This paper is one of the results, developed within the project OXERAM II by the Kompetenzzentrum Wasser Berlin. A pilot plant, equipped with a full (microfiltration) Berlin/Ruhleben. During the is operated for advanced wastewater project, different scale monolithic ceramic membrane treatment at WWTP pre-treatments, namely coagulation and the combination of coagulation and ozonation are applied. Multi-filtration trials in dead-end mode and constant flux operation are performed for over 6 months, with varying operational parameters like flux, time of filtration, dosages of coagulant and ozone. Operational behaviour is evaluated through the evolution of trans-membrane pressure via time. Also total and irreversible fouling rates are calculated showing benefits within the combined pre-treatment, regarding membrane fouling and stable operation at high recoveries (98 %). The application of 15 mgO3 · L-1, respectively a specific ozone dosage from 1.0 to 1.4 mgO3 · (mgDOC)-1 leads to a total fouling rate reduction of 75 %. LC-OCD analysis is furthermore used for a more detailed view on changes in DOC, especially biopolymers. Sampling of the pilot plants influent and effluent water is additionally used for the evaluation of treatment efficiency, e.g. disinfection and in particular phosphorous, where emissions are reduced to 20 ± 5 µg P · L-1 in accordance with the European Water Framework Directive (Directive 2000/60/EC).

In this study the applicability of the microsieve technology together with coagulation and flocculation for advanced phosphorus removal was investigated. A pilot unit including a microsieve with 10 µm mesh size is operated continuously with secondary effluent. By applying a pretreatment of 0.07-0.09 mmol/L coagulant and 1.5-2 mg/L cationic polymer total phosphorus values below 80 µg/L were achieved. Coagulation with polyalumium chloride (PACl) produced better effluent quality compared to FeCl3 as less suspended solids and less residual coagulant were found in the microsieve effluent. Also the transmittance of UV radiation through the water is improved by using PACl. The amount of backwash water was very low (< 3 %). Results after rebuilding the chemical pre-treatment showed that under optimized mixing conditions polymer doses << 1 mg/L are possible without losses in water quality and filtration performance. In total microsieving with chemical pretreatment is a viable option for high quality effluent polishing.

Pre-treatments minimizing membrane fouling are extensively studied, to extend membrane life span and decrease the operating costs. In this study, the effect of several pre-treatment options before tertiary membrane treatment was investigated with a submicron particle counter from Nanosight (UK). This device using the Nanoparticle Tracking Analysis method is able to measure the particle size distribution and the absolute particle concentration of particles between 50 and 1000 nm in secondary effluent. The goal of this study is to enhance the understanding of MF/UF membrane fouling by monitoring the submicron particle fraction in the water. Experiments were carried out at lab-scale. Reliability and reproducibility of the device were determined as well as the impact of the pre-filtration on the measurements. The impact of ozonation (0-15 mg O3/L) and/or coagulation (0-12 mg Fe3+/L) on particle size distribution and on the filtration performance was studied on a polyethersulfone ultrafiltration membrane. Results showed a clear relationship between the amount of nanoparticles below 200 nm and the filtration behavior. Lower particle concentrations in this size range resulted in lower flux decline due to reversible fouling. Coagulation and ozonation pre-treatment decreased the particle concentration below 200 nm. The combination of ozonation/coagulation shows synergistic effects and leads to an additional decrease of submicron particle content and further improvement of the filtration performance. Long term impact on hydraulic irreversible fouling still needs to be clarified.

In the future, advanced phosphorus removal will be necessary in many WWTP in order to meet the demands of the European water framework directive. The project OXERAM deals with the comparison of different technologies with regard to their efficiency and applicability in tertiary treatment. In the course of the project membrane and microsieve filtration are tested in pilot scale at the Ruhleben STP. In this thesis the optimization of coagulation and flocculation prior to microsieve filtration for advanced phosphorus removal (< 80 µg/L TP; total phosphorus) was investigated. For the optimization of the coagulation/ flocculation several test series were conducted with the aid of jar test and the mircosieve pilot plant. A direct comparison of jar tests and the pilot plant showed that jar tests are an appropriate method to predict the approximate outcome of optimization steps (e.g. variation of chemical doses) in the pilot plant. The pilot trials were able to demonstrate that the microsieve technology (10 µm pore size) in combination with chemical pre-treatment of 0.036 - 0.179 mmol/L coagulant (Fe or Al) and 2 mg/L cationic polymer could easily achieve good and reliable TP removal. The phosphorus removal was comparable to dual media filtration (< 80 µg/L TP) and partly even to membrane filtration (< 50 µg/L TP). The reduction of the residual coagulant contents in the filtrate was identified as the main challenge of this technology. High iron contents of about 1 mg/L were accompanied by floc formation behind the mircosieve in filtrate tank and pipe. In a microsieve the formed flocs have to endure high shear forces. Thus, the so-called post-flocculation was most probably caused by re-flocculation of floc fragments. Very low phosphorus values < 50 µg/L were possible at high metal dosing. But the higher suspended solid load reduced the filtration capacity of the microsieve. Coagulation with polyalumium chloride (PACl) produced better effluent quality compared to FeCl3 as less suspended solids and less residual coagulant were found in the microsieve effluent. Furthermore, the transmission of UV radiation through the water was improved from 47 up to 66 % by using PACl which is favorable if a downstream UV disinfection is considered. When using FeCl3 the transmission was not improved or even reduced. Due to the influence on the performance of the microsieve cationic polymers were preferred to anionic polymers. However, the tested anionic polymer proved to be not applicable in the given process configuration due to very low filtrate flows. When cationic polymer was applied the polymer dose had a high impact on the particle removal and moreover on the contents of phosphorus and coagulant residuals in the effluent. In most cases 2 mg/L polymer was necessary. In total, the microsieve technology in combination with chemical pre-treatment is a suitable option for advanced phosphorus removal. Through a dynamic adjustment of the chemical dosing to the influent water quality (e.g. ortho phosphate and turbidity online measurement) and the choice of polymer the process could be optimized in the future with regard to efficient chemical application.

In this study the applicability of the microsieve technology together with coagulation and flocculation for advanced phosphorus removal was investigated. A pilot unit including a microsieve with 10 µm mesh size is operated continuously with secondary effluent. By applying a pretreatment of 0.036 – 0.179 mmol/L coagulant and 2 mg/L cationic polymer total phosphorus values below 100 µg/L were easily achieved. Values below 50 µg/L were possible at high metal dosing, but the higher suspended solid load reduced the capacity of the pilot unit. Coagulation with polyalumium chloride (PACl) produced better effluent quality compared to FeCl3 as less suspended solids and less residual coagulant were found in the microsieve effluent. Also the transmission of UV radiation through the water is improved by using PACl. The amount of backwash water was very low (< 3 %). In total, if combined with UV disinfection, microsieving with chemical pretreatment is a viable option for high quality effluent polishing.

In this study the applicability of the microsieve technology together with coagulation and flocculation for advanced phosphorus removal was investigated. A pilot unit including a microsieve with 10 µm mesh size is operated continuously with secondary effluent. By applying a pretreatment of 0.036 – 0.179 mmol/L coagulant and 2 mg/L cationic polymer total phosphorus values below 100 µg/L were easily achieved. Values below 50 µg/L were possible at high metal dosing, but the higher suspended solid load reduced the capacity of the pilot unit. Coagulation with polyalumium chloride (PACl) produced better effluent quality compared to FeCl3 as less suspended solids and less residual coagulant were found in the microsieve effluent. Also the transmission of UV radiation through the water is improved by using PACl. The amount of backwash water was very low (< 3 %). In total, if combined with UV disinfection, microsieving with chemical pretreatment is a viable option for high quality effluent polishing.

Triggered by climate change, local freshwater scarcity and rising public awareness towards ecological issues, environmental aspects are becoming key decision criteria for planning of urban water management infrastructure. Simultaneously, the implementation of measures according to the EU Water Framework Directive requires huge investments in the coming years for both upgrading of existing infrastructure and the construction of sewer networks or treatment plants. Among existing tools for environmental impact assessment, LCA offers the most accepted and comprehensive method to support decision makers with information on the environmental profile of new investments or upgrading of existing infrastructure. This paper describes on-going case studies using LCA for systems of urban water management and raises potential difficulties while applying LCA in the water sector.

The impact of a pre-treatment by pre-ozonation (2-10 mg O3/L) and subsequent coagulation (FeCl3: 2-6 mg Fe3+/L) on the performance of a polymeric ultrafiltration membrane was studied. No free dissolved ozone was in contact with the membrane. Lab tests were performed using Amicon test cells fed with secondary effluent and the flux decline during filtration tests was measured. Flux decline was reduced with increasing coagulant concentration as well as with increasing ozone dosage. This effect was confirmed by a reduction in the amount of biopolymers measured with size exclusion chromatography by organic carbon detection (LC-OCD). Conducted multi filtration cycles revealed a significant increase in irreversible fouling after pre-ozonation that might be caused by increasing colloidal iron concentrations. Phosphorus in the permeate was successfully reduced to concentrations < 60 µg/L