Part IV: Fitness for Aquatic Systems Long-term Forecast: Key to groundwater protection

Groundwater resources are at risk from pollution, climate change and land-management practices. Long-term forecast is a tool to demonstrate future development and to support decisions on measures which can be implemented, controlled and eventually corrected. As the basis for preventive action, a forecast can be viewed as a key to groundwater protection. The soil zone plays a vital role in groundwater protection. Research on soil and groundwater trends, as affected by change of climate and/or land-management practices, is on the agenda. Integrated research is necessary to develop numerical soil-water system models reflecting all relevant transport processes at various scales. Even relatively simple problems like forecasting pollutant release from contaminated materials are difficult to resolve. Batch tests may be sufficient in low-risk cases. At higher risk when contaminated substrates are chosen for deposition on a large scale, a thorough characterization of the materials is necessary covering all aspects of stability and possible changes of the environment.     

Spatial and Temporal Features of Ambient Air-Quality over Taiwan

This study analyzed a time series data of daily subPSI values to determine the temporal and spatial characteristics of ambient air-quality in Taiwan by employing the Varimax rotational method. The first and second rotational principal components nearly accounted for 54 and 19% for the variation of subPSI values over Taiwan. The factor loadings between rotational principal components and subPSI values of air pollutants identified the first and second components as combustion and photochemical sources, respectively. Time series analysis of rotational component scores associated with regions showed the relationships between rotational components and subPSI values and also revealed the optimum simulation period for combustion and photochemical sources.     

Formation and emission of chloroanisoles as indoor pollutants

GOAL, SCOPE AND BACKGROUND: Complaints by residents of frame-houses about musty odour in the houses has become an increasing problem within the last years. An additional problem is that the odour is transferred to clothes and skin. The persons themselves do not recognize the smell after a while because of adaptation. Serious social problems are the result. For a long time, the smell was explained to be from mould due to construction-based humidity problems. However, in an increasing number of houses, no indications were found for elevated levels of mould growth. METHODS: Air and material samples were taken from 5 houses, which show typical musty odours, and analysed with respect to chlorophenols and chloroanisoles. Additionally, some samples were analysed for lindane and its metabolites, because lindane was commonly used together with pentachlorophenol (PCP) for wood protection. RESULTS AND DISCUSSION: Meticulous analysis resulted in the identification of chloroanisoles, mainly 2,3,4,6-tetrachloroanisole. These substances are known from corky wines and from contamination of food from pentachlorophenol (PCP) treated pallets and result from microbiological metabolic processes. Pentachlorophenol was commonly used to protect wood from fungi in Germany mainly in the later 60s and 70s. Details of these processes, as well as effective methods to identify chloroanisoles in the problem houses, are described. CONCLUSIONS: Chloroanisoles formed by metabolism of PCP have been well known to contaminate food or wine. Here, they were identified and are probably responsible for the musty odours in the frame houses. Since it is quite clear that these substances were not components of building materials used in the houses, an explanation for chloroanisole formation is proposed. Localized dampness probably favours microbial growth associated with metabolic conversion of chlorophenols to the corresponding chloroanisoles, primarily 2,3,4,6-tetrachloroanisol, which spread throughout the buildings, resulting in the observed odours. RECOMMENDATIONS AND OUTLOOK: The group of chloroanisoles has been recognized as important indoor pollutants as they possess musty odours at extremely low concentrations, e.g. for 2,4,6-trichloroanisole in a range of 5-10 ppt in air (Staples 2000). On the basis of currently available toxicological data, exposure of the occupants to the concentrations of chloroanisoles measured is not associated with a health risk. No correlation could be observed between concentrations of chloroanisoles and PCP in house dust and indoor air. However, chloroanisoles are good indicators for possible PCP-treatment of wood in frame houses and their detection should initiate investigations on PCP contamination. Research is continuing to identify the microorganisms involved and to devise a remediation procedure for affected houses.     

Decolorization and biodegradation of dye wastewaters by a facultative-aerobic process

BACKGROUND: Dye wastewater is one of the main pollution sources of water bodies in China. Conventional biological processes are relatively ineffective for color removal, the development of alternative treatment methods will become important. Our subjective was that of introducing a new biotreatment technology which combined a facultative biofilm reactor (FBR) with an aerobic reactor (AR) to treat a dye wastewater. The efficiencies of color and chemical oxygen demand (COD) removal and the mechanism of dye degradation were investigated. METHODS: The anthraquinone acid dye (acid blue BRLL) concentration, organic loading rate (OLR) and hydraulic retention time (HRT) were varied in the experiments to evaluate the treatment efficiency and process stability. The biodegradation products were detected by infrared (IR) and high performance liquid chromatography and mass spectrometry (HPLC-MS). RESULTS AND DISCUSSION: The results demonstrated that the facultative biofilm process was more effective for decolorization than the anaerobic stage of an anaerobic-aerobic process. Most color removal occurred in the facultative reaction (maximum to 88.5%) and the BOD (biochemical oxygen demand): COD of the FBR effluent increased by 82.2%, thus improving the biodegradability of dyes for further aerobic treatment. The dye concentration, OLR and HRT will be the factors affecting decolorization. Color removal efficiency falls as the influent dye concentration increases, but rises with increased HRT. The infrared and HPLC-MS analyses of the effluents of FBR and AR reveal that the dye parent compound was degraded in each reactor during the process. CONCLUSION: The Facultative-aerobic (F-A) system can effectively remove both color and COD from the dye wastewater. The FBR played an essential role in the process. The average overall color and COD in the system were removed by more than 93.9% and 97.1%, respectively, at an OLR of 1.1 kg COD m(-3) d(-1) and at the HRT of 18-20 hours in the FBR and 4-5 hours in the AR. The color removal mechanism in each reactor was not only a sort of biosorption on the floc materials, but even more an effect of biodegradation, especially in the facultative process. Recommendation and Outlook. In applying the F-A system to treat a dye wastewater, the control of facultative processes and the set up of appropriate operation conditions appear to be critical factors. Also, it is suggested a moderate COD loading rate and about a 24-hour HRT will favor the F-A system.     

Der Weg in die Nachhaltigkeit

Ohne Zusammenfassung     

Persistence of methyl <Emphasis Type="Italic">tertiary</Emphasis> butyl ether (MTBE) against metabolism by Danish vegetation

BACKGROUND: Methyl tertiary butyl ether (MTBE) is the second most highly produced industrial chemical in the US and a frequent groundwater pollutant. At the same time, MTBE is quite persistent to biotic and abiotic decomposition. The goal of this study was to find plant species that could degrade MTBE and might be used in phytoremediation. METHODS: Excised roots and leaves (0.3 g) from more than 24 Danish plant species out of 15 families were kept in glass vessels with 25 ml spiked aqueous solution for 2 to 4 days. MTBE concentrations were 1 to 5 mg/L. Samples were taken directly from the solution with a needle and injected to a purge and trap unit. MTBE and the main metabolite, TBA, were measured by GC/FID. RESULTS AND DISCUSSION: Solutions with roots of poplar (Populus robusta) and a willow hybrid (Salix viminalis x schwerinii) produced TBA in trace amounts, probably stemming from bacteria. Significant MTBE reduction (> 10%) was not observed in any of the tests. Leaves from none of the species (trees, grasses and herbs) reduced the concentration of MTBE in the solution and no TBA, nor any other known metabolite of MTBE, was detected. CONCLUSION: It was not possible to find plants capable of efficiently degrading MTBE. This gives rise to the conclusion that plants probably cannot degrade MTBE at all, or only very slowly. RECOMMENDATIONS AND OUTLOOK: For phytoremediation projects, this has, as consequence, that the volatilization by plants (except with genetically engineered plants) is the only relevant removal process for MTBE. For risk assessment of MTBE, degradation by the plant empire is not a relevant sink process.     

Herausforderungen des Klimawandels

Ohne Zusammenfassung     

Operating parameters for high nitrite accumulation during nitrification in a rotating biological nitrifying contactor.

Incomplete nitrification was studied in a completely and partially submerged rotating biological contactor (RBC). In a partially submerged RBC without additional aeration, 50 to 90% nitrite accumulation (alpha) was achieved at rotation speeds (omega) of 2 to 18 min(-1). In a completely submerged RBC operating during 80 days, a higher alpha of 96% was achieved at omega = 2 min(-1). Incomplete nitrification in a completely submerged RBC at oxygen concentrations of 1.5 to 6.8 mg O2/L indicated that the mass transfer of oxygen is rate-limiting. Modeling of the completely submerged RBC predicts that the oxygen profile will not penetrate the biofilm more than 30 microm, thereby strongly limiting the nitrite-oxidizer growth and causing high nitrite accumulation. Molecular analysis (i.e., fluorescence in situ hybridization) indicated that the nitrite-oxidizers are superficially located (<200 microm) and that the ammonia-oxidizers comprise up to approximately 800 microm of the biofilm.