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Aufgrund ihrer Struktur sind insbesondere urbane Strukturen von Klimafolgen wie z.B. Hitze, Stürme oder Starkregen betroffen. Der Raum- und Umweltplanung kommt dabei hinsichtlich der sozial-ökologischen Naturverhältnisse eine wichtige Rolle zu, sofern sie die Aufgaben der Krisenbewältigung annehmen und verantwortungsvoll wahrnehmen will. Auch die Hansestadt Lüneburg steht zukünftig vor einigen Herausforderungen. Durch den allgemeinen Trend der Urbanisierung und als Teil der Metropolregion Hamburg gilt Lüneburg als beliebter Wohnraum. Die vorliegende Arbeit lenkt den Blick auf die Klimafolgenanpassung bei Starkregen in der Stadtplanung allgemein und auf die Hansestadt Lüneburg. Zunächst werden die der Ausarbeitung zugrundegelegten Begriffe sowie die Bedeutung von Starkregenereignissen in der Stadtplanung definiert und näher erläutert. Darauf folgt die Darstellung der zur Beantwortung der Forschungsfrage verwendeten Methoden. Anschließend werden in der empirischen Forschung das bisherige Auftreten von Starkregen analysiert, bestehende Adaptionsstrategien norddeutscher Städte und Regionen aufgezeigt, ein Zukunftsausblick auf Grundlage wissenschaftlicher Prognosen gegeben und konkrete, auf die Hansestadt Lüneburg bezogene Analysen und Szenarien erstellt, bevor ein Resümee der empirischen Forschung gezogen werden kann. Abschließend wird das methodische Vorgehen reflektiert, die Ergebnisse diskutiert und ein kurzer Ausblick auf zukünftige Herausforderungen gegeben.
Der hochwassergebundene Sedimenteintrag ist Motor der Bodenbildung in Auen. Der mit dem Sedimenteintrag einhergehende Schadstofftransport in die flussbegleitenden Auen ist Ursache für die Akkumulation von Schadstoffen in den aquatischen und semiterretrischen Systemen. Er wirkt in weiten Teilen der Elbauen nicht nur einschränkend auf die landwirtschaftliche Nutzung des Grünlandes sondern beeinträchtigt daneben auch weitere Schutzgüter, wie z. B. Habitate und Lebensgemeinschaften. Diese Arbeit hatte das Ziel, die Steuergrößen des Sediment- und Schadstoffeintrags anhand von langjährig erhobenen Messdaten zu untersuchen und gleichzeitig die zeitliche und räumliche Verbreitung ausgewählter Schadstoffe als Baustein eines belastungsangepassten Auenmanagements aufzuklären. Dafür wurden eigene Daten über Hochflutsedimente und Böden ebenso ausgewertet wie Daten anderer Autoren. Außerdem lag ein Schwerpunkt der Arbeit in der kombinierten Auswertung von Zeitreihen der Sedimentbelastung von Gewässern und von Auenböden, die eine Grundlage für das Verständnis des elbespezifischen Belastungsmosaiks von Böden mit Schwermetallen und Dioxinen/Furanen darstellt. Zunächst erfolgte eine detaillierte Recherche und Analyse der retentionsfördernden Eigenschaften der Elbauen. Es wurden abschnittsspezifische Flächengrößen, Landnutzungsunterschiede und Flächenbetroffenheiten bei unterschiedlichen Hochwasserzuständen herausgearbeitet. Mit Hilfe der darauf aufbauenden, datenbasierten Analysen über ereignisbezogene Sedimenteinträge in die Elbauen konnten wesentliche Steuergrößen des Sedimenteintrags identifiziert werden. Die Distanz der Standorte zur Elbe ist die wesentliche Kenngröße, sodass die größten Sedimenteinträge in Flussnähe stattfinden. Darüber hinaus ist die Höhe des Sedimenteintrags abflussabhängig. Auf dieser Grundlage wurde ein Ansatz zur Berechnung des großräumigen Sedimenteintrags entwickelt, mit dessen Hilfe die Retentionsfunktion der Auen im Abfluss- und Stofftransportgeschehen der Elbe abgeschätzt werden konnte. Die Sedimentretention der Elbauen hatte im Betrachtungszeitraum zwischen 2003 und 2008 einen Anteil von 7 bis 30 % an den Jahresschwebstofffrachten in Hitzacker. Die Analysen von verschiedenen Zeitreihen der Sediment- und Bodenbelastungen mit Schwermetallen, Arsen sowie Dioxinen/Furanen verdeutlichte, dass die Stoffgruppen ganz unterschiedliche Belastungsentwicklungen durchlaufen haben. Der Schwerpunkt der Dioxinkontamination in Sedimenten und Böden trat in den 1950er bis 1960er Jahren auf, während Metalle im Allgemeinen erst später Belastungsmaxima zeigten. Allerdings konnte mit dem Pb/Zn-Verhältnis ein Metallmuster identifiziert werden, mit dessen Hilfe auch in Oberböden auf der Basis von Metalldaten auf Dioxinbelastungen geschlossen werden konnte. Darüber hinaus wurde unter Kenntnis der spezifischen Belastungshistorien mittels Kategorisierung der Standorteigenschaften Höhenlage, Distanz, Bioturbation und Sedimenteintrag ein Erklärungsschema zur Vorhersage von räumlichen Schadstoffmustern für ausgewählte Metalle und Dioxine/Furane entwickelt. Sowohl die Untersuchungen zum Sedimentationsgeschehen als auch zur Aufklärung des Belastungsmosaiks in den Elbauen ließen Ableitungen von Maßnahmenvorschlägen zur Förderung der Sedimentationsdynamik, des Hochwasserschutzes, zur schadstoffspezifischen Verbesserung der Bodenbelastung als auch zur belastungsangepassten Landnutzung zu.
Agricultural production of smallholder farmers in Myanmar is facing soil fertility degradation and in consequence, crop yields decline due to the imbalances of nutrient supply. In most cases, all above ground biomass is removed from the fields after harvesting the crops and during land preparation for the next crop. Higher temperatures also stimulate the higher mineralisation rates and released mineral nutrients are lost from fallow lands before sowing the next crops. Regarding the addition of mineral fertilizers, except for cash crops, farmers are reluctant to apply fertilizers for the crops that are sown for household’s self-sufficiency. In the Dry Zone, irrigated agriculture is available in recent years and farmers could overcome water scarcity through irrigation. With the availability of irrigation water, farmers could prolong the cropping period, nevertheless crop yields are decreasing year by year. In recent decades, research findings are indicating the benefits of biochar application for soil fertility improvement and food security. Smallholder farmers can produce biochar from agricultural by-products such as pigeon pea stems, cotton stems and rice husks by using biochar stoves. Large-scale production is possible by producing both biochar and thermal energy simultaneously, such as getting rice husk biochar and producing thermal energy by burning rice husks. By those means, environmental pollution due to the smokes from stubble burnings and the health hazards from smokes arise from kitchens can also be reduced. Present research was conducted to test the effects of the application of biochars produced from different crop residues together with NPK fertilizers on crop yields and soil properties in the rice-chickpea-cotton cropping system of the Central Dry Zone area of Myanmar during 2012 and 2013 cropping seasons at Shwe Daung Farm, Mandalay Division, Myanmar. Effects of biochar applications in combination with NPK fertilizers were compared with NPK fertilizer (without biochar) application and the control (without biochar and NPK fertilizers). Biochars used in the experiments were produced from three kinds of locally available raw materials (rice husk, rice straw and, pigeon pea stem) at temperature above 550°C by using a kiln made from a 200-Liter diesel barrel. Field experiments were conducted on sandy loam soil in the Central Dry Zone of Myanmar. After harvesting rice in 2012, chickpea was sown without application of both organic and inorganic fertilizers. After harvesting chickpea in 2013, cotton was sown on the same experimental plots. Treatments were rice husk biochar (Rh) 20 Mg ha-1 + NPK fertilizers; rice straw biochar (Rs) 20 Mg ha-1 + NPK fertilizers; pigeon pea stem biochar (Ps) 20 Mg ha-1 + NPK fertilizers; rice husk biochar and farmyard manure mixture (Rh biochar + FYM) 10 Mg ha-1 + NPK fertilizers; NPK fertilizers (without biochar); and the control (without fertilizer and biochar). Biochar weights represented fresh biochar weights. Equal rate of NPK fertilizers were applied in all treatments. However, fertilizer rates were different with respect to the crops. In rice experiment, 100:50:50 kg ha-1 rate of Urea (N): Triple Super Phosphate (P): Muriate of potash (K) was applied. In cotton experiment, 100:30:117 kg ha-1 rate of Urea (N): Triple Super Phosphate (P): Muriate of potash (K) was applied. Crop growth data, yield component data and yield data of each treatment were recorded. Soil samples from topsoil (0-0.2 m) were taken before starting the experiments, after harvesting rice and cotton, respectively, and analysed. A biogeochemical model, denitrification decomposition (DNDC) model, was used to estimate soil organic carbon storage and greenhouse gas emissions during crop growing seasons and to quantify the long-term impact of biochar applications on rice, chickpea and cotton yields.The results from soil analyses indicated that although initial soil pH was at 8.0 and pH values of biochars ranged between 8.0 and 10.0 soil pH after two years of biochar application did not increase. pH values were below 8.0. That value was lower than initial soil pH. That could be due to the effect of the change of cropping system from upland to lowland rice cultivation and the effects of biochar additions to the alkaline sandy loamy soil of the experimental site. Although total exchangeable cation value was not significantly different among the treatments, compositions of major cations were significantly different among the treatments. Exchangeable potassium increased in Rs biochar + NPK applied soils. Exchangeable sodium increased in control, and conventional NPK fertilizer applied soils. Reduction of soil bulk density from 1.8 g cm-3 to 1.6-1.7 g cm-3 occurred in biochar treatments compared to control and conventional NPK fertilizer application treatments. Positive changes of total carbon and total nitrogen of soils were found in biochar treatments compared to control and conventional NPK fertilizer application. Application of pigeon pea stem biochar + NPK fertilizers showed the highest crop growth and the highest yield in rice. The highest chickpea yield was obtained from the plot that applied rice husk biochar + NPK fertilizers. Cotton crop growth and yield was the highest in rice husk biochar and farmyard manure mixture + NPK fertilizer application. The lowest crop growth and yield was obtained from the control in cotton. The results of this study suggested that biochars from different biomass materials had different effects on soil properties and crop yields under different growing conditions and cultivated crops. Although the applied biochars had a high pH, soil pH did not increase after biochar applications. The growth and yield of tested crops were higher than that of the control and conventional NPK fertilizer application. Rice husk biochar and farmyard manure mixture + NPK fertilizer application can be assumed as a suitable soil amendment application under upland crop cultivation. Pigeon pea stems biochar + NPK fertilizers should be applied in rice cultivation. Rice husk biochar + NPK fertilizers and rice husk biochar-farmyard manure mixture + NPK fertilizers showed as the appropriate biochar soil amendments for the study area compared to rice straw biochar + NPK fertilizers and pigeon pea stem biochar + NPK fertilizers. Application of these biochars increased total exchangeable cations, reduced bulk density, increased organic carbon, regulated soil pH and, can easily be accessed by smallholder farmers by promising crop yields for sustainable agricultural production. Rice straw biochar + NPK fertilizers and pigeon pea stem biochar + NPK fertilizers also showed positive influences on soil fertility and crop growth. However, extensive application of those biochars might require large-scale productions and distributions. To obtain the detail information regarding the impact of biochar application on the agro-ecosystem and surrounding atmosphere, further research activities may need to carry out under different agricultural production conditions. When model fitness was tested, it was found that DNDC model was fit for the simulation of crop yields and soil organic carbon under the conditions of the experimental site. Simulation of soil organic carbon dynamics and crop yields for 30 years and 50 years after the addition of biochars in combination with NPK fertilizers showed that such applications could maintain the crop yields at the same level up to 50 years. That could maintain soil organic carbon at a level higher than conventional NPK fertilizer application. Regarding the simulation of GHGs emissions, the model simulated nitrous oxide emission close to actual emissions of agricultural soils of Myanmar. Simulated CH4 emissions from control and conventional NPK fertilizer application variant were consistent with the well-known emissions of Myanmar rice fields. To confirm the accuracy of simulated CH4 emissions from biochar applied soils, it may need field investigations and validations of model results. Simulated effects of rice husk-, rice straw- and pigeon pea stem fresh biomass applications and that of rice husk-, rice straw- and pigeon pea stem biochar applications on rice, chickpea, cotton yields and soil organic carbon (SOC) were compared. Objective of this simulation was to compare the effects of fresh biomass-applications and the application of biochars produced from the same biomass on crop yields and SOC by using DNDC model. The results showed that simulated rice yields of rice husk biochar and rice straw biochar applications were 33% and 31%, respectively, higher than that of pigeon pea green manure applications. However, simulated rice yield from pigeon pea stem biochar application was 4% higher than that of iv pigeon pea stem green manure application. Simulated chickpea yield from pigeon pea green manure treatment was the highest among all of biochar and biomass applications. Simulated cotton yields obtained from fresh biomass applications were lower than that of biochar applications. In estimating the future yields, all crop yields from rice husk and rice straw biomass applications were lower than that of rice husk and rice straw biochar applications in the initial year of simulation. However, in the following years, the yields remained at the same level up to the end of simulated years. In pigeon pea stem green manure application, crop yields were higher than the other treatments since the initial year up to the end of simulated years. Simulated SOC was lower in fresh biomass applications compared to biochar applications.
Die Entfernung von Phosphor aus Abwasser bleibt ein Forschungsthema, das in Zukunft nur an Wichtigkeit gewinnen kann. Das wird durch die Umweltauswirkungen der Eutrophierung und den Verlust eines essentiellen Nährstoffes für die Nahrungsmittelproduktion dessen Knappheit immer offensichtlicher wird, immer deutlicher. Auf Kläranlagen werden heute hauptsächlich zwei Techniken verwendet um Phosphor zu entfernen, biologisch aktive Verfahren wie das Enhanced Biological Phosphorus Removal (EBPR) Verfahren und Fällungstechniken unter Verwendung von Metallsalzen. Bei beiden Methoden gibt es gegenwärtig Schwierigkeiten wie z.B. die Instabilität des EBPR Prozesses wegen des Mangels an Wissen über die Grundlagen des Stoffwechselprozesses. Bei der Verwendung von Fällungsmitteln kommt es zu vielen Nachteilen im Zusammenhang mit der Nachbehandlung des Schlammes, bei der Entsorgung kommt es zu dem Verlust der Schlammmassen und damit auch des Phosphors aus dem Nährstoffkreislauf. Das Ergebnis dieser Forschung ist, dass es möglich ist, die Phosphorspeicherkapazität von Belebtschlamm zu erhöhen wenn dieser spezifische Anforderungen erfüllt. Diese Anforderungen werden wie folgt zusammengefasst: Die Schlammmasse muss in der Lage sein, EBPR Prozesse zu entwickeln, auch muss der Schlamm aus einem Belebungsbecken-System kommen, weil die Schlammflocken unter den Umgebungsbedingungen des Reaktors stabilisiert worden sind. Schließlich muss der Belebtschlamm aus einem Verfahren kommen, bei dem man für die Phosphorentfernung keine Metallsalze verwendet. Die erhöhte Phosphorstoffspeicherkapazität der Belebtschlammmassen in Verbindung mit der Möglichkeit den Phosphor aus dem Belebtschlamm über Rücklösung in die wässrige Phase wieder gewinnen zu können, bietet großes Potential in der Zukunft einen in der Abwasserwirtschaft geschlossenen Phosphorkreislauf zu entwickeln und so den Verlust des wichtigen Nährstoffes nachhaltig zu verhindern.
El-Salam Canal Project aims at increasing the Egyptian agricultural productivity through agricultural and stock development by irrigating about 263,500 ha gross of new lands. In order to stretch the limited water supply to cover these reclaimed areas, fresh River Nile water is augmented with agriculture drainage water from Hadus and Lower Serw drains to meet crop requirements, especially during summer months (peak demand). With a growing population and intensified industrial and agricultural activities, water pollution is spreading in Egypt, especially in main drains, which receive almost all kinds of wastes (municipal, rural, domestic and industrial wastes). The medical records indicate that significant numbers of waterborne-disease cases (bilharzias, typhoid, paratyphoid, diarrhoea, hepatitis A, B and C) have been reported in many areas in Egypt (MOHP, 2000). The National Water Quality Monitoring Program (NWQMP) in Egypt covers the Nile River, irrigation canals, drains and groundwater aquifers to assess the status of water quality for different water uses and users. The overall objective of this research is to introduce a rationalization technique for the drainage water quality-monitoring network for Hadus drain as a main feeder of El-Salam Canal Project. Later on, this technique can be applied for other parts in the NWQMP. The rationalization process started firstly with assessing and reformulating the current objectives of the network. Then, the monitoring locations were identified using integrated logical and statistical approaches. Finally, a sampling frequency regime was recommended to facilitate proper and integrated information management. The monitoring objectives were classified into three classes: design oriented, short-term and long-term deductible objectives. Mainly, the objectives “assess compliance with standards”, “define water quality problems”, “determine fate and transport of pollutants”, “make waste-load allocations” and “detect possible trends” were considered in the redesign process of the network. A combination of uni-, bi-, and multi-variate statistical techniques supported by spatial and temporal analysis for the important tributaries (key players) in Hadus drain system, were used for locating the monitoring sites. The key players analysis was carried out in the light of monitoring objectives. As a result, the monitoring network was divided into three priority levels (Layers I, II and III) as following: Layer I: It has the highest priority level and includes eight monitoring locations Layer II: It has the second priority level and includes three monitoring locations Layer III: It has the lowest priority level and includes five monitoring locations Using the method proposed by Lettenmaier (1976), the sampling frequencies were initially estimated and then evaluated for 36 water quality parameters, which were collected on monthly basis during the period from August 1997 to January 2005. The evaluation process was carried out by generating new data sets (subsets) from the original data. Then, the common required statistics from the monitoring network were extracted. The information obtained from different data sets was assessed using visual and statistical comparisons. Three integrated validation methods were employed to ensure that any decisions concerning the proposed program would not affect its ability to accomplish the monitoring objectives. These validation methods employed: descriptive statistics, regression analysis and linear multiple regression in an integrated approach. The validation results ensured that excluding the monitoring locations in layer III did not significantly affect the information produced by the monitoring network. Therefore, a monitoring network including only 11 sites (out of 16) representing the layers I and II was recommended. Based on the evaluation of sampling frequencies, it is recommended to have 6 (instead of 12) samples per year for 18 water quality parameters (COD, TSS, TVS, N-NO3, Pb, Ca, Na, Cl, Visib, BOD, Cu, Fe, Mn, pH, TDS, K, SO4_m and DO). The measured parameter SO4m will automatically replace the SO4 (calculated). SAR and Adj. SAR also can be calculated from the other parameters. For the other fifteen parameters (Mg, EC, Br, Ni, Sal, Cd, TN, TP, Temp, Fecal, Coli and N-NH4, Zn, P and Turb), it is recommended to continue with twelve samples per year. These recommendations may ensure significant reduction in the total cost of the monitoring network. This facilitates a fiscal resource, which is a key prerequisite in developing a successful program. The rescued budget can be redirected to achieve better performance in terms of improving the current resources. In addition, a frame of stakeholders-participation mechanism was proposed to not only facilitate a better coordination among the Egyptian Ministries involved in the water sector but also guarantee effective landowners/farmers involvement. However, applying such a mechanism requires more detailed studies of all the previous experiences gained by many projects trying to achieve better integration between objectives, plans and activities for the different environmental institutions in Egypt.
Die Arbeit liefert die Grundlagen zur chemischen Entfernung von Biodiesel aus dem Motoröl, um eine Minderung der Einschleppungsproblematiken beim Einsatz von biogenen Kraftstoffen und Dieselpartikelfiltern zu erzielen. Das Prinzip beruht auf einer wechselwirkenden Beimischkomponenten die eine Azeotropbildung mit Biodiesel einleitet. Eine gaschromatographische Headspace-Screening-Methode diente der Messung von Aktivitätskoeffizienten in Anwesenheit von Biodiesel. Die Ergebnisse dieser Analysen lieferten erste Erkenntnisse welche funktionalen Gruppen eine notwendige starke Wechselwirkung mit Biodiesel besitzen. Die gaschromatographischen Analysen wurden zudem mit Simulationsrechnungen mittels COSMOtherm untermauert. Im Laborversuch haben sich polare Säuren wie Ameisensäure oder Essigsäure als gute Beimischkomponenten erwiesen. Aldehyde, Ketone oder Alkohole sind weniger geeignet. Säuren wirken als Hydrogen Bond Donator und besitzen hohe Aktivitätskoeffizienten mit Biodiesel. Durch die Destillation des gebildeten azeotropen Gemischs kann die Entfernung von Biodiesel aus dem Motoröl bei niedrigen Temperaturen von ca. 180 Grad Celsius bis 190 Grad Celsius realisiert werden. Ohne den Einsatz von Beimischkomponenten liegt die Destillationstemperatur von Biodiesel bei ca. 330 Grad Celsius.
Urban areas are prone to climate change impacts. Simultaneously the world's population increasingly resides in cities. In this light, there is a growing need to equip urban decision makers with evidence-based climate information tailored to their specific context to adequately adapt to and prepare for future climate change. To construct climate information high-resolution regional climate models and their projections are pivotal. There is a need to move beyond commonly investigated variables, such as temperature and precipitation, to cover a wider breath of possible climate impacts. In this light, the research presented in this thesis is centered around enhancing the understanding about regional-to-local climate change in Berlin and its surroundings, with a focus on humidity. More specifically, following a regional climate modelling and data analysis approach, this research aims to understand the potential of regional climate models, and the possible added value of convection-permitting simulations, to support the development of high-quality climate information for urban regions, to support knowledge-based decision-making. The first part of the thesis investigates what can already be understood with available regional climate model simulations about future climate change in Berlin and its surroundings, particularly with respect to humidity and related variables. Ten EURO-CORDEX model combinations are analyzed, for the RCP8.5 emission scenario during the time period 1970-2100, for the Berlin region. The results are the first to show an urban-rural humidity contrast under a changing climate, simulated by the EURO-CORDEX ensemble, of around 6% relative humidity, and a robust enlarging urban drying effect, of approximately 2-4% relative humidity, in Berlin compared to its surroundings throughout the 21st century. The second part explores how crossing spatial scales from 12.5km to 3km model grid size affects unprecedented humidity extremes and related variables under future climate conditions for Berlin and its surroundings. Based on the unique HAPPI regional climate model dataset, two unprecedented humidity extremes are identified happening under 1.5°C and 2°C global mean warming, respectively SH>0.02 kg/kg and RH<30%. Employing a double-nesting approach, specifically designed for this study, the two humidity extremes are downscaled to the 12.5km grid resolution with the regional climate model REMO, and thereafter to the 3km with the convection-permitting model version of REMO (REMO NH). The findings indicate that the convection-permitting scale mitigates the SH>0.02kg/kg moist extreme and intensifies the RH<30% dry extreme. The multi-variate process analysis shows that the more profound urban drying effect on the convection-permitting resolution is mainly due to better resolving the physical processes related to the land surface scheme and land-atmosphere interactions on the 3km compared to the 12.5km grid resolution. The results demonstrate the added value of the convection-permitting resolution to simulate future humidity extremes in the urban-rural context. The third part of the research investigates the added value of convection-permitting models to simulate humidity related meteorological conditions driving specific climate change impacts, for the Berlin region. Three novel humidity related impact cases are defined for this research: influenza spread and survival; ragweed pollen dispersion; and in-door mold growth. Simulations by the regional climate model REMO are analyzed for the near future (2041-2050) under emission scenario RCP8.5, on the 12.5km and 3km grid resolution. The findings show that the change signal reverses on the convection-permitting resolution for the impact cases pollen, and mold (positive and negative). For influenza, the convection-permitting resolution intensifies the decrease of influenza days under climate change. Longer periods of consecutive influenza and mold days are projected under near-term climate change. The results show the potential of convection-permitting simulations to generate improved information about climate change impacts in urban regions to support decision makers. Generally, all results show an urban drying effect in Berlin compared to its surroundings for relative and specific humidity under climate change, respectively for the urban-rural contrast throughout the 21st century, for the downscaled future extreme conditions, and for the three humidity related impact cases. Added value for the convection-permitting resolution is found to simulate humidity extremes and the meteorological conditions driving the three impacts cases.
Algae-bacteria-based biotechnology has received more and more attention in recent years, especially in the subtropical and tropical regions, as an alternative method of conventional multistep wastewater treatment processes. Moreover, the algal biomass generated during wastewater treatment is regarded as a sustainable bioresource which could be used for producing biofuel, agricultural fertilizers or animal feeds. Although this technology is attractive, a number of obstacles need to be solved before large-scale applications. The main purposes of this work are to find more effective biomass harvesting strategies and develop high-effective algal-bacterial systems to improve wastewater treatment performance, biomass generation rate and biomass settleability. A wastewater-borne algal-bacterial culture, cultivated and trained through alternate mixing and non-mixing strategy, was used to treat pretreated municipal wastewater. After one month cultivation and training, the acclimatized algal-bacterial system showed high carbon and nutrient removal capacity and good settleability within 20 minutes of sedimentation. Algal biomass uptake was the main removal mechanism of nitrogen and phosphorus. The biomass productivity, nitrogen and phosphorus accumulation in biomass during the wastewater treatment process were investigated. The characterization of the microbial consortium composition in the enriched algal-bacterial system provided new insights in this research field. Aerobic activated sludge which already showed good settleability was used as bacterial inoculum to enhance the wastewater treatment performance and biomass settleability of algal-bacterial culture. The influence of different algae and sludge inoculum ratios on the treatment efficiency and biomass settleability was investigated. There was no significant effect of the inoculation ratios on the chemical oxygen demand (COD) removal. But algae/sludge inoculum ratio of 5 showed the best nitrogen and phosphorus removal efficiencies (91.0 ± 7.0% and 93.5 ± 2.5%, respectively) within 10 days. Furthermore, 16S rDNA gene analysis showed that the bacterial communities were varying with different algae and sludge inoculation ratios and some specific bacteria species were enriched during the operation. Four commonly used and high-potential microalgae species including one cyanobacteria (Phormidium sp.) and three green microalgae species (Chlamydomonas reinhardtii, Chlorella vulgaris and Scenedesmus rubescens) were cultivated and trained through alternate mixing and non-mixing strategy for tertiary municipal wastewater treatment. After one month of cultivation, the four microalgae species were compared in terms of biomass settleability, nutrient removal rates and biomass productivity. The three green microalgae showed good settleability within 1 h sedimentation and had higher biomass generation rates (above 6 g/m2/d). The nutrient removal efficiencies were 99% for the four selected microalgae species but within different retention time, resulting in 3.66 ± 0.17, 6.39 ± 0.20, 4.39 ± 0.06 and 4.31 ± 0.18 mg N/l/d (N removal rate) and 0.56 ± 0.07, 0.89 ± 0.05, 0.76 ± 0.09 and 0.60 ± 0.05 mg P/l/d (P removal rate) for Phormidium sp., Chlamydomonas reinhardtii, Chlorella vulgaris and Scenedesmus rubescens, respectively. A mixed algal culture composed of three selected high-effective green microalgae (Chlamydomonas reinhardtii, Chlorella vulgaris and Scenedesmus rubescens) was used for tertiary municipal wastewater treatment. The key biotic factor (algal inoculum concentration) and abiotic factors such as illumination cycle, mixing velocity and nutrient strength were studied. Based on the nitrogen and phosphorus balance, it was found that assimilation into algal biomass was the main removal mechanism.