As part of the EU-Life ENREM demonstration project the Department of Chemical Engineering, TU Berlin, was appointed to conduct the preliminary pilot trials in a representative site for verification of basic process design and operation criteria of the full-scale MBR demonstration plant. In addition to conception and construction of the pilot plant, this investigation consisted of two successive trial phases with distinct operation conditions. The first one was dedicated to the assessment of the “irregular sludge removal strategy” (the biomass is accumulating in the reactor, which is partly emptied when the sludge concentration reaches a given value). In the second trials phase normal operation conditions with daily sludge wastage were implemented with 28,5d SRT. The major outcome of the trials was that COD removal, enhanced biological phosphorus removal and the post-denitrification performed a similar way under both operational conditions. The denitrification rate was approximately 1 mgN/(h goTS). An influence of the anaerobic sludge loading on the post-denitrification rate was observed with higher rates (up to 4 mgN/(h goTS)) corresponding to higher organic loading. An influence of storage compounds built up in the anaerobic phase is assumed. Nitrification was better in the second phase when 4 mgN/(h goTS) were constantly reached while nitrification was unstable with an average of 2 mgN/(h goTS) in the phase of irregular sludge removal. The aerobic and anoxic reactors were enlarged during the regular sludge withdrawal phase by 23% resulting in 35d SRT. This led to a better COD removal and slightly better nitrogen removal. The enhanced SRT produced possibly a deterioration of biological P removal due to overloaded poly-P storage. A second possible reason is the massive reproduction of sludge worm Tubifex tubifex, which was observed after the plant enlargement. Different strategies to reduce the worm population were attempted. Ammonium dosing had no success. Copper dosing reduced the number of worms significantly but the population grew back after the dosing was stopped. The prolongation of SRT reduced the sludge yield from 0.23 gTS/gCOD at 28.5d to 0.18 gTS/gCOD at 35d.

Two parallel membrane bioreactors (2m³ each) were operated over a period of 2 years. Both pilots were optimised for nitrification, denitrification, and enhanced biological phosphorous elimination, treating identical municipal waste water under comparable operating conditions. The only constructional difference between the pilots was the position of the denitrification zone (pre-denitrification in pilot 1 and post-denitrification in pilot 2). Despite identical modules and conditions, the two MBRs showed different permeabilities and fouling rates. The differences were not related to the denitrification scheme. In order to find an explanation for the different membrane performances, a one-year investigation was initiated and the membrane performance as well as the operating regime and characteristics of the activated sludge were closely studied. MLSS concentrations, solid retention time, loading rates, and filtration flux were found not to be responsible for the different performance of the submerged modules. These parameters were kept identical in the two pilot plants. Instead, the non-settable fraction of the sludges (soluble and colloidal material, i.e. polysaccharides, proteins and organic colloids) was found to impact fouling and to cause the difference in membrane performance between the two MBR. This fraction was analysed by spectrophotometric and size exclusion chromatography (SEC) methods. In a second step, the origin of these substances was investigated. The results point to microbiologically produced substances such as extracellular polymeric substances (EPS) or soluble microbial product.

Bank filtration and artificial recharge provide an important drinking water source to the city of Berlin. Due to the practice of water recycling through a semi-closed urban water cycle, the introduction of effluent organic matter (EfOM) and persistent trace organic pollutants in the drinking water is of potential concern. In the work reported herein, the research objectives are to study the removal of bulk and trace organics at bank filtration and artificial recharge sites and to assess important factors of influence for the Berlin area. The monthly analytical program is comprised of dissolved organic carbon (DOC), UV absorbance (UVA254), liquid chromatography with organic carbon detection (LC-OCD), differentiated adsorbable organic halogens (AOX) and single organic compound analysis of a few model compounds. More than 1 year of monitoring was conducted on observation wells located along the flowpaths of the infiltrating water at two field sites that have different characteristics regarding redox conditions, travel time, and travel distance. Two transects are highlighted: one associated with a bank filtration site dominated by anoxic/anaerobic conditions with a travel time of up to 4–5 months, and another with an artificial recharge site dominated by aerobic conditions with a travel time of up to 50 days. It was found that redox conditions and travel time significantly influence the DOC degradation kinetics and the efficiency of AOX and trace compound removal.

Artificial recharge of groundwater is often used to either purify partially treated wastewater or to enhance the quality of surface water by percolation through a variably saturated zone. In many cases, the most substantial purification process within the infiltration water is the redox-dependent biodegradation of organic substances. The present study was aimed at understanding the spatial and temporal distribution of the redox reactions that develop below an artificial recharge pond near Lake Tegel, Germany. At this site, like at many artificial recharge sites, the hydraulic regime immediately below the pond is characterised by cyclic changes between saturated and unsaturated conditions. These changes, which occur during each operational cycle, result from the repeated formation of a clogging layer at the pond bottom. Regular hydrogeochemical analyses of groundwater and seepage water in combination with continuous hydraulic measurements indicate that NO3 - and Mn-reducing conditions dominate beneath the pond as long as water-saturated conditions prevail. Manganese-, Fe- and SO24 -reducing conditions are confined to a narrow zone directly below the clogging layer and in zones of lower hydraulic conductivity. The formation of the clogging layer leads to a steady decrease of the infiltration rate, which ultimatively causes a shift to unsaturated conditions below the clogging layer. Atmospheric O2 then starts to penetrate from the pond fringes into this region, leading to: (i) the re-oxidation of the previously formed sulphide minerals and (ii) the enhanced mineralisation of sedimentary particulate organic C. The mineralisation of sedimentary particulate organic C leads to an increased H2CO3 production and subsequent dissolution of calcite.

This study investigates a post-denitrification process without the addition of an external carbon source combined with an enhanced biological phosphorus removal (EBPR) in a membrane bioreactor (MBR). Three trial plants, with two different process configurations, were operated on two different sites, and a variety of accompanying batch tests were conducted. It was shown that even without dosing of an external carbon source, denitrification rates (DNR) much above endogenous rates could be obtained in post-denitrification systems. Furthermore, the anaerobic reactor located a head of the process had a positive impact on the DNR. Given these surprising results, the project team decided to identify the carbon source used by the microorganisms in the postdenitrification process. Batch tests could demonstrate that lysis products do not play a major role as a C-source for postdenitrification. The following hypothesis was proposed to explain the observations: the glycogen, internally stored by the substrate accumulating bacteria, if anaerobic conditions are followed by aerobic conditions could act as carbon source for denitrification in post-denitrification system. First exploratory batch tests, where the glycogen evolution was monitored, corroborate this

The main goal of this project is to develop new sustainable sanitation concepts which have significant advantages in relation to ecological as well as to economical aspects compared to the conventional systems (end-of-pipe-system). After successful project completion the new sanitation concepts should be used in Berlin areas, where sewer systems are not installed and these concepts are appropriate, as well as other locations (national and international). The technical management of the project has been achieved as foreseen, but the administrative project manger has changed in July 2005 since the head of the Berlin Centre of Competence for Water has changed. All technical equipments, besides of the bio-gas plant, are realised. The bio-gas plant will be installed about the end of 2005. In contrary to the EU-proposal the concept with vacuum separation toilets has been installed for technical reasons in the office building instead in the apartment house. Before installing of these toilets gravity separation toilets have been operated for 1 ½ years. Furthermore not in 15 but in 10 flats of the apartment house was it possible to install gravity separation toilets. The addition tasks Life-Cycle-Assessment (Task 5), Industrial style urine treatment for utilization (Task 7) and Fertiliser usage (Task 8) undertaken by different Universities are in the works. The users accept the separation toilets in general, but more the gravity than the vacuum separation toilets. Both have to be improved, especially the flush. The worse assessment for the vacuum separation toilets was expected since they are altered gravity separation toilets. An optimised vacuum separation toilet is not available on the market at present. The results from the faeces separator show that far the most solids can be retained in the filter bags, but there is still a high solids-concentration in the filtrate. For huge settlements a different, continuously working separator is necessary. Due to the high solid concentration in the faecal filtrate the soil filter as a pre-treatment step was blocked very soon and went out of operation. With the 2-chamber septic tank for greywater and faecal filtrate treatment an effluent quality could be obtained which does not lead to clogging of the downstream constructed wetland. The results of the constructed wetland are as expected. From the work of Task 5 and the experiments of Task 7 no reliable results are available until now. The experiments of Task 8 show that the fertilising results from the urine are similar with those from mineral fertilisers. Until the end of the project the different tasks will continue. The digestion of the faeces from the vacuum separation toilets with the bio-gas plant will start in January 2006. In relation to the financial issues 790,482 € (51 %) of the total eligible costs of 1,552,116 € and 1,230,640 € (55 %) of the total real costs of 2,223,474 € respectively have been spent until now. Herewith, the 30 % threshold of the total real costs is transcended.

As part of the EU-Life ENREM demonstration project the Department of Chemical Engineering, TU Berlin, was appointed to conduct the preliminary pilot trials in a representative site for verification of basic process designs and operation criteria of the full-scale MBR demonstration plant. In addition to conception and construction of the pilot plant, this investigation consists of two successive trial phases with distinct operation conditions: the first one being dedicated to the assessment of the “irregular sludge wastage strategy” (the biomass is accumulating in the reactor, which is partly emptied when the sludge concentration reaches a given value), and the second one being planned to verify normal operation conditions with daily sludge wastage. This progress report describes implementation and results of the first phase, for which a pilot plant of 140L was operated over 6 months with waste water of a decentralized area. The influent contained high concentrations of nitrogen (100-200 mg/L), phosphorus (10- 20 mg/l) and COD (1000-2000 mg/L). Also surprising were the high VFA concentrations (100-300 mg/L) which ensured a good EBPR process. The COD and also the enhanced biological phosphorus removal (EBPR) were not impacted by the irregular sludge wastage. COD effluent concentrations were around 50 mg/L and TP effluent was 0.1 to 0.3 mg/L. The high nitrogen influent concentrations were problematic. Due to changing TS concentrations and changing nitrification rates TN effluent was 10 to 30 mg/L with a NH4-N content of 0 to 20 mg/L. Denitrification rates were measured between 1 and 3 mgN/gVS h and were depending on TS concentration, with higher rates at lower TS concentrations. Polysaccharide concentrations in the sludge water phase were higher with low TS concentrations and low oxygen concentrations. Higher PS values led to faster fouling. Results of the trials suggest that the oxygen concentration should be kept above 2mg/L to ensure both sufficient nitrification and lower fouling. Since also high TS concentrations are needed to ensure complete nutrients removal the optimum TS range is relatively small and it must be concluded that the irregular sludge wastage strategy was not beneficial in this case and the demonstration plant should be run with regular sludge removal.

The ENREM project aims at demonstrating a novel wastewater treatment process based on the technology of membrane bioreactor (MBR), set up in a configuration to enable enhanced biological elimination of nutrients. A new plant, and the related sewer system, is to be built in a yet unsewered remote area of Berlin. The plant will be then operated over more than one year, and the process will be optimised. Performances and costs of the treatment system will be then assessed for the size 250 – 10,000pe, corresponding to semi-central schemes. The management of the project has been achieved according to the organisation identified in the LIFE proposal. No relevant modification has been required. Annex 3.1 presents and discusses the key deliverables and milestones depending on the LIFE proposal and the current status. In relation to the technical content, Task 2 “Site and process definition” and Task 4 “Detailed design” are quasi-completed, with however a four month delay which will put back consequently the following actions, such as start of sewer and plant construction, and plant commissioning. Specifically, the following actions were completed, or are on the verge of completion: - Cost-comparison of decentralised treatment solutions to serve 20 unsewered areas of Berlin and selection of demonstration site (district of Margaretenhöhe); - Revision of cost evaluation for infrastructure; - Planning and specification of MBR plant; - Preparation and release of call for tender of MBR plant; - Planning and specification of low-pressure sewer; - Preparation and release of call for tender of low-pressure sewer construction; - Acquisition of legal permits (for plant construction & operation, water discharge); - Acquisition of parcel for MBR plant. In addition, the first trials phase of Task 3 “Preliminary testing on representative site” (period with irregular excess sludge withdrawal) was completed and enabled to validate the design criteria of the MBR demonstration plant. The relationship with the inhabitants of Margaretenhöhe was initiated in order to ensure a smooth construction phase, and a quick connection to the new sewer system. Dissemination activities were undertaken accordingly as shown in Annexes 7.1-7.3, and the project web-site in three languages was set up (see in www.kompetenz-wasser.de). The communications on project are expected to ramp up in 2005 and 2006, as more outcomes and results are getting available. The main task in 2005 will be the construction and commissioning of the low sewer system and the MBR demonstration plant. The start-up of the novel treatment scheme is now expected for October / November 2005. From the budget perspective, the total costs incurred over 2004 were 198,353€. This is 6% of the total budget of the LIFE proposal. The infrastructure costs and most of equipment costs (expected 62% of total budget) should occur in 2005 during the construction and commissioning phases of the scheme. No major budget deviation was noticed so far, and the re-evaluation of the infrastructure costs fit with those of the LIFE proposal.