The AQUISAFE research project aims at mitigation of diffuse pollution from agricultural sources to protect surface water resources. The project has several objectives including optimizing system-analytical tools for the planning and implementation of mitigation zones, demonstrating the effectiveness of mitigation zones in international case studies in the US Midwest and Brittany, France and developing recommendations for the implementation of near-natural mitigation zones, which are efficient in attenuating nutrients and selected pesticides. A series of different types of mitigation systems, including constructed wetlands and reactive trenches are being constructed in 2010 at identified agricultural sites in France and the USA. A preliminary monitoring of a drainage-fed surface flow wetland showed good nitrate retention when water infiltrated or had significant residence times, but no discernable effect during major storm events. As a result, future designs aim at higher reaction times by adapting size of end-of-drainage solutions to expected flows and by developing new mitigation systems for existing drainage ditches. Moreover, reaction rates are improved by forming favourable conditions for underground passage and by addition of organic carbon sources, such as straw or wood chips. Whereas nutrients are the focus for the field sites in France, both nutrients and atrazine are the focus in the US. Reactive trenches are being tested for pesticide retention at laboratory and technical scale at the experimental field of the German Federal Environment Agency. In the latter experiments, Bentazon and Atrazine are used as test substances, given their relevance for European and US surface waters, respectivelyseveral objectives including optimizing system-analytical tools for the planning and implementation of mitigation zones, demonstrating the effectiveness of mitigation zones in international case studies in the US Midwest and Brittany, France, and developing recommendations for the implementation of near-natural mitigation zones, which are efficient in attenuating nutrients and selected pesticides. A series of different types of mitigation systems, including constructed wetlands and reactive trenches are being constructed in 2010 at identified agricultural sites in France and the USA. A preliminary monitoring of a drainage-fed surface flow wetland showed good nitrate retention when water infiltrated or had significant residence times, but no discernable effect during major storm events. As a result, future designs aim at higher reaction times by adapting size of end-of-drainage solutions to expected flows and by developing new mitigation systems for existing drainage ditches. Moreover, reaction rates are improved by forming favourable conditions for underground passage and by addition of organic carbon sources, such as straw or wood chips. Whereas nutrients are the focus for the field sites in France, both nutrients and atrazine are the focus in the US. Reactive trenches are being tested for pesticide retention at laboratory and technical scale at the experimental field of the German Federal Environment Agency. In the latter experiments, Bentazon and Atrazine are used as test substances, given their relevance for European and US surface waters, respectively.

Advances in the analysis of organic trace compounds revealed that many of the in high amounts prescribed pharmaceutical active components as well as diagnostic agents are not removed by conventional waste water treatment techniques and that some of them can accumulate in the aquatic environment. Because most of the compounds applied in medicine are excreted via urine the emission into the aquatic environment could be reduced if the urine is separated at the source and treated by a specific process. In the project PharmaTreat it was studied if the reductive treatment with zero-valent iron is a suitable, simple and low cost process for the treatment of urine. The results show that the selected antibiotics (Ciprofloxacine, Piperacillin, Cefuroxime), cytostatic drugs (Ifosfamide and Methotrexate) and iodinated X-ray contrast media (Iopromide and Diatrizoate) are transformed by the treatment with zero-valent iron. The reaction rate constant depends highly on the pH. Under acidic conditions the mechanism of the transformation is most probably the reaction with adsorbed atomic hydrogen which is produced on the iron surface. The increase of the pH-value from 3 to 7, which might happen if the solution is discharged into the waste water system, leads to the precipitation of the dissolved iron resulting in a strong removal of the transformation products out of the solution by co-precipitation. The toxicity of the remaining transformation products was determined using the growth inhibition test (DIN 38412-37). It could be demonstrated that the biological impact of the pharmaceuticals is reduced by the transformation with zero-valent iron. By using the Zahn-Wellens-Test (DIN EN ISO 9888) it could be shown that the transformation products are better biodegradable in contrast to the original compounds, except for the iodinated Xraycontrast media. The treatment of one cubic meter urine costs 9.88 Euro. The cost estimation is based on conditions with the lowest material consumption and not on the reaction time. According to the calculated price for on cubic meter the treatment of about 6,525 m3 urine (the amount of urine produced in all hospitals of Berlin) costs ca. 64,500 Euro/a. By accelerating the reaction the treatment time can be shorten but the specific material consumption is higher whereas the energy costs are lower. In dependence of the actual prices for iron, acid and electricity the costs can be optimized for the treatment.

Subsurface passage as utilized during river bank filtration and artificial groundwater recharge has shown to be an effective barrier for multiple substances present in surface waters during drinking water production. Additionally it is widely used as polishing step after wastewater treatment. However, there are limitations concerning the removal of DOC and specific trace organics. The project ”OXIRED“ aims at assessing possibilities to overcome these limitations by combining subsurface passage with pre-oxidation by ozone. In the first phase of the project, laboratory-scale column experiments were conducted in order to quantify removal for different settings under varying conditions. In a previous study different combinations of advanced oxidation and subsurface passage were evaluated concerning their potential removal efficiency and practical implementation on the basis of existing, published experiences and theoretical considerations. Two different scenarios were identified as promising for experiments in laboratory-scale columns with surface water and sewage treatment plant effluent: (A) surface water - oxidation - groundwater recharge and (B) surface water - short bankfiltration - oxidation - groundwater recharge. The investigations were designed to lead to recommendations for the implementation of a combined system of subsurface passage and advanced oxidation in pilot scale experiments that will be carried out in the second phase of the project. Prior to column experiments, batch tests following the RCT-concept by Elovitz and von Gunten (1999) were carried out to characterize the reaction of ozone with the investigated water qualities [1]. Additional batch ozonation tests with subsequent analysis of biodegradable dissolved organic carbon (BDOC) were conducted in order to determine optimal ozone doses for DOC removal in column experiments. For laboratory-scale experiments a set of 8 soil columns (length: 1 m; diameter: 0.3 m) was operated at TUB to evaluate the effects of pre-ozonation of different source waters (secondary effluent, surface water, bank filtrate). Ozonation was conducted with gaseous ozone in a 13-L stirred tank reactor. Specific ozone doses of 0.7 mg O3/mg DOC0 and 0.9 mg O3/mg DOC0 were investigated. Trace organic compounds to be targeted were identified in a prior literature study on existing data on subsurface removal. Results from laboratory-scale soil column experiments led to recommend specific ozone doses (z) of 0.7 mg O3/mg DOC0 for the following technical- and pilot-scale applications. Removal of surface water DOC in the soil columns was increased from 22% without ozonation to 40% (z = 0.7) and 45% (z = 0.9) with preozonation and the DOC in the column effluent reached the level of tap water in Berlin within less than one week of retention time. At bank filtration and artificial recharge sites in Berlin similar removal rates were only observed within 3 - 6 months of retention [2]. The transformation of many trace compounds was efficient with specific ozone doses of 0.6-0.7 mg O3/mg DOC0. Realistic surface water concentrations of carbamazepine,sulfamethoxazole, diclofenac and bentazone were reduced below the limits of quantification (LOQ). The pesticides diuron and linuron were reduced close to LOQ. The substances MTBE, ETBE and atrazine were only partly transformed during ozonation. For efficient transformation of these substances, higher ozone doses or an optimisation of the oxidation process, for example as advanced oxidation process (AOP), should be considered. Operating a preceding bank filtration (scenario B) will enhance the transformation efficiency of MTBE and ETBE. With similar ozone consumption the transformation of MTBE and ETBE was increased by 27-31% and 28-33% of the original removal, respectively. Other investigated compounds were efficiently transformed during ozonation of surface water independently of the preceding bank filtration step. For the removal of bulk organic carbon only little improvement was observed for scenario B. Overall DOC removal increased from 45% with direct ozonation of surface water to up to 50% with a preceding soil column. Despite the presence of relevant bromide concentrations (~ 100 µg/L) formation of the oxidation by-product bromate was not observed (< 5 µg/L). However, this could also be a result of analytical problems, as later spiking tests showed. Formation of brominated organic compounds was also not observed. Adsorbable organic bromide (AOBr) even decreased by 50 - 60% for secondary effluent and 80 - 90% for surface water. The reduction of AOBr concentrations was accompanied by an increase of inorganic bromide by up to 40 µg/L during ozonation of surface water. In the two conducted in vitro genotoxicity tests (Ames test, micronucleus assay) no genotoxicity caused by ozonation of water samples was observed. Testing for cytotoxicity (glucose consumption rate, ROS generation) showed positive results in several samples. However, a systematic attribution of toxic effects to ozonation or subsequent soil passage was not possible. Reasons for cytotoxic effects were not evaluated within the scope of this project but it is assumed that they were caused by unknown cofactors. These results show that the objectives of enhanced removal of trace organics and DOC by combining ozonation and subsurface passage are well met. Further investigations need to confirm this for the pilot scale, especially taking into account the formation, retention and toxicity of oxidation by-products.

Twelve years after the first full scale municipal application in Europe of the membrane bioreactor (MBR) technology, the process is now accepted as a technology of choice for wastewater treatment, and the market is showing sustained growth. However early misconceptions about the technology are persistent and false statements are commonly encountered in articles and conferences, generating unnecessary research efforts or even fuelling either fascination or scepticism with regards to the technology, which is ultimately detrimental to the perception of the process by water professionals. We try to provide some factual and rational clarifications on ten issues which are often wrongly reported about MBR technology.

A new method for the assessment of the filterability in membrane bioreactors was tested for five months in four MBR units in Berlin. The new method BFM (Berlin Filtration Method) for filterability assessment uses a small membrane filtration test cell which can be submerged directly in the biological tanks to determine the filterability of the activated sludge in-situ. The test cell contains an aerated flat-sheet membrane which operates at similar conditions as in the plant. Filterability is expressed in terms of critical flux obtained by performing flux-stepping experiments. The ultimate goal of monitoring the filterability with the device is to detect in real time fouling occurrences due to changes in sludge composition and to adapt accordingly the operating conditions. The usefulness of the device for this purpose was evaluated for five months after monitoring four MBR plants in Berlin with different activated sludge characteristics (MLSS from 5 to 21 g/L, SRT 12–35d and COD in the supernatant 30–400 mg/L). The first results show a good agreement between the filterability of the sludge with the portable filtration test cell and the filtration performance of the plant. Critical flux values varied between 3 and 30L/m2 h during the studied period. Useful information concerning the irreversibility of the fouling was provided by looking at the hysteresis curve of the flux-stepping experiments.

Membrane bioreactors (MBRs) have been increasingly employed for municipal and industrial wastewater treatment in the last decade. The efforts for modelling of such wastewater treatment systems have always targeted either the biological processes (treatment quality target) as well as the various aspects of engineering (cost effective design and operation). The development of Activated Sludge Models (ASM) was an important evolution in the modelling of Conventional Activated Sludge (CAS) processes and their use is now very well established. However, although they were initially developed to describe CAS processes, they have simply been transferred and applied to MBR processes. Recent studies on MBR biological processes have reported several crucial specificities: medium to very high sludge retention times, high mixed liquor concentration, accumulation of soluble microbial products (SMP) rejected by the membrane filtration step, and high aeration rates for scouring purposes. These aspects raise the question as to what extent the ASM framework is applicable to MBR processes. Several studies highlighting some of the aforementioned issues are scattered through the literature. Hence, through a concise and structured overview of the past developments and current state-of-the-art in biological modelling of MBR, this review explores ASMebased modelling applied to MBR processes. The work aims to synthesize previous studies and differentiates between unmodified and modified applications of ASM to MBR. Particular emphasis is placed on influent fractionation, biokinetics, and soluble microbial products (SMPs)/exo-polymeric substances (EPS) modelling

This paper deals with the performance and the optimisation of the hydraulic operating conditions of the A3 Water Solutions flat sheet membrane technology in a MBR pilot-plant to achieve a satisfying fouling control and also a reduction in the required aeration. Two vertically stacked modules were tested at pilot-scale at Anjou Recherche under typical biological operating conditions (mixed liquor suspended solids concentration (MLSS) = 10 g/l; sludge retention time (SRT) = 28 days; food to microorganism ratio (F/M) = 0.12 kg COD/kg MLSS/d). The use of a double-deck and of specific backwashes for this membrane technology enabled to achieve satisfying membrane performances for a net flux of 25 L h-1m-2, 20°C at a low specific aeration demand per membrane surface (SADm = 0.2Nm3 h-1m-2) which corresponds to a specific aeration demand per permeate volume unit (SADp) of 8Nm3 air/m3 permeate, which is lower than reported for many commercial membrane systems. The mixed liquor characteristics (foaming, MLSS concentration) appeared to influence the fouling behaviour of the membranes but no correlation was found with the fouling rate. However, with the new operating conditions, the system is robust and can cope with fouling resulting from biological stress and daily peak flows for MLSS concentrations in the membrane tank up to 18 g/l.

Work package WP 5.2 “Combination of Managed Aquifer Recharge (MAR) and adjusted conventional treatment processes for an Integrated Water Resources Management“ within the European Project TECHNEAU (“Technology enabled universal access to safe water”) investigates bank filtration (BF) + post-treatment as a MAR technique to provide sustainable and safe drinking water supply to developing and newly industrialised countries. One of the tasks within the project was the identification of state-of-the-art tools in the field of well field optimization modelling. Most of the currently used tools are process-driven simulation models like MODFLOW or FEFLOW. These are sometimes also combined with optimization models to reduce the computational demand and are utilized as strategic planning tools for water supply managers. However, in case of optimizing well field operation (i) under relatively constant boundary conditions and (ii) enough field data (temporal and spatial resolution dependent of the dynamics of the state parameter of interest, e.g. groundwater table, contaminant concentrations) data-driven approaches like support vector machines (SVM) can be used instead. If the water manager’s key interest is only a good predictive capability in combination with low computational demand, the application of this approach is more goal-orientated to simulate the dynamics of well field performance indicators efficiently. The contents of this report were presented to possible end-users, experts from Berliner Wasserbetriebe and Veolia. In agreement with their recommendations it was decided to focus further research within TECHNEAU on the empirical, data driven modelling approach. The selected approach is currently tested in the framework of a diploma thesis for a Berlin waterworks with the objective to analyse available production and observation well hydrographs by using modern statistical methods like principal component analysis and SVM (www.support-vector-machines.org).

Bank filtration (BF) is a well established and proven natural water treatment technology, where surface water is infiltrated to an aquifer through river or lake banks. Improvement of water quality is achieved by a series of chemical, biological and physical processes during subsurface passage. This paper aims at identifying climate sensitive factors affecting bank filtration performance and assesses their relevance based on hypothetical 'drought' and 'flood' climate scenarios. The climate sensitive factors influencing water quantity and quality also have influence on substance removal parameters such as redox conditions and travel time. Droughts are found to promote anaerobic conditions during bank filtration passage, while flood events can drastically shorten travel time and cause breakthrough of pathogens, metals, suspended solids, DOC and organic micropollutants. The study revealed that only BF systems comprising an oxic to anoxic redox sequence ensure maximum removal efficiency. The storage capacity of the banks and availability of two source waters renders BF for drinking water supply less vulnerable than surface water or groundwater abstraction alone. Overall, BF is vulnerable to climate change although anthropogenic impacts are at least as important.