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Amofah, Lea Rastas
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Publications (10 of 11) Show all publications
Amofah, L. R. (2012). Towards sustainability of environmental protection: recovery of nutrients from wastewater filtration and the washing of arsenic contaminated soils (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Towards sustainability of environmental protection: recovery of nutrients from wastewater filtration and the washing of arsenic contaminated soils
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Conventional methods for wastewater treatment and remediation of the sites withcontaminated soils focus on protection of human health, receiving waters and theenvironment. Towards this end, these methods concentrate on the reduction or removal of polluting substances, and therefore, are not well suited for creating resources through the recovery of nutrients, energy and decontaminated soils. Hence, a new, more sustainable approach is promoted in this thesis and, besides meeting the protection requirements, takes into consideration the resources that can be recovered from the treatment processes, keeping in mind the energy use during such a recovery. To achieve this goal, a better knowledge of wastewater and contaminated soil treatment approaches needs to be developed, from a resource recovery perspective.In this thesis project, laboratory, pilot-scale and full-scale investigations were conducted to study phosphorus (P) sorption in blast furnace slag (BF slag) filters. Further, ammonium adsorption by, and desorption from, clinoptilolite was studied in laboratory columns. A full-scale wastewater treatment system, comprising a willow bed followed by two parallel P–filters with BF slag and Filtralite® P media was examined for the wastewater treatment efficiency, nutrient accumulation in willow biomass, and biomass production. In a similar way, laboratory, pilot-scale and full-scale investigations were conducted to examine arsenic (As) removal from As contaminated soils using physical separation and chemical extraction. Finally, the decontamination of the extraction effluents (contaminated by As) was studied by adjusting pH and adding a coagulant, iron chloride.Pollutant mobilisation and immobilisation were affected by pH, the organic mattercontent, redox potential, time (process duration) and temperature. Results showed that pollutants in the studied media have complex characteristics in terms of charge of species and redox speciation, and therefore, no general conclusions addressing all the conditions studied could be given. The P sorption capacity of BF slag was reduced by outdoor storage and weathering, and the content of organic substances in sewage seemed to have a more negative impact on the sorption process when using weathered BF slag. Arsenic mobilisation from As contaminated soils was affected by pH, the content of organic substances, and redox potential and the nature of these effects depended on the polluting chemicals (i.e. wood preservatives) and the content of calcium in the soil. Extractions at elevated temperatures facilitated high As mobilisation from the contaminated soils for short contact times, assuming that the extraction solution features vital for As mobilisation were not altered, and the fastest As mobilisation was achieved by using an acid oxalate citrate solution rather than reductive or alkaline extraction solutions at room temperatures.In the full-scale treatment system, the willow bed efficiently reduced the content of total suspended solids and biodegradable organic matter in the influent wastewater and prevented the clogging of downstream phosphorus filters during the one year of operation. The Filtralite® P treatment train simultaneously removed over 90 and 70% of BOD and P, respectively, during the experimental period, and therefore, fulfilled the requirements for the low protection level over the period of one year, except for tot-P excesses during the snowmelt period. In the case of tot-N reduction (50%), the high protection level was achieved. On the other hand, the treatment system with BF slag did not fulfil requirements for either low or high protection level, because the coarse-grained BF slag was inefficient in retaining P and the concentrations of oxygen consuming compounds were elevated downstream of the filter.The studied methods for recovering resources through treatment of wastewater and contaminated soils demonstrated a potential for improving environmental sustainability of these processes. Even though the willow bed did not accumulate nutrients from the fed wastewater to a high degree, it facilitated nutrient recovery in other treatment steps located downstream. Fresh, fine-grained BF slag showed capacity to recover P from wastewater, which was comparable to that of other efficient P sorbents. The BF slag material released high amounts of sulphuric compounds during the initial loading phase which consequently increased the concentration of oxygen consuming compounds in the filter effluent. Thus, the use of BF slag for P retention is not recommended when the effluent is discharged to sensitive receiving waters. Natural clinoptilolite studied showed a high capacity for adsorbing ammonium from the pre-treated wastewater, at low operating temperatures. Hence, the clinoptilolite filter has a potential to enhance N retention during the plant dormancy or prior to the maturity of willow beds when N retention is needed. However, the recovery of ammonium was limited by the inefficient desorption process using tap water without recycling the eluate. Fertigated willows grew nearly as well as in the south of Sweden, but in the highly loaded horizontal flow willow bed, the potential to produce biofuel was limited. To recover nutrients, willow clones with lateral growth are preferable. 90% of nutrients accumulated in the above-ground parts of willows could be recovered from the experimental site operated over three growing seasons, particularly when using dense planting and annual harvesting prior to leaf fall.Soil treatment, comprising the exclusion of the fine soil fraction prior to the chemical extraction with strong extraction agents applied at an elevated temperature, was efficient in decontaminating soils, even for short contact times. However, this treatment procedure results in an incomplete soil recovery (i.e. the recovered mass of soil after decontamination is appreciably smaller than the soil mass prior to decontamination), consumes a high amount of energy and lowers the soil quality, which limits the potential end-use of the decontaminated soil. The alkaline extraction effluents could be decontaminated at a pH of 4-5 with the addition of a coagulant. Also, the treatment of alkaline extraction effluents was facilitated by the exclusion of the fine soil fraction from the chemical extraction step. The use of acid oxalate-citrate extraction solution was judged infeasible because the decontamination of such extraction solution is complicated due to the high pH buffering and complexing capacity of the solution.

Abstract [sv]

Konventionella metoder för avloppsvattenbehandling och efterbehandling av förorenade områden fokuserar på att skydda människors hälsa, recipient och miljö. Därmed inriktar dessa metoder sig på att reducera och avskilja föroreningar och är därför inte lämpade att skapa resurser genom återvinning av näringsämnen, energi eller sanerade jordar. Därför riktar sig denna avhandling på en ny, mer hållbar strategi som inte enbart uppfyller miljöskyddskraven, utan även tar tillvara resurser som kan erhållas vid behandling. För att uppnå detta mål behövs en mer fördjupad kunskap om metoder för behandling av avloppsvatten och efterbehandling av förorenade jordar, utifrån resurshushållnings perspektiv.I denna avhandling utfördes laboratorie, pilotskale och fullskale försök för att studera fosfor (P) sorption i masugnsslaggfilter. Ammoniumadsorption och desorption från klinoptilolit undersöktes i kolonnförsök. En fullskaleanläggning för avloppsvattenbehandling som bestod av en salixbädd följd av två parallella fosforfilter med masugnsslagg och Filtralite® P sorbenter undersöktes med avseende på avloppsrening, upptag av näringsämnen i salixbiomassa och biomasseproduktion. På liknande sätt utfördes laboratorie-, pilotskale- och fullskaleförsök för att undersöka arsenik (As) avskiljning från As förorenade jordar m.h.a. fysisk separation och kemisk extraktion. Även rening av As förorenade extraktionslösningar undersöktes genom pH justering och tillsats av järnklorid.Resultaten visade att avskiljningen av ämnen i avlopp och As förorenade jordar påverkades av pH, innehållet av organiskt material, redoxpotential, tid och temperatur. Resultaten visade även att föroreningar i de studerade medierna hade komplexa egenskaper i form av ladding och redox speciering, och därmed kan inga generella slutsatser dras för alla studerade förhållanden. Masugnsslaggens sorptionskapacitet m.a.p. fosfor ändrades genom vittring och förvaring av material utomhus. Närvaro av organiskt material tycktes påverka ha en mer negativ påverkan på fosforsorption för den mer vittrade masugnsslaggen. Frigörandet av As från As förorenade jordar påverkades av pH, innehåll av organiska ämnen och redoxpotential, och karaktären av dessa effekter berodde på den kemikalie som förorenade jorden (impregneringsmedel) samt innehåll av kalcium i jorden. Extraktion i förhöjd temperatur ökade As mobilisering från förorenade jordarna för korta kontakttider, förutsatt att avgörande egenskaper för As mobilisering hos extraktionslösning inte förändrades. Den snabbaste mobiliseringen uppnåddesm.h.a. en sur oxalat-citrat lösning istället för reduktiva eller alkaliska extraktionslösningar.I fullskaleanläggningens salixbädd reducerades halten av suspenderat material och biologiskt nedbrytbart organiskt material effektivt från avloppsvattnet och förhindrade igensättning av de efterföljande fosforfiltren under ett års drift. Behandlingssystemet med filtermaterialet Filtralite® P avskiljde >90% organiskt material och 70% fosfor under den ett år långa försöksperioden, och uppfyllde därmed kraven för den normala skyddsnivån, förutom under snösmältperioden då kravet för tot-P inte uppnåddes. Dessutom uppfylldes kravet för tot-N reduktion (50%) för den höga skyddsnivån. För systemet med masugnsslagg uppfylldes däremot inte reningskraven, varken för normal eller hög skyddsnivå eftersom den grovkorniga slaggen var ineffektiv på att sorbera P och halterna av syreförbrukande ämnen var förhöjda i utflödet.De studerade metoderna för återvinning av resurser genom behandling av avloppsvatten och förorenad jord visade potential på resurshushållning genom dessa studerade processerna. Även om salixbädden inte ackumulerade näringsämnen från det inkommande avloppsvattnet i större grad, främjade den näringsupptag i efterföljande reningssteg. Färsk, finkorning masugnsslagg visade sig ha förmåga att sorbera P från avloppsvatten och kapaciteten var jämförbar med andra effektiva P sorbenter. Dock lakades signifikanta mängder svavelföreningar ut från filtret med masugnsslagg initialt vilket följaktligen ökade koncentrationen av syreförbrukande ämnen i filtrets utflöde. Därför rekommenderas inte användning av masugnsslagg som P sorbent när utflödet leds ut till känsliga recipienter. Den undersökta naturliga klinoptiloliten visade på hög ammoniumadsorptionskapacitet från förbehandlat avloppsvatten vid låga temperaturer. Därmed har klinoptilolit potential att öka N reduktionen från avloppsvatten under vintern eller före full etablering av salix när N reduktion krävs. Återvinningen av ammonium var dock begränsad p.g.a. låg desorption med kranvatten utan återföring av eluatet. Salix bevattnad med avloppsvatten växte nästan lika bra som i referensanläggningar i södra Sverige, men i den högbelastade salixbädden med horisontelt flöde var potentialen att producera biobränsle låg. För att återvinna näringsämnen förordas salixkloner med horisontell tillväxt. 90% av de ackumulerade näringsämnena i salixens växtdelar ovan jord kunde avlägnas från anläggningen som drevs under tre växtsäsonger, speciellt eftersom salixen var tätt planterad och skördandet genomfördes årligen innan löv fällningen. Att utesluta den fina jordfraktionen från kemisk extraktion var tillsammans med starka extraktionslösningar vid förhöjda extraktionstemperaturer ett effektivt sätt att tvätta jorden, även vid korta kontakttider. Denna behandling resulterade dock i en ofullständig återvinning av jorden (d.v.s. den behandlade jordmassan efter sanering var mindre än före sanering), förbrukade en stor mängd energi och minskade jordens kvalitet vilket i sin tur begränsar möjlig återanvändning av den behandlade jorden. Den alkaliska extraktionslösning som erhölls efter jordtvätt kunde behandlas vid pH 4-5 m.h.a. tillsats av en koagulant. Behandlingen av den alkaliska extraktionslösningen underlättades dessutom genom avskiljning av den fina jordfraktionen före kemisk extraktion. Sur oxalat-citrat extraktionslösning lämpar sig inte för behandling av As förorenade jordar eftersom en behandling med en sådan extraktionslösning är komplicerad p.g.a. hög pH buffrande och komplexbildande kapacitet.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2012. p. 90
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-17279 (URN)293d18fe-0bac-4ac6-92d7-17f5a2d6e9ab (Local ID)978-91-7439-389-7 (ISBN)293d18fe-0bac-4ac6-92d7-17f5a2d6e9ab (Archive number)293d18fe-0bac-4ac6-92d7-17f5a2d6e9ab (OAI)
Note
Godkänd; 2012; 20120117 (learas); DISPUTATION Ämnesområde: VA-teknik/Sanitary Engineering Opponent: Associate Professor Helen French, Universitetet for miljø- og biovitenskap, Ås, Norge Ordförande: Professor Maria Viklander, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Onsdag den 4 april 2012, kl 09.30 Plats: F1031, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Amofah, L. R., Mattsson, J. & Hedström, A. (2012). Willow bed fertigated with domestic wastewater to recover nutrients in subarctic climates (ed.). Paper presented at . Ecological Engineering: The Journal of Ecotechnology, 47, 174-181
Open this publication in new window or tab >>Willow bed fertigated with domestic wastewater to recover nutrients in subarctic climates
2012 (English)In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 47, p. 174-181Article in journal (Refereed) Published
Abstract [en]

Conventional methods for wastewater treatment emphasise protecting human health, receiving waters and the environment. Consequently, they are generally designed to reduce pollutant levels and are not well-suited for creating resources. This paper describes a new, more sustainable and energy-efficient approach to wastewater treatment that satisfies health and environmental standards while also facilitating resource recovery. A full-scale compact willow bed was intensively fertigated with domestic wastewater in a cold climate to examine biomass production, the recovery of nutrients in willow biomass, and wastewater treatment. The performance of the willow bed was assessed for two years, covering three growing seasons. The studied frost-tolerant willow clones produced good biomass yields per unit area (6–7 ton dry matter/ha and year) under intensive fertigation with dense planting and continuous harvesting. The biomass yield of willow species exhibiting vertical growth seemed to be greater than that for lateral growth species in the dense stands studied. In contrast to biomass production, nutrient recovery was facilitated by intensive fertigation, continuous harvesting and less dense planting with a horizontally growing willow clone. The estimated nitrogen accumulation in above-ground biomass was 210 kg/ha and that of phosphorus was 30 kg/ha. 90% of the accumulated nutrients in the above-ground biomass were removed from the site during the experimental period. However, the quantity of nutrients accumulated in the willow biomass represented only a small fraction of the loaded or removed amount. The willow bed was shown to be an efficient prefilter for reducing the abundance of particulate and organic matter, leaving the bulk of the remaining nutrients in forms that could be recovered in subsequent treatment steps.

Keywords
Civil engineering and architecture - Water engineering, Samhällsbyggnadsteknik och arkitektur - Vattenteknik
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-9015 (URN)10.1016/j.ecoleng.2012.06.030 (DOI)000309433600024 ()2-s2.0-84864027655 (Scopus ID)79256e05-51a0-4810-b63a-548e0639f9e1 (Local ID)79256e05-51a0-4810-b63a-548e0639f9e1 (Archive number)79256e05-51a0-4810-b63a-548e0639f9e1 (OAI)
Note
Validerad; 2012; 20120720 (learas)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Rastas Amofah, L., Maurice, C., Kumpiene, J. & Prosun, B. (2011). Projekt: Pilotskale utvärdering av jordtvätt för sanering av arsenik-kontaminerad jord. Paper presented at .
Open this publication in new window or tab >>Projekt: Pilotskale utvärdering av jordtvätt för sanering av arsenik-kontaminerad jord
2011 (Swedish)Other (Other (popular science, discussion, etc.))
Abstract [sv]

Jordtvätt - en lämplig metod för behandling av CCA förorenad jord? I samband med Länsstyrelsernas kartläggning av förorenade områden har upptäckts objekt som är förorenade med arsenik. En del av objekt är så förorenade att de har negativ påverkan på miljön eller människors hälsa så att de behöver åtgärdas senast år 2010. I träimpregneringsindustrin användes kromerad koppar arsenat (CCA) som impregneringsmedel. Olika steg i impregneringsprocessen har lett till att jord förorenats med As. Deponering är idag en vanlig metod att omhänderta arsenikförorenad jord och en betydande del av efterbehandlingskostnaderna består ofta av transport- och deponeringsavgifter. Nyligen har regelverk för bedömning av avfall förändrats vilket har banat väg för nya behandlingsmetoder för förorenad jord såsom jordtvätt. Huvudsyftet med detta projekt är att bedöma om jordtvätt är en lämplig behandlingsmetod för CCA-förorenad jord. Andra syften med projektet är att hitta en lämplig kemikalietillsats för att höja metodens effektivitet samt att hitta en effektiv metod att behandla As förorenad tvättvätska. Kan man säkerställa att den behandlade jorden är stabil och inte har några negativa effekter på omgivningen kan det bidra till att etablera jordtvätt som en hållbar behandlingsmetod. Deponering av jord är varken en hållbar eller en effektiv användning av resurser. Behandling av föroreningarna och återanvändning av det behandlade jordmaterialet kan däremot leda till minskad förbrukning av jord, minskade transporter, etc.

Keywords
jordtvätt, förorenad jord, behandling
National Category
Geochemistry Other Environmental Engineering
Research subject
Applied Geology; Waste Science and Technology
Identifiers
urn:nbn:se:ltu:diva-36006 (URN)2081ee79-7048-4201-b9ca-6e9546cbc79b (Local ID)2081ee79-7048-4201-b9ca-6e9546cbc79b (Archive number)2081ee79-7048-4201-b9ca-6e9546cbc79b (OAI)
Note

Publikation: Pilotskale utvärdering av jordtvätt för sanering av arsenik-kontaminerad jord; Status: Pågående; Period: 04/06/2007 → …; Faktiskt slutdatum: 30/12/2011

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Amofah, L. R., Maurice, C., Kumpiene, J. & Bhattacharya, P. (2011). The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil (ed.). Paper presented at . Journal of Soils and Sediments, 11(8), 1334-1344
Open this publication in new window or tab >>The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil
2011 (English)In: Journal of Soils and Sediments, ISSN 1439-0108, E-ISSN 1614-7480, Vol. 11, no 8, p. 1334-1344Article in journal (Refereed) Published
Abstract [en]

Purpose: Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. Materials and methods: A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20°C, 30°C and 40°C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. Results and discussion: In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. Conclusions: For all extractants, mobilisation was most efficient at elevated temperature (40°C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed by OC solutions (affording significant reductions in As, Cr and Zn levels in the soil with short extraction times) at 40°C is recommended

Keywords
Other technology - Environmental engineering, Övriga teknikvetenskaper - Miljöteknik
National Category
Geochemistry Other Environmental Engineering
Research subject
Applied Geology; Waste Science and Technology
Identifiers
urn:nbn:se:ltu:diva-11249 (URN)10.1007/s11368-011-0411-y (DOI)000297257100004 ()2-s2.0-81355149684 (Scopus ID)a2d7fd26-23a1-4ec7-8207-554787f6be9c (Local ID)a2d7fd26-23a1-4ec7-8207-554787f6be9c (Archive number)a2d7fd26-23a1-4ec7-8207-554787f6be9c (OAI)
Projects
Pilotskale utvärdering av jordtvätt för sanering av arsenik-kontaminerad jord
Note
Validerad; 2011; 20110823 (learas)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Amofah, L. R., Maurice, C. & Bhattacharya, P. (2010). Extraction of arsenic from soils contaminated with wood preservation chemicals (ed.). Paper presented at . Soil & sediment contamination, 19(2), 142-159
Open this publication in new window or tab >>Extraction of arsenic from soils contaminated with wood preservation chemicals
2010 (English)In: Soil & sediment contamination, ISSN 1532-0383, E-ISSN 1549-7887, Vol. 19, no 2, p. 142-159Article in journal (Refereed) Published
Abstract [en]

Three soil samples contaminated by chromated zinc arsenate (CZA) or chromated copper arsenate (CCA) were investigated in a laboratory scale to study As mobilization and to identify a chemical agent that could be used in soil washing to extract arsenic. Besides high As extraction, the cost, occupational health issues and technical aspects were considered when selecting the chemical. Arsenic is strongly bound to CZA/CCA soils; only ∼50% of the tot-As was removed from water-washed soils. High Fe or Al mobilization is not necessarily indicative of high As removal from CZA/CCA soils. A high Cu/As-ratio and a large amount of soluble Ca in the soil hampered As extraction. The high ratio can be an indication of stable Cu-arsenates in soil. Calcium can react with the extraction agent or with As during extraction. Sodium hydroxide, dithionite with citrate (and oxalate) (dithionite solutions), and oxalate with citrate were the most efficient chemicals for removing As from the soils. The disadvantages of using these strong chemicals are: a high cost (oxalate with citrate); damage to equipment (dithionite solutions); an adverse impact on occupational health (dithionite solutions); or a deterioration in soil quality after extraction (NaOH and dithionite solutons). Phosphate, solutions based on NH2OH·HCl, or citrate were not efficient in mobilizing As from the soils.

Keywords
Arsenic, Extraction, CCA, Contaminated soil, Soil washing, Other technology - Environmental engineering, Arsenik, Extraktion, CCA, Förorenad jord, Jordtvätt, Övriga teknikvetenskaper - Miljöteknik
National Category
Geochemistry Water Engineering
Research subject
Applied Geology; Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-12572 (URN)10.1080/15320380903390539 (DOI)000276430500002 ()2-s2.0-77951146414 (Scopus ID)bbc66ec0-319b-11df-806d-000ea68e967b (Local ID)bbc66ec0-319b-11df-806d-000ea68e967b (Archive number)bbc66ec0-319b-11df-806d-000ea68e967b (OAI)
Projects
Pilotskale utvärdering av jordtvätt för sanering av arsenik-kontaminerad jord
Note
Validerad; 2010; 20100317 (learas)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Hedström, A. & Amofah, L. R. (2008). Adsorption and desorption of ammonium by clinoptilolite adsorbent in municipal wastewater treatment systems (ed.). Paper presented at . Journal of Environmental Engineering and Science, 7(1), 53-61
Open this publication in new window or tab >>Adsorption and desorption of ammonium by clinoptilolite adsorbent in municipal wastewater treatment systems
2008 (English)In: Journal of Environmental Engineering and Science, ISSN 1496-2551, E-ISSN 1496-256X, Vol. 7, no 1, p. 53-61Article in journal (Refereed) Published
Abstract [en]

Natural zeolites as clinoptilolite may be used to recover wastewater ammonium, decrease the nitrogen content in the effluent from on-site sanitation systems and in wastewater treatment plants when nitrification-denitrification efficiency is low. The objective of this study was to estimate the ammonium adsorption capacity of clinoptilolite when being loaded with wastewater. Phosphorus and potassium sorption, ammonium desorption with tap water, and clogging were also studied. The study was performed by column experiments. Results of the investigation showed the ammonium adsorption capacity to increase with decreasing grain size, and the highest experimental adsorption capacity was 2.7 mg NH4-N/g. The breakthrough occurred immediately, probably due to a too high loading rate. Phosphorus and potassium sorption were minor. Of adsorbed ammonium, 23% was desorbed by tap water and desorption was more pronounced during saturated conditions. Filter clogging was extensive and probably caused by particles in the effluent wastewater and by microbiological growth.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-6479 (URN)10.1139/S07-029 (DOI)000254759800007 ()2-s2.0-38749146861 (Scopus ID)4b3a1610-c8c6-11dc-b13a-000ea68e967b (Local ID)4b3a1610-c8c6-11dc-b13a-000ea68e967b (Archive number)4b3a1610-c8c6-11dc-b13a-000ea68e967b (OAI)
Note
Validerad; 2008; 20080122 (learas)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Amofah, L. R., Maurice, C. & Bhattacharya, P. (2008). Chemical extraction of As from a polluted soil (ed.). In: (Ed.), (Ed.), Arsenic in the environment - Arsenic from nature to humans: Book of Abstracts. Paper presented at International congress: Arsenic in the environment : Arsenic from nature to humans 21/05/2008 - 23/05/2008 (pp. 205).
Open this publication in new window or tab >>Chemical extraction of As from a polluted soil
2008 (English)In: Arsenic in the environment - Arsenic from nature to humans: Book of Abstracts, 2008, p. 205-Conference paper, Meeting abstract (Other academic)
Keywords
Civil engineering and architecture - Architecture and architectural conservation and restoration, Samhällsbyggnadsteknik och arkitektur - Arkitektur och bebyggelsevård
National Category
Water Engineering Geochemistry
Research subject
Urban Water Engineering; Applied Geology
Identifiers
urn:nbn:se:ltu:diva-30710 (URN)49c58ea0-a93c-11df-a707-000ea68e967b (Local ID)49c58ea0-a93c-11df-a707-000ea68e967b (Archive number)49c58ea0-a93c-11df-a707-000ea68e967b (OAI)
Conference
International congress: Arsenic in the environment : Arsenic from nature to humans 21/05/2008 - 23/05/2008
Projects
Pilotskale utvärdering av jordtvätt för sanering av arsenik-kontaminerad jord
Note
Godkänd; 2008; 20100816 (learas)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Amofah, L. R. (2007). A small scale wastewater treatment system adapted to nutrient recovery in cold climate: performance and possible sorbents (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>A small scale wastewater treatment system adapted to nutrient recovery in cold climate: performance and possible sorbents
2007 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Waterbodies are impaired by, among other things, discharge from onsite small- scale wastewater (WW) treatment systems. Hence, these systems need to be updated to improve the effluent quality and the reuse of nutrients within society. The objectives of this thesis were to find suitable sorbents for a small scale WW treatment system, to investigate the performance of a willow bed in cold climate and to evaluate the function of a proposed WW treatment system adapted to sustainable development in cold climate.Column experiments were performed to study the ammonium adsorption and desorption of clinoptilolite. Laboratory scale studies were conducted to estimate the phosphorus (P) retention of blast furnace slag (BF slag). Further, a full-scale WW treatment system was implemented in northern Sweden to evaluate the function of the system and its units over 16 months. The system comprised of a willow bed and two parallel P filters, namely BF slag and Filtralite-P. A stream of primarily treated WW from a village was pumped to the treatment system.The results from the column experiments showed that ammonium adsorption of the studied clinoptilolite and the desorption of previously adsorbed ammonium was too low to be an economically reasonable alternative for WW ammonium retention in small-scale WW treatment systems.The investigated weathered and coarse-grained BF slag had a low WW P retention, with the overall P sorption below 100 mg P/kg. Therefore, the material is not suitable for P retention. Fresh and fine-grained BF slag demonstrated to be an effective P sorbent in laboratory experiments. However, the release of sulphuric compounds from the BF slag was extensive and may hinder its utilisation as P sorbent.Filtralite-P was found to be a promising P sorbent with a WW P sorption of about 370 mg P/kg at the end of the full-scale experimental period, and still with remaining capacity to retain P.The willow bed functioned as a treatment step due the reduction of nutrients, solids and BOD, and there was no significant difference in winter and summer performance. Climatic conditions seemed not to be a hindrance for willow beds in northern Sweden. However, the stemwood produced in the willow bed would replace only a small fraction of a household’s energy need for heating and warm water.In the full-scale study, the treatment system with BF slag filter attained neither of the protection levels given by Swedish Environmental Protection Agency (SEPA) during the experimental period. The Filtralite-P treatment line fulfilled the requirements of the low protection level by SEPA for the 1 year operating period and the requirements of the high protection level for 2 months. The need of maintanance in the studied treatment system was small and the operation was steady.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2007. p. 24
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 2007:05
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-17505 (URN)3b3bb0a0-c0db-11db-834c-000ea68e967b (Local ID)3b3bb0a0-c0db-11db-834c-000ea68e967b (Archive number)3b3bb0a0-c0db-11db-834c-000ea68e967b (OAI)
Note
Godkänd; 2007; 20070213 (pafi)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Hedström, A., Amofah, L. R. & Hanaeus, J. (2007). Småskalig avloppsanläggning med salixbädd och sorbenter (ed.). Paper presented at . Stockholm: Svenskt vatten
Open this publication in new window or tab >>Småskalig avloppsanläggning med salixbädd och sorbenter
2007 (Swedish)Report (Other academic)
Alternative title[en]
A small scale wastewater treatment system including a willow bed and sorbents
Abstract [en]

In residential and rural areas in Sweden, a considerable number of houses are not connected to municipal wastewater treatment plants but the wastewater is treated in on-site sanitation systems. These systems contribute significantly to the anthropogenic discharge of phosphorus. Therefore, further development of small scale wastewater treatment systems is necessary. The aim of this project was to develop a small-scale wastewater treatment system to facilitate nutrient recovery. A full-scale experimental system with two treatment lines for a total flow of 1 m3/d was built. Investigated components of the system were a distribution layer, a willow bed with a root zone, followed by two parallel containers filled with filter materials for sorption of phosphorus. Filter material investigated in full-scale were Filtralite P and blast furnace (BF) slag. Besides the full-scale investigation, filter materials were investigated in laboratory. BF slag was investigated with respect to phosphorus sorption, wollastonite with respect to phosphorus and ammonium sorption and clinoptilolite with respect to ammonium adsorption.In the full-scale experiment suspended solids and organic matter was effectively reduced in the willow bed. The reduction of SS was 93% in average and the reduction of BOD was 86%. The effluent wastewater from the willow bed was sufficiently treated to avoid clogging of the following phosphorus filters. However, the nutrient reduction in the willow bed was moderate. The reduction of both total nitrogen and total phosphorus varied between 10 and 60%.The filter volume of Filtralite P and BF slag used in the full-scale investigation, 2,2 m3, was too small to achieve an efficient phosphorus reduction during one year. The investigated fresh slag sorbed more phosphorus compared to weathered slag. Thus, if the slag is covered during storage to prevent active substances to be leached out by precipitation, the phosphorus sorption of the slag will probably be preserved. BF slag contains sulphuric compounds. In both the laboratory and the full-scale studies, sulphuric compounds leached out when wastewater percolated through the filter. This can be a hinder for using BF slag in a wastewater treatment system.The investigated wollastonite and clinoptilolite can not be recommended to be used in small-scale wastewater treatment with respect to phosphorus and ammonium sorption. The investigated willow clones "Karin" and "Gudrun" could be establish as far north as in Luleå. The biomass production of the second growing season was as high as for salix clones with wastewater in southern Scandinavia.A willow bed combined with a phosphorus filter could be a robust small-scale wastewater treatment method but some components must be further developed.

Abstract [sv]

I Sverige är många hus på landsbygden och i så kallade omvandlingsområden inte anslutna till kommunala reningsverk utan avloppsvattnet behandlas i enskilda system. Dessa system bidar signifikant till det antropogena utsläppet av fosfor. En fortsatt utveckling av småskaliga avloppslösningar är därför nödvändig.Syftet med detta projekt var att utveckla en avloppsanläggning så att fosfor och kväve från avloppsvattnet i så stor utsträckning som möjligt skulle kunna tas till vara. Inom ramen för projektet byggdes en fullskaleanläggning dimensionerad för ett flöde på 1 m3/d med två behandlingslinjer. De anläggningskomponenter som ingick i det undersökta systemet var en spridningszon med efterföljande salixbädd som belastades med avloppsvatten genom rotzonen. Denna följdes av två parallella behållare fyllda med filtermaterial för att sorbera fosfor från avloppsvattnet. De filtermaterial som undersöktes i fullskala var Filtralite P och masugnsslagg. Vid sidan av fullskaleförsöket undersöktes olika filtermaterial med laboratorieförsök. Masugnsslagg utvärderades med avseende på fosforsorption, wollastonit med avseende på fosfor och ammoniumsorption samt klinoptilolit på ammoniumadsorption.Resultaten från fullskaleförsöket visade att suspenderat material och organiskt material reducerades effektivt i salixbädden. Reduktionen av SS var i medeltal 93 % och BOD 86%. Det utgående avloppsvattnet från salixbädden var tillräckligt behandlat för att undvika igensättningar av de efterföljande fosforfiltren. Däremot var reduktionen av näringsämnen i salixbädden inte lika omfattande. Reduktionen av totalkväve var 10-60% och av fosfor 10-60%. Den volym Filtralite P och masugnsslagg som användes i fullskaleförsöket, 2,2 m3, var för liten för att erhålla en höggradig fosforreduktion under 1 år. Den färska slaggen som undersöktes i laboratorieförsök sorberade mer fosfor än gammal slagg. Slutsatsen är att om slaggen är övertäckt vid lagring så att nederbörd inte sköljer ur aktiva substanser bör slaggens sorptionsförmåga bättre bibehållas. Masugnsslagg innehåller svavel. I både laboratorieförsök och fullskaleförsök lakades svavelföreningar ut när avloppsvatten perkolerade genom slaggen. Detta kan vara ett hinder för att använda masugnsslagg i avloppsanläggningar.Utifrån resultaten från laboratorieförsöken kan de undersökta materialen wollastonit och klinoptilolit idag inte rekommenderas för att behandla avloppsvatten med avseende på fosfor och ammonium i en småskalig VA-lösning.De undersökta salixssorterna "Karin" och "Gudrun" kunde etableras så långt norrut som i Luleå och den andra växtsäsongen var produktionen av biomassa i salixbädden i samma storleksordning som för salixodlingar i södra Skandinavien som bevattnats med avloppsvatten.Salixbädden i kombination med ett fosforfilter har potential att bli en robust metod för småskalig avloppsvattenbehandling men vissa anläggningskomponenter måste utvecklas vidare.

Place, publisher, year, edition, pages
Stockholm: Svenskt vatten, 2007. p. 36
Series
Rapport / Svenskt vatten ; 2007:08
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-25171 (URN)e0c0ae50-5554-11dc-8e15-000ea68e967b (Local ID)e0c0ae50-5554-11dc-8e15-000ea68e967b (Archive number)e0c0ae50-5554-11dc-8e15-000ea68e967b (OAI)
Note
Godkänd; 2007; 20070828 (anneli)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Hedström, A. & Amofah, L. R. (2006). Methodological aspects of using blast furnace slag for wastewater phosphorus removal (ed.). Paper presented at . Journal of environmental engineering, 132(11), 1431-1438
Open this publication in new window or tab >>Methodological aspects of using blast furnace slag for wastewater phosphorus removal
2006 (English)In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 132, no 11, p. 1431-1438Article in journal (Refereed) Published
Abstract [en]

Blast furnace (BF) slag is a by-product of steel plants. The objective of this study was to evaluate experimental methods to determine the phosphorus sorption capacity of BF slag. The handling of BF slag, before usage and clogging were also considered, as well as estimating the phosphorus retention capacity. Agitation and pilot-scale experiments were performed using both wastewater and phosphate solutions. This investigation showed that sorption capacities derived by wastewater experiments were considerably lower compared to those by phosphate solutions. Fresh BF slag briefly exposed to rainfall had a higher phosphorus sorption than weathered BF slag, indicating the importance of handling the slag carefully before usage. The risk for leakage of sulfuric compounds is considerable, especially during the initial operation phase of BF slag filters. Locations of BF slag filter beds for wastewater treatment must be carefully chosen from an environmental point of view.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-10553 (URN)10.1061/(ASCE)0733-9372(2006)132:11(1431) (DOI)000241574100005 ()2-s2.0-33750168311 (Scopus ID)960b1f50-6dae-11db-83c6-000ea68e967b (Local ID)960b1f50-6dae-11db-83c6-000ea68e967b (Archive number)960b1f50-6dae-11db-83c6-000ea68e967b (OAI)
Note
Validerad; 2006; 20061106 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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