Spectrometric characterization of the effluent dissolved organic matter from an anammox reactor shows correlation between the EEM signature and anammox growth.

Anaerobic ammonium oxidation (anammox) is a cost-effective process to treat high-strength nitrogenous wastewater. Even without organic carbon input, the effluent contains bioproducts from autotrophic and heterotrophic bacteria. In this work, excitation-emission matrix (EEM) fluorescence spectroscopy was used to characterize the effluent dissolved organic matter (EfOM) from an anammox reactor treating synthetic wastewater. Two dominant EEM components were identified as humic acid-like (component 1) and protein-like (component 2) substances with excitation/emission peaks at <240, 355, 420/464 nm and <240, 280, 330/346 nm, respectively. The presence of both compounds in the effluent was tracked during an activity recovery period (nitrogen load increased from 0.2 to 1.3 kg Nm(-3)d(-1)). The effluent concentration of both components increased during this period, indicating correlation between production and bacterial activity. The dynamics of these bioproducts during both substrate consumption and starvation phases was analyzed in batch experiments. Component 1 was only formed during substrate consumption in a rate proportional to ammonium removal and was considered an up-take associated product characteristic of anammox activity. The results show that the composition of the EfOM was qualitatively and quantitatively influenced by process performance. Monitoring the EfOM could, therefore, offer a useful approach to assess anammox process performance and must be further explored.

A potential approach for monitoring drinking water quality from groundwater systems using organic matter fluorescence as an early warning for contamination events.

The fluorescence characteristics of natural organic matter in a groundwater based drinking water supply plant were studied with the aim of applying it as a technique to identify contamination of the water supply. Excitation-emission matrices were measured and modeled using parallel factor analysis (PARAFAC) and used to identify which wavelengths provide the optimal signal for monitoring contamination events. The fluorescence was characterized by four components: three humic-like and one amino acid-like. The results revealed that the relative amounts of two of the humic-like components were very stable within the supply plant and distribution net and changed in a predictable fashion depending on which wells were supplying the water. A third humic-like component and an amino acid-like component did not differ between wells. Laboratory contamination experiments with wastewater revealed that combined they could be used as an indicator of microbial contamination. Their fluorescence spectra did not overlap with the other components and therefore the raw broadband fluorescence at the wavelengths specific to their fluorescence could be used to detect contamination. Contamination could be detected at levels equivalent to the addition of 60 µg C/L in drinking water with a TOC concentration of 3.3 mg C/L. The results of this study suggest that these types of drinking water systems, which are vulnerable to microbial contamination due to the lack of disinfectant treatment, can be easily monitored using online organic matter fluorescence as an early warning system to prompt further intensive sampling and appropriate corrective measures.

Monitoring organic loading to swimming pools by fluorescence excitation-emission matrix with parallel factor analysis (PARAFAC).

Fluorescence Excitation-Emission Matrix spectroscopy combined with parallel factor analysis was employed to monitor water quality and organic contamination in swimming pools. The fluorescence signal of the swimming pool organic matter was low but increased slightly through the day. The analysis revealed that the organic matter fluorescence was characterised by five different components, one of which was unique to swimming pool organic matter and one which was specific to organic contamination. The latter component had emission peaks at 420 nm and was found to be a sensitive indicator of organic loading in swimming pool water. The fluorescence at 420 nm gradually increased during opening hours and represented material accumulating through the day.

Characterisation of colloidal and particulate organic carbon in freshwaters by thermal fluorescence quenching.

Three-dimensional excitation-emission matrix (EEM) fluorescence with thermal quenching has been applied to raw and size-fractionated freshwaters. To size-fractionate organic matter, sequential filtration through mixed-ester-cellulose membrane filters with nominal pore size of 1.2, 0.1 and 0.025 microm were used. Humic-like fluorophores (peaks A and C) have been found to dominate EEMs of raw and all size fractions of studied waters. Peak A fluorescence intensity has been found to be more thermally sensitive than peak C fluorescence intensity. Humic-like fluorescence intensity was generally size independent, which indicated that it was present mainly in the smallest size fraction (<0.025 microm). This was confirmed by total organic carbon (TOC) measurements. Peak T (tryptophan-like) fluorescence, that is widely associated with biological activity, exhibited a greater thermal sensitivity of fluorescence intensity in the larger size fractions, demonstrating the presence of more than one fluorophore in different size fractions at this location in optical space. Thermal fluorescence quenching provides insights into organic matter variability and associated colloidal characteristics.

Biological activation of carbon filters.

To prepare biological activated carbon (BAC), raw surface water was circulated through granular activated carbon (GAC) beds. Biological activity of carbon filters was initiated after about 6 months of filter operation and was confirmed by two methods: measurement of the amount of biomass attached to the carbon and by the fluorescein diacetate (FDA) test. The effect of carbon pre-washing on WG-12 carbon properties was also studied. For this purpose, the nitrogen adsorption isotherms at 77K and Fourier transform-infrared (FT-IR) spectra analyses were performed. Moreover, iodine number, decolorizing power and adsorption properties of carbon in relation to phenol were studied. Analysis of the results revealed that after WG-12 carbon pre-washing its BET surface increased a little, the pH value of the carbon water extract decreased from 11.0 to 9.4, decolorizing power remained at the same level, and the iodine number and phenol adsorption rate increased. In preliminary studies of the ozonation-biofiltration process, a model phenol solution with concentration of approximately 10mg/l was applied. During the ozonation process a dose of 1.64 mg O(3)/mg TOC (total organic carbon) was employed and the contact time was 5 min. Four empty bed contact times (EBCTs) in the range of 2.4-24.0 min were used in the biofiltration experiment. The effectiveness of purification was measured by the following parameters: chemical oxygen demand (COD(Mn)), TOC, phenol concentration and UV(254)-absorbance. The parameters were found to decrease with EBCT.