Kazuo Matsushige

Characterization of dissolved organic matter in effluents from wastewater treatment plants

Dissolved organic matter (DOM) in effluents from sewage and human-wastes treatment plants (STPEs and HWTPEs) was fractionated using resin adsorbents into six classes: aquatic humic substances (AHS), hydrophobic bases (HoB), hydrophobic neutrals (HoN), hydrophilic acids (HiA), hydrophilic bases (HiB), and hydrophilic neutrals (HiN). DOM-fraction distribution varied substantially depending on the kind of wastewater and the type of treatment process. AHS and HiA dominated in all effluents, collectively accounting for more than 55% of the DOM measured as dissolved organic carbon (DOC). In particular, HiA were the most abundant fraction in the effluents, constituting 32-74% of the DOM. AHS appeared to be the second most dominant fraction and varied considerably, accounting for 3-28% of the DOM. The HoN fraction also varied from 0-21%. AHS, HoN, and HiA were the fractions that changed substantially and differed characteristically among the samples studied. The ratios of ultraviolet absorbance to DOC (UV: DOC ratio) in all effluents exhibited a common relationship: AHS> total DOM > HiA. Nevertheless, the ratios were substantially different between STPEs and HWTPEs and among HWTPEs. For HWTPEs, the effluent from the chemical coagulation process had the highest UV: DOC ratios. On the other hand, the effluent from the ultrafiltration and activated carbon adsorption processes had the lowest ratios. Molecular size distribution of the effluents was determined by size exclusion chromatography and found to exhibit a relatively narrow size range and low weight-averaged molecular weights ranging from 380 to 830 g mol(-1). The weight-averaged molecular weight of DOM increased as the UV: DOC ratio of total DOM increased.

Fractionation and characterization of dissolved organic matter in a shallow eutrophic lake, its inflowing rivers, and other organic matter sources.

Dissolved organic matter (DOM) in water from eutrophic Lake Kasumigaura, its inflowing rivers, and several other DOM sources in the lake catchment area was fractionated using resin adsorbents into five classes: aquatic humic substances (AHS), hydrophobic neutrals (HoN), hydrophilic acids (HiA), bases (BaS), and hydrophilic neutrals (HiN). The DOM-fraction distribution pattern and the ultraviolet absorbance to dissolved organic carbon ratio (UV/DOC ratio) were found remarkably effective for evaluating the characteristics of DOM in water. DOM-fraction distribution patterns were significantly different depending on the origin of the sample. AHS and HiA were found to be the dominant fractions in DOM in all samples studied. HiA prevailed over AHS in the lake water, whereas AHS were slightly more abundant than HiA in the river waters. AHS were in the great majority in forest streams and plowed-field percolates. HiA abounded in paddy-field outflow, domestic sewage, and sewage-treatment-plant effluent. Only domestic sewage contained a significant amount of HoN. The UV/DOC ratio also varied depending on the origin of the sample: the ratios in total DOM, AHS, and HiA were greater in river waters than in the lake water. The greatest ratio of AHS was found in paddy-field outflow and the lowest in domestic sewage. The UV/DOC ratios in the sewage-treatment-plant effluent were very similar to those in the lake water.

Trihalomethane formation potential of dissolved organic matter in a shallow eutrophic lake

Dissolved organic matter (DOM) in water samples from the shallow eutrophic Lake Kasumigaura, the second largest lake in Japan, was fractionated and characterized by using resin adsorbents into 5 classes: aquatic humic substances (AHS), hydrophobic neutrals, hydrophilic acids (HiA), bases (BaS) and hydrophilic neutrals (HiN). Subsequently, the trihalomethane formation potential (THMFP), ultraviolet absorbance to dissolved organic carbon (UV:DOC) ratio, and molecular size distribution of the DOM, AHS and hydrophilic fractions (HiF) (HiF=HiA+BaS+HiN) were examined. The THMFP of HiF, normalized on a DOC basis, was found to be comparable to that of AHS (0.176 microM THM mg C(-1) vs. 0.195 microM THM mg C(-1), respectively). The importance of HiF over AHS as a THM precursor became more pronounced when THMFP was evaluated in terms of concentration. In this case, the THMFP of HiF was much greater than that of AHS (0.374 microM THM l(-1) vs. 0.229 microM THM l(-1), respectively). Molecular size distributions all exhibited a narrow size range and relatively low molecular weights. The weight-averaged molecular weights of DOM, AHS and HiF were 780, 957 and 606 g M(-1), respectively.

Dissolved organic carbon in a eutrophic lake; dynamics, biodegradability and origin

The seasonal and spatial changes in dissolved organic carbon (DOC) in Lake Kasumigaura, a shallow, eutrophic lake, were analyzed and the lability of DOC was tested by long-term incubations. There was a nearly 1 mgCl−1 downstream increase in refractory DOC in the lake; at the center it fluctuated little seasonally. The characteristic UV-absorbance: DOC ratios were determined for samples from the influent rivers (pedogenic: used interchangeably with “allochthonous”) and outdoor experimental ponds (autochthonous) during incubations. These ratios were then used to calculate the proportion of total measured lake water DOC in each of four components: pedogenic-refractory (PR), pedogenic-labile (PL), autochthonous-refractory (AR) and autochthonous-labile (AL). PR was uniform (around 1.5 mgCl−1) or diminished very slightly over time. AR increased from nearly zero at the station closest to an influent river to 1 mgCl−1 at the lake center. PL declined downstream from 0.3 mgCl−1 to zero. AL was virtually constant at 0.8 mgCl−1 except at the station closest to the influent river. The constancy of the UV-absorbance: DOC ratio during the biodegradation process was confirmed for Lake Kasumigaura; hence a two-component model (pedogenic-autochthonous) could be applied here without consideration of DOC lability. However, this assumption is not always met for other water bodies, and therefore it should be checked before applying a two-component model elsewhere.

Voltammetric determination of dissolved iron and its speciation in freshwater

Analytical methods were developed to determine the concentration of total dissolved iron and its chemical speciation in freshwater using cathodic stripping voltammetry (CSV) with 1-nitroso-2-naphthol (NN) at pH 8.1. The concentrations of total dissolved iron in river water that iron concentration was certified and in natural water samples from Lake Kasumigaura were determined successfully. The natural iron ligand concentration and the conditional stability constant were determined by ligand competition between NN and the natural ligands present in the sample. In the water samples from Lake Kasumigaura, the concentrations of total dissolved iron and natural ligand were 47.8 ± 4.4 nM and 80.0 ± 19.6 nM and the conditional stability constant (K′FeL) was 1025.9±0.4 M−1 (n = 3). The value of K′FeL was greater than any reported K′FeL for seawater. More than 99.9% of the dissolved iron existed as organic species due to the very high value of the conditional stability constant. The inorganic iron concentration calculated from these results was 10−13.4 M, indicating that the inorganic iron level in Lake Kasumigaura was similar to that in the open ocean and therefore that iron can be a limiting factor for algal growth in Lake Kasumigaura. This is the first report of the complexation of iron(III) and inorganic iron levels in lake water determined by CSV.

The effects of temperature on anaerobic filter treatment for low‐strength organic wastewater

Abstract The effects of water temperature and HRT on treatment efficiency in the anaerobic filter process were examined based on laboratory‐scale experiments. The treatment efficiency of the anaerobic filter process was affected by water temperature and HRT. The dependency of the first‐order rate constant in the specific substrate removal process on water temperature was shown by the activation energy in Arrhenius plotting and temperature coefficient, which were 23,500 cal·mole−1 and 1.515 with BOD and 16,600 cal·mole−1 and 1.105 with TOC.

Growth characteristics and growth modeling of Microcystis aeruginosa and Planktothrix agardhii under iron limitation

Although iron is a key nutrient for algal growth just as are nitrogen and phosphorus in aquatic systems, the effects of iron on algal growth are not well understood. The growth characteristics of two species of cyanobacteria, Microcystis aeruginosa and Planktothrix agardhii, in iron-limited continuous cultures were investigated. The relationships between dissolved iron concentration, cell quota of iron, and population growth rate were determined applying two equations, Monod’s and Droop’s equations. Both species produced hydroxamate-type siderophores, but neither species produced catechol-type siderophores. The cell quota of nitrogen for both M. aeruginosa and P. agardhii decreased with decreasing cell quota of iron. The cell quota of phosphorus for M. aeruginosa decreased with decreasing cell quota of iron, whereas those for P. agardhii did not decrease. Iron uptake rate was measured in ironlimited batch cultures under different degrees of iron starvation. The results of the iron uptake experiments suggest that iron uptake rates are independent of the cell quota of iron for M. aeruginosa and highly dependent on the cell quota for P. agardhii. A kinetic model under iron limitation was developed based on the growth characteristics determined in our study, and this model predicted accurately the algal population growth and iron consumption. The model simulation suggested that M. aeruginosa is a superior competitor under iron limitation. The differences in growth characteristics between the species would be important determinants of the dominance of these algal species.

Forecasting the changes in lake water quality in response to climate changes, using past relationships between meteorological conditions and water quality

In order to forecast the effects of global warming on the water environment, the relationship between meteorological conditions and lake water quality was investigated statistically using 17 years of monitoring data obtained from a shallow eutrophic lake, Lake Kasumigaura. The usefulness of the DPY (difference from the previous year) method was confirmed for removing the watershed change (e.g. land cover, population, etc.). From the analysis of the relationships between air temperature and water temperature on a monthly basis, the delay of time was seen to be negligible, but the gain was reduced due to the high frequency of change. As the amount of precipitation affected their relationship on a yearly basis, the slopes of 1·0–1·2 °C water temperature/ °C air temperature were determined with the DPY method by excluding the combinations of the years having large difference in annual precipitation. The deterioration of lake water quality, such as increases in COD (chemical oxygen demand) and decreases in transparency, was quantitatively assessed as corresponding to an increase in air temperature. In addition, we found that higher precipitation led to high nitrogen concentrations on a monthly basis, as well as on a yearly basis, probably induced by both the runoff of soilwater having high concentrations and the lowering of residence times of lake water. Copyright

Removal of refractory organics and nitrogen from landfill leachate by the microorganism-attached activated carbon fluidized bed process

Abstract The microorganism-attached activated carbon fluidized bed (MAACFB) process was applied to treat a real landfill leachate containing refractory organics and a high concentration of ammonium nitrogen. The MAACFB process consisted of two fluidized bed reactors in series: anaerobic and aerobic. The MAACFB process was found to be effective in treating the landfill leachate. The MAACFB process removed about 60 and 70% of refractory organics and nitrogen, respectively, from the landfill leachate simultaneously and steadily over more than 700 days of the operation period. A mass balance of the organics around the MAACFB process revealed that most of the removed organics may be biodegraded.

Fast and precise method for HPLC-size exclusion chromatography with UV and TOC (NDIR) detection: importance of multiple detectors to evaluate the characteristics of dissolved organic matter.

A new type of high-performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) system with ultraviolet (UV) absorbance detection and non-dispersive infrared (NDIR) detection of total organic carbon is described. The introduction of an online degassing tube and a low-volume HPLC column helped to reduce the analytical time and increase the sensitivity of the SEC system. This study is the first in which linear calibration curves (R(2)>0.99) were obtained for both UV absorbance and NDIR data for polystyrene sulfonate standards, which are the most suitable standards for molecular size analysis of aquatic humic substances as well as dissolved organic matter (DOM). Using the calibration curves, the molecular size distribution of DOM in water collected from Lake Kasumigaura and in pore water from lake sediments was estimated. Most of the DOM had a molecular weight less than 4000 Daltons (Da), and the amount of low-molecular-weight DOM (∼ 2000 Da) with low UV absorbance increased with depth in the sediment pore water. This result shows the importance of combining quantitative analysis by NDIR detection with qualitative analysis by UV detection to determine the chemical and physical properties of DOM. The possible sources and reactivity of DOM in Lake Kasumigaura and its sediment pore water are also discussed.