Effectiveness of struvite precipitation and ammonia stripping for recovery of phosphorus and nitrogen from anaerobic digestate: a systematic review

Background: A regular supply of nutrients such as nitrogen and phosphorus to agriculture is needed for global food security, and increased recycling of nutrients back to agriculture from organic waste streams is necessary for increased rural-urban sustainability. Anaerobic digestion of sewage sludge and agricultural wastes is widely applied to stabilize the substrate and capture some of its energetic value via biogas production. Anaerobic digestate is a concentrated source of nutrients to which nutrient recovery technologies can be applied. By combining anaerobic digestion and nutrient recovery technologies on the digestate, both energy and nutrient recovery can be achieved. Two promising technologies that could increase nutrient recycling from different types of wastewater are struvite precipitation and ammonia stripping. This review examined the effectiveness of these ecotechnologies for the recovery of nitrogen and phosphorus from anaerobic digestate with the aim of reducing the impact of waste on the environment.Methods: We searched for academic and grey literature published after 2013. Searches were performed in 5 bibliographic databases in English, in the search engine Google Scholar in English, Swedish, Finnish and Polish, and across a range of organisational websites in English, Swedish, Finnish and Polish. Eligibility screening was conducted at two levels: 'title and abstract' and 'full text'. Included eligible studies were subject to a critical appraisal that assessed external and internal study validity. We extracted information on study characteristics, intervention, comparators, effect modifiers, and measured outcomes. Data synthesis included narrative synthesis of each study of sufficient validity. We performed quantitative synthesis on a subset of studies.Review findings: The review included 30 studies on struvite precipitation and 8 studies on ammonia stripping. Both pH and Mg:PO4 ratio were found to have a clear influence on the effectiveness of struvite precipitation process (and thus nutrient removal rates). The response to pH was found to be non-linear, resembling a bell curve with a maximum around pH 9.5. Mg:PO4 ratio was found to have a positive effect on removal up to a ratio as high as 4:1. However, it should be noted that high removal efficiencies were sometimes achieved at a ratio as low as 1:1 as well. Although the effects of pH and Mg:PO4 ratio were clear, the model developed could not accurately predict removal based on these two parameters alone. Studies on ammonia stripping were relatively heterogeneous. Due to the small size of the evidence base, and the heterogeneity between studies, no conclusions are presented regarding the influence of different process parameters on the outcome of ammonia stripping.Conclusions: In conclusion, when performed under the right conditions (i.e. pH around 9.5 and Mg:PO4 ratio of at least 1:1), available evidence suggests that struvite precipitation is an effective technology for the recovery of nutrients from the liquid phase of anaerobic digestate. The evidence base is limited for ammonia stripping. We provided suggestions of which data to report in future studies

All the (Many, Many) Things We Know: Extended Knowledge *

Abstract In this paper we explore the potential bearing of the extended mind thesis-the thesis that the mind extends into the world-on epistemology. We do three things. First, we argue that the combination of the extended mind thesis and reliabilism about knowledge entails that ordinary subjects can easily come to enjoy various forms of restricted omniscience. Second, we discuss the conceptual foundations of the extended mind and knowledge debate. We suggest that the theses of extended mind and extended knowledge lead to a bifurcation with respect to the concepts of belief and knowledge. We suggest that this conceptual bifurcation supports a form of pluralism about these concepts. Third, we discuss whether something similar can be said at the metaphysical level

Noise reduction strategies : socially sustainable design in the urban environment

Denna kandidatuppsats utforskar immissionsbaserade strategier för reducering av trafikbuller i urbana miljöer som omfattar bullerskärmar, markbehandling, refraktiva ljudkristaller, jordvallar och vegetation. Strategierna undersöks dels utifrån deras bullerdämpande effektivitet, men också utifrån Jan Gehls principer för socialt hållbar stadsplanering. Den bedömer de fysiska egenskaperna och placeringen av vegetation, barriärer och andra material för att minska trafikbuller samtidigt som den beaktar stadsrummet som en plats för människor och sociala interaktioner. Resultaten visar att en kombination av olika vegetationstyper och innovativa strukturella lösningar kan minska städers bullernivåer avsevärt. Dock erkänner uppsatsen strukturella utmaningarna med att implementera dessa lösningar i tätbebyggda stadsmiljöer. Faktorer såsom rumsbildning, tillgänglighet, siktlinjer, estetik, luft- och ljusinsläpp, vindklimat, säkerhet, grönska och årstidsvariationer bedöms som viktiga element att beakta vid etablering av dessa bullerdämpande gestaltningsstrategier. Baserat på dessa överväganden föreslås olika strategiska anpassningar för de nämnda bulleråtgärderna med målet att uppnå en balans mellan minskad trafikbuller och människocentrerad gestaltning i stadsmiljö. Uppsatsen föreslår ett holistiskt tillvägagångssätt till stadsdesign som inte bara adresserar bullerreducering utan också förbättrar social välfärd, i enlighet med Gehls vision om städer gestaltade för människor.This bachelor thesis explores immission-based strategies for reducing traffic noise in urban environments that include noise barriers, ground attenuation, refractive sound crystals and vegetation. The strategies are examined in terms of their noise mitigation effectiveness as well as Jan Gehl's principles for socially sustainable urban planning. It assesses the physical characteristics and placement of vegetation, barriers and other materials to reduce traffic noise while considering urban space as a place for people and social interactions. The results show that a combination of different vegetation types and innovative structural solutions can significantly reduce urban noise levels. However, the paper recognizes the structural challenges of implementing these solutions in dense urban environments. Factors such as spatial formation, accessibility, sightlines, aesthetics, air and light intake, wind climate, safety, greenery and seasonal variations are deemed important elements to take into account when establishing these noise mitigation design strategies. Based on these considerations, different strategic adjustments are proposed for the aforementioned noise mitigation measures with the aim of achieving a balance between traffic noise reduction and human-centered design in the urban environment. The paper proposes a holistic approach to urban design that not only addresses noise reduction but also improves social welfare, in accordance with Gehl's vision of cities designed for people

Online sensors in wastewater treatment plants : status today and the effects of sensor faults on the treatment process

Effektiviteten av automatiserade reningsprocesser inom avloppsreningsverk beror ytterst på kvaliteten av de mätdata som fås från installerade instrument. Givarfel påverkar verkens styrning och är ofta anledningen till att olika reglerstrategier fallerar. Idag saknas standardiserade riktlinjer för hur instrumenteringsarbetet på svenska reningsverk bör organiseras vilket ger begränsade förutsättningar för reningsverken att resurseffektivt nå sina utsläppskrav. Mycket forskning har gjorts på att optimera olika reglerstrategier men instrumentens roll i verkens effektivitet har inte givits samma uppmärksamhet. Syftet med detta examensarbete har varit att undersöka hur instrumentering på reningsverk kan organiseras och struktureras för att säkerställa mätdata av god kvalitet och att undersöka effekter av givarfel på reningsprocessen. Inom arbetet genomfördes en litteraturstudie där instrumentering på reningsverk under-söktes. Effekter av givarfel på reningsprocessen undersöktes genom att simulera en fördenitrifikationsprocess i Benchmark Simulation Model no. 2 där bias och drift implementerades i olika givare. Simuleringar visade att positiva bias (0,10–0,50 mg/l) i en ammoniumgivare inom en kaskadreglering bidrar till att öka luftförbrukningen med cirka 4–25 %. Vidare resulterade alla typer av fel i DO-givare i den sista aeroba bassängen i en markant större påverkan på reningsprocessen än samma fel i DO-givare i någon av de tidigare aeroba bassängerna. Om den sista aeroba bassängen är designad för att hålla lägre syrehalter är DO-givaren i den bassängen den viktigaste DO-givaren att underhålla. Positiva bias (200–1 000 mg/l) i TSS-givare som används för att styra uttaget av överskottsslam bidrog till kraftiga ökningar av mängden ammonium med cirka 29–464 % i utgående vatten. Negativ drift i DO-givare visade att stora besparingar i luftningsenergi, cirka 4 %, var möjliga genom ett mer frekvent underhåll av DO-givarna. Huruvida ett instrument lider av ett positivt eller negativt givarfel, bias eller drift, kommer att påverka hur mycket och i vilken mån reningsprocessen påverkas. Studien av givarfel visade att effekten av ett positivt eller ett negativt fel varierade och att effekten på reningsprocessen inte var linjär. Effekten av givarfel på reningsprocessen kommer i slutändan att bero på den implementerade reglerstrategin, inställningar i regulatorerna och på den styrda processen.The effectiveness of automated treatment processes within wastewater treatment plants ultimately depend on the quality of the measurement data that is given from the installed sensors. Sensor faults affect the control of the treatment plants and are often the reason different control strategies fail. Today there is a lack of standardized guidelines for how to organize and work with online sensors at Swedish wastewater treatment plants which limits the opportunities for treatment plants to reach their effluent criteria in a resource efficient manner. Much research has been done on ways to optimize control strategies but the role of sensors in the efficiency of the treatment plants has not been given the same level of attention. The purpose of this thesis has been to examine how instrumentation at wastewater treatment plants can be organized and structured to ensure good quality measurement data and to examine how sensor faults affect the treatment process. Within the thesis a literature study was conducted where instrumentation at wastewater treatment plants was examined. The effects of sensor faults were examined by simulating a pre-denitrification process in Benchmark Simulation Model no. 2 where off-sets (biases) and drift where added to measurements from different implemented sensors. The simulations showed that positive off-sets (0.10–0.50 mg/l) in an ammonium sensor within a cascaded feedback-loop adds to the energy consumption used for aeration by roughly 4-25%. It could further be shown that all types of faults in a DO sensor in the last aerated basin had significantly larger effect on the treatment process than the same fault in any of the other DO sensors in the preceding basins. If the last aerated basin is designed to have low DO concentrations the DO sensor in that basin is the most important DO sensor to maintain. Positive off-sets (200–1 000 mg TSS/l) in suspended solids sensors used for control of waste activated sludge flow contributed to large increases of ammonia, by 29-464%, in effluent waters. Negative drift in DO sensors showed that significant savings in aeration energy, roughly 4%, was possible to achieve with more frequent maintenance. Whether a sensor is affected by a positive or a negative fault, be it off-set or drift, will affect how much and in what way the treatment process will be affected. The study of sensor faults showed that the effect of a positive or a negative fault varied and that the effect on the treatment process was not linear. The effect of a sensor fault on the treatment process will ultimately depend on the implemented control strategy, settings in the controllers and on the controlled process

Att Bredda Läsupplevelsen på Mobiltelefoner genom Gyroskopiska Interaktioner : En Utforskande Designstudie

This thesis is an explorative study aimed at the possibility of integrating tilt-based input to improve the reading experience on smartphones. Previous works from the early 2000s have been skeptical towards tilt-based navigation, deeming it unruly and imprecise. To investigate if today’s technology has unlocked new possibilities; two experimental reading methods were designed, created and tested iteratively on 20, respectively 18 participants. The first method is a reassessment of tilt-based auto-scrolling and the second is a novel approach comparable to tilt-based paging. Data from the reading sessions were collected quantitatively in tandem with qualitative data from post-session interviews. The results indicate good potential and a reading performance similar to the standard navigation method. The importance of accommodating people with different reading behaviours was also discussed.Detta examensarbete utforskar om gyroskopiska interaktioner kan användas för att förbättra läsupplevelsen på mobiltelefoner. Tidigare forskning från det tidiga 2000-talet har varit skeptiska mot gyroskopisk navigation, på grund av dålig precision och stabilitet. För att utforska om dagens teknologi har öppnat nya möjligheter; skapades, designades och testades två experimentella läsmetoder på 20 respektive 18 deltagare. Den första metoden är en återkoppling till tidigare forskning medans den andra utforskar ett nytt sätt som liknar gyroskopisk sidindelning. Data från läs sessionerna samlades i både kvantitativ och kvalitativ form, varav den senare med semistrukturerade intervjuer. Resultaten indikerar god potential och en läsprestanda som liknar den standardiserade läsmetoden. Vikten av att tillgodose människors individuella läsningsbeteende blev också diskuterat

Att Bredda Läsupplevelsen på Mobiltelefoner genom Gyroskopiska Interaktioner : En Utforskande Designstudie

This thesis is an explorative study aimed at the possibility of integrating tilt-based input to improve the reading experience on smartphones. Previous works from the early 2000s have been skeptical towards tilt-based navigation, deeming it unruly and imprecise. To investigate if today’s technology has unlocked new possibilities; two experimental reading methods were designed, created and tested iteratively on 20, respectively 18 participants. The first method is a reassessment of tilt-based auto-scrolling and the second is a novel approach comparable to tilt-based paging. Data from the reading sessions were collected quantitatively in tandem with qualitative data from post-session interviews. The results indicate good potential and a reading performance similar to the standard navigation method. The importance of accommodating people with different reading behaviours was also discussed.Detta examensarbete utforskar om gyroskopiska interaktioner kan användas för att förbättra läsupplevelsen på mobiltelefoner. Tidigare forskning från det tidiga 2000-talet har varit skeptiska mot gyroskopisk navigation, på grund av dålig precision och stabilitet. För att utforska om dagens teknologi har öppnat nya möjligheter; skapades, designades och testades två experimentella läsmetoder på 20 respektive 18 deltagare. Den första metoden är en återkoppling till tidigare forskning medans den andra utforskar ett nytt sätt som liknar gyroskopisk sidindelning. Data från läs sessionerna samlades i både kvantitativ och kvalitativ form, varav den senare med semistrukturerade intervjuer. Resultaten indikerar god potential och en läsprestanda som liknar den standardiserade läsmetoden. Vikten av att tillgodose människors individuella läsningsbeteende blev också diskuterat

Online sensors in wastewater treatment plants : status today and the effects of sensor faults on the treatment process

Effektiviteten av automatiserade reningsprocesser inom avloppsreningsverk beror ytterst på kvaliteten av de mätdata som fås från installerade instrument. Givarfel påverkar verkens styrning och är ofta anledningen till att olika reglerstrategier fallerar. Idag saknas standardiserade riktlinjer för hur instrumenteringsarbetet på svenska reningsverk bör organiseras vilket ger begränsade förutsättningar för reningsverken att resurseffektivt nå sina utsläppskrav. Mycket forskning har gjorts på att optimera olika reglerstrategier men instrumentens roll i verkens effektivitet har inte givits samma uppmärksamhet. Syftet med detta examensarbete har varit att undersöka hur instrumentering på reningsverk kan organiseras och struktureras för att säkerställa mätdata av god kvalitet och att undersöka effekter av givarfel på reningsprocessen. Inom arbetet genomfördes en litteraturstudie där instrumentering på reningsverk under-söktes. Effekter av givarfel på reningsprocessen undersöktes genom att simulera en fördenitrifikationsprocess i Benchmark Simulation Model no. 2 där bias och drift implementerades i olika givare. Simuleringar visade att positiva bias (0,10–0,50 mg/l) i en ammoniumgivare inom en kaskadreglering bidrar till att öka luftförbrukningen med cirka 4–25 %. Vidare resulterade alla typer av fel i DO-givare i den sista aeroba bassängen i en markant större påverkan på reningsprocessen än samma fel i DO-givare i någon av de tidigare aeroba bassängerna. Om den sista aeroba bassängen är designad för att hålla lägre syrehalter är DO-givaren i den bassängen den viktigaste DO-givaren att underhålla. Positiva bias (200–1 000 mg/l) i TSS-givare som används för att styra uttaget av överskottsslam bidrog till kraftiga ökningar av mängden ammonium med cirka 29–464 % i utgående vatten. Negativ drift i DO-givare visade att stora besparingar i luftningsenergi, cirka 4 %, var möjliga genom ett mer frekvent underhåll av DO-givarna. Huruvida ett instrument lider av ett positivt eller negativt givarfel, bias eller drift, kommer att påverka hur mycket och i vilken mån reningsprocessen påverkas. Studien av givarfel visade att effekten av ett positivt eller ett negativt fel varierade och att effekten på reningsprocessen inte var linjär. Effekten av givarfel på reningsprocessen kommer i slutändan att bero på den implementerade reglerstrategin, inställningar i regulatorerna och på den styrda processen.The effectiveness of automated treatment processes within wastewater treatment plants ultimately depend on the quality of the measurement data that is given from the installed sensors. Sensor faults affect the control of the treatment plants and are often the reason different control strategies fail. Today there is a lack of standardized guidelines for how to organize and work with online sensors at Swedish wastewater treatment plants which limits the opportunities for treatment plants to reach their effluent criteria in a resource efficient manner. Much research has been done on ways to optimize control strategies but the role of sensors in the efficiency of the treatment plants has not been given the same level of attention. The purpose of this thesis has been to examine how instrumentation at wastewater treatment plants can be organized and structured to ensure good quality measurement data and to examine how sensor faults affect the treatment process. Within the thesis a literature study was conducted where instrumentation at wastewater treatment plants was examined. The effects of sensor faults were examined by simulating a pre-denitrification process in Benchmark Simulation Model no. 2 where off-sets (biases) and drift where added to measurements from different implemented sensors. The simulations showed that positive off-sets (0.10–0.50 mg/l) in an ammonium sensor within a cascaded feedback-loop adds to the energy consumption used for aeration by roughly 4-25%. It could further be shown that all types of faults in a DO sensor in the last aerated basin had significantly larger effect on the treatment process than the same fault in any of the other DO sensors in the preceding basins. If the last aerated basin is designed to have low DO concentrations the DO sensor in that basin is the most important DO sensor to maintain. Positive off-sets (200–1 000 mg TSS/l) in suspended solids sensors used for control of waste activated sludge flow contributed to large increases of ammonia, by 29-464%, in effluent waters. Negative drift in DO sensors showed that significant savings in aeration energy, roughly 4%, was possible to achieve with more frequent maintenance. Whether a sensor is affected by a positive or a negative fault, be it off-set or drift, will affect how much and in what way the treatment process will be affected. The study of sensor faults showed that the effect of a positive or a negative fault varied and that the effect on the treatment process was not linear. The effect of a sensor fault on the treatment process will ultimately depend on the implemented control strategy, settings in the controllers and on the controlled process