirculating systems - nitrogen - nutrients - fertilizers
In the Netherlands most crops grown in greenhouses reuse drain water. However, in the cultivation of amaryllis
cut flowers (Hippeastrum) little drainage water is being reused so far because of strong suspicions of inhibitory
substances in the drainage water. To reduce the emission of nutrients to the environment an experiment was
started on request of the amaryllis growers. In a greenhouse experiment drainage water of amaryllis was treated
with advanced oxidation and reused. This was compared with the reuse of drainage water treated with an UV
disinfector and a control treatment without the reuse of drainage water. In three years of cultivation, there was
no difference in production and no adverse effects were seen in crop growth. This research was funded by the
Dutch amaryllis growers, the ‘Topsector Tuinbouw en Uitgangsmaterialen’, the Product Board for Horticulture, the
project ‘Samenwerken aan Vaardigheden’ and Koppert.
Maatwerk voor opkweekbedrijven vormt insteek demoproject Goed Gietwater : pilotinstallatie levert water in verschillende zuiveringsklassen
Blok, Chris - \ 2016
horticulture - greenhouse horticulture - water management - agricultural research - purification plants - waste water - cost control - water reuse - water quality - water filters

Goed Gietwater startte vijf jaar geleden als demoproject voor plantenkwekers. Begin november werd bij een plantenkweker in Naaldwijk een getrapte zuiveringsinstallatie geïnstalleerd, die als blauwdruk kan dienen voor de opkweeksector en voor glastuinbouwbedrijven met gedifferentieerde teeltplannen. Daar was wel een flinke aanloop voor nodig.

Purifying manure effluents with duckweed
Timmerman, M. ; Hoving, I.E. - \ 2016
Wageningen UR Livestock Research (Livestock Research rapport 942) - 27 p.
animal manures - effluents - lemna - aquatic weeds - feeds - nutrients - ingredients - animal feeding - animal nutrition - waste water - biogas - biomass production - cultivation - biobased economy - dierlijke meststoffen - afvoerwater - schadelijke waterplanten - voer - voedingsstoffen - ingrediënten - diervoedering - diervoeding - afvalwater - biomassa productie - teelt
The objective of this study was to perform a short literature survey to provide information about purifying manure effluents with duckweed with regard to varieties, cultivation, harvesting methods, utilization and valorisation of duckweed. The results of the study show that duckweed can be used to recuperate nutrients from manure effluents and that the concerning duckweed can be utilized as a source of feed, energy and ingredients
Phosphorus recycling from the waste sector
Ruijter, F.J. de; Dijk, W. Van; Curth-van Middelkoop, J.C. ; Reuler, H. van - \ 2015
Plant Research International, Wageningen UR (Rapport / Plant Research International 641) - 29 p.
phosphorus - waste water - composts - recycling - sewage sludge - sludges - fosfor - afvalwater - compost - rioolslib - slib
An efficient use of phosphorus (P) is necessary as phosphate rock is a finite resource and P is essential for crop production. From the waste sector in the Netherlands, 23 Mkg P is sequestered in landfill, incineration ashes and cement. Flows containing P are discussed, together with options to recover P and reduce P losses, and the interactions between these options.
Fate of pharmaceuticals in full-scale source separated sanitation system
Butkovskyi, A. ; Hernandez Leal, L. ; Rijnaarts, H.H.M. ; Zeeman, G. - \ 2015
Water Research 85 (2015). - ISSN 0043-1354 - p. 384 - 392.
Anaerobic degradation - Black water - Grey water - Micropollutant removal - Pharmaceuticals - UASB reactor

Removal of 14 pharmaceuticals and 3 of their transformation products was studied in a full-scale source separated sanitation system with separate collection and treatment of black water and grey water. Black water is treated in an up-flow anaerobic sludge blanket (UASB) reactor followed by oxygen-limited autotrophic nitrification-denitrification in a rotating biological contactor and struvite precipitation. Grey water is treated in an aerobic activated sludge process. Concentration of 10 pharmaceuticals and 2 transformation products in black water ranged between low μg/l to low mg/l. Additionally, 5 pharmaceuticals were also present in grey water in low μg/l range. Pharmaceutical influent loads were distributed over two streams, i.e. diclofenac was present for 70% in grey water, while the other compounds were predominantly associated to black water. Removal in the UASB reactor fed with black water exceeded 70% for 9 pharmaceuticals out of the 12 detected, with only two pharmaceuticals removed by sorption to sludge. Ibuprofen and the transformation product of naproxen, desmethylnaproxen, were removed in the rotating biological contactor. In contrast, only paracetamol removal exceeded 90% in the grey water treatment system while removal of other 7 pharmaceuticals was below 40% or even negative. The efficiency of pharmaceutical removal in the source separated sanitation system was compared with removal in the conventional sewage treatment plants. Furthermore, effluent concentrations of black water and grey water treatment systems were compared with predicted no-effect concentrations to assess toxicity of the effluent. Concentrations of diclofenac, ibuprofen and oxazepam in both effluents were higher than predicted no-effect concentrations, indicating the necessity of post-treatment. Ciprofloxacin, metoprolol and propranolol were found in UASB sludge in μg/g range, while pharmaceutical concentrations in struvite did not exceed the detection limits.

Alg groeit goed op plas en poep van NIOO
Sikkema, A. ; Lamers, P.P. - \ 2015
Resource: weekblad voor Wageningen UR 10 (2015)8. - ISSN 1874-3625
afvalwater - afvalwaterbehandeling - nieuwe sanitatie - biobased economy - algen - chlorella sorokiniana - organische meststoffen - algenteelt - waste water - waste water treatment - new sanitation - algae - organic fertilizers - algae culture
Chlorella sorokiniana reinigt geconcentreerd wc-water. Resultaat: schoon water én meststof
A Downflow Hanging Sponge (DHS) reactor for faecal coliform removal from an Upflow Anaerobic Sludge Bed (UASB) effluent
Yaya Beas, R.E. ; Kujawa-Roeleveld, K. ; Lier, J.B. van; Zeeman, G. - \ 2015
Water Science and Technology 72 (2015)11. - ISSN 0273-1223 - p. 2034 - 2044.
faecal coliforms - biochemical oxygen demand - chemical oxygen demand - waste water - waste water treatment - anaerobic treatment - waste water treatment plants - fecale coliformen - biochemisch zuurstofverbruik - chemisch zuurstofverbruik - afvalwater - afvalwaterbehandeling - anaërobe behandeling - afvalwaterbehandelingsinstallaties
This research was conducted to study the faecal coliforms removal capacity of Downflow Hanging Sponge (DHS) reactors as a post-treatment for an Upflow Anaerobic Sludge Blanket (UASB) reactor. Three long-term continuous lab-scale DHS reactors i.e. a reactor with cube type sponges without recirculation, a similar one with recirculation and a reactor with curtain type sponges. The porosities of the applied medium were 91%, 87% and 47% respectively. The organic loading rates were 0.86 kgCOD m-3 d-1, 0.53 kgCOD m-3 d-1 and 0.24 kgCOD m-3 d-1 correspondingly at hydraulic loading rates of 1.92 m3 m-2 d-1, 2.97 m3 m-2 d-1 and 1.32 m3 m-2 d-1, respectively. The corresponding averages for faecal coliform removal were 99.997%, 99.919% and 92.121% respectively. The WHO (1989) standards, in terms of faecal coliform content for unrestricted irrigation (Category A), was achieved with the effluent of the cube type DHS (G1) without recirculation. Restricted irrigation, category B and C is assigned to the effluent of the cube type with recirculation and the curtain type, respectively. Particularly for organic compounds, the effluent of evaluated DHS reactors complies with USEPA standards for irrigation of so called non-food crops like pasture for milking animals, fodder, fibre, and seed crops.
Closing Domestic Nutrient Cycles Using Microalgae
Vasconcelos Fernandes, T. ; Shresthat, R. ; Suit, Y. ; Papini, G. ; Zeeman, G. ; Vet, L.E.M. ; Wijffels, R.H. ; Lamers, P.P. - \ 2015
Environmental Science and Technology 49 (2015)20. - ISSN 0013-936X - p. 12450 - 12456.
algen - afvalwater - afvalwaterbehandeling - stikstof - fosfor - biomassa productie - proefopzet - nieuwe sanitatie - algae - waste water - waste water treatment - nitrogen - phosphorus - biomass production - experimental design - new sanitation
This study demonstrates that microalgae can effectively recover all P and N from anaerobically treated black water (toilet wastewater). Thus, enabling the removal of nutrients from the black water and the generation of a valuable algae product in one step. Screening experiments with green microalgae and cyanobacteria showed that all tested green microalgae species successfully grew on anaerobically treated black water. In a subsequent controlled experiment in flat-panel photobioreactors, Chlorella sorokiniana was able to remove 100% of the phosphorus and nitrogen from the medium. Phosphorus was depleted within 4 days while nitrogen took 12 days to reach depletion. The phosphorus and nitrogen removal rates during the initial linear growth phase were 17 and 122 mg·L–1·d–1, respectively. After this initial phase, the phosphorus was depleted. The nitrogen removal rate continued to decrease in the second phase, resulting in an overall removal rate of 80 mg·L–1·d–1. The biomass concentration at the end of the experiment was 11.5 g·L–1, with a P content of approximately 1% and a N content of 7.6%. This high algal biomass concentration, together with a relatively short P recovery time, is a promising finding for future post-treatment of black water while gaining valuable algal biomass for further application.
Bio-induced solid selenium for recovery from water
Hageman, S.P.W. - \ 2015
University. Promotor(en): Cees Buisman, co-promotor(en): Renata van der Weijden; Fons Stams. - Wageningen : Wageningen University - ISBN 9789462575103 - 156
selenium - waste water - waste water treatment - recovery - toxicity - bioreactors - afvalwater - afvalwaterbehandeling - terugwinning - toxiciteit - bioreactoren

Selenium in the form of selenate or selenite in wastewater needs to be removed due to its potential toxicity in the environment. Also, selenium is a valuable element that is used in several industries and current selenium resources are likely to be exhausted in less than 50 years. Waste streams containing selenium can therefore be used as a source of selenium. This requires conversion of the selenium in wastewater into a form that can be recovered. Biologically induced selenate reduction to recoverable selenium has the advantage that it uses the selective reduction capacities of biomass and a renewable electron donor.

To improve the recoverability of selenium the conversion of selenate to selenite was seen as an interesting opportunity. Selenite is more reactive than selenate and can be removed in a second step. As described in Chapter 2, it proved possible to convert selenate to mainly selenite at a low electron donor concentration.

Another method which is reviewed in this thesis is direct biological reduction of selenate to elemental selenium. After reduction the solids can be removed by a liquid solid separation process. Previously amorphous selenium particles were produced, which hampered recovery. In this research it is demonstrated that at a higher temperature, around 40 - 50°C, and at a higher pH, around pH 8 - 9, a more hexagonal selenium structure can be produced (Chapter 3). Crystalline acicular selenium particles of different sizes were thus obtained. This implies that selenium particles formation can be controlled and that selenium particles can grow. Large selenium particles make the separation process economic.

To grow larger selenium particles, a long-term experiment was performed at 50°C (Chapter 4). The reduction rate was poor, but selenium acicular particles were produced. These particles were also detected as clusters. These clusters open up new recovery opportunities. With Eerbeek sludge the optimal conditions for selenate conversion are around pH=7 and 30°C. To enlarge the selenium particles it is strongly recommended to use a different sludge since the optimal conditions with Eerbeek sludge do not match the conditions needed for acicular particle formation.

When selenate is converted to selenite, the selenite can be precipitated by sulphide to form selenium sulphide. Emmtec sludge was used to reduce the sulphur compounds to sulphide, leaving selenium as the sole remaining element. This process was performed at T=30°C and a pH between 6 and 7. The selenium thus recovered had a crystalline hexagonal structure (revealed by x-ray diffraction) and the particles were as large as 125µm3.

Future research on the two routes that are explored in this thesis can give insights into selenium reduction mechanisms and the formation of large selenium particles. The recoverability of biological selenium particles has also been improved (as discussed in this thesis). In conclusion, this thesis has resulted in a new, bio-selective, renewable selenium recovery method via selenium sulphide.

Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

 
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.