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The Deep Space Gateway is a crewed platform that will be assembled and operated in the vicinity of the Moon by ESA and its international partners in the early 2020s and will offer new opportunities for fundamental and applied scientific research. The Moon is a unique location to study the deep space plasma environment, due to the absence of a substantial intrinsic magnetic field and the direct exposure to the solar wind, galactic cosmic rays (GCRs) and solar energetic particles (SEPs). However, 5-6 days each orbit, the Moon crosses the tail of the terrestrial magnetosphere facilitating the in-situ study of the terrestrial magnetotail plasma environment as well as atmospheric escape from the ionosphere. When back outside of the magnetosphere, a variety of these and other phenomena, e.g. those driving solar-terrestrial relationships, can be investigated through remote sensing using a variety of imaging techniques. Most importantly, the lunar environment offers a unique opportunity to study the interaction of the solar wind and the magnetosphere with the lunar surface and the lunar surface-bounded exosphere. In preparation of the scientific payload of the Deep Space Gateway, we have undertaken a conceptual design study for a Space Plasma Physics Payload Package onboard the Gateway (SP4GATEWAY). The main goal is first to provide a science rationale for hosting space plasma physics instrumentation on the Gateway and to translate that into a set of technical requirements. A conceptual payload design, that identifies a strawman payload and is compatible with the technical requirements, is then put forward. The final outcome of this project, which is undertaken following an ESA AO, is an implementation plan for this space plasma physics payload package.

Extraction of chitin from mechanically pre-purified shrimp shells can be achieved by successive NaOH/HCl treatment, protease/HCl treatment or by environmentally friendly fermentation with proteolytic/lactic acid bacteria (LAB). For the last mentioned alternative, scale-up of shrimp shell chitin purification was investigated in 0.25 L (F1), 10 L (F2), and 300 L (F3) fermenters using an anaerobic, chitinase-deficient, proteolytic enrichment culture from ground meat for deproteination and a mixed culture of LAB from bio-yoghurt for decalcification. Protein removal in F1, F2, and F3 proceeded in parallel within 40 h at an efficiency of 89-91 %. Between 85 and 90 % of the calcit was removed from the shells by LAB in another 40 h in F1, F2, and F3. After deproteination of shrimp shells in F3, spent fermentation liquor was re-used for a next batch of 30-kg shrimp shells in F4 (300 L) which eliminated 85.5 % protein. The purity of the resulting chitin was comparable in F1, F2, F3, and F4. Viscosities of chitosan, obtained after chitin deacetylation and of chitin, prepared biologically or chemically in the laboratory, were much higher than those of commercially available chitin and chitosan.

The exact circumstances that cause the widespread enrichment of Mn and As in groundwater of the Bengal Delta Plain (BDP) and many other Asian delta areas still remain a matter of debate in the scientific community. We conducted an in situ field experiment in the central BDP region to investigate the influence of organic matter on the mobility of Fe, Mn and As in shallow aquifers. The groundwater at our study site was initially characterized by a circum-neutral pH, low concentrations of O 2 , NO 3 − and SO 4 2 − , and increased Fe, Mn and As concentrations, reflecting reducing conditions in the aquifer. Since organic matter controls microbially mediated redox processes which are believed to result in the mobilization of Fe, Mn and As from Holocene aquifer sediments, an easily degradable carbon source (sucrose) was introduced into a shallow aquifer via four nested monitoring wells and distributed by circular pumping. Initial sucrose concentrations reached up to 2.55 mM in the local groundwater and induced a strong increase in the activity of indigenous microbes that decomposed the sucrose within the following 14 days stepwise into intermediate catabolic products (e.g., acetic acid), and finally to CO 2 /HCO 3 − . The formation of organic acids was accompanied by a temporary decline in the pH and the redox potential, as well as an increase in the concentration of most major and trace elements in the groundwater by several times. While Mn concentrations rose up to 81.3 μM (representing a 7.5 fold increase), Fe (on average 96.7% Fe(II)) concentrations reached a considerable transient maximum of 1390 μM, which was 36 times higher than the initial baseline value. The most significant observation of this experiment is that the relative increments of dissolved As (on average 95.8% As(III)) reached between 19 and 49% only, which is in clear contrast to the pronounced mobilization of Fe, Mn and other trace elements. Changes in the groundwater composition during the experiment imply that the mobilization of Fe and Mn was primarily caused by a reductive dissolution of Mn-oxides and Fe-(oxyhydr)oxides, resulting from the stimulation of indigenous bacteria by the addition sucrose. In this context, the release of As can be attributed to the dissolution of Fe-(oxyhydr)oxides, which constitute the principal source of As in the aquifer sediments according to mineralogical and geochemical analyses. In contrast to the pronounced mobilization of Fe, the response of groundwater arsenic concentrations appeared to be muted, as indicated by subsequently declining As to Fe mol ratios that dropped one order in magnitude. The remarkable decoupling of As from Fe mobilization indicates that the aquifer sediments were apparently capable of compensating for the additional release of As. We attribute this As buffer potential to remaining Fe-minerals and potentially newly formed Fe(II)- and mixed Fe(II/III)-mineral phases, which were able to readily immobilize dissolved As. Sequential extraction results of the initial aquifer sediments further support this interpretation, revealing that up to 85% of the total As in the sediments was already present in adsorbed form, with Fe-minerals as principal hosts. Hence, the experimental data implies that a biogeochemically controlled environment of competing As release and retention arose after the addition of sucrose, where Fe-mineral phases played a key role in buffering the release of As. We further conclude that organic carbon limited aquifer systems in the BDP with increased As concentrations in groundwater may exhibit an unexpected buffer potential towards an additional As release, even when vast amounts of easily degradable organic carbon are introduced into the system.

Here we report temporal changes of As concentrations in shallow groundwater of the Bengal Delta Plain (BDP). Observed fluctuations are primarily induced by seasonally occurring groundwater movement, but can also be connected to anthropogenic groundwater extraction. Between December 2009 and July 2010, pronounced variations in the groundwater hydrochemistry were recorded in groundwater samples of a shallow monitoring well tapping the aquifer in 22-25 m depth, where Astot concentrations increased within weeks from 100 to 315 μg L(-1). These trends are attributed to a vertically shift of the hydrochemically stratified water column at the beginning of the monsoon season. This naturally occurring effect can be additionally superimposed by groundwater extraction, as demonstrated on a local scale by an in situ experiment simulating extensive groundwater withdrawal during the dry post-monsoon season. Results of this experiment suggest that groundwater extraction promoted an enduring change within the distribution of dissolved As in the local aquifer. Presented outcomes contribute to the discussion of anthropogenic pumping influences that endanger the limited and yet arsenic-free groundwater resources of the BDP.

High strength automobile industry wastewater, collected from decanters (DECA) of the pre-treatment plant after oil, grease and sludge separation, was investigated for production of methane in the absence and presence of glucose or excess aerobic sludge (AS) from a lab scale suspension reactor as co-substrates. The highest methane production from DECA wastewater was 335.4 L CH4/kg CODsoluble removal which decreased in the presence of the co-substrates to 232.5 (with 2 g/L glucose) and to 179 (with 40% AS) L CH4/kg CODsoluble removal, respectively. Around 95% of total methane was produced within 5 days of incubation of DECA at 37 °C when no co-substrate was added. Addition of co-substrates did not improve biodegradation of DECA but overall methane production from DECA + co-substrates was increased due to co-substrate biodegradation. The anaerobic inoculum, capable of producing 2.4 mol of hydrogen/mol of glucose under zinc induced inhibitory conditions, was unable to produce hydrogen from DECA as substrate under the same conditions.

A mixed culture from an anaerobic biowaste digester was enriched on propionate and used to investigate interspecies hydrogen transfer in dependence of spatial distances between propionate degraders and methanogens. From 20.3 mM propionate, 20.8 mM acetate and 15.5 mM methane were formed. Maximum specific propionate oxidation and methane formation rates were 49 and 23 mmol mg(-1) day(-1), respectively. Propionate oxidation was inhibited by only 20 mM acetate by about 50 %. Intermediate formate formation during inhibited methanogensis was observed. The spatial distribution and the biovolume fraction of propionate degraders and of methanogens in relation to the total population during aggregate formation were determined. Measurements of interbacterial distances were conducted with fluorescence in situ hybridization by application of group-specific 16S rRNA-targeted probes and 3D image analyses. With increasing incubation time, floc formation and growth up to 54 μm were observed. Propionate degraders and methanogens were distributed randomly in the flocs. The methanogenic biovolume fraction was high at the beginning and remained constant over 42 days, whereas the fraction of propionate degraders increased with time during propionate feeding. Interbacterial distances between propionate degraders and methanogens decreased with time from 5.30 to 0.29 μm, causing an increase of the maximum possible hydrogen flux from 1.1 to 10.3 nmol ml(-1) min(-1). The maximum possible hydrogen flux was always higher than the hydrogen formation and consumption rate, indicating that reducing the interspecies distance by aggregation is advantageous in complex ecosystems.

Aircraft parabolic flights provide repetitively short periods of reduced gravity and are used to conduct scientific and technology microgravity investigations, to test instrumentation prior to space flights and to train astronauts before a space mission. Since 1997, ESA, CNES and DLR use the Airbus A300 ZERO-G, currently the largest airplane in the world for this type of experimental research flight. This mean is managed by the French company Novespace. Since 2010, Novespace offers the possibility of flying reduced gravity levels equivalent to those on the Moon and Mars achieved repetitively for periods of more than 20 s. ESA, CNES and DLR issued an international call for experiments inviting European Scientists to submit experiment proposals to be conducted at these partial gravity levels. The scientific objectives are on one hand to obtain results at intermediate levels of gravity (between 0 and 1 g) allowing a better study of the influence of gravity, and on the other hand to give them some elements to prepare for research and exploration during space flights and future planetary exploration missions. ESA, CNES and DLR jointly organised in June 2011 the first Joint European Partial-G Parabolic Flight campaign with 13 experiments selected among 42 received proposals. Parabolas were flown during three flights providing micro-, Moon and Mars gravity levels with duration typically of 20 s, 25 s and 32 s with a mixed complement of investigations in physical and life sciences and in technology. The paper presents the approach taken to organise this campaign and the 13 selected experiments with some preliminary results are presented to show the interest of this unique research tool for microgravity and partial gravity investigations.

Biowaste digestion is a possibility to gain biogas as a renewable fuel source. However, the anaerobic food chain may be disrupted by, e.g., substrate overload or by inhibitors, leading to the accumulation of volatile fatty acids (VFAs), predominantly of propanoic acid (PA). VFA Accumulation may cause a rapid pH decrease, less biogas production, or even a total inhibition. To maintain high biogas productivity or to prevent a collapse of methanogenesis, metabolic properties of the degrading microorganisms must be elucidated, e.g., by investigation of the established pathways for degradation of VFAs. A Dani 3950 headspace system (HS), a Varian 431 gas chromatograph (GC), and a Varian 210 mass spectrometer (MS) have been combined to quantify and specifically identify metabolites of PA oxidation. The use of [1-(13)C]-labeled PA as a carbon source for microorganisms allows differentiation between the methyl-malonyl-CoA or the C(6)-dismutation pathway, both resulting in AcOH production. Appearance of the (13)C-moiety either in the COO or Me group of AcO can easily be detected by MS. The methyl-malonyl-CoA pathway was successfully identified as the only pathway of PA degradation by organisms in a lab-scale anaerobic digester. A similar approach can be applied to any degradation pathway involving VFAs.

Deproteination of decalcified chitin from Crangon crangon shells and deacetylation to chitosan was investigated to find out optimum conditions for a high viscosity chitosan. Deproteination was carried out with an optimum shrimp shell:alkali (s:a) ratio of 1:4 from 30 °C to 65 °C and at each temperature, incubation times were varied from 2 to 5 h for maximal efficiency. Viscosity of the chemically extracted chitin samples at different temperature–time conditions ranged from 195 to 391 mPa s. A two-way ANOVA with Bonferroni post test was performed on experimental data. Chitin extracted at various temperatures and incubation times was deacetylated with 50% (w/w) NaOH at increasing reaction times. The highest chitosan viscosity of 1976 mPa s was observed in a sample deproteinated for 5 h at 55 °C and deacetylated for 1 h at 105 °C and 2 bar N 2 pressure. One-way ANOVA test for chitosan viscosity measurements indicated a significant P value of

In tests with Hele–Shaw cells containing silica sand, O2 profiles were measured after formation of a capillary fringe (CF) with a nutrient broth, that was inoculated with Pseudomonas putida. After 7 d, the CF became anaerobic up to 2 cm above the water level. Within the next 3 cm at decreasing water saturation, the O2 concentration approached its maximum value. After growth, most P. putida cells were found at the 4- to 5-cm height of the CF, whereas cell densities decreased significantly toward the top of the CF due to water-limited respiratory activity. This was shown in separate batch experiments by measuring respiration rates of P. putida for defined water saturations. In silica sand (rough surface) or glass beads (smooth surface), respiration of P. putida was significantly reduced at a water saturation of ≤7.5% but was always higher for growth on sand than on glass beads, presumably due to different water bioavailability at the surface. The highest O2 consumption rates of P. putida in both media were measured at 60 to 85% water saturation, which represents the saturated–unsaturated interface region in a CF. To find the minimum required water availability for respiration, batch assays with increasing agar concentrations in LB medium were conducted. The O2 consumption rates of P. putida decreased to zero above an agar concentration of 18% (w/v), equivalent to a water activity

Soil and groundwater samples were collected for bulk elemental analyses in particular for selenium (Se) concentrations from six agricultural sites located in states of Punjab and Haryana in North-West India. Toxic concentrations of Se (45-341 μg L(-1)) were present in groundwater (76 m deep) of Jainpur and Barwa villages in Punjab. Selenium enrichments were also found in top soil layers (0-15 cm) of Jainpur (2.3-11.6 mg kg(-1)) and Barwa (3.1 mg kg(-1)). Mineralogical analyses confirmed silicates and phyllosilicates as main components of these soils, also reflected by the high content of SiO(2) (40-62 wt.%), Al(2)O(3) (9-21 wt.%) and K(2)O (2.2-3.2 wt.%). Prevailing intensive irrigation practices in Punjab with Se enriched groundwater may be the cause of Se accumulation in soils. Sequential extraction revealed50% Se bioavailability in Jainpur soils. Appearance of selenite was observed in some of the batch assays with soil slurries under reducing conditions. Although safe Se concentrations were found in Hisar, Haryana, yet high levels of As, Mo and U present in groundwater indicated its unsuitability for drinking purposes. Detailed biogeochemical studies of Se in sediments or groundwater of Punjab are not available so far; intensive investigations should be started for better understanding of the problem of Se toxicity.

Anaerobic growth of a newly isolated Pseudomonas putida strain WB from an arsenic-contaminated soil in West Bengal, India on glucose, L: -lactate, and acetate required the presence of arsenate, which was reduced to arsenite. During aerobic growth in the presence of arsenite arsenate was formed. Anaerobic growth of P. putida WB on glucose was made possible presumably by the non-energy-conserving arsenate reductase ArsC with energy derived only from substrate level phosphorylation. Two moles of acetate were generated intermediarily and the reducing equivalents of glycolysis and pyruvate decarboxylation served for arsenate reduction or were released as H(2). Anaerobic growth on acetate and lactate was apparently made possible by arsenate reductase ArrA coupled to respiratory electron chain energy conservation. In the presence of arsenate, both substrates were totally oxidized to CO(2) and H(2) with part of the H(2) serving for respiratory arsenate reduction to deliver energy for growth. The growth yield for anaerobic glucose degradation to acetate was Y (Glucose) = 20 g/mol, leading to an energy coefficient of Y (ATP) = 10 g/mol adenosine-5'-triphosphate (ATP), if the Emden-Meyerhof-Parnas pathway with generation of 2 mol ATP/mol glucose was used. During growth on lactate and acetate no substrate chain phosphorylation was possible. The energy gain by reduction of arsenate was Y (Arsenate) = 6.9 g/mol, which would be little less than one ATP/mol of arsenate.

Retention of bacterial cells as "particles" by silica sand during formation of a capillary fringe (CF) and the influence of motility was examined with motile Pseudomonas putida and non-motile Corynebacterium glutamicum suspensions in the absence of nutrients. The fractional retention of C. glutamicum cells at all regions of the CF was higher than for P. putida cells, most probably due to the motility of P. putida. Only about 5% of P. putida cells and almost no C. glutamicum cells reached the upper end of a CF of 10 cm height. With cell suspensions of P. putida and C. glutamicum in nutrient broth the development of a CF in silica sand fractions of 355-710 microm and 710-1000 microm respectively, was finished after about 6 h. Growth of cells proceeded for about 6 days. P. putida formed a biofilm on silica grains, whereas no attachment of C. glutamicum on silica sand occurred. Relative cell densities of C. glutamicum on the bottom and in the upper regions of the CF were always lower than those of P. putida and were also lower than those reached in suspended cultures with the same medium. In coarse sand the motile P. putida cells reached significantly higher cell densities in upper CF regions than in fine sand. Growth of C. glutamicum in the CF apparently was slower and a higher proportion of the energy was required for maintenance. Whereas cell densities of P. putida, in CFs of both sand fractions, varied less than one order of magnitude, those of C. glutamicum varied in a wider range from the basis to the top of the CF. Analyses of the esterase activity of P. putida and C. glutamicum with fluorescein diacetate (FDA) revealed that the cells in higher CF regions were significantly more active than those at the bottom of the CF. Furthermore, a significant correlation (r = 0.66, p < 0.01) between cells ml(-1) and the FDA conversion to fluorescein was found.

Biodegradation of 0.25–7.0 mmol l−1 phenol with a mixed bacterial consortium at a temperature of 25 ± 2 °C and a pH of 7.2 was studied in batch aerobic reactors. Substrate inhibition was calculated from experimental growth parameters using the Haldane equation. Kinetic parameters were derived by non-linear regression with a correlation factor (R2) of 0.987. The values for Haldane constants μmax, Ks and Ki were 0.3095 h−1, 0.7933 mmol l−1 and 6.887 mmol l−1, respectively. The value of Ki is one of the highest values obtained for mixed cultures degrading phenol under batch conditions. The yield factor (units A578 mmol−1 phenol) ranged from 0.10 to 0.16. The biokinetic parameters were used to predict the biodegradation profile, which agreed well with the experimental data. The results obtained from this study could be useful for an estimation of the relationship between growth rate and substrate utilization, which may be used to evaluate mass balance for a phenol containing wastewater treatment system involving mixed culture as the “biocatalysts”.

The use of foodwaste as a supplementary substrate for an anaerobic municipal biowaste digester during night times and as the sole substrate during weeks ends, when no biowaste suspension was available was studied in order to equilibrate biogas production. Assays were performed in semi-continuously fed laboratory reactors with real substrates, simulating practical feed conditions. Biogas production of biowaste or foodwaste reached 0.39 or 0.52 m3·kg−1 CODadded, with an average methane content of 62–66%, respectively. By foodwaste co-digestion during the night in a semi-continuously fed bioreactor, the total biogas production of the reactor increased by 21–37% compared to biogas production during biowaste-only-fed periods during the day and no feeding during the night. After three weeks of supplemenary foodwaste digestion during the nights and during week ends, the COD elimination efficiency of the reactor reached the same level as in biowaste-only-fed periods (51–65%). During co-digestion of foodwaste with biowaste, the volatile solids elimination efficiency was between 62–65%, which was insignificantly less compared to the volatile solids elimination during biowaste-only-fed periods (63–68%).

An anaerobic fixed bed reactor (AFBR) was run for 550 days with a mixed microbial flora to stabilize synthetic wastewater that contained glucose and phenol as main carbon sources. The influent phenol concentration was gradually increased from 2 to 40 mmol/l within 221 days. The microbial flora was able to adapt to this high phenol concentration with an average of 94% phenol removal. Microbial adaptation at such a high phenol concentration is not reported elsewhere. The maximum phenol removal observed before the phenol shock load was 39.47 mmol/l or 3.7 g phenol/l at a hydraulic retention time (HRT) of 2.5 days and an organic loading rate (OLR) of 5.3 g/l.d which amounts to a phenol removal rate of ca. 15.8 mmol phenol/l.d. The chemical oxygen demand (COD) removal before exposing the reactor to a shock load corresponded with phenol removal. A shock load was induced in the reactor by increasing the phenol concentration from 40 to 50 mmol/l in the influent. The maximum phenol removal rate observed after shock load was 18 mmol/l.d at 5.7 g COD/l.d. But this was not a stable rate and a consistent drop in COD and phenol removal was observed for 1 week, followed by a sharp decline and production of fatty acids. Recovery of the reactor was possible only when no feed was provided to the reactor for 1 month and the phenol concentration was increased gradually. When glucose was omitted from the influent, unknown intermediates of anaerobic phenol metabolism were observed for some time.

The continuous aerobic degradation of phenol, mixed with readily degradable synthetic wastewater was studied over a period of 400 days at 25+/-5 degrees C temperature in a fixed bed biofilm reactor using 'Liapor' clay beads as packing material. The phenol concentration added to the reactor ranged from 0.19 to 5.17g/l and was achieved by a gradual increase of phenol in wastewater, thus adapting the microbial flora to high contaminant concentrations. A maximal removal rate of 2.92g phenol/(ld) at a hydraulic retention time (HRT) of 0.95 days and a total organic loading rate (OLR) of 15.3g COD/(ld) with a phenol concentration of 4.9g/l was observed. However, this was not a stable rate at such high phenol loading. At the end of reactor operation on day 405, the phenol removal rate was 2.3g/(ld) at a influent phenol concentration of 4.9g/l. There were no phenol intermediates present in the reactor, as evident from corresponding COD, phenol removal and the absence of fatty acids. Omission of organic nitrogen compounds or of urea in influent feed was not favourable for optimal phenol removal. The phenol degradation profile that was studied in shake flasks indicated that the presence of a acetate which represent as an intermediate of phenol degradation retarded the phenol degradation. The highest phenol degradation rate observed in batch assays was 3.54g/(ld).

In this study the continuous treatment of 2-chlorophenol (2-CP) containing synthetic wastewater at increasing concentrations up to 2600 mg L-1 in an anaerobic fixed bed reactor was achieved. As a source of microorganisms municipal sewage sludge was acclimatised to maximally 50 mg L-1 2-CP by 3 successive feedings within 1.5 months. Then, an anaerobic fixed bed reactor was inoculated with this sludge and was operated for 318 d, during which the 2-CP influent concentration was stepwise increased from 50 to 2600 mg L-1 within 265 d. At a hydraulic retention time (HRT) of 2.2 d the 2-CP loading rate was 2 g L-1 d-1 and the average 2-CP removal rate was 0.87 g L-1 d-1, accounting for 73% removal. This is the highest 2-CP removal rate ever reported. The negative effect of a 2-CP loading rate of 1.36 g L-1 d-1 on 2-CP removal was reversible within 2 wk when lower loading conditions (e.g. 0.76 g 2-CP L-1 d-1) were re-established. The median chloride ion release per unit 2-CP degraded was 0.24, which was reasonably close to the theoretically expected value of 0.28. In a batch assay, carried out with relatively clear reactor effluent, the highest removal rate of 2-CP was 175 mg L-1 d-1. At the time of reactor termination on day 318, the 2-CP removal rate by the biofilm in the reactor was 0.61 g L-1 d-1, corresponding to a HRT of 3.4 d and a 2-CP loading rate of 0.76 g L-1 d-1. At these very stable conditions removal of COD was 84% and of 2-CP 81%

Aerobic degradation of 7 mmol/L phenol in the presence of alternative carbon sources (7 mmol/L glucose or acetate or 1-2 mmol/L 2-chlorophenol) was investigated using non-acclimatized and acclimatized sewage sludges and enrichment cultures. The substrates represented an intermediate of phenol degradation (acetate), an independent substrate (glucose) or a "precursor-substrate" of phenol degradation (2-chlorophenol). Bacteria from sewage sludge, not pre-adapted to phenol (2 mmol/L), rapidly respired acetate and glucose in the presence of phenol, whereas phenol was only bioconverted to any unknown aromatic metabolite after 24 h. In the presence of phenol and 2-chlorophenol, no removal of both substances was observed when using the unacclimatized sludge. Sludge that was acclimatized to the degradation of phenol showed an initial preference for easily degradable co-substrates such as glucose or acetate with only a slow concomitant respiration of phenol. Respiration of phenol increased rapidly after the co-substrates were depleted. The highest phenol degradation rates were 51.6 mmol/L d, when phenol was the sole carbon substrate. Vice versa, phenol was preferentially respired in the presence of a less easily degradable co-substrate such as 2-chlorophenol at a rate of around 7 mmol/L d. Further studies with an enrichment culture that was obtained after 7 successive transfers of phenol-adapted sludge into mineral medium with phenol as the only carbon source indicated that the acetate and glucose-degrading capabilities were diminished or almost completely lost. In these enrichment cultures, phenol degradation was not affected by the presence of glucose, but glucose was not degraded. In contrary, the presence of acetate slightly slowed down the phenol degradation rate of the enrichment culture. Growth of the microorganisms apparently occurred at the expense of phenol and acetate respiration. The result of this work may be of practical importance in determining the feeding strategy, which is the key factor for most biological wastewater treatment systems. When acetate was present together with phenol in a wastewater, the phenol degradation rates were influenced by acetate, since acetate was an intermediate of phenol degradation. Glucose as an "independent substrate" was apparently degraded by other bacteria via acetate, and in this way it also influenced the phenol degradation rates. Glucose-degrading bacteria could be "washed out" from the acclimatized sludge during several transfers into mineral medium with phenol as the sole carbon source. If later on, glucose was added again, it remained undegraded and did not influence phenol degradation. 2-Chlorophenol degradation also requires other bacteria than phenol degraders.

The methane formation rate of 300 m(3) of sludge from a full scale biowaste reactor, that was stored without feeding for six weeks during a maintenance period, was about 60% of the methanogenic activity before maintenance. The 300 m(3) sludge was then pumped back into the biowaste reactor. On the third day, after refilling of the stored biowaste suspension, anaerobic conditions were obtained and feeding was started by addition of 36.1 m(3) of fresh biowaste suspension (=11.3 tons biowaste). The pH dropped from originally pH 7.7 to pH 7.3 and later on to pH 6.8, which was considered the minimum allowed pH for methanogenesis to recover. Maximum concentrations of acetate (1.78 gl(-1)), n-butyrate (0.57 gl(-1)) and n-valerate (0.44 gl(-1)) accumulated during the following days with feeding of 11.8 tons on day 5 and twice 6.5 tons on days 7 and 9, respectively. Thereafter, acetate, n-butyrate and n-valerate were degraded completely, whereas the concentration of propionate was still increasing. Propionic acid was the dominant fatty acid during the restart period and reached its maximum concentration of 6.2 gl(-1) 17 days after start of feeding. This high level of propionate was degraded completely in about 5 days with maximum degradation rates of 2.14 gl(-1)d(-1), and the pH of the anaerobic sludge increased from 7.1 to 7.4. During restart, the methane content of the biogas increased successively to 65%. Samples that were taken at different time intervals during the restart phase of the methane reactor showed different fatty acid degradation capabilities. After 10 days, when acetate and n-butyrate still accumulated in the methane reactor the maximum acetate degradation rate was 1.52 gl(-1)d(-1) and the n-butyrate degradation rate was 0.51 gl(-1)d(-1). Oxidation of n-valerate caused an increase of propionate, which was degraded after a lag phase of 6 days with a maximum rate of 0.6 gl(-1)d(-1). In the samples taken after 16 and 23 days, the propionate degradation rate increased to 1.42 gl(-1)d(-1) and 1.55 gl(-1)d(-1), respectively, and the lag phase for propionate degradation was reduced or had disappeared completely. The maximum propionate degradation rate was measured in the methane reactor in the fourth week after restart. The synthrophic propionate oxidizing bacteria were apparently the most suffering bacteria during sludge storage. If the propionate oxidizing bacteria could be kept active and the propionate degrading activity of the biowaste suspension of 6.16 gl(-1)d(-1) before the maintenance period could be maintained, then accumulation of 6.2 gl(-1) propionate in the methane reactor after restart could be avoided and full activity reached even earlier.

The possible deterioration of the microbiological quality of groundwater due to leaky sewer systems was investigated in a medium-sized city (Rastatt) in SW-Germany. Specially constructed focus observation wells drilled close to leaky sewers have been compared with the background observation wells in urban and rural areas. The sampling was performed in March (shallow depth of groundwater) and in July and October (deep groundwater table). It included the measurement of ammonium ions, temperature, electric conductivity, oxygen, and the depth of the groundwater table. Coliforms, Escherichia coli, and enterococci were enumerated as indicator organisms for wastewater contamination. In addition, the total number of colony forming units was determined. Bacterial counts of coliforms and E. coli generally increased during the course of the investigation (March to October). This may have been caused either by a slightly increased groundwater temperature (higher activity rates) or by a higher proportion of sewage in the urban groundwater system as a result of the dry season (summer). The contamination with faecal indicator bacteria was greater adjacent to leakage locations. In addition, elevated concentrations of ammonium ions were observed at these areas. The results provide evidence that leaky sewer systems elevate faecal indicator concentrations in groundwater with associated potential health risk where such waters are used for potable water supply. Mikrobiologischer Zustand von urbanem Grundwasser in der Nahe von Kanalleckagen Die mogliche Beeintrachtigung der mikrobiellen Flora des Grundwassers durch undichte Abwasserkanale wurde in einer mittelgrosen Stadt im Sudwesten Deutschlands (Rastatt) untersucht. Hierzu wurden speziell angelegte Grundwassermessstellen in der Nahe von undichten Kanalen gebohrt. Die gemessenen Parameter wurden mit mikrobiologischen Daten aus Grundwassermessstellen im urbanen Gebiet und aus Referenzmessstellen im landlichen Raum verglichen. Die Probenahmen wurden im Marz (hoher Grundwasserstand) und im Juli und im Oktober (niedriger Grundwasserstand) durchgefuhrt. Die Beprobung beinhaltete die Messung der Standard-Parameter Ammonium, Temperatur, elektrische Leitfahigkeit, Sauerstoffgehalt und des Grundwasserspiegels. Coliforme Keime, Escherichia coli und Enterokokken wurden analysiert und dienten als Indikatororganismen fur eine Kontamination mit Abwasser. Zusatzlich wurde die Anzahl der koloniebildenden Keime gemessen. Die Zellzahlen der coliformen Keime und des Bakteriums E. coli stiegen im Verlauf der Untersuchung (Marz bis Oktober) an. Dieser Anstieg ist moglicherweise verursacht durch geringfugig hohere Grundwassertemperaturen oder einen hoheren Anteil an Abwasser im urbanen Grundwassersystem als Folge einer Trockenwetterperiode (Sommer). Die Kontamination des Grundwassers mit Abwasserbakterien lasst eine Abhangigkeit von der Nahe zur Leckage erkennen. Die Ergebnisse liefern einen Hinweis darauf, dass undichte Abwasserkanale eine Gefahrdung fur die Qualitat des Grundwassers darstellen.

The effect of leaking sewers on soil and groundwater was simulated by trickling sewage through 125 cm sand columns in the laboratory. The filtering effect of sludge and soil was tested and a detailed analysis of the soil and column effluent was performed after 3 months and 18 months. The trickling rates were highly variable. Sewage components that sedimented on top of the sand or were swept into the upper sand layers reduced the trickling rates to almost zero after a few days. However, biogas production by the anaerobic bacterial consortium in the sludge and upper soil layers periodically led to a significant increase of the trickling rates for a while, after the gas bubbles escaped and destroyed the dense sludge structure that restricted trickling with increasing trickling time. The COD elimination averaged 71.7…74 %. The total nitrogen content of the sewage was reduced after trickling through the sand column by 34 %. The column effluent contained mainly Norg and ammonia. Since the sand columns were not explicitly kept anaerobic, some oxygen was apparently available and little nitrite/nitrate was generated. As judged from the COD, TOC, or the total organic solids, the organic matter on the sand grains decreased rapidly and exponentially from top to bottom. This was in accordance with a decrease of the population density that was determined after resolution of the biofilm from the sand at different depth. More culturable bacteria per gram sand at every depth were found in the column that was run for 18 months than in the column that was run for only 3 months. This may be an indication for a less developed biofilm after 3 months in comparison to a more developed, thicker biofilm after 18 months. After trickling of sewage for 3 months the biofilm on the sand grains contained more aerobic bacteria, the biofilm that had developed after 18 months contained a higher portion of anaerobic bacteria. Veranderung chemischer und biologischer Kenngrosen des Bodens nach Abwasserversickerung Der Einfluss von versickerndem kommunalen Abwasser aus undichten Kanalen auf Boden und Grundwasser wurde in Sandsaulen von 125 cm Lange im Labor simuliert. Die Elimination von Abwasserkomponenten bei Aufgabe von mechanisch gereinigtem Abwasser auf Sandsaulen wurde bestimmt. Nach 3 Monaten und 18 Monaten Laufzeit wurde der Sand entnommen und untersucht. Die Sickerraten schwankten in einem weiten Bereich. Schlammpartikel aus dem Abwasser wurden auf dem Sand zuruckgehalten und in die obersten Sandschichten eingeschwemmt. Sie fuhrten nach kurzer Zeit zu einem starken Ruckgang der Sickerraten. Die Bildung von Biogas durch die anaerobe Population in der Schlammschicht und das Entweichen der Gasblasen aus dem Schlamm fuhrte zu einer periodischen Zunahme der Sickerraten. In den Sandsaulen wurden zwischen 71.7 bis 74 % des zugefuhrten CSB und 34 % des N-Gehaltes eliminiert. Im Saulenablauf wurden hauptsachlich Ammoniak und organischer Stickstoff gefunden. Da die Saulen nicht vollkommen anaerob betrieben wurden, befanden sich auch geringe Mengen an Nitrit und Nitrat im Ablauf. Der organische Gehalt des Sandes der Saulen nahm von oben nach unten drastisch ab, was mit der Abnahme der Populationsdichte mit zunehmender Sickerstrecke korrelierte. Nach gleicher Sickerstrecke nahm die Dichte kultivierbarer Bakterien pro Gramm Sand nach 3 Monaten bis nach 18 Monaten Laufzeit zu, was auf einen noch wachsenden Biofilm auf den Sandkornern hindeutete. Nach insgesamt 3 Monaten Sickerzeit enthielt der Biofilm mehr aerobe Bakterien, wahrend nach 18 Monaten Sickerzeit ein hoherer Anteil von anaeroben Bakterien im immer noch dunnen Biofilm gefunden wurde.

Sulfate-reducing bacteria contribute considerably to the degradation of organic matter in sewage contaminated soils, particularly below leaking sewers. Molybdate as a specific inhibitor of sulfate reduction is known to be present in sewage. Its influence on sulfur isotope fractionation during sulfate reduction was explored in batch experiments with pure cultures of Desulfovibrio desulfuricans and with natural populations enriched from sewage-contaminated soil. Results with D. desulfuricans show that molybdate (0.1 mmol/l) caused a decrease of 6‰ in the isotope enrichment factor compared to an uninhibited control. The decrease in sulfur isotope fractionation may be explained by a depletion of ATP resulting in a lesser amount of activated sulfate available for sulfate reduction in the organism. Experiments carried out at 15 and 37°C reveal a decrease of about 4‰ in the isotope enrichment factor at the low temperature, which is attributed to limited uptake of sulfate. The sulfate-reducing enrichment cultures...

To simulate the filtration and/or degradation of trickling sewage from leaky sewers through the non-water-saturated underground, sewage was trickled through sand of 0.4–2 mm from the Rhine valley in glass columns of 125 cm length. For the same sewage the chemical oxygen demand (COD) removal was almost independent of low or high trickling rates. The COD removal efficiency varied, however, from 67% to 79%, for sewage from rain and dry weather periods, respectively. The water content of the moist sand increased from initially 80 ml kg −1 with increasing sewage trickling rates to 108 ml kg −1 sand. It remained at 108 ml kg −1 at higher trickling rates higher than 600 ml d −1 . Analyses of effluent of five consecutive 25-cm soil columns revealed that about 50% of the initial COD were filtrated off on top of the sand or degraded in the uppermost 25 cm at varying trickling rates. Another 6–12% of the COD were removed in the following 25–50 cm of sand, whereas almost no further COD removal was seen in the subsequent two or three 25-cm columns. The COD elimination during trickling of sewage through the segmented column (interrupted random flow) was slightly better than that in the non-segmented column. Total and faecal coliform bacteria decreased faster with increasing trickling depth than that of total aerobic or anaerobic bacteria. After a filter/degradation stretch of 125 cm elimination of all bacteria reached 96.2–99.9%. The sewage contained low concentrations of at least 10 different pharmaceuticals or X-ray media. During trickling of sewage through sand, elimination of these compounds by adsorption onto sand and/or biodegradation varied from a complete removal, e.g. Ibuprofen or Naproxen, to almost no removal for several X-ray contrast media. Some of the medicals were removed as effectively as during conventional sewage treatment.

In the City of Karlsruhe/Germany anaerobic digestion of 7200 t a −1 of separately collected biowaste has proven its feasibility at an organic loading rate (OLR) of up to 8.5 kg COD m −3 d −1 . An extension of biowaste collection over the whole city area would increase the amount of biowaste to 12,000 t a −1 , leading to an OLR of the existing anaerobic reactor of up to 15 kg COD m −3 d −1 . To test, whether the increased amount of biowaste could be stabilized in the existing plant, biowaste suspensions were digested in a laboratory reactor at a maximum OLR, that exceeded the future OLR of the full-scale plant. The laboratory reactor was started with effluent of the full-scale biowaste digester. Like in full-scale, biowaste suspension from the hydropulper was added in a fed-batch mode. The elimination of organic material (measured as COD, chemical oxygen demand) and the volumetric gas production were linearly increasing with the OLR from 4.3 to 19 kg COD m −3 d −1 . Thus, safe operation of the full-scale plant at an OLR of 15 kg COD m −3 d −1 should be possible, leaving still some reserve capacity. To determine the metabolic reserves for fatty acid degradation during digestion at an OLR of 10 kg COD m −3 d −1 , digester effluent was supplemented with either 40 mmol l −1 acetate, propionate, i -butyrate or n -butyrate. Results of these batch assays indicated a rapid degradation of all fatty acids and fatty acid conversion rates, that would allow a stable anaerobic fermentation at 15 kg COD m −3 d −1 OLR. On the basis of the laboratory results the OLR of the full-scale methane reactor was increased to 15 kg COD m −3 d −1 . After 7 months, results of full-scale digestion were still consistent with the previously obtained laboratory results.

Im Kapitel 2 werden zunachst die mikrobiellen Grundlagen der Methangarung und anschliesend die chemischen Grundlagen anaerober Prozesse vorgestellt. Insbesondere werden im mikrobiellen Teil die thermodynamischen Grundlagen, die anaerobe Nahrungskette und auch die Einflussfaktoren auf die Methangarung beschrieben. Die gesamte Biomasse auf der Erde entsteht durch Kohlendioxid-Fixierung bei der Photosynthese von Pflanzen und aquatischen Mikroorganismen. Sie dient Tieren oder dem Menschen als Nahrungsquelle. Die Re-Mineralisation pflanzlicher und tierischer Reststoffe zu CO2 erfolgt durch Mikroorganismen und kann unter aeroben und anaeroben Bedingungen stattfinden. Unter aeroben Bedingungen werden abgestorbene pflanzliche und tierische Reststoffe mit Sauerstoff zu Kohlendioxid und Wasser mineralisiert, wobei auch Ammonium und Sulfid hauptsachlich aus dem Eiweisabbau und Phosphat aus dem Abbau phosphathaltiger Zellkomponenten freigesetzt werden. Unter anoxischen bzw. anaeroben Bedingungen, wenn kein Sauerstoff als terminaler Elektronenakzeptor fur Reduktionsaquivalente zur Verfugung steht, werden die Elektronen auf andere Elektronenakzeptoren wie z. B. Nitrat, Eisen, Mangan, Sulfat oder Carbonat ubertragen. Sind unter anaeroben Bedingungen auch diese anorganischen Elektronenakzeptoren nicht verfugbar, werden die Elektronen auf organische Zwischenprodukte des Stoffwechsels ubertragen und es entstehen Garprodukte wie z. B. Milchsaure aus Pyruvat oder fluchtige Fettsauren und Alkohole aus Acetat. Diese Garprodukte sind „reduzierter“ als ihre aus dem Stoffwechsel stammenden organischen Elektronenakzeptoren. Garungen werden nach den dominierenden Abbauprodukten benannt, so z. B. Milchsauregarung bei der Yoghurt-, Buttermilch- oder Silageherstellung, alkoholische Garung bei der Bier- oder Weinbereitung bzw. der technischen Alkoholherstellung und Propionsauregarung im Pansen von Rindern, in Anaerobreaktoren (Faulbehaltern) von Klaranlagen oder in industriellen und landwirtschaftlichen Biogasanlagen. Garungen sind wichtig fur die Haltbarmachung von Lebens- und Futtermitteln, sind aber auch die entscheidenden Prozesse fur den anaeroben Abbau von Biomasse zu Sumpf-, Faul- oder Biogas im Anschluss an die Hydrolyse von pflanzlichen oder tierischen Biopolymeren. Bei einigen Garungen, z. B. der Buttersauregarung wird neben Butyrat und CO2 bereits molekularer Wasserstoff gebildet und ausgeschieden. Weiterer Wasserstoff entsteht bei der Acetogenese von Propionat, Butyrat, und hoheren Fettsauren, die aber nur bei sehr niedrigem Wasserstoffpartialdruck zu Acetat und CO2 umgesetzt werden konnen. Fur einen vollstandigen Abbau von z. B. Butyrat mussen Methanbakterien den Wasserstoff mit CO2 und auch das Acetat zu Methan umsetzen. Wasserstoff hat uber den Partialdruck eine zentrale Regelfunktion fur den anaeroben Abbau organischer Substanzen zu Biogas.

Acidification of wheat bread (WBS), rye bread (RBS) and fresh biowaste suspensions (FBS), leading to lactate+acetate, lactate+acetate+n-buyrate, and acetate+propionate+n-butyrate, respectively, and biogas production as well as population dynamics were investigated. Co-fermentation of FBS (14 kg m(-3) d(-1) organic loading rate (OLR)) with WBS or RBS was stable up to an OLR of 22 kg m(-3) d(-1) and resulted in up to 3 times as much biogas. During co-fermentation at more than 20 kg m(-3) d(-1) OLR the total population increased more than 2-fold, but the originally low share of propionate-oxidizing bacteria significantly decreased. The proportion of methanogens also decreased. Whereas the proportion of Methanosarcinales to Methanomicrobiales in biowaste and biowaste+WBS remained constant, Methanosarcinales and in particular Methanosaeta spec. in the biowaste+RBS assay almost completely disappeared. Methanomicrobiales increased instead, indicating propionate oxidation via acetate cleavage to CO2 and hydrogen.

Elimination of bacteria by ozonation in combination with charcoal or slow sand filtration for advanced sewage treatment to improve the quality of treated sewage and to reduce the potential risk for human health of receiving surface waters was investigated in pilot scale at the sewage treatment plant Eriskirch, Baden-Wuerttemberg/Germany. To determine the elimination of sewage bacteria, inflowing and leaving wastewater of different treatment processes was analysed in a culture-based approach for its content of Escherichia coli, enterococci and staphylococci and their resistance against selected antibiotics over a period of 17 month. For enterococci, single species and their antibiotic resistances were identified. In comparison to the established flocculation filtration at Eriskirch, ozonation plus charcoal or sand filtration (pilot-scale) reduced the concentrations of total and antibiotic resistant E. coli, enterococci and staphylococci. However, antibiotic resistant E. coli and staphylococci apparently survived ozone treatment better than antibiotic sensitive strains. Neither vancomycin resistant enterococci nor methicillin resistant Staphylococcus aureus (MRSA) were detected. The decreased percentage of antibiotic resistant enterococci after ozonation may be explained by a different ozone sensitivity of species: Enterococcus faecium and Enterococcus faecalis, which determined the resistance-level, seemed to be more sensitive for ozone than other Enterococcus-species. Overall, ozonation followed by charcoal or sand filtration led to 0.8-1.1 log-units less total and antibiotic resistant E. coli, enterococci and staphylococci, as compared to the respective concentrations in treated sewage by only flocculation filtration. Thus, advanced wastewater treatment by ozonation plus charcoal or sand filtration after common sewage treatment is an effective tool for further elimination of microorganisms from sewage before discharge in surface waters.

Background Selenium and Tellurium have many common chemical properties as both belong to group 16 of the periodic table. High toxicities of Se and Te oxyanions cause environmental problems in contaminated soils and waters. Three strains (C4, C6 and C7) of selenite reducing and nanoparticle forming aerobic bacteria which were isolated from agricultural soils of India containing high concentrations of Se were investigated after 3.5 months of freeze-storage for their resistance against the toxic oxyanion tellurite and its reduction to non toxic elemental form Te0 as well as nanoparticles formation. Results Strains C4, C6 and C7 reduced tellurite at maximum reduction rates of 2.3, 1.5 and 2.1 mg Te (IV)/L/d, respectively and produced extracellular Te0 nanospheres as revealed from SEM-EDX analysis. Production of extracellular Te nanospheres has been described seldom. Further, concurrent reduction of both selenite and tellurite by bacteria was examined as these toxic oxyanions are often present together in natural environments, mine tailings or wastewater from copper refining. Interestingly, bioreduction of 100 mg/L selenite in shake flasks was not much affected by the presence of 10 mg/L tellurite but tellurite reduction rate increased 13 fold with selenite in the medium. The concurrent reduction of these oxyanions resulted in rarely described bioformation of extracellular nanoparticles composed of both Se and Te, reported first time for aerobically growing heterotrophic non-halophilic bacterial cultures. Duganella violacienigra, the closely related strain to C4 was also found to be resistant to oxyanions of Se and Te. Conclusions Selenite reducing heterotrophic non-halophilic aerobic bacteria revived from 3.5 months freeze storage could successfully reduce toxic tellurite to non toxic elemental form and produced extracellular nanospheres during detoxification. Presence of relatively less toxic selenite in the medium triggers bioreduction of more toxic tellurite leading to formation of extracellular SeTe nanospheres which are sought by solar and optical recording media industry because of their excellent photovoltaic and optical properties. The bacterial cultures investigated in this study could be exploited commercially to remediate not only selenite and tellurite-contaminated soil and water but also for green synthesis of extracellular Se, Te and Se + Te nanospheres.

Volatile fatty acid (VFA) metabolism and population changes during re-start of a wet anaerobic digester for treatment of biowaste suspensions were investigated. Initially acetate and propionate accumulated. However, VFA degradation rates improved within 2 weeks, reaching a balanced metabolism with constantly low VFA concentrations. The total microbial population consisted of 60% acidogenic + acetogenic and 40% methanogenic bacteria. Maximally 5.1% of all bacteria in the digester were propionate-oxidizing bacteria. Pelotomaculum species were dominant, followed by much lower numbers of Smithella species and Syntrophobacter species. Pelotomaculum and Smithella spec. decreased during acetate and propionate accumulation and recovered later on, whereas Syntrophobacter spec. was steadily increasing during start-up. A nearly constant proportion of Methanosaeta spec. was present all time, while Methanosarcina spec. decreased and Methanomicrobiales increased during accumulation and degradation of acetate and propionate. During steady state proportions as in the inoculum were obtained.

Aus der Ahrdorf-Formation (Eifel-Stufe) der Eifel werden in K-Bentonite umgewandelte air-fall Aschen-Horizonte beschrieben, die zur tephrostratigraphischen Korrelation eingesetzt werden. Die sekundar hochgradig veranderten air-fall Aschen werden durch ihre stabilen magmatogenen Zirkon-Populationen identifiziert. Dazu werden die variablen Tracht- und Habitusmerkmale der Zirkon-Populationen aus den einzelnen Aschenlagen in REM-Aufnahmen quantitativ erfast und in Zirkon-Morphocodes dargestellt. Die Zirkon-Morphocodes sind zur Identifizierung der time-marker-Horizonte geeignet und liefern eine zuverlassige Basis fur die exakte tephrostratigraphische Korrelation. Bezogen auf das AQUILA I-Isochron ergibt ein Vergleich mit der auf Brachiopoden-Faunen basierenden Feinstratigraphie, das die Untergrenze des Bildstock-Member diachron verlauft. Die Tephrostratigraphie mit Zirkon-Morphocodes wird zur Klarung der feinstratigraphischen Korrelation bisher schwer fasbarer Einheiten („Geeser Trilobiten-Horizont“) und der komplexen Beziehungen von Fazies und Feinstratigraphie in der Nahe des Schelfrands der variszischen Geosynklinale eingesetzt. Einzelne Bentonit-Horizonte erlauben eine Korrelation mit der Schichtfolge der Mulde von Dinant.

In pilot plant studies, permeates of ultrafiltration of boron- and ethanolamine-containing coolants were used as a carbon source for denitrification of NO 2 –N and NO 3 –N in the wastewater from electrochemical deburring after metal ion precipitation. Treatment of the two wastewater streams in a cascade of submerged fixed bed reactors at increasing pH-values revealed that a more alkaline pH resulted in a lower denitrification rate and an increasing nitrite concentration in the effluent. The DOC-removal efficiency was about 70% for pH values of 7.8–9. It was not possible to establish a nitrification. The biomass in the treated wastewater was fine-particulate and could hardly be separated. For evaluation of the maximal biodegradability of the DOC of the permeates in batch experiments, the long-term BOD instead of the BOD 5 was more suitable. Results of BOD 21 -determinations corresponded with the DOC-removal efficiency of the immobilized population in the pilot plant at HRTs ranging from 3.9–13.5 d. Whereas the nitrate content of the EC-wastewater could be reduced completely, even at high loading rates, about 30% of the COD of the permeates remained undegraded. A COD of 2 /l could only be obtained after chemical oxidation of the effluent by UV-activated H 2 O 2 . Production-related variations of the boron- and DOC-concentrations in the permeates of ultrafiltration of cooling lubricants apparently prevented the establishment of a nitrification of ammonia, that was released during denitrification with ethanolamines as a carbon source. Only when both wastewater streams were co-treated with a, only slightly polluted third, non-toxic wastewater stream of the factory, elimination of nitrate and ammonia from EC-wastewater and permeate, respectively, was successful.

The degradation of single polycyclic aromatic hydrocarbons (PAHs: naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene) and a mixture of all seven PAHs by a bacterial culture enriched from contaminated soil resulted in the formation of a dark-coloured residual fraction of dissolved (DOM) and particulate organic matter (POM). This fraction was highly resistant to bacterial degradation. Analysis of the DOM revealed a molecular-size-distribution similar to that of natural humic acids. A complete degradation of PAHs was apparently prevented by an irreversible incorporation of about 10% of the carbon from single PAHs or 20% of the carbon from the mixture of seven PAHs into the DOM- and POM- fraction. Some metabolites excreted during bacterial PAH-degradation were identified as known precursors for humification.