The project Aquisafe assesses the potential of selected near-natural mitigation systems, such as constructed wetlands or infiltration,zones, to reduce diffuse pollution from agricultural sources and consequently protect surface water resources. A particular aim is the attenuation of nutrients and pesticides. Based on the review of available information and preliminary tests within Aquisafe 1 (2007-2009), the second project phase Aquisafe 2 (2009-2012) is structured along the following main components: (i) Development and evaluation of GIS-based approaches for the identification of diffuse pollution hotspots, as well as model-based tools for the simulation of nutrient reduction from mitigation zones (ii) Assessment of nutrient retention capacity of different types of mitigation zones in international case studies in the Ic watershed in France and the Upper White River watershed in the USA under natural conditions, such as variable flow. (iii) Identification of efficient mitigation zone designs for the retention of relevant pesticides in laboratory and technical scale experiments at UBA in Berlin.The present study focused on (i) and aimed at testing GIS approaches for the localization of critical source areas (CSAs) of diffuse NO3- pollution in rural catchments with low data availability as a basis for the planning of mitigation measures. We tested a universal GIS-based approach, which is a combination of published methods. The five parameters land use, soil, slope, riparian buffer strips and distance to surface waters were identified as most relevant for diffuse agricultural NO3 - pollution. Each parameter was classified into three risk classes, based on a literature review. The risk classes of the five parameters were then averaged in a GIS overlay in order to find areas with highest risk. The Ic catchment in Brittany, France, served as a study site to test the applicability of the chosen approach. The result of the overlay was compared (a) with measured NO3 - loads in seven subcatchments of the Ic catchment and (b) with the results of a previous analysis by the numerical model Soil and Water Assessment Tool (SWAT). Regarding (a) it was found that higher mean risk classes in a subcatchment correspond with higher measured NO3- loads. However, due to the small number of data points a reliable statistical analysis was not possible. Regarding (b), the plotting of the loads predicted by SWAT against the mean risk class for the 32 SWAT subcatchments show a similar, but poorer relationship. The GIS approach was further analyzed regarding its sensitivity to each of the parameters. The analysis showed that the method is not very sensitive to most of the parameters, i.e. risk class distribution (or the choice of CSA) does not change greatly if one parameter is omitted. Nevertheless, if data quality for some parameters is known to be low, sensitivity of the result to the parameter should be considered in addition.In summary, it can be stated that the applied GIS overlay is a promising, easy to handle approach. First experiences on the Ic catchment indicate that GIS-based approaches can be robust, even for lower data availability. As a result, further work is suggested towards developing a universally applicable GIS method for nitrate CSA identification. Main points to be assessed are the number of classes, the necessary weighting of parameters and the best inclusion of different nitrogen pathways between field and surface water.

We quantified the areal hypolimnetic mineralization rate (AHM; total areal hypolimnetic oxygen depletion including the formation of reduced substances) in two formerly eutrophic lakes based on 20 yr of water-column data collected during oligotrophication. The upward diffusion of reduced substances originating from the decomposition of organic matter in the sediment was determined from pore-water profiles and related to the time of deposition. More than 80% of AHM was due to degradation of organic matter in the water column (including sediment surface) and diffusion of reduced substances from sediment layers younger than 10 yr. Sediments older than 10 yr, including the eutrophic past, accounted for , 15% of AHM. This ‘‘old’’ contribution corresponds to a 20–43% fraction of the total sediment-based AHM. The contribution from old sediment layers to AHM is expected to be even lower in lakes with deeper hypolimnia (. 12 m). In summary, oxygen consumption in stratified hypolimnia is controlled mainly by the present lake productivity. As a result, technical lake management measures, such as oxygenation, artificial mixing, or sediment dredging, cannot efficiently decrease the flux of

The neurotoxin anatoxin-a (ATX), has been detected in several northeast German lakes during the last two decades, but no ATX producers have been identified in German water bodies so far. In 2007 and 2008, we analyzed phytoplankton composition and ATX concentration in Lake tolpsee (NE Germany) in order to identify ATX producers. Sixty-one Aphanizomenon spp. strains were isolated, morphologically and phylogenetically characterized, and tested for ATX production potential by liquid chromatography–tandem mass spectrometry (LC–MS/MS). New primers were specifically designed to identify a fragment of a polyketide synthase gene putatively involved in ATX synthesis and tested on all 61 Aphanizomenon spp. strains from L. Stolpsee and 92 non-ATX-producing Aphanizomenon spp., Anabaena spp. and Anabaenopsis spp. strains from German lakes Langersee, Melangsee and Scharmützelsee. As demonstrated by LC–MS/MS, ATX concentrations in L. Stolpsee were undetectable in 2007 and ranged from 0.01 to 0.12 µg l-1 in 2008. Fifty-nine of the 61 strains isolated were classified as Aphanizomenon gracile and two as Aphanizomenon issatschenkoi. One A. issatschenkoi strain was found to produce ATX at concentrations of 2354 ± 273 µg g-1 fresh weight, whereas the other A. issatschenkoi strain and A. gracile strains tested negative. The polyketide synthase gene putatively involved in ATX biosynthesis was found in the ATX-producing A. issatschenkoi strain from L. Stolpsee but not in the non-ATX-producing Aphanizomenon spp., Anabaena spp. and Anabaenopsis spp. strains from lakes Stolpsee, Langersee, Melangsee, and Scharmützelsee. This study is the first confirming A. issatschenkoi as an ATX producer in German water bodies.

Neurotoxic paralytic shellfish poisoning (PSP) toxins, anatoxin-a (ATX), and hepatotoxic cylindrospermopsin (CYN) have been detected in several lakes in northeast Germany during the last 2 decades. They are produced worldwide by members of the nostocalean genera Anabaena, Cylindrospermopsis, and Aphanizomenon. Although no additional sources of PSP toxins and ATX have been identified in German water bodies to date, the observed CYN concentrations cannot be produced solely by Aphanizomenon flos-aquae, the only known CYN producer in Germany. Therefore, we attempted to identify PSP toxin, ATX, and CYN producers by isolating and characterizing 92 Anabaena, Aphanizomenon, and Anabaenopsis strains from five lakes in northeast Germany. In a polyphasic approach, all strains were morphologically and phylogenetically classified and then tested for PSP toxins, ATX, and CYN by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA) and screened for the presence of PSP toxin- and CYN-encoding gene fragments. As demonstrated by ELISA and LC-MS, 14 Aphanizomenon gracile strains from Lakes Melang and Scharmützel produced four PSP toxin variants (gonyautoxin 5 [GTX5], decarbamoylsaxitoxin [dcSTX], saxitoxin [STX], and neosaxitoxin [NEO]). GTX5 was the most prevalent PSP toxin variant among the seven strains from Lake Scharmützel, and NEO was the most prevalent among the seven strains from Lake Melang. The sxtA gene, which is part of the saxitoxin gene cluster, was found in the 14 PSP toxin-producing A. gracile strains and in 11 non-PSP toxin-producing Aphanizomenon issatschenkoi, A. flos-aquae, Anabaena planktonica, and Anabaenopsis elenkinii strains. ATX and CYN were not detected in any of the isolated strains. This study is the first confirming the role of A. gracile as a PSP toxin producer in German water bodies.

Submersible data loggers are widely used for groundwater monitoring, but their application often runs the risk of hardware and data loss through vandalism or theft. During a field study in India, the authors of this article experienced that well locks attract the attention of unauthorized persons and do not provide secure protection in unattended areas. To minimize the risk of losing data loggers, a cheap and simple solution has been invented to hide the instruments and associated attachments below the ground surface, inside observation wells. It relies on attaching the logger to a length of small-diameter pipe that is submerged at the bottom of the well, instead of attaching it to the top of the well. The small-diameter pipe with the logger is connected to a small bottle containing a magnet that floats on the water surface of the well and can be recovered using another bottle also with a magnet. A logger that is concealed in this way is difficult to detect and access without knowledge of the method and adequate removal tools. The system was tested and successfully applied for monitoring shallow

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.