Matthias Zessner

Phosphorus recovery from municipal wastewater: An integrated comparative technological, environmental and economic assessment of P recovery technologies

Phosphorus (P) is an essential and limited resource. Municipal wastewater is a promising source of P via reuse and could be used to replace P derived from phosphate rocks. The agricultural use of sewage sludge is restricted by legislation or is not practiced in several European countries due to environmental risks posed by organic micropollutants and pathogens. Several technologies have been developed in recent years to recover wastewater P. However, these technologies target different P-containing flows in wastewater treatment plants (effluent, digester supernatant, sewage sludge, and sewage sludge ash), use diverse engineering approaches and differ greatly with respect to P recycling rate, potential of removing or destroying pollutants, product quality, environmental impact and cost. This work compares 19 relevant P recovery technologies by considering their relationships with existing wastewater and sludge treatment systems. A combination of different methods, such as material flow analysis, damage units, reference soil method, annuity method, integrated cost calculation and a literature study on solubility, fertilizing effects and handling of recovered materials, is used to evaluate the different technologies with respect to technical, ecological and economic aspects. With regard to the manifold origins of data an uncertainty concept considering validity of data sources is applied. This analysis revealed that recovery from flows with dissolved P produces clean and plant-available materials. These techniques may even be beneficial from economic and technical perspectives under specific circumstances. However, the recovery rates (a maximum of 25%) relative to the wastewater treatment plant influent are relatively low. The approaches that recover P from sewage sludge apply complex technologies and generally achieve effective removal of heavy metals at moderate recovery rates (~40-50% relative to the WWTP input) and comparatively high costs. Sewage sludge ash is the most promising P source, with recovery rates of 60-90% relative to the wastewater P. The costs highly depend on the purity requirements of the recycled products but can be kept comparatively low, especially if synergies with existing industrial processes are exploited.

Identification of phosphorus emission hotspots in agricultural catchments

An enhanced transport-based management approach is presented, which is able to support cost-effective water quality management with respect to diffuse phosphorus pollution. Suspended solids and particulate phosphorus emissions and their transport were modeled in two hilly agricultural watersheds (Wulka River in Austria and Zala River in Hungary) with an improved version of the catchment-scale PhosFate model. Source and transmission areas were ranked by an optimization method in order to provide a priority list of the areas of economically efficient (optimal) management alternatives. The model was calibrated and validated at different gauges and for various years. The spatial distribution of the emissions shows that approximately one third of the catchment area is responsible for the majority of the emissions. However, only a few percent of the source areas can transport fluxes to the catchment outlet. These effective source areas, together with the main transmission areas are potential candidates for improved management practices. In accordance with the critical area concept, it was shown that intervention with better management practices on a properly selected small proportion of the total area (1–3%) is sufficient to reach a remarkable improvement in water quality. If soil nutrient management is also considered in addition to water quality, intervention on 4–12% of the catchment areas can fulfill both aspects.

Identification of relevant micropollutants in Austrian municipal wastewater and their behaviour during wastewater treatment

The European Union has defined environmental quality standards (EQSs) for surface waters for priority substances and several other pollutants. Furthermore national EQSs for several chemicals are valid in Austria. The study investigated the occurrence of these compounds in municipal wastewater treatment plant (WWTP) effluents. In a first screening of 15 WWTPs relevant substances were identified, which subsequently were monitored in 9 WWTPs over 1 year (every 2 months). Out of 77 substances or groups of substances (including more than 90 substances) 13 were identified as potentially relevant in respect to water pollution and subjected to the monitoring, whereas most other compounds were detected in concentrations far below the respective EQS for surface waters and therefore not further considered. The preselected 13 compounds for monitoring were cadmium (Cd), nickel (Ni), copper (Cu), selenium (Se), zinc (Zn), diuron, polybrominated diphenyl ethers (PBDEs), di(ethyl-hydroxyl)phthalate (DEHP), tributyltin compounds (TBT), nonylphenoles (NP), adsorbable organic halogens (AOX) and the complexing agents ethylenediaminetetraacetic acid (EDTA) as well as nitrilotriacetic acid (NTA). In the effluents of WWTPs the concentrations of the priority substances Cd, NP, TBT and diuron frequently exceeded the respective EQS, whereas the concentrations for DEHP and Ni were below the respective EQS. The effluent concentrations for AOX, EDTA, NTA, Cu, Se and Zn frequently are in the range or above the Austrian EQS for surface waters. Besides diuron and EDTA all compounds are removed at least partially during wastewater treatment and for most substances the removal via the excess sludge is the major removal pathway. For the 13 compounds which were monitored in WWTP effluents population equivalent specific discharges were calculated. Since for many compounds no or only few information is available, these population equivalent specific discharges can be used to assess emissions from municipal WWTPs to surface waters as well as to make a first assessment of the impact of a discharge on surface waters chemical status. Comparing discharges and river pollution on a load basis, the influence of diffuse sources becomes obvious and therefore should also be taken into consideration in river management.

Considerations on methodological challenges for water footprint calculations

We have investigated how different approaches for water footprint (WF) calculations lead to different results, taking sugar beet production and sugar refining as examples. To a large extent, results obtained from any WF calculation are reflective of the method used and the assumptions made. Real irrigation data for 59 European sugar beet growing areas showed inadequate estimation of irrigation water when a widely used simple approach was used. The method resulted in an overestimation of blue water and an underestimation of green water usage. Dependent on the chosen (available) water quality standard, the final grey WF can differ up to a factor of 10 and more. We conclude that further development and standardisation of the WF is needed to reach comparable and reliable results. A special focus should be on standardisation of the grey WF methodology based on receiving water quality standards.

Occurrence of human-associated Bacteroidetes genetic source tracking markers in raw and treated wastewater of municipal and domestic origin and comparison to standard and alternative indicators of faecal pollution.

This was a detailed investigation of the seasonal occurrence, dynamics, removal and resistance of human-associated genetic Bacteroidetes faecal markers (GeBaM) compared with ISO-based standard faecal indicator bacteria (SFIB), human-specific viral faecal markers and one human-associated Bacteroidetes phage in raw and treated wastewater of municipal and domestic origin. Characteristics of the selected activated sludge wastewater treatment plants (WWTPs) from Austria and Germany were studied in detail (WWTPs, n = 13, connected populations from 3 to 49000 individuals), supported by volume-proportional automated 24-h sampling and chemical water quality analysis. GeBaM were consistently detected in high concentrations in raw (median log10 8.6 marker equivalents (ME) 100 ml−1) and biologically treated wastewater samples (median log10 6.2–6.5 ME 100 ml−1), irrespective of plant size, type and time of the season (n = 53–65). GeBaM, Escherichia coli, and enterococci concentrations revealed the same range of statistical variability for raw (multiplicative standard deviations s* = 2.3–3.0) and treated wastewater (s* = 3.7–4.5), with increased variability after treatment. Clostridium perfringens spores revealed the lowest variability for raw wastewater (s* = 1.5). In raw wastewater correlations among microbiological parameters were only detectable between GeBaM, C. perfringens and JC polyomaviruses. Statistical associations amongst microbial parameters increased during wastewater treatment. Two plants with advanced treatment were also investigated, revealing a minimum log10 5.0 (10th percentile) reduction of GeBaM in the activated sludge membrane bioreactor, but no reduction of the genetic markers during UV irradiation (254 nm). This study highlights the potential of human-associated GeBaM to complement wastewater impact monitoring based on the determination of SFIB. In addition, human-specific JC polyomaviruses and adenoviruses seem to be a valuable support if highly specific markers are needed.

Supporting phosphorus management in Austria: Potential, priorities and limitations.

Protecting water bodies from eutrophication, ensuring long-term food security and shifting to a circular economy represent compelling objectives to phosphorus management strategies. This study determines how and to which extent the management of phosphorus in Austria can be optimized. A detailed national model, obtained for the year 2013 through Material Flow Analysis, represents the reference situation. Applicability and limitations are discussed for a range of actions aimed at reducing consumption, increasing recycling, and lowering emissions. The potential contribution of each field of action is quantified and compared using three indicators: Import dependency, Consumption of fossil-P fertilizers and Emissions to water bodies. Further, the uncertainty of this assessment is characterized and priorities for the upgrade of data collection are identified. Moreover, all the potential gains discussed in the article are applied to the reference situation to generate an ideal target model. The results show that in Austria a large scope for phosphorus stewardship exists. Strategies based exclusively either on recycling or on the decline of P consumption hold a similar potential to reduce import dependency by 50% each. An enhanced P recycling from meat and bone meal, sewage sludge and compost could replace the current use of fossil-P fertilizers by 70%. The target model, i.e. the maximum that could be achieved taking into account trade-offs between different actions, is characterized by an extremely low import dependency of 0.23kgPcap(-1)y(-1) (2.2kgPcap(-1)y(-1) in 2013), by a 28% decline of emissions to water bodies and by null consumption of fossil-P fertilizers. This case study shows the added value of using Material Flow Analysis as a basis to design sound management strategies. The systemic approach inherent to it allows performing a proper comparative assessment of different actions, identifying priorities, and visualizing a target model.

Cost comparison of wastewater treatment in Danubian countries.

This paper investigates the costs of wastewater treatment (including sludge management) within the Danube catchment countries A, CZ, SK, HU, SL, RO, BG and UA. TK is considered as well. Additionally, the paper compares the total costs of wastewater management (including sewage) with the incomes in the different countries. The annual costs of wastewater treatment in Austria are about 30 euro/p.e. y for large plants with nitrogen and phosphorus removal. In low income countries of the Danube and Black Sea catchment areas they are at a maximum 30% lower than in Austria. However, the incomes in countries like Bulgaria, Romania or Ukraine are 85% to 90% lower. The total annual costs for wastewater management (sewer development plus treatment) amount at least to 90 euro/p.e. y. Considering the level of income in those countries, financing of wastewater management completely by charges of the population equivalents connected is not feasible. Therefore other approaches for financing wastewater treatment are required.

Added Values of Time Series in Material Flow Analysis: The Austrian Phosphorus Budget from 1990 to 2011

Summary Material flow analysis is a tool that is increasingly used as a foundation for resource management and environmental protection. This tool is primarily applied in a static manner to individual years, ignoring the impact of time on the material budgets. In this study, a detailed multiyear model of the Austrian phosphorus budget covering the period 1990–2011 was built to investigate its behavior over time and test the hypothesis that a multiyear approach can also contribute to the improvement of static budgets. Further, a novel method was applied to investigate the quality and characteristics of the data and quantify the uncertainty. The degree of change between the budgets was assessed and showed that approximately half of the flows have changed significantly and, at times, abruptly since 1990, but it is not possible to distinguish unequivocally between constant and moderately changing flows given their uncertainty. The study reveals that the phosphorus transported in waste flows has increased more rapidly than its recovery, which accounted for 55% to 60% of the total waste phosphorus in 1990 and only 40% in 2011. The loss ratio in landfills and cement kilns has oscillated in the range of 40% to 50%. From a methodological point of view, the multiyear approach has broadened the conceptual model of the budget, making it more suitable as a basis for material accounting and monitoring. Moreover, the analysis of the data reconciliation process over a long period of time proved to be a useful tool for identifying systematic errors in the model.

The Water Framework Directive: Can more information be extracted from groundwater data? A case study of Seewinkel, Burgenland, eastern Austria

Water protection is one of the most important goals in environmental protection. The Clean Water Act in the USA and the Water Framework Directive (WFD) in Europe are the legal frameworks to facilitate the achievement of this goal. The question is raised of whether more information can be extracted from WFD-related groundwater data. To answer it, a methodology has been developed that is easy to use and could be implemented into official practice. A case study is presented in which the groundwater data of a sodic area in Austria (Seewinkel) is assessed. Eighteen parameters in groundwater sampled from 23 wells (1991–2011) were analyzed. With basic statistics, trend-, cluster-, Wilks’ λ and spatial sampling density analysis, local phosphorus and boron phenomena were described, along with the determining role of sulphate, groundwater flow, and the oxygen gradient in the area. As a final step, the spatial sampling density was determined. Regarding the current set of parameters, all the sampling sites are necessary and only in the case of certain parameters (Ca2+, Mg2+, K+, NO3−, pH) could one sampling site be abandoned. The methodology applied brings a new perspective to exploring groundwater data collected according to the requirements of the WFD.ZusammenfassungGewässerschutz ist eines der wichtigsten Ziele im Umweltschutz. Der “Clean Water Act” in den USA und die Wasserrahmenrichtlinie (WRRL) in Europa sind die rechtlichen Rahmenbedingungen, um dieses Ziel zu erreichen. Dabei stellt sich die Frage, ob weitere verbesserte Informationen aus den derzeitigen Grundwasserqualitätsmessungen, die im Rahmen der WRRL erhoben werden, gewonnen werden können. Um diese Frage zu beantworten, wurde eine Methodik entwickelt, die einfach zu bedienen ist und leicht in die offizielle Auswertungspraxis umgesetzt werden könnte. In der vorgestellten Fallstudie wurden die Daten eines Grundwasserkörpers in Österreich (Seewinkel) mit der entwickelten Methode ausgewertet. Dazu wurden achtzehn Parameter aus 23 Grundwassergütemessstellen für die Jahre 1991–2011 analysiert. Dazu wurden grundlegende statistische Methoden wie Trend -, Cluster -, Wilks’ λ Analyse und die Auswertung der räumlichen Verteilung der Messdichte verwendet. Unter Berücksichtigung mit der bestimmenden Rolle von Sulfat, der Grundwasserfließrichtung und -zeit und dem Sauerstoffgradienten im Untersuchungsgebiet Seewinkel konnten lokale Phosphor und Bor Phänomene beschrieben werden. Im letzten Schritt wurde die räumliche Verteilung der Messdichte bestimmt. Die Datenanalysen zeigten, dass alle, bis auf eine Ausnahme, vorhandenen Messstellen und deren Parameter (Ca2+, Mg2+, K+, NO3−, pH-Wert) für Auswertungen verwendet werden konnten. Die angewandte Methodik bringt bei der Analyse der erhobenen Grundwasserqualitätsdaten, welche nach den Anforderungen der WRRL erhoben werden, eine neue Perspektive.RésuméLa protection de l’eau est l’un des objectifs les plus importants de la protection environnementale. Le Clean Water Act aux Etats Unis et la Directive-Cadre sur l’Eau (DCE) en Europe sont les cadres légaux pour favoriser l’atteinte de cet objectif. La question est posée de savoir si l’on peut tirer d’avantages d’informations des données sur l’eau souterraine relatives à la DCE. Pour répondre à celle-ci, on a développé une méthodologie simple, pouvant être mise en pratique de façon officielle. Le cas présenté considère les données sur l’eau souterraine d’un district sodique d’Autriche (Seewinkel). Dix huit paramètres de l’eau de 23 puits échantillonnés (1991–2011) ont été analysés. Avec les paramètres statistiques de base, tendance, classes, paramètre λ de Wilks et analyse de la densité spatiale d’échantillonnage, les phénomènes locaux liés au phosphore et au bore ont été décrits, ainsi que le rôle déterminant du sulfate, le flux d’écoulement souterrain et le gradient de l’oxygène dans la zone. En phase finale, la densité d’échantillonnage spatial a été déterminée. Etant donné le jeu de paramètres considérés, tous les sites échantillonnés sont nécessaires, les sites où certains paramètres (Ca2+, Mg2+, K+, NO3−, pH) ne pouvaient être mesurés étant abandonnés. La méthodologie appliquée ouvre une nouvelle perspective dans l’exploitation des données sur l’eau souterraine prélevées selon les dispositions de la Directive-Cadre sur l’Eau.ResumenLa protección del agua es uno de los objetivos más importantes en la protección ambiental. La Ley de Aguas Limpias en EEUU y la Directiva Marco del Agua (WFD) en Europa son los marcos legales para facilitar el logro de este objetivo. La cuestión se plantea si se puede extraer mayor información de los datos de agua subterránea relacionados con WDF. Para responder se desarrolla una una metodología que es fácil de usar y podría ser implementada dentro de la práctica oficial. Se presenta un caso de estudio en el cual se evaluaron los datos de agua subterránea de un área sódica en Austria (Seewinkel). Se analizaron dieciocho parámetros en el agua subterránea muestreada de 23 pozos (1991–2011). Con estadísticas básicas, tendencias, clusters, Wilks’ λ y análisis de densidad espacial de muestreo se describieron los fenómenos locales de fósforo y de boro fueron descriptos, conjuntamente con el rol determinante del sulfato, del flujo de agua subterránea, y del gradiente de oxígeno en el área. Como una etapa final, se determinó la densidad de muestreo espacial. En relación con el conjunto actual de parámetros, todos los sitios de muestreos son necesarios y solamente en el caso de ciertos parámetros (Ca2+, Mg2+, K+, NO3−, pH) podría un sitio de muestreo ser abandonado. La metodología aplicada otorga una nueva perspectiva para explorar los datos de agua subterránea recolectados de acuerdo a los requerimientos de la WFD.الملخصحماية المياه هي واحدة من اهم الاهداف في الحماية البيئية. قانون المياه النظيفة في الولايات المتحدة الامريكية والاطار التوجيهي للمياه(WFD) في اوروبا هما من الاطر القانونية لتسهيل تحقيق هذا الهدف . اثيرت مسألة ما اذا كان مزيد من المعلومات يمكن استخصلاصها من الاطار التوجيهي للمياه (WFD) – المتعلقة ببيانات المياه الجوفية. للاجابة على ذلك ، تم تطوير منهجية سهلة الاستخدام ويمكن تنفيذها في الممارسة الرسمية . قدمت دراسة الحالة التي يتم فيها تقييم بيانات المياه الجوفية من منطقة سوديك في النمسا .(Seewinkel) حللت ثمانية عشر معيارا في المياه الجوفية قد تم اخذ عيناتها من ٢٣ بئرا (١٩٩١-٢٠١١).مع احصائية بسيطة، الاتجاه ،الكتلة ، ويلكس λ ومكانية تحليل كثافة اخذ العينات . ظاهرة الفوسفور والبورون المحلية قد وصفت جنبا الى جنب مع دور تحديد الكبريتات ، تدفق المياه الجوفية، والتدرج الاوكسجين في المنطقة . كخطوة نهائية ، تم تحديد كثافة اخذ العينات المكانية . وفيما يتعلق المجموعة الحالية من المعاير ، جميع مواقع اخذ العينات ضرورية و فقط في حالة معايير معينة (Ca2+, Mg2+, K+, NO3-, pH) يمكن ان يتم التخلي عن موقع واحد.المنهجية المطبقة يجلب منظورا جديدا لاستكشاف بيانات المياه الجوفية التي تم جمعها وفق لمتطلبات الاطار التوجيهي للمياه (WFD) .摘要水保护是环境保护中最重要的目标之一。美国的清洁水法及欧洲水框架指令是促进完成这个目标的法律体系。是否能从水框架指令有关的地下水数据中提取更多信息的问题被提了出来。为回答这个问题,开发了便于使用、能够正式实施的方法。展示了一个研究实例,在这个实例中,评价了奥地利(Seewinkel)含钠区的地下水数据。分析了23口井(1991–2011年)中地下水样品的十八个参数。描述了基本统计数字以及趋势的、簇群的Wilks’ λ、空间采样密度分析、局部磷和硼现象,并确定了该区的硫酸盐的作用、地下水流和氧梯度。作为最后一步,确定了空间采样密度。关于目前参数(Ca2+, Mg2+, K+, NO3−, pH)的设置,所有的采样地点都很必要,只有在某些参数情况下,一个采样点可以放弃。所应用的方法给探索按照水框架指令要求收集到的地下水数据带来了新的前景。SamenvattingWater bescherming is een van de belangrijkste doelen in bescherming van het milieu. De Clean Water Act in de Verenigde Staten en de Water Framework Directive in Europa zijn de wettelijke kaders waarin deze doelen worden bereikt. De vraag is opgekomen of meer informatie verkregen kan worden van WFD gerelateerde grondwater data. Om deze vraag te beantwoorden is een methode ontwikkeld die makkelijk te gebruiken is en geimplementeerd kan worden door officiele instanties. Een case study wordt gepresenteerd waarin grondwater data van een alkali regio in Oostenrijk (Seewinkel) wordt beoordeeld. Achttien parameters in grondwater bemonsterd in 23 verschillende peilbuizen (1991–2011) zijn geanalyseerd. Met behulp van basis statistiek, trend-, cluster-, Wilks’ λ en ruimtelijke bemonster dichtheid analyses, werden lokale fosfor en boor fenomenen beschreven, net als de bepalende rol van sulfaat, grondwater stroming, en de zuurstof gradient in het onderzoeksgebied. Als laatste stap werd de ruimtelijke bemonster dichtheid bepaald. Met betrekking tot de huidige set aan parameters, waren alle bemonsteringsplekken noodzakelijk. Slechts bij sommige parameters (Ca2+, Mg2+, K+, NO3-, pH) kon één bemonsteringsplek worden opgegeven. De gebruikte methodologie geeft een nieuw perspectief aan het onderzoeken van grondwater data die verzameld zijn volgens de eisen van de WFD. KivonatA felszíni és felszín alatti vizeink jó állapotban való megőrzése a környezetvédelem egyik legfontosabb célja. Az Amerikai Egyesült Államokban a “Clean Water Act”, Európában pedig a Víz Keretirányelv biztosítja a jogi keretet ezen célok eléréséhez. Felmerül azonban a kérdés, hogy hordoznak-e számottevő többletinformációt a felszín alatti víz monitoring adatok a Víz Keretirányelv által előírt vizsgálatok eredményein túl. A kérdés megválaszolására egy olyan módszertant dolgoztunk ki, amely könnyen alkalmazható a környezetvédelmi hivatali gyakorlatban is. Esettanulmányként, egy ausztriai szikes terület (Seewinkel) 23 felszín alatti víz monitoring kútjának 18 paraméterének idősorait dolgoztuk fel az 1991–2011-es időintervallum vonatkozásában alap- és Wilks’ λ statisztikák, valamint trend-, klaszter-, és variogram analízis felhasználásával. Az eredmények alapján a terület bizonyos részein lokális foszfor, bór és szulfát anomália, illetve az egész területre vonatkozó oxigén gradiens figyelhető meg. Végezetül meghatároztuk a szükséges térbeli mintavételezési gyakoriságot. Az összes mért paramétert figyelembe véve minden mintavételi pontra szükség van a területen, csak néhány paraméter vonatkozásában (Ca2+, Mg2+, K+, NO3−, pH) lehetne egy mintavételi pontot megszüntetni. Az alkalmazott módszertan egy újszerű megk

daNUbs: Lessons learned for nutrient management in the Danube Basin and its relation to Black Sea euthrophication

The results of the daNUbs-project deliver a basis for a proper management of nutrients in the Danube Basin. The understanding of the sources, pathways, and sinks of nutrients in the Basin and their effects on the Western ad North-Western Black Sea (WBS) ecosystem has been improved. Quantitative models on the emission of nutrients, their transport along the rivers, and their impact on the WBS have been further developed and combined. Phosphorus loads discharged by the Danube are 30–50% lower than in the 1980s (dissolved P even to a higher extent). Nitrogen emissions have decreased considerably as well. The lower nutrient discharges from the Danube have led to a significant improvement in the WBS ecosystem. Current low discharges of N and P to the WBS are the result of (1) improved nutrient removal from waste water in Germany, Austria, and Czech Republic, (2) reduced P-discharges from detergents and (3) the consequences of the economic crisis in central and eastern European countries following the political changes of 1989/1990. As the decrease is partly due to the economic breakdown in the formerly communist countries, economic development in these countries has to go along with proper nutrient management. Otherwise, the situation in the WBS ecosystem will deteriorate again.