Bei der Verwertung von Grünabfällen werden holzige Anteile teilweise separiert und als Brennstoff abgegeben. Die bei der thermischen Nutzung von diesen und anderen biogenen Brennstoffen anfallende Holzasche wird u.a. Betreibern von Kompostierungsanlagen zur Zumischung bei der Kompostierung angeboten. Da Holzaschen unterschiedliche Verwertungs- und Entsorgungswege gehen können, wird empfohlen, nur qualitätsgesicherte Holzasche anzunehmen.

This study exemplifies the use of Life Cycle Assessment (LCA) as a tool to quantify the environmental impacts of processes for wastewater treatment. In a case study, the sludge treatment line of a large wastewater treatment plant (WWTP) is analysed in terms of cumulative energy demand and the emission of greenhouse gases (carbon footprint). Sludge treatment consists of anaerobic digestion, dewatering, drying, and disposal of stabilized sludge in mono- or co-incineration in power plants or cement kilns. All relevant forms of energy demand (electricity, heat, chemicals, fossil fuels, transport) and greenhouse gas emissions (fossil CO2,CH4,N2O) are accounted in the assessment, including the treatment of return liquor from dewatering in the WWTP. Results show that the existing process is positive in energy balance (–162 MJ/PECOD * a) and carbon footprint (–11.6 kg CO2-eq/PECOD *a) by supplying secondary products such as electricity from biogas production or mono-incineration and substituting fossil fuels in co-incineration. However, disposal routes for stabilized sludge differ considerably in their energy and greenhouse gas profiles. In total, LCA proves to be a suitable tool to support future investment decisions with information of environmental relevance on the impact of wastewater treatment, but also urban water systems in general.

To sustain good harvests, about 975,000 tons of mineral phosphorus need to be imported to Europe every year, while the potentials to recover and recycle this essential resource remain untapped or are just inefficiently used as in the case of sewage sludge. In the recent years various technical alternatives to the traditional but disputed application of sludge in agriculture have been developed to recover the nutrient. Especially user friendly solutions have already made their way to full-scale or at least pilot-scale application. National and international initiatives are dedicated to foster the implementation of new solutions, to bridge the gaps between the relevant sectors of science, policy and industry to finally increase the overall anthropogenic phosphorus efficiency according to the motto of the recent First European Sustainable Phosphorus Conference: use less, recycle more and cooperate smart. (www.phosphorusplatform.eu)

A pilot plant with a full scale monolithic ceramic membrane was operated at Ruhleben wastewater treatment plant (WWTP), Berlin Germany, for more than 12 months. Filtration performance according to the applied pre-treatment (dose of ozone and coagulant) were investigated. Trial runs with and without ozone, varying the operational parameters such as flux, coagulant dosage, and filtration time were conducted in order to identify the benefits of pre-ozonation. The reduction of the total fouling rate by ~70 % when applying a specific ozone dose between 1.0 and 1.4 mg mgDOC–1 highlights the potential of ozonation as pre-treatment step. Using LC-OCD measurements, the effect of ozone on the biopolymer concentration and the DOC fraction was demonstrated.

Die reinigung von Abwasser ist sehr energieintensiv. die kommunale abwasserbehandlung zählt deshalb noch vor Schulen und krankenhäusern zu den größten Stromverbrauchern. in den rund 10.000 deutschen kläranlagen schlummern allerdings erhebliche einsparpotenziale und sogar bislang ungenutzte energieressourcen, die noch erschlossen werden können.

Data play an important role in water-related research. In the field of limnology, monitoring data are needed to assess the ecological status of water bodies and understand the bio-geochemical processes that affect this status. In wastewater management, measured or simulated data are the basis for planning and control of sewer networks. Given the importance of data in water-related research makes them a valuable resource, which should be handled in an adequate way. Based on experiences in data collection and data processing in water-related research this paper proposes – both from a computer scientist’s and an environmental engineer’s point of view – a set of rules for data handling: Rule 1: Protect raw data. Rule 2: Save metadata. Rule 3: Use databases. Rule 4: Separate data from processing. Rule 5: Use programming. Rule 6: Avoid redundancy. Rule 7: Be transparent. Rule 8: Use standards and naming conventions. Applying these rules (i) increases the quality of data and results, (ii) allows to prepare data for long-term usage and make data accessible to different people, (iii) makes data processing transparent and results reproducible, and (iv) saves – at least in the long run – time and effort. With this contribution the authors would like to start a discussion about best data handling practices and present a first checklist of data handling and data processing for practitioners and researchers working in the water sector.

The study aims at assessing in long-term trials a gravity-driven ultrafiltration pilot plant designed for a capacity of 5 m3/d. The unit was operated in South Africa with Ogunjini surface water and was run with restricted chemical intervention or maintenance (no backflush, no aeration, no crossflow and no chemical). Under South African environmental conditions and with direct filtration of the river water and only one manual drainage of the membrane reactor every weekday, the unit could fulfil the design specification in terms of water production (5 m3/d) as long as the turbidity of the raw water remained in a reasonable level (up to 160 NTU), with a filtration flux typically 4 to 6 L/h.m² (corrected at 20°C). This value was in the same range as the lab results and was consistent with the first phase results (around 5-7 L/h.m² after biosand filtration). However, the flux dropped significantly to a range of 2 to 4 L/h.m² after a rain event resulting in a turbidity peak over several days up to > 600 NTU. This demonstrated that for variable raw water types with expected turbidity peaks above 100 NTU, a pre-treatment would be required for the system (biosand filter or other). The performance of microbiological tests confirmed the integrity of the membrane and the ability of the system to achieve advanced disinfection.

Im Rahmen eines Forschungsprojektes wurden die Auswirkungen von Mischwasserentlastungen auf die Berliner Stadtspree untersucht und ein Planungsinstrument zur Reduzierung der Auswirkungen von Mischwasserüberläufen entwickelt.

Der Einsatz von Filtern zur Reduzierung von Stickstoff- und Phosphoreinträgen aus der Landwirtschaft in die Oberflächengewässer wurde in Deutschland bisher kaum untersucht. In einem Workshop wurde der Stand der Untersuchungen von Projekten in Polen, Dänemark, Deutschland und Frankreich vorgestellt. Um das Potential dieser Maßnahmen auszuschöpfen, sind die Entwicklung von Entscheidungsunterstützungssystemen für geeignete Einsatzorte und weitere Demonstrationsprojekte unter Feldbedingungen notwendig.