Search

Avloppsvatten innehåller näring, bland annat kväve och fosfor som kan orsaka övergödningom det kommer ut i sjöar och vattendrag. Samtidigt behöver stora mängder näringsämnen tillföras i jordbruket för att producera mat. Ett sätt att effektivt ta till vara på näringen i avlopp och återföra den till jordbruket skulle kunna vara källsortering av avlopp. På så sätt samlas näringsämnena i en mindre volym och blandas inte med bad-, disk-, och tvättvatten. Examensarbetet syftade till att undersöka rötning som behandlingsmetod och teknik för att utnyttja energin i latrin. I rötning bryter mikroorganismer ner organiskt material anaerobt och producerar energirik biogas som kan användas till värme, el eller fordonsbränsle. Rötresten som blir kvar efter rötningen innehåller näringsämnen men också föroreningar. I studien undersöktes latrinens innehåll av tungmetaller och läkemedelsrester och hur läkemedelshalten påverkades under rötningsprocessen. För att utvärdera rötning som behandlingsmetod av latrin gjordes 44 satsvisa utrötningsför-sök i laboratorium. Latrinen hämtades från en latrininsamling i Norrtälje. Ymp från två aktiva rötningsanläggningar blandades med latrinen i gastäta glasflaskor vilka sattes på skakbord i ca 60 dagar. En del flaskor innehöll en tillsats av läkemedel lösta i metanol. Två parallella försök utfördes i olika temperaturer, i mesofil temperatur (37ºC) och i termofil temperatur (52ºC). Gasproduktion och gasens metanhalt mättes under försöksperioden för att beräkna latrinens biogaspotential. Efter avslutad rötningsperiod separerades vätskan och det fasta materialet i rötresten och frystes in i väntan på analys av läkemedelsrester. Biogasproduktionen var drygt 250 Nml CH4/g VS (ml metan per gram organiskt material vid tryck 1 atm och 0ºC) efter 60 dagar, vilket antas vara biogaspotentialen hos latrin. Det är i samma nivå som biogaspotentialen från hönsgödsel och svinkletgödsel. Gasproduktionen i flaskorna med tillsats av läkemedel var något högre och någo, Wastewater contains nutrients such as nitrogen and phosphorous which can cause eutrophi-cation in lakes and streams. Meanwhile, large quantities of nutrients are used in agriculture in order to produce food. One way to utilize nutrients in wastewater and return them to agriculture could be source separation of sewage. This way, nutrients are collected in smallvolumes and are not mixed with bathing, washing, and cleaning water. This thesis aimed at investigating anaerobic digestion as a treatment method and technology to make use of the energy in latrine. In anaerobic digestion, microorganisms degrade organic material and produce energy rich biogas that can be used for heating, electricity, or vehicle fuel. The residue remaining after digestion contains nutrients but also pollutants. The study examined the content of heavy metals and drug residues in latrine, and to what extent the digestion process affected the pharmaceutical content. To evaluate the anaerobic digestion as treatment of latrines, 44 batch experiments wereperformed at laboratory scale. Latrine was taken from a collection basin in Norrtälje. Inoculum from two active anaerobic digestion plants were mixed with latrine in sealed glass bottles and put on shaking tables for approximately 60 days. Some bottles contained an addition of eight drugs dissolved in methanol. Two parallel experiments were performed one at mesophilic temperature (37ºC) and one at thermophilic temperature (52ºC). The volume of gas produced and methane content was measured for calculation of the biogas potential. After completion of the digestion period, the liquid and solids were separated and frozen pending analysis of drug residues. The biogas produced was a little over 250 Nml CH4/gVS after 60 days being comparable to production from pig and chicken manure. The bottles containing added substances showed no inhibition of the biogas process since the gas production was slightly greater in these. The nitrogen content of latrine was 3

It has recently been realized that sponges take up much of the dissolved organic matter (DOM) available in the water of reefs. The energy derived from this DOM is suggested to be invested in renewing the sponge filter cells (choanocytes) every few hours, generating an outflow of detrital particulate organic matter (POM) that is rapidly ingested by other invertebrates. By this DOM-to- POM recycling, sponges are proposed to fuel the food web of oligotrophic marine communities, including reefs, caves and deep-sea environments. In four species studied herein by electron microscopy, the POM found in the outgoing aquiferous canals had a complex composition, with large between-species differences. It may include choanocytes (0–52%), and also mesohyl cells, such as archeocytes (9–20%) and spherulous, and granular cells with inclusions (27–90%). Exocytosed vesicles also occurred. Surprisingly, to end up into the outgoing canals, the internal mesohyl cells squeezed between the epithelial cells (endopinacocytes) of the canal wall. Mesohyl cells were also able to transfer their inclusions to the endopinacocytes, which in turn extruded their acquired vesicle loads into the canal lumen. The unanticipated abundant participation of mesohyl cells and endopinacocytes in the production of POM appears to be an ordinary process that occurs continuously in the sponges, mostly related to elimination of digestion leftovers and excretion by-products. Therefore, POM is generated by sponges irrespective of whether the primary food source is particulate (evidence from this study) or DOM (previous literature). Altogether, these results indicate that the cellular mechanisms behind the relevant organic-matter recycling carried out by sponges are more diverse than initially anticipated. The varying ratios of choanocytes/mesohyl cells in the POM across species suggest that different sponge species may impact differently the energetics of food webs of the respective oligotrophic habitats where they

Wastewater is an excellent source of nutrients and energy. By treating the wastewater in a clever way, it is possible to both recycle nutrients and recover energy, and thereby create opportunities for a sustainable system. In conventional wastewater treatment where the activated sludge process is used, aeration is needed and a lot of biomass is produced. In regions with warmer climate, or if low-valuable heat is available for heating this technique could be replaced with an anaerobic one. With anaerobic techniques, less sludge is produced, the need for aeration is decreased and potentially more energy can be recovered. An increased interest in renewable energy sources has put demand on finding suitable substrates for production of biobased fuels. For this purpose, algal biomass presents interesting characteristics. Algae use sunlight, carbon dioxide and nutrients for growth. One of the hurdles with production of algal biomass is nutrient supply but this can be solved by growing algae in wastewater. In this way two problems are solved: the algae are supplied with nutrients at the same time as nutrient reduction in the wastewater is accomplished. In this study, the feasibility of integrating an algal step in a wastewater treatment system was evaluated based on a series of laboratory experiments. Further, a concept for wastewater treatment including an Anaerobic Moving Bed Biofilm Reactor (AnMBBR) and algal cultivation was compared to an existing wastewater treatment plant (WWTP). Nutrient reduction over the algal cultivation showed more than 97% reduction of phosphate and more than 84% reduction of ammonium. Algal harvesting experiments showed that it was possible to efficiently separate algal biomass and treated water by sedimentation for 30 minutes after flocculation by addition of ferric chloride and cationic polymer. These experiments also showed that it was possible to meet the discharge limits for P-tot (0.3 mg/L), N-tot (10 mg/L) and COD (70 mg/L). Harvesting e, I dagens samhälle används stora mängder vatten som måste renas innan det släpps tillbaka ut i naturen. Rening av vattnet sker i avloppsreningsverk som ska minska mängden organiskt material och mängden näringsämnen i vattnet innan det släpps ut. Om vattnet inte renas finns det en risk för negativ påverkan på sjöar och vattendrag, t.ex. övergödning. Fosfor är ett av de näringsämnen som finns i avloppsvatten och som ofta behöver tillsättas som gödsel i jordbruk. Genom att återvinna fosforn som finns i avloppsvatten minskar belastningen på jordklotets ändliga fosforreserver. En annan vinst med att återvinna näringsämnen från avloppsvatten är att energiförbrukningen kan minska. Vanligtvis fixeras kväve från luften, i en energikrävande process, för att användas som gödningsmedel. Om kvävet i avloppsvattnet istället används minskar energiförbrukningen. Eftersom efterfrågan på förnybara energikällor ökar, krävs det nya system för att möta efterfrågan. Genom att betrakta avloppsvatten som en resurs finns det positiva vinster att göra. Det organiska materialet i avloppsvattnet kan omvandlas till biogas genom att det behandlas i syrefri miljö. Biogasen kan användas för att generera el och värme eller som fordonsbränsle. I konventionell avloppsvattenrening används ofta ett luftat steg där mycket av energin går förlorad. Genom att byta ut detta steg mot ett syrefritt kan mer av energin tas tillvara. Detta är möjligt i lite varmare klimat, eller om spillvärme finns tillgänglig för uppvärmning. Vidare har det även föreslagits att biobaserade bränslen, t.ex. biogas kan produceras från mikroalger. Mikroalger är mikroskopiskt små organismer som på samma sätt som växter utnyttjar fotosyntesen. Det betyder att de med hjälp av solljus kan omvandla koldioxid och vatten till kolhydrater. Förutom koldioxid och solljus behöver algerna näringsämnen såsom kväve och fosfor. Ett problem har varit att på ett hållbart sätt förse algerna med tillräckliga mängder näringsämnen. Därför har det föresl

The intensive breeding of beef cattle in Juncosa de les Garrigues (Catalonia, Spain) leads to the production of a large volume of manure that needs appropriate management. Land application in the area at agronomic rates is not enough to ensure good management practices, making necessary extended on-farm storage and the export of part of the production to long distances. In this context, the implementation of a collective treatment based on composting could help in enhancing the handling of manure. We assessed a full-scale composting process based on turned windrows (W), and involving treatment of beef cattle manure (CM) alone (two typologies were considered according to carbon-to-nitrogen ratios of ~25 (CM1, W1) and ~14 (CM2, W2)), or mixed with bulking agent (CM2/BA, W3) and dewatered digested sewage sludge (CM2/BA/DDSS, W4). Composting significantly improved the transportability of nutrients (final volumes were 40–54% of the initial volume). Temperature >55°C was reached in all the treatments but following different time patterns. Under the applied conditions of turning and rewetting, 14 weeks of processing did not ensure the production of stable, and mature, compost. Thus, only compost from W1 attained the maximum degree of stability as well as concentration of ammonium–N < 0.01% (with ammonium–N/nitrate–N ratio of 0.2) and low phytotoxicity. However, high pH, salinity, and heavy metal contents (Cu and Zn) may limit its final use. Addition of BA was advised to be kept to minimum, whereas use of DDSS as a co-substrate was not recommended in agreement to the higher loss of N and levels of heavy metals in the final compost., Postprint (updated version)

Jätevedenpuhdistusprosesseissa syntyy Suomessa vuosittain n. 150 000 kuivatonnia lietettä. Jätevesilietteeseen sitoutuu runsaasti orgaanista ainesta ja ravinteita mutta myös mahdollisesti laaja kirjo erilaisia haitallisia aineita aina pysyvistä orgaanisista yhdisteistä lääkeaineisiin. Puhdistamoliete on jätettä, josta täytyy hankkiutua jollain tapaa eroon. Pyrittäessä suljettuihin ravinnekiertoihin on mielenkiinto puhdistamolietteen maatalouskäytön lisäämiseksi kasvanut myös Suomessa. Tässä tutkimuksessa selvitettiin matemaattisten mallien avulla, voivatko lietteen sisältämät orgaaniset haitta-aineet muodostua Suomessa ongelmaksi lietteen maatalouskäytölle. Työssä simuloitiin kirjallisuudesta valittujen 34:n orgaanisen yhdisteen kertyvyyttä maaperään, kun lietettä levitetään vuosittain suomalaisen lannoitelainsäädännön rajoissa. Lisäksi seitsemälle yhdisteelle simuloitiin huuhtoutumista maaprofiilissa. Tuloksia verrattiin kirjallisuudessa kullekin yhdisteelle ilmoitettuun haitattomaksi arvioituun pitoisuustasoon (PNEC). Mallinnuksissa käytetyt lähtöarvot kerättiin kirjallisuudesta. Eri lähteissä ilmoitettujen lähtöarvojen vaihtelevuuden takia kullekin yhdisteelle ajettiin simulaatioita käyttäen eri lähtöarvojen yhdistelmiä. Kutakin yhdistettä kohti kertyi 3–23 simulaatiota. Mallintamiseen käytettiin kasvinsuojeluaineille kehitettyä PECsoil-laskuria, MACRO 5.2. huuhtoumamallia sekä suomalaista sää- ja maaperäaineistoa. Simuloidut pitoisuudet eri ympäristön osissa ovat monien yhdisteiden osalta samaa suuruusluokkaa kuin kenttäkokeissa havaitut. Suoritettujen simulaatioiden perusteella ongelmallisimpia lietteessä esiintyviä yhdisteitä ovat triklosaani, 17α-etinyyliestradioli, ibuprofeeni sekä karbamatsepiini. Vain triklosaani ja 17α-etinyyliestradioli ylittivät niille ilmoitetut PNECsoil-tasot. Myös pysyvät orgaaniset yhdisteet, kuten PFAS- ja PBDE-yhdisteet kertyivät maaperään hyvin tehokkaasti kuitenkaan ylittämättä niille ilmoitettuja haitattomaksi arvioituja pitois, Sewage treatment plants produce circa 150 000 dry tons of sewage sludge in Finland each year. Sewage sludge contains a great amount of organic matter and nutrients but also a wide variety of harmful substances such as persistent organic pollutants and pharmaceuticals. Sewage sludge is waste material that must be properly disposed of. While more efforts are made to close nutrient cycles, the use of sewage sludge in agriculture has become a more attractive option also in Finland. In this study it was assessed whether or not organic contaminants present in sewage sludge may prove to be a problem for sludge applications in Finnish agriculture. The study was performed using mathematical models and data collected from literature. 34 different organic contaminants were selected and their accumulation into agricultural soil was simulated assuming that sludge was applied yearly. In addition, leaching was simulated for seven of the compounds. The simulated concentrations in soil and drain water were compared to predicted no effect concentrations (PNEC) given for each compound. Compound-specific data on each substances’ behavior in soil environment and concentrations in sewage sludge was collected from literature. Because the data given in different sources varied, simulations were run for each compound using combinations of different values. For each compound 3–23 simulations were run. Simulations were performed with two models developed for simulating pesticide behavior in agricultural soils, PECsoil-calculator and MACRO 5.2. Finnish data on weather and soil properties were used in the simulations. For many compounds the simulated concentrations in soil and water were in the range of concentrations measured in field trials. According to the simulations, the most problematic compounds present in sludge are triclosan, 17α-ethinylestradiol, ibuprofen and carbamazepine. Triclosan and 17α-ethinylestradiol were the only compounds that exceeded their PNECsoil-values. Persistent org

Harvest of forest biomass for energy production may lead to export of nutrients from the forest. Recirculation of nutrients from wood chip combustion by ash spreading in forests has been proposed as a means for counteracting the nutrient export. This study was carried out to examine the effect of wood chip ash application on soil chemistry in a 44-year-old Norway spruce (Picea abies) plantation on a nutrient-poor soil in Denmark and to investigate the effect of applying different ash types and doses. Soil samples were collected and analyzed 2.5years (3 growing seasons) after ash application. This study shows that, regardless of ash formulation, preparation or dose, application of wood ash to forest soil has a liming effect in the O-horizon manifested as an increase in CECe, BS and pH. This effect was not seen in the mineral soil within the time frame of this study. At the same time, an increase in Cd was found in the O-horizon, corresponding to the amount added in the ashes. Generally, no other increase in soil contents of the heavy metals was seen. Hardening of the wood ash did not decrease the chemical impact on the soil chemistry as compared to non-treated ash whereas an increase in ash application dose increases the liming effect.

Harvest of forest biomass for energy production may lead to export of nutrients from the forest. Recirculation of nutrients from wood chip combustion by ash spreading in forests has been proposed as a means for counteracting the nutrient export. This study was carried out to examine the effect of wood chip ash application on soil chemistry in a 44-year-old Norway spruce (Picea abies) plantation on a nutrient-poor soil in Denmark and to investigate the effect of applying different ash types and doses. Soil samples were collected and analyzed 2.5years (3 growing seasons) after ash application. This study shows that, regardless of ash formulation, preparation or dose, application of wood ash to forest soil has a liming effect in the O-horizon manifested as an increase in CECe, BS and pH. This effect was not seen in the mineral soil within the time frame of this study. At the same time, an increase in Cd was found in the O-horizon, corresponding to the amount added in the ashes. Generally, no other increase in soil contents of the heavy metals was seen. Hardening of the wood ash did not decrease the chemical impact on the soil chemistry as compared to non-treated ash whereas an increase in ash application dose increases the liming effect.

Several ongoing projects are harvesting maritime biomass from the Baltic Sea for eutrophication mitigation and utilisation of the recovered biomass. Some of this biomass comprises common reed (Phragmites australis), one of the most widespread vascular plants on Earth. Reed utilisation from eutrophied coastal areas needs to be evaluated. Therefore, a system analysis was performed of reed harvesting for biofuel and biofertiliser production. The specific objectives of the analysis were to: investigate the methane yield associated with anaerobic co-digestion of reed; make a primary energy assessment of the system; quantify Greenhouse Gas (GHG) savings when a fossil reference system is replaced; and estimate the nutrient recycling potential of the system. The results from energy and GHG calculations are highly dependent on conditions such as system boundaries, system design, allocation methods and selected indicators. Therefore a pilot project taking place in Kalmar County, Sweden, was used as a case study system. Laboratory experiments using continuously stirred tank reactor digesters indicated an increased methane yield of about 220 m(3) CH4/t volatile solids from co-digestion of reed. The energy balance for the case study system was positive, with energy requirements amounting to about 40% of the energy content in the biomethane produced and with the non-renewable energy input comprising about 50% of the total energy requirements of the system. The net energy value proved to be equivalent to about 40 L of petrol/t reed wet weight. The potential to save GHG emissions compared with a fossil reference system was considerable (about 80%). Furthermore an estimated 60% of the nitrogen and almost all the phosphorus in the biomass could be re-circulated to arable land as biofertiliser. Considering the combined benefits from all factors investigated in this study, harvesting of common reed from coastal zones has the potential to be beneficial, assuming an appropriate system de, QC 20130812

Several ongoing projects are harvesting maritime biomass from the Baltic Sea for eutrophication mitigation and utilisation of the recovered biomass. Some of this biomass comprises common reed (Phragmites australis), one of the most widespread vascular plants on Earth. Reed utilisation from eutrophied coastal areas needs to be evaluated. Therefore, a system analysis was performed of reed harvesting for biofuel and biofertiliser production. The specific objectives of the analysis were to: investigate the methane yield associated with anaerobic co-digestion of reed; make a primary energy assessment of the system; quantify Greenhouse Gas (GHG) savings when a fossil reference system is replaced; and estimate the nutrient recycling potential of the system. The results from energy and GHG calculations are highly dependent on conditions such as system boundaries, system design, allocation methods and selected indicators. Therefore a pilot project taking place in Kalmar County, Sweden, was used as a case study system. Laboratory experiments using continuously stirred tank reactor digesters indicated an increased methane yield of about 220 m3 CH4/t volatile solids from co-digestion of reed. The energy balance for the case study system was positive, with energy requirements amounting to about 40% of the energy content in the biomethane produced and with the non-renewable energy input comprising about 50% of the total energy requirements of the system. The net energy value proved to be equivalent to about 40 L of petrol/t reed wet weight. The potential to save GHG emissions compared with a fossil reference system was considerable (about 80%). Furthermore an estimated 60% of the nitrogen and almost all the phosphorus in the biomass could be re-circulated to arable land as biofertiliser. Considering the combined benefits from all factors investigated in this study, harvesting of common reed from coastal zones has the potential to be beneficial, assuming an appropriate system desi

In open soilless cropping systems contamination from nutrientlixiviation is generated making it necessary to design closed orsemi-closed systems, which require the determination of themaximum saline levels in recycling solutions. In this study, theelectric conductivity (EC) and pH behaviors were analyzed indrainage solution intended for recycling in the crop; in addi-tion, parameters were used to estimate nutrient availability forthe plants in a substrate based cropping system. This researchproject was carried out under greenhouse conditions in the mu-nicipality of Mosquera (Colombia). Rose cv. Charlotte graftedon ‘Natal briar’ stocks were used, sown in pots arranged onelevated beds, 15 m in length. This project was carried out usinga split-plot design with sub-plots (with the substrate as the mainplot and the recycling as the sub-plot), three kinds of substrateand three recycling percentages (0, 50, and 100%), for a total of27 experimental units. Substrate mixtures based on burned ricehusk and coconut fiber were used. Recycling during one harvestcycle of the roses did not show EC and pH values above thosethat are considered to have a negative impact on production;however, an increasing behavior in the EC and pH values wasobserved. Likewise, no significant differences between the 50and 100% recycling were observed, which means 100% recyclingcan be used, optimizing nutrient use and water conservation.

The conventional use inorganic fertilizers is expensive and growers are looking towards alternative inputs such as compost, manure, and crop residues to improve/maintain soil fertility. There is a need to improve nutrient management by eggplant growers to manage inputs more efficiently. The use of vermicompost and worm juice is becoming popular issue as part of integrated nutrient and pest management in vegetables particularly in Solanaceous crops. Eggplant (Solanum melongena L.) is cultivated for the immature fruits which are either roasted, fried, stuffed, cooked pickled or processed. Young fruits are also eaten raw.

The conventional use inorganic fertilizers is expensive and growers are looking towards alternative inputs such as compost, manure, and crop residues to improve/maintain soil fertility. There is a need to improve nutrient management by eggplant growers to manage inputs more efficiently. The use of vermicompost and worm juice is becoming popular issue as part of integrated nutrient and pest management in vegetables particularly in Solanaceous crops. Eggplant (Solanum melongena L.) is cultivated for the immature fruits which are either roasted, fried, stuffed, cooked pickled or processed. Young fruits are also eaten raw.

All life forms require the nutrient phosphorus and it cannot be substituted by any other element. The global cycle of phosphorus is special among the major biogeochemical cycles, since it has no significant gaseous compounds and only closes every 10-100 million years. However, human activities, as application of mineral fertilizers, conversion of natural ecosystems to arable land and releases of untreated waste, intensify remarkably thephosphorus flows. The problems with linear flows of a limited resource leading to eutrophication of aquaticenvironments, for instance, have generated national environmental quality objectives for phosphorus in Sweden. The main objective of this master thesis is to get a holistic overview of how phosphorus is moving through Gothenburg today, using Material Flow Analysis as method. The spatial system boundary is the municipality of Gothenburg and the temporal system boundary is the year of 2009. One way of dealing with the linear flows ofphosphorus might be to develop the wastewater systems used in Gothenburg today. Possible changes in phosphorus flows, if kitchen grinders or urine-diverting toilets were installed in Gothenburg, are evaluated. In order to make the phosphorus management more sustainable, the linear flows have to be closed to a larger extent than today. One way towards this ambition is to emphasize other fertilizers than the mineral ones, like urine and low-contaminated sludge. The MFA shows that the absolutely largest input of phosphorus to Gothenburg is via the food. The two large outputs of the same magnitude are the digested sludge from the wastewater treatment plant of Rya and the ashes from the waste-fuelled district heating power plant of Sävenäs. About 7% of the phosphorus input to Gothenburg continues into the aquatic environment. According to this study, urine diversion and separate collection of food seem prospective in order to decrease the phosphorus flows in digested sludge from the wastewater treatment plan, Näringsämnet fosfor är nödvändigt för alla levande organismer och kan inte ersättas av något annat grundämne. Den globala fosforcykeln är speciell då den inte innehåller några gasformiga föreningar och sluts var 10-100 miljonte år. Användning av konstgödsel, omvandling av tidigare orörda ekosystem till odlingsmark och utsläppav förorenat avfall är exempel på mänskliga aktiviteter som intensifierar fosforflöden. Problemet med att linjäraflöden av denna begränsade resurs leder till övergödning av vattenmiljöer har genererat nationella miljömål i Sverige för fosfor. Det huvudsakliga målet med detta examensarbete är att få en översikt av hur fosfor rör sig genom Göteborg idag med hjälp av substansflödesanalys. Den rumsliga systemgränsen är kommungränsen för Göteborg och den tidsmässiga avgränsningen är året 2009. Ett sätt att förbättra de linjära fosforflödena kan vara att utveckla deavloppssystem som idag används i Göteborg. Förändringarna som uppstår i fosforflödena vid installation av urinsorterande toaletter alternativt köksavfallskvarnar undersöks. Linjära flöden måste bli återcirkulerade i en högre utsträckning än idag ifall fosforhushållningen ska gå mot hållbarhet. Ett sätt att nå denna ambition är att lyfta fram andra gödselprodukter än konstgödsel, exempelvis urin och renare slam. Flödesanalysen visar att det definitivt största inflödet av fosfor till Göteborg är via livsmedel. De två största fosforutflödena, båda i samma storleksordning, är rötat slam från Ryaverket och aska från sopförbränningsanläggningen Sävenäs. Cirka 7% av den fosfor som flödar in i Göteborg fortsätter vidare ut i vattenmiljön. Enligt denna studie verkar urinsortering och separat insamling av matavfall vara goda lösningar för en framtid med mindre fosfor i slammet från Rya och i aska samt till vattenmiljön. En ytterligare fördel skulle vara erhållandet av hållbara gödselprodukter med god kvalitet., This master thesis has also been published as a technical report at Chalmers with Report No. 2011:124.

In the transition from a fossil to a bio-based economy, it has become an important challenge to maximally recuperate and recycle valuable nutrients coming from manure and digestate processing. Membrane filtration is a suitable technology to separate valuable nutrients in easily transportable concentrates which could potentially be re-used as green fertilizers, in the meantime producing high quality water. However, traditional membrane filtration systems often suffer technical problems in waste stream treatment. The aim of this study was to evaluate the performance of vibratory shear enhanced processing (VSEP) in the removal of macronutrients (N, P, K, Na, Ca, Mg) from the liquid fraction of digestates, reducing their concentrations down to dischargeable/re-usable water. In addition, the re-use potential of VSEP-concentrates as sustainable substitutes for fossil-based mineral fertilizers was evaluated. Removal efficiencies for N and P by two VSEP filtration steps were high, though not sufficient to continuously reach the Flemish legislation criteria for discharge into surface waters (15 mg N l−1 and 2 mg P l−1). Additional purification can occur in a subsequent lagoon, yet further optimization of the VSEP filtration system is advised. Furthermore, concentrates produced by one membrane filtration step showed potential as N–K fertilizer with an economic value of €6.3 ± 1.1 t−1 fresh weight (FW). Further research is, however, required to evaluate the impact on crop production and soil quality by application of these new potential green fertilizers.

All life forms require the nutrient phosphorus and it cannot be substituted by any other element. The global cycle of phosphorus is special among the major biogeochemical cycles, since it has no significant gaseous compounds and only closes every 10-100 million years. However, human activities, as application of mineral fertilizers, conversion of natural ecosystems to arable land and releases of untreated waste, intensify remarkably thephosphorus flows. The problems with linear flows of a limited resource leading to eutrophication of aquaticenvironments, for instance, have generated national environmental quality objectives for phosphorus in Sweden. The main objective of this master thesis is to get a holistic overview of how phosphorus is moving through Gothenburg today, using Material Flow Analysis as method. The spatial system boundary is the municipality of Gothenburg and the temporal system boundary is the year of 2009. One way of dealing with the linear flows ofphosphorus might be to develop the wastewater systems used in Gothenburg today. Possible changes in phosphorus flows, if kitchen grinders or urine-diverting toilets were installed in Gothenburg, are evaluated. In order to make the phosphorus management more sustainable, the linear flows have to be closed to a larger extent than today. One way towards this ambition is to emphasize other fertilizers than the mineral ones, like urine and low-contaminated sludge. The MFA shows that the absolutely largest input of phosphorus to Gothenburg is via the food. The two large outputs of the same magnitude are the digested sludge from the wastewater treatment plant of Rya and the ashes from the waste-fuelled district heating power plant of Sävenäs. About 7% of the phosphorus input to Gothenburg continues into the aquatic environment. According to this study, urine diversion and separate collection of food seem prospective in order to decrease the phosphorus flows in digested sludge from the wastewater treatment plan, Näringsämnet fosfor är nödvändigt för alla levande organismer och kan inte ersättas av något annat grundämne. Den globala fosforcykeln är speciell då den inte innehåller några gasformiga föreningar och sluts var 10-100 miljonte år. Användning av konstgödsel, omvandling av tidigare orörda ekosystem till odlingsmark och utsläppav förorenat avfall är exempel på mänskliga aktiviteter som intensifierar fosforflöden. Problemet med att linjäraflöden av denna begränsade resurs leder till övergödning av vattenmiljöer har genererat nationella miljömål i Sverige för fosfor. Det huvudsakliga målet med detta examensarbete är att få en översikt av hur fosfor rör sig genom Göteborg idag med hjälp av substansflödesanalys. Den rumsliga systemgränsen är kommungränsen för Göteborg och den tidsmässiga avgränsningen är året 2009. Ett sätt att förbättra de linjära fosforflödena kan vara att utveckla deavloppssystem som idag används i Göteborg. Förändringarna som uppstår i fosforflödena vid installation av urinsorterande toaletter alternativt köksavfallskvarnar undersöks. Linjära flöden måste bli återcirkulerade i en högre utsträckning än idag ifall fosforhushållningen ska gå mot hållbarhet. Ett sätt att nå denna ambition är att lyfta fram andra gödselprodukter än konstgödsel, exempelvis urin och renare slam. Flödesanalysen visar att det definitivt största inflödet av fosfor till Göteborg är via livsmedel. De två största fosforutflödena, båda i samma storleksordning, är rötat slam från Ryaverket och aska från sopförbränningsanläggningen Sävenäs. Cirka 7% av den fosfor som flödar in i Göteborg fortsätter vidare ut i vattenmiljön. Enligt denna studie verkar urinsortering och separat insamling av matavfall vara goda lösningar för en framtid med mindre fosfor i slammet från Rya och i aska samt till vattenmiljön. En ytterligare fördel skulle vara erhållandet av hållbara gödselprodukter med god kvalitet., This master thesis has also been published as a technical report at Chalmers with Report No. 2011:124.

Submersed aquatic macrophytes play an important role in stabilizing sediment from resuspension, sequestering nutrients, and reducing algal growth in shallow lakes. Loss of vegetation is usually accompanied by changes in stable state to one characterized by higher turbidity, low light penetration, and frequent noxious algal blooms. Aquatic vegetation once played an important role in stabilizing the sediment and providing important fish and water fowl habitat in Marinuka Lake, Wisconsin. However, macrophyte biomass levels have declined significantly in the last decade with accompanying shifts toward blue-green algal dominance. Although reasons for this vegetation decline are not precisely known, it may be related to changes in light regime due to excessive algal growth induced by watershed phosphorus loading. Other possible factors include changes in sediment fertility, carp damage, or a physical stress such as drought or excessive pool fluctuations. The objectives of this research were to evaluate environmental factors that my inhibit submersed aquatic macrophyte growth in this lake and to use these findings to develop management scenarios for improving growth and successful propagation

TSBF-CIAT and its partners are working in western Kenya to develop, evaluate and disseminate integrated soil fertility management practices in which legumes are a prominent component. A substantial part of this work is implemented through PhD projects co-supervised by Cornell University, Wageningen University and TSBF-CIAT. A field trip by scientists from TSBF-CIAT, the Rockefeller Foundation, Kenya Forestry Research Institute (KEFRI), Moi University, Cornell University and Wageningen University to some of the research sites on 10 11 November 2003 examined the progress in these activities. This newsletter/report summarizes some results of the various projects.

Objetivos del estudio presente: analizar el estado de fertilidad de los suelos en el área de Cotacachi; identificar los factores que limitan el crecimiento de cultivos en las diferentes zonas del área; examinar los efectos a largo plazo de la fertilización con nitrógeno, el manejo de residuos y el riego en los rendimientos de maíz.

TSBF-CIAT and its partners are working in western Kenya to develop, evaluate and disseminate integrated soil fertility management practices in which legumes are a prominent component. A substantial part of this work is implemented through PhD projects co-supervised by Cornell University, Wageningen University and TSBF-CIAT. A field trip by scientists from TSBF-CIAT, the Rockefeller Foundation, Kenya Forestry Research Institute (KEFRI), Moi University, Cornell University and Wageningen University to some of the research sites on 10 11 November 2003 examined the progress in these activities. This newsletter/report summarizes some results of the various projects.

Objetivos del estudio presente: analizar el estado de fertilidad de los suelos en el área de Cotacachi; identificar los factores que limitan el crecimiento de cultivos en las diferentes zonas del área; examinar los efectos a largo plazo de la fertilización con nitrógeno, el manejo de residuos y el riego en los rendimientos de maíz.

The vast majority of land users at the Central Plateau of Burkina Faso make a living by farming small plots, where mainly staple crops are produced for subsistence use. Both area interventions and line interventions comprising indigenous techniques as well as introduced techniques can be encountered at the Central Plateau and have proved to be effective. There is a preference for semipermeable line measures that slow down runoff and prevent water logging in wet periods.

The vast majority of land users at the Central Plateau of Burkina Faso make a living by farming small plots, where mainly staple crops are produced for subsistence use. Both area interventions and line interventions comprising indigenous techniques as well as introduced techniques can be encountered at the Central Plateau and have proved to be effective. There is a preference for semipermeable line measures that slow down runoff and prevent water logging in wet periods.

In this paper, a model of the nitrogen cycle in the soil is incorporated in a computable general equilibrium model of the Tanzanian economy, thus establishing a two-way link between the environment and the economy. For a given level of natural soil productivity, profit-maximizing farmers choose input levels (and hence production volumes) which in turn influence soil productivity in the following years through the recycling of nitrogen from the residues of roots and stover and the degree of erosion. The model is used to simulate the effects of typical structural adjustment policies like a reduction in agrochemicals' subsidies, reduced implicit export tax rate, etc. After 10 years, the result of a joint implementation is a 9% higher gross domestic product (GDP) level compared to the baseline scenario. The effect of soil degradation is found to represent a reduction in the GDP level of more than 5% for the same time period.

For a complete picture of the lake ecosystem, it is necessary to understand the mechanisms regulating biomass and nutrient status (nutrient limitation, optimal supply, or surplus) of benthic algae, which are important primary producers and a food resource for grazers. This thesis gives an overview of the natural variation of benthic algae at different scales of space and time and on different substrates, and unravels some of the underlying factors. Algal nutrient status was assessed using the C:N:P (carbon:nitrogen:phosphorus) ratio of the entire natural benthic community. A review, observations, and experiments confirmed that a C:N:P ratio of about 158:18:1 (molar basis) represented an optimal nutrient supply, and that substantially higher C:N, N:P, or C:P ratios reflected algal growth limitation caused by an N or P nutrient deficiency. Horizontal variation of benthic algal biomass and nutrient status was patchy, of similar amount for all investigated distances, substrates, and lakes, and constituted a dominant proportion of the total variation. For example, patches of nutrient limited algae were found within only 10 m distance from patches with a nutrient surplus. Thus, horizontal variation should not be neglected when sampling benthic algae in lakes. Field observations suggested an impact of wind, nutrients, and grazers on the horizontal variation. Light and nutrients might have caused the observed vertical and temporal variation. Field experiments confirmed a simultaneous control of benthic algal biomass by nutrients and grazing, mediated by light and temperature. Grazing effects were larger than nutrient effects, but the comparison of natural communities in lakes of different trophy suggested that benthic algal biomass was controlled by nutrients in the long run. An important nutrient supply was animal excretions, causing a low C:N:P ratio of epizoon on zebra mussels, and algal communities associated with macrograzers. A field experiment revealed that 15N circu

For a complete picture of the lake ecosystem, it is necessary to understand the mechanisms regulating biomass and nutrient status (nutrient limitation, optimal supply, or surplus) of benthic algae, which are important primary producers and a food resource for grazers. This thesis gives an overview of the natural variation of benthic algae at different scales of space and time and on different substrates, and unravels some of the underlying factors. Algal nutrient status was assessed using the C:N:P (carbon:nitrogen:phosphorus) ratio of the entire natural benthic community. A review, observations, and experiments confirmed that a C:N:P ratio of about 158:18:1 (molar basis) represented an optimal nutrient supply, and that substantially higher C:N, N:P, or C:P ratios reflected algal growth limitation caused by an N or P nutrient deficiency. Horizontal variation of benthic algal biomass and nutrient status was patchy, of similar amount for all investigated distances, substrates, and lakes, and constituted a dominant proportion of the total variation. For example, patches of nutrient limited algae were found within only 10 m distance from patches with a nutrient surplus. Thus, horizontal variation should not be neglected when sampling benthic algae in lakes. Field observations suggested an impact of wind, nutrients, and grazers on the horizontal variation. Light and nutrients might have caused the observed vertical and temporal variation. Field experiments confirmed a simultaneous control of benthic algal biomass by nutrients and grazing, mediated by light and temperature. Grazing effects were larger than nutrient effects, but the comparison of natural communities in lakes of different trophy suggested that benthic algal biomass was controlled by nutrients in the long run. An important nutrient supply was animal excretions, causing a low C:N:P ratio of epizoon on zebra mussels, and algal communities associated with macrograzers. A field experiment revealed that 15N circu

For a complete picture of the lake ecosystem, it is necessary to understand the mechanisms regulating biomass and nutrient status (nutrient limitation, optimal supply, or surplus) of benthic algae, which are important primary producers and a food resource for grazers. This thesis gives an overview of the natural variation of benthic algae at different scales of space and time and on different substrates, and unravels some of the underlying factors. Algal nutrient status was assessed using the C:N:P (carbon:nitrogen:phosphorus) ratio of the entire natural benthic community. A review, observations, and experiments confirmed that a C:N:P ratio of about 158:18:1 (molar basis) represented an optimal nutrient supply, and that substantially higher C:N, N:P, or C:P ratios reflected algal growth limitation caused by an N or P nutrient deficiency. Horizontal variation of benthic algal biomass and nutrient status was patchy, of similar amount for all investigated distances, substrates, and lakes, and constituted a dominant proportion of the total variation. For example, patches of nutrient limited algae were found within only 10 m distance from patches with a nutrient surplus. Thus, horizontal variation should not be neglected when sampling benthic algae in lakes. Field observations suggested an impact of wind, nutrients, and grazers on the horizontal variation. Light and nutrients might have caused the observed vertical and temporal variation. Field experiments confirmed a simultaneous control of benthic algal biomass by nutrients and grazing, mediated by light and temperature. Grazing effects were larger than nutrient effects, but the comparison of natural communities in lakes of different trophy suggested that benthic algal biomass was controlled by nutrients in the long run. An important nutrient supply was animal excretions, causing a low C:N:P ratio of epizoon on zebra mussels, and algal communities associated with macrograzers. A field experiment revealed that 15N circu

For a complete picture of the lake ecosystem, it is necessary to understand the mechanisms regulating biomass and nutrient status (nutrient limitation, optimal supply, or surplus) of benthic algae, which are important primary producers and a food resource for grazers. This thesis gives an overview of the natural variation of benthic algae at different scales of space and time and on different substrates, and unravels some of the underlying factors. Algal nutrient status was assessed using the C:N:P (carbon:nitrogen:phosphorus) ratio of the entire natural benthic community. A review, observations, and experiments confirmed that a C:N:P ratio of about 158:18:1 (molar basis) represented an optimal nutrient supply, and that substantially higher C:N, N:P, or C:P ratios reflected algal growth limitation caused by an N or P nutrient deficiency. Horizontal variation of benthic algal biomass and nutrient status was patchy, of similar amount for all investigated distances, substrates, and lakes, and constituted a dominant proportion of the total variation. For example, patches of nutrient limited algae were found within only 10 m distance from patches with a nutrient surplus. Thus, horizontal variation should not be neglected when sampling benthic algae in lakes. Field observations suggested an impact of wind, nutrients, and grazers on the horizontal variation. Light and nutrients might have caused the observed vertical and temporal variation. Field experiments confirmed a simultaneous control of benthic algal biomass by nutrients and grazing, mediated by light and temperature. Grazing effects were larger than nutrient effects, but the comparison of natural communities in lakes of different trophy suggested that benthic algal biomass was controlled by nutrients in the long run. An important nutrient supply was animal excretions, causing a low C:N:P ratio of epizoon on zebra mussels, and algal communities associated with macrograzers. A field experiment revealed that 15N circu

In this paper, a model of the nitrogen cycle in the soil is incorporated in a computable general equilibrium model of the Tanzanian economy, thus establishing a two-way link between the environment and the economy. For a given level of natural soil productivity, profit-maximizing farmers choose input levels (and hence production volumes) which in turn influence soil productivity in the following years through the recycling of nitrogen from the residues of roots and stover and the degree of erosion. The model is used to simulate the effects of typical structural adjustment policies like a reduction in agrochemicals' subsidies, reduced implicit export tax rate, etc. After 10 years, the result of a joint implementation is a 9% higher gross domestic product (GDP) level compared to the baseline scenario. The effect of soil degradation is found to represent a reduction in the GDP level of more than 5% for the same time period.

For a complete picture of the lake ecosystem, it is necessary to understand the mechanisms regulating biomass and nutrient status (nutrient limitation, optimal supply, or surplus) of benthic algae, which are important primary producers and a food resource for grazers. This thesis gives an overview of the natural variation of benthic algae at different scales of space and time and on different substrates, and unravels some of the underlying factors. Algal nutrient status was assessed using the C:N:P (carbon:nitrogen:phosphorus) ratio of the entire natural benthic community. A review, observations, and experiments confirmed that a C:N:P ratio of about 158:18:1 (molar basis) represented an optimal nutrient supply, and that substantially higher C:N, N:P, or C:P ratios reflected algal growth limitation caused by an N or P nutrient deficiency. Horizontal variation of benthic algal biomass and nutrient status was patchy, of similar amount for all investigated distances, substrates, and lakes, and constituted a dominant proportion of the total variation. For example, patches of nutrient limited algae were found within only 10 m distance from patches with a nutrient surplus. Thus, horizontal variation should not be neglected when sampling benthic algae in lakes. Field observations suggested an impact of wind, nutrients, and grazers on the horizontal variation. Light and nutrients might have caused the observed vertical and temporal variation. Field experiments confirmed a simultaneous control of benthic algal biomass by nutrients and grazing, mediated by light and temperature. Grazing effects were larger than nutrient effects, but the comparison of natural communities in lakes of different trophy suggested that benthic algal biomass was controlled by nutrients in the long run. An important nutrient supply was animal excretions, causing a low C:N:P ratio of epizoon on zebra mussels, and algal communities associated with macrograzers. A field experiment revealed that 15N circu

The environmental impact of the management of biodegradable waste in Stockholm, based mainly on incineration and landfilling, was compared to systems with significant nutrient recycling; large-scale composting, anaerobic digestion, and separate collection and utilization of urine. The systems' emissions, residual products, energy turnover, and resource consumption were evaluated from a life-cycle perspective, using a computerized model, ORWARE (ORganic WAste REsearch model). Transportation was of relatively low importance to overall environmental impact, even at high rates of nutrient recycling. This is remarkable considering the geographical setting of Stockholm, with high population density and little nearby farmland. Ancillary systems, such as generation of electricity and district heating, were crucial for the overall outcome. Increased recycling of nutrients in solid biodegradable waste in Stockholm can reduce net environmental impact, whereas separation of human urine to be spread as fertilizer cannot yet be introduced without increased acidification. Increased nutrient recycling from solid biodegradable waste inevitably increases spreading of metals on arable land. Urine is by far the least contaminated residual product. Spreading of all other residuals would be limited by their metal content., QC 20100415

Recycling is the central axis for the conservaron of ecosystems ¡n the scenario of sustainable development. This subject implies the study of an important frame of interactions. Nevertheless, the complex study of nutrient recycling in agroecosystems would be reduced on the basis of the actual knowledge of the soil biocenoses, mainly represented by soil nematodes. Nematodes are indicator organisms of several processes related with the trophic structure of soil systems. This question, combined with the study of nematode interactions with the herbaceous communities growing over these soils, can provide guidelines for a more rational planning of pasture management. The results of our work show that nematode density is posrtively correlated wrth grass species richness and with the number of perennial species. Moreover, the quantity of nematodes decreases when grazing pressure is intensified. All that implies that the degree of maturity of a pasture may be intimately related to the biológica! recycling of nutrients.

QC 20100415