The ResourcePlan—An Instrument for Resource-Efficient Development of Urban Neighborhoods

In Germany, the current sectoral urban planning often leads to inefficient use of resources, partly because municipalities lack integrated planning instruments and argumentation strength toward politics, investors, or citizens. The paper develops the ResourcePlan as (i) legal and (ii) a planning instrument to support the efficient use of resources in urban neighborhoods. The integrative, multi-methodological approach addresses the use of natural resources in the building and infrastructural sectors of (i) water (storm- and wastewater) management, (ii) construction and maintenance of buildings and infrastructure, (iii) urban energy system planning, and (iv) land-use planning. First, the development as legal instrument is carried out, providing (i) premises for integrating resource protection at all legal levels and (ii) options for implementing the ResourcePlan within German municipal structures. Second, the evaluation framework for resource efficiency of the urban neighborhoods is set up for usage as a planning instrument. The framework provides a two-stage process that runs through the phases of setting up and implementing the ResourcePlan. (Eco)system services are evaluated as well as life cycle assessment and economic aspects. As a legal instrument, the ResourcePlan integrates resource protection into municipal planning and decision-making processes. The multi-methodological evaluation framework helps to assess inter-disciplinary resource efficiency, supports the spatial identification of synergies and conflicting goals, and contributes to transparent, resource-optimized planning decisions.BMBF, 033W102E, RESZ - Verbundvorhaben: R2Q - RessourcenPlan im Quartier - Teilprojekt 5: Ganzheitliche Bewertung der Ressourceneffizienz von Stadtquartiere

Organic Membrane Fouling in Ultrafiltration of Municipal Secondary Effluents - Causes, Mechanisms, and Measures for its Reduction

Die Filtration von Kläranlagenabläufen über Niederdruckmembranen ermöglicht die weitreichende Entfernung von pathogenen Mikroorganismen sowie die vollständige Entfernung von Fällungsprodukten der chemischen Phosphorelimation zum weitergehenden Schutz der aufnehmenden Gewässer. Ein großes Problem beim Einsatz von Niederdruckmembranen ist der Verlust der Filtrationsleistung aufgrund deren Verblockung durch Wasserinhaltsstoffe, das sog. Membranfouling. Untersuchungsgegenstand dieser Arbeit ist das durch gelöste organische Substanzen verursachte Fouling von Ultrafiltrationsmembranen bei der Filtration von Kläranlagenabläufen. Anhand von Testzellenversuchen mit Flach- und Hohlfasermembranen wurde mittels Größenausschlusschromatographie (LC-OCD) die hochmolekulare Fraktion der Biopolymere (Polysaccharide, Proteine sowie weitere organische Makromoleküle bzw. Kolloide mikrobiellen Ursprungs) im Kläranlagenablauf als Hauptverursacher des organischen Foulings identifiziert. Der Einfluss von Huminstoffen und niedermolekularen Verbindungen auf die Filtrationsleistung der Membranen erwies sich als gering. Zur gezielten Variation der Biopolymerkonzentration im Kläranlagenablauf wurde eine Methode zur Anreicherung und Extraktion natürlicher extrazellulärer polymerer Substanzen (EPS) aus einer Kultur des Bakteriums Sinorhizobium sp. entwickelt. Der Zusammenhang zwischen Biopolymerkonzentration und Intensität des Foulings wurde in Filtrationsversuchen mit Lösungen dieser bakteriellen EPS bestätigt. Das durch klarlaufeigene Biopolymere verursachte Fouling konnte mit den bakteriellen EPS nicht exakt simuliert werden, was auf die Bedeutung der qualitativen Zusammensetzung der Biopolymerfraktion hinweist. Anhand von Filtrationsversuchen mit Hohlfasermembranen wurde eine Differenzierung zwischen hydraulisch reversiblem und irreversiblem Fouling vorgenommen. Es wurde eine gute Korrelation zwischen der Biopolymerkonzentration und der Höhe des reversiblen Filtrationswiderstands gefunden. Das Ausmaß des irreversiblen Foulings wird hingegen von der qualitativen Zusammensetzung der Biopolymerfraktion bestimmt. Mittels Fluoreszenzanalyse wurden Hinweise auf eine hohe Relevanz porengängiger Proteine hinsichtlich des irreversiblen Foulings gefunden. Die weitgehende Entfernung proteinartiger Substanzen durch biologische Langsamsandfiltration führte zur Elimination des irreversiblen Foulings. Neben der Biopolymerkonzentration wurden die Einflüsse von Adsorptionsprozessen, Permeatrückspülung sowie Calciumkonzentration berücksichtigt. Auf Grundlage der Ergebnisse werden die Mechanismen des organischen Foulings von Ultrafiltrationsmembranen und die Relevanz der Einflussfaktoren zusammenfassend diskutiert. Mit dem Ziel der selektiven Entfernung Fouling verursachender Biopolymere wurden Becherglasversuche zur Flockung und Adsorption von Kläranlagenablauf durchgeführt. Während an Aktivkohle organische Substanzen aller Größenfraktionen unselektiv adsorbieren, werden bei der Flockung mittels Eisen(III)- sowie Aluminiumchlorid Biopolymere im Vergleich zu den übrigen organischen Fraktionen überproportional entfernt. Nach Flockung von Kläranlagenablauf mit niedrigen Eisen(III)chloridkonzentrationen wurde bei der Ultrafiltration über Hohlfasermembranen eine Reduktion des irreversiblen Foulings aufgrund der überproportionalen Entfernung proteinartiger Substanzen beobachtet. Somit stellt die Vorbehandlung mittels Flockung eine Option zur Verringerung des organischen Membranfoulings dar.Municipal wastewater treatment is currently facing increasing demands regarding the enhanced protection of receiving water bodies and the reuse of secondary effluents as resource for drinking water production in scarcity areas. Low-pressure membrane filtration provides a potential alternative for the advanced removal of pathogens and, in combination with chemical coagulation, phosphorus. However, the loss of filtration performance due to membrane fouling is still a fundamental drawback. The objectives of this study were the characterisation of the principal dissolved organic foulants and the relevant fouling mechanisms in ultrafiltration of secondary effluent, as well as the investigation of pre-treatment processes. Bench-scale tests using flat-sheet and hollow-fibre membranes in combination with size exclusion chromatography (LC-OCD) revealed the predominant fouling potential of high-molecular biopolymers (i.e., polysaccharides, proteins, and other organic macromolecules of microbial origin) in secondary effluent. Humic substances and low-molecular organic compounds were shown to be of minor importance in terms of the filtration performance. A method for the production and extraction of extracellular polymeric substances (EPS) from the bacterium Sinorhizobium sp. was developed, allowing controlled variations of the concentration of natural EPS in secondary effluent. Ultrafiltration of solutions of these EPS confirmed the impact of biopolymers on the intensity of membrane fouling. However, the fouling due to biopolymers contained in secondary effluent could not exactly be reproduced by extracted bacterial EPS, indicating the relevance of the qualitative composition of the biopolymer fraction. The differentiation in terms of hydraulically reversible and irreversible fouling was conducted by ultrafiltration tests using backwashable hollow-fibre membranes. A good correlation between the reversible filtration resistance and the total concentration of biopolymers was found. However, the extent of the irreversible fouling depends on the qualitative composition of the biopolymer fraction. Fluorescence analysis indicated the high impact of proteins regarding the irreversible fouling, probably due to interactions with the membrane pores. The removal of protein-like substances by biologically active slow sand filtration resulted in the elimination of irreversible fouling. Further investigations were carried out considering the influence of permeate backwash, calcium concentration and the adsorption of organic substances on the membrane surface. Based on these results, a mechanistic concept regarding the mechanisms of organic membrane fouling and the relevance of influencing factors is suggested. In order to investigate possibilities for the selective removal of fouling-active biopolymers from secondary effluent, coagulation and adsorption batch tests were conducted. Organic compounds of all molecular weight fractions adsorb onto activated carbon, whereas the coagulation using ferric chloride and aluminium chloride removes predominantly biopolymers and large humic substances. Coagulation of secondary effluent using comparatively low dosages of ferric chloride prior to hollow-fibre ultrafiltration resulted in the significant reduction of irreversible fouling. Fluorescence analysis indicated the preferential removal of protein-like substances by coagulation. Therefore, coagulation seems to be a promising pre-treatment process for the reduction of irreversible organic membrane fouling

The ResourcePlan—An Instrument for Resource-Efficient Development of Urban Neighborhoods

In Germany, the current sectoral urban planning often leads to inefficient use of resources, partly because municipalities lack integrated planning instruments and argumentation strength toward politics, investors, or citizens. The paper develops the ResourcePlan as (i) legal and (ii) a planning instrument to support the efficient use of resources in urban neighborhoods. The integrative, multi-methodological approach addresses the use of natural resources in the building and infrastructural sectors of (i) water (storm- and wastewater) management, (ii) construction and maintenance of buildings and infrastructure, (iii) urban energy system planning, and (iv) land-use planning. First, the development as legal instrument is carried out, providing (i) premises for integrating resource protection at all legal levels and (ii) options for implementing the ResourcePlan within German municipal structures. Second, the evaluation framework for resource efficiency of the urban neighborhoods is set up for usage as a planning instrument. The framework provides a two-stage process that runs through the phases of setting up and implementing the ResourcePlan. (Eco)system services are evaluated as well as life cycle assessment and economic aspects. As a legal instrument, the ResourcePlan integrates resource protection into municipal planning and decision-making processes. The multi-methodological evaluation framework helps to assess inter-disciplinary resource efficiency, supports the spatial identification of synergies and conflicting goals, and contributes to transparent, resource-optimized planning decisions