Ryuichi Sudo

Simultaneous determination of total nitrogen and total phosphorus in freshwater samples using persulfate digestion

The accuracy and precision of total nitrogen (T‐N) and total phosphorus (T‐P) determinations in freshwater samples by the simultaneous digestion method using an oxidizing reagent solution of NaOH‐K2S2O8 were assessed. Detection limits based on the blank test of nitrogen and phosphorus were 0.02 mgN/1 and 0.001 mgP/1, respectively. This simultaneous digestion method gave not only a high recovery and reproducibility over a wide range of various nitrogen and/or phosphorus compounds of known nitrogen and phosphorus compositions, but also high recoveries of nitrogen and phosphorus from standard reference materials, such as orchard leaves, pond sediment and chlorella. No significant difference was found between the determinations of T‐N and T‐P in freshwater samples by this method and those determined by the standard methods of T‐N and T‐P, respectively. This method should be useful for the routine analysis of T‐N and T‐P in freshwater samples containing particulate material and samples of low T‐N and/or T‐P co...

The growth inhibition of planktonic algae due to surfactants used in washing agents

Abstract A survey of inhibitory effects of nonionic and anionic surfactants, including a soap, used in washing agents, on the growth on three species of freshwater phytoplankton, Selenastrum capricornutum, Nitzschia fonticola and Microcystis aeruginosa was conducted. Based on the specific growth rate, μu estimated from a short period (2 or 3 days) cultivation of test algae, the growth inhibition was determined using EC 50 values where μu in the culture medium with surfactant decreased 50% of that without surfactant. The EC 50 values of nonionic and anionic surfactants tested here for S. capricornutum ranged from 2 to 50 mg l −1 and from 10 to 100 mg l −1 , respectively. The tolerances of three species of algae tested with three surfactants, LAS, AE (EO:9) and soap, were different and the inhibitory effects were species specific. EC 50 values of LAS, AE (EO:9) and soap for S. capricornutum were 50–100, 4–8 and 10–50 mg l −1 , respectively. Those for N. fonticola were 20–50, 5–10 and 20–50 mg l −1 , and those for M. aeruginosa were 10–20, 10–50 and 10–20 mg l −1 , respectively.

Release of phosphorus from lake sediments

Abstract The relationship between the content of various forms of phosphorus in lakesediments and the amount of phosphorus released under aerobic and anaerobic conditions was studied. Total phosphorus content in the sediment of Lake Kasumigaura was highest at the 0–5 cm surface layer and decreased with depth. The constant value below 15 cm was consistent with the decrease of iron-bound phosphorus conent (FeP). The amount of phosphorus released from the sediments was proportional to the decrease of FeP under both aerobic and anaerobic conditions. Under anaerobic conditions, 90% of the FeP initially held in the sediments was released in 55 days. Using dialysis apparatus, maximum growth yield of algae was shown to be linearly dependent on the amount of phosphorus released under aerobic conditions.

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.

Musty odor from blue‐green alga, Phormidium tenue in Lake Kasumigaura

Abstract A musty odor compound, 2‐methylisoborneol was detected in the water of Lake Kasumigaura located in the south‐east part of Japan. There was a significant relationship between the intensity of the musty odor and trichome numbers of Phormidium tenue during the odor episodes. It was considered that 2‐methylisqborneol, which was produced by the unialgal culture of P. tenue isolated from the lake, might be responsible for the musty odor occurrence in the lake.

MONOXENIC AND MIXED CULTURES OF THE SMALL METAZOA PHILODINA ERYTHROPHTHALMA AND AEOLOSOMA HEMPRICHI ISOLATED FROM A WASTE-WATER TREATMENT PROCESS

SummaryPhilodina erythrophthalma (an euryphagous Rotatoria) and Aeolosoma hemprichi (a stenophagous Oligochaeta), isolated from a waste-water treatment process, were grown in monoxemic and mixed cultures using a variety of bacterial species as prey. In monoxenic cultures, P. erythrophthalma could grow by feeding on a wide range of bacterial species, while A. hemprichi exhibited a relatively high prey specificity. The growth rates of P. erythrophthalma and A. hemprichi increased in the mixed culture, compared with those in the respective monoxenic cultures. Interestingly, the sizes of bacterial flocs were observed to increase in the presence of P. erythrophthalma. On the basis of the experimental results, the role of metazoa in a waste-water purification process is discussed.

Some ecological observation on the decomposition of periphytic algae and aquatic plants

Abstract Stigeoclonium tenue, Chlamydomonas sp. and Chlorella sp., which are dominant periphytic algae in a shallow river (Tama-gawa, running through the Metropolitan area of Tokyo) were subjected to dark- and aerobic-decomposition tests using Selenastrum capricornutum as control. The decomposition of aquatic plants, Potamogeton crispus and Potamogeton pusillus which become dominant in the river mid- and downstream during summer was also studied. Successions of protozoa and smaller metazoa were noted from the decomposition tests. Regardless of the species of algae and aquatic plants studied the decomposition rate could be simulated as the 1st-order reaction if the refractory fraction, f of each organism was used as the datum of assessment. The value of f was roughly from 0.2 to 0.4, also irrespective of the organisms examined. The rate constant, k thus assessed extended from 0.08 to 0.2 day −1 at 20°C. Phosphorus and nitrogenous compounds regenerated into liquid (decomposer) amounted at 50th day of decomposition test to a level of 50 to 75% of that retained initially with the cells. Thus far, the seriousness of secondary pollution due to decomposition of periphytic algae and aquatic plants was pointed out. Lastly, the significance of removing nutrients from effluent of the wastewater treatment was demonstrated.

Simulation of water-bloom in a eutrophic lake—I. Photosynthetic characteristics of Microsystis aeruginosa

Abstract A perspective of how to simulate “emergence and/or disappearance of the water-bloom… dense population of a blue-green alga, Microcystis aeruginosa at the surface of eutrophic waters… ” was presented. The algal photosynthetic activity. Qo2 as a function of irradiation light intensity. I, could be represented by the Blackman model, taking the algal content. C of chlorophyll-α and water temperature. 0 as parameters. When the cells that had been cultured under dim light were transferred to a new environment, wherein the light intensity was from 0 (dark) to the level much brighter than the dim light, the value of C exhibited various responses against time. Subtracting the rate of chlorophyll-α degradation from that of chlorophyll-α synthesis, the rate of change in C values during the light-adaptation period was studied.

Evaluation of Activated Carbons for Removal of Musty Odor Compounds in the Presence of Competitive Organics

Isotherm studies were conducted to evaluate the influence of pH and organics associated with algae on adsorption of the two musty odor compounds, 2-methylisoborneol and geosmin by three types of activated carbons (wood activated carbon: WAC, coal activated carbon: CAC, coconut shells activated carbon: YAC). Within a wide range of pH values (4.0, 7.0, 9.0), little influence on adsorption of the two musty odor compounds was observed. In the presence of organics, especially humic acids and glycolic acid, removal capacity and adsorption intensity of 2-MIB were significantly reduced comparing with those of geosmin in the three ACs. And the reduction magnitudes were greater in WAC and CAC than in YAC. However, little influence on those of geosmin was observed in all ACs. It was suggested that the organics such as glucose, mannose, especially humic acids and glycolic acid competed for the adsorption sites with 2-MIB, while their competition were quite low with geosmin.

Effect of carbohydrate in the sediment on the musty odor production by actinomycetes

Abstract The musty odor producing microorganisms, the musty odor compounds and several environmental factors relating to the musty odor occurrence in Lake Kasumigaura were determined. When the musty odor occurred in the water of Tsuchiurairi site in October 1984, 2‐methylisoborneol was detected in the sediment with high actinomycete numbers. Moreover, a remarkable increase of carbohydrate was found in the sediment. Musty odor producing potential of sediment using actinomycetes was very high at the odor occurrence. It seemed that the investigation of actinomycete numbers and carbohydrate content in the sediment was important for the prognostication of the musty odor occurrence in Lake Kasumigaura.