In work package 4 the influence of different treatments (ozonation, coagulation) on macromolecular organic substances (biopolymers) in secondary effluent and the effects on subsequent ultrafiltration were investigated at lab-scale. Furthermore, fouling mechanisms were intensively investigated and an analytical method was developed to observe the formation of ozonation by-products. Analyses with LC-OCD showed a significant reduction of major organic foulants (biopolymers) for coagulation while ozonation appears to transform macromolecules into compounds smaller than approx. 50 nm. With ultrafiltration tests (PES membranes) it could be shown that coagulation is capable to reduce total fouling resistance to some extent and additional ozonation can further enhance the membrane filtration process. However ozonation as a pretreatment step caused more irreversible fouling. The lowest irreversible fouling was achieved with coagulation. LC-OCD analyses showed that the transformation of organic matter by ozonation is mainly responsible for the observed increased irreversible fouling of ultrafiltration membranes. Tests with different membranes showed comparable results for pretreated secondary effluent concerning total fouling resistance. Total fouling resistance was reduced with additional ozonation compared to coagulation without ozonation. In contrast to the observations with all tested UF membranes, for the tested microfiltration membranes irreversible fouling was reduced with additional ozonation. In general, the pore size seems to be strongly influencing irreversible fouling if ozonation is used for pretreatment of membrane filtration. Intensive investigations of fouling mechanisms using filtration laws identified cake filtration as the dominant filtration process for coagulation while additional ozonation leads to increased pore blocking/in pore fouling. Experiments with secondary effluents from different sewage treatment plants in Berlin showed comparable fouling behavior for all observed pretreatments. Thus membrane filtration results generated with samples from WWTP Ruhleben seem to be transferable to other WWTPs in Berlin. MALDI-TOF-MS analyses of secondary effluent were not suitable to identify major organic foulants, neither in solution nor on top of the membrane after filtration. Consequently, MALDI-TOF-MS was primarily used for investigations of theoretical aspects of fouling by using model fouling substances. An analytical procedure for bromate was successfully developed with LC-MS/MS at TUB. With the procedure it was possible to quantify samples up to a limit of quantification of 0.5 µg bromate per liter. Higher concentrations of bromate (> 10 µg/L) were produced only at specific ozone consumptions higher than 0.9 mgO3/mgDOC0.

The pilot trials at the Ruhleben wastewater treatment plant proved that the microsieve technology combined with chemical pre-treatment achieves good and reliable phosphorus removal with effluent values < 80 µg/L TP. The first three months of pilot operation confirmed the general process performance observed during the pre-trials in 2009 but also revealed a need for process optimization with regard to the removal of suspended solids and the reduction of coagulant breakthrough. An improved performance was achieved through change from ferric chloride (FeCl3) to polyaluminum chloride (PACl). In the presented case, PACl gave clearly better results for the removal of phosphorus and suspended solids than FeCl3. Additionally, the occurrence of coagulant residues could be noticeably reduced. In contrast to FeCl3, dosing PACl led to an improvement of the water transmittance simplifying disinfection with UV irradiation. Load proportional dosing of PACl and polymer was introduced in order to avoid under as well as over dosing of the chemicals. The dose of cationic polymer had a significant impact on water quality and backwash time: With the initial process configuration 1.5 to 2 mg/L cationic polymer were recommended for a safe and stable operation with adequate backwash time resulting in an average polymer dose of 1.7 mg/L. However, latest results showed that a polymer dose of only 0.6 mg/L is possible without losses in water quality and filtration performance when mixing conditions were optimized. During the constructional modifications the hydraulic retention time of the coagulation was reduced from 4 to 1 min at peak flow. Due to the installation of a TurbomixTM short-circuiting could be avoided. Furthermore, the turbulence in the flocculation tank was increased. Despite the noticeable reduction of the hydraulic retention time and the polymer dose the rebuild resulted in improved reduction of suspended solids (2.2 mg/L) and coagulant residues in the microsieve effluent. The operation regime of the chemical treatment prior to the microsieve filtration showed to be a trade-off between the energy demand for mixing and the polymer consumption. Due to the continuous operation over more than 20 months important operational experience was gained with regard to backwash behavior and cleaning intervals. The backwash time mainly correlates with the influent flow (1030 m3/h), the influent water characteristics and the properties of the formed flocs. Due to progressing fouling of the filter panels chemical cleaning was necessary every 4 to 7 weeks. A shorter cleaning interval (e.g. every 4 weeks) might be beneficial as the backwash time and thus the energy demand could be kept on a lower level. In this application the microsieve produced on average 1.8 % of backwash water. The backwash water showed excellent settling properties (SVI << 50 mL/g) and might be easily treated via returning to the primary clarifiers. The UV disinfection plant behind the microsieve was operated with a fluence of 730 J/m2. Good disinfection could be provided for a continuous operation of 7 months. During this period there were always less than 100 MPN/100 mL of E. coli and Enterococci in the effluent of the UV disinfection. Overall, the microsieve in combination with dosing of coagulant and polymer is a robust technology with low phosphorus effluent values (< 80 µg/L) and a low energy demand of about 21 Wh/m3 (+ site-specific energy demand for water lifting). Microsieving, together with UV disinfection, can be an option for applications targeting phosphorus removal and disinfection, e.g. effluent polishing for sensitive areas or landscape irrigation.

Im Projekt OXERAM wurden verschiedene Technologien im Hinblick auf die Anforderungen an die 4. Reinigungsstufe, vor allem Phosphorentfernung, in Pilot- und Laborversuchen untersucht. Ferner wurden die Leistungsfähigkeit der Verfahren sowohl durch eine Ökobilanz als auch eine Kostenrechnung bewertet. Der vorliegende Bericht fasst diese Ergebnisse aus den Jahren 2010 bis 2013 zusammen. Die Vorgehensweise und eine ausführliche Ergebnisdiskussion sind in den Kapiteln 2 - 6 beschrieben.

For a future upgrade of the wastewater treatment plant (WWTP) Ruhleben targeting advanced removal of total phosphorus (TP) (< 50-120 µg/L TP) and seasonal disinfection, various technological options for tertiary treatment of secondary effluent are suitable to fulfill these goals. This study applies the holistic methods of Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) to assess and compare those options for tertiary treatment at WWTP Ruhleben in their environmental and economic impacts, including all relevant direct and indirect processes and effects of the WWTP upgrade. Options for tertiary treatment include gravity-driven processess such as dual media filtration (DMF), microsieve filtration (MSF), or high-rate sedimentation (HRS), and membrane-based processes such as ultrafiltration with polymer membranes (Polymer UF) or microfiltration with ceramic membranes (Ceramic MF). For disinfection in the summer period, gravity-driven processes are complemented by downstream UV disinfection, which is only applied in rain weather bypass for membrane processes. Process data for operational parameters and infrastructure design are based on longterm pilot trials at technical scale (DMF, MSF, Polymer UF, Ceramic MF) or process modelling based on supplier information (HRS). LCA shows that the existing phosphorus load in secondary effluent of WWTP Ruhleben (28 t/a TP) can be reduced substantially by all processes, eliminating 19-25 t/a TP (6790%) depending on the process. A minor side-benefit for effluent quality is also expected from the further elimination of heavy metals adsorbed to particulate matter in secondary effluent. At the same time, tertiary treatment schemes will increase energy demand and related emissions of greenhouse gases (carbon footprint) of the existing WWTP process by an estimated 12-21% and 7-13%, respectively. Gravity-driven processes with low coagulant dosing (DMF, MSF, HRS) have a considerably lower energy demand and carbon footprint than membrane-based processes with high electricity demand for feed pumps and higher coagulant dose. At the same time, low-energy treatment processes do not reach the exceptional high effluent quality of membrane-based processes. Consequently, a certain trade-off between energy demand/carbon footprint and effluent quality can be quantified. In analogy to the environmental assessment and effluent quality, LCC results show that total annual costs are lowest for HRS (5.1 Mio €/a) and comparable between DMF and MSF (5.7 Mio €/a), followed by Polymer UF (10.2 Mio €/a) and Ceramic MF (12.2 Mio €/a). In comparison to gravity-driven processes, membrane-based processes are characterized by both higher investment costs (factor 1.5 – 3x) and higher operational costs (factor 2 – 2.5x), mainly due to high costs of membranes, machinery, electricity, and coagulants. Comparing the relative resource efficiency for selected environmental and economic parameters related to the total load of eliminated phosphorus, DMF and MSF are the most efficient of the assessed technologies for tertiary treatment, spending ~ 250 €/kg Pelim and causing 180 kg CO2-eq/kg Pelim (both with UV disinfection as post-treatment). HRS + UV has higher relative costs (270 €/kg Pelim) and higher carbon footprint (235 kg CO2-eq/kg Pelim) due to the lower effluent quality of the process (= less reduction in TP loads). Membrane-based processes have the highest relative costs for P removal (400475 €/kg Pelim) and the highest carbon footprint (275 kg CO2-eq/kg Pelim): even though their superior effluent quality leads to the highest total reduction in TP loads, the high energy demand and costs of membrane processes yield higher relative spending of resources related to the final goal.

Purpose: The transport behavior of human pharmaceuticals in groundwater depends on a multitude of factors such as the physico-chemical conditions in the aquifer and the organic carbon content of the sediment, and, in particular, on the redox conditions in the groundwater. This is of special interest at managed aquifer recharge sites where the occurrence of trace organics is important for drinking water production. The aim of this study was to evaluate the possibility of influencing the redox system of the aquifer in a way that optimizes the potential of managed aquifer recharge systems to reduce the amount of trace organics. Materials and methods: Column studies were performed using natural and thermally treated sediments from an infiltration basin of the Berlin area, Germany. Special emphasis was placed on thermal treatment of the sediments to influence the total organic carbon (TOC) content in the sediment. In one experiment, the sediment was thermally pretreated at 550 °C, in two experiments the sediment was pretreated at 200 °C, and in one the sediment was untreated. Furthermore, the influence of ozonation, a very common disinfectant used in drinking water production, was studied in the experiments. The retardation and degradation parameters for primidone (PMD), carbamazepine (CBZ), and sulfamethoxazole (SMX) under different redox conditions were evaluated. Results and discussion: Oxic conditions were obtained in the experiment with low TOC (0. 06 wt%) in the sediment pre-treated at 550 °C. Anoxic conditions were predominant in two column experiments with a TOC content of 0. 17 wt% in the sediment, irrespective of the mode of treatment (natural or 200 °C). All three pharmaceutical compounds show almost conservative transport behavior with retardation factors between 1. 02 and 1. 25 for PMD, between 1. 06 and 1. 37 for CBZ, and between 1. 00 and 1. 08 for SMX. Differences in the transport behavior were observed depending on the TOC content of the sediment. For CBZ, and to a minor extent for PMD, the higher retardation factors were observed in the sediment with a TOC content of 0. 17 wt% under anoxic conditions. The ozonation of the influent water affects the influent concentrations of PMD, CBZ and SMX. However, it has no influence on the oxygen concentration of the column outflow. Conclusions: CBZ and PMD are retarded in the presence of organic matter in the aquifer. Variations of the TOC content of the sediment have a direct influence on the retardation of CBZ and PMD. The three human pharmaceuticals may be ranked in order of decreasing retardation: CBZ & PMD & SMX. The microbial activity in the experiments was not studied, although it can be assumed that the thermal pretreatment influences the microbial activity in the sediments. In particular, the microbial activity was severely inhibited at 550 °C, resulting in a shift of the redox conditions.