M. Ukita

Mercury pollution in Tokuyama Bay

The sediments and aquatic life of Tokuyama Bay, Japan, have been polluted by mercury effluent from chloro-alkali plants. In total, about 3&0 tons mercury were released from these plants and 6.64 tons of mercury were discharged into the bay in waste waters between 1952 and 1975, when mercury cells were employed. A number of surveys to study mercury pollution and the effectiveness of control measures in this area were conducted in the early 1970’s by our laboroatory and other agencies. Analysis of human hair from Tokuyama Bay residents contained less mercury than those in Minamata and Agano districts, Japan, where serious mercury poisoning had occurred, but were contaminated with more mercury than those in other unpolluted areas. No occurrence of Minamata disease has been reported in the Tokuyama district.

Decolorization of alcohol distillery wastewater by thermotolerant white-rot fungi.

To determine a thermotolerant fungus strain for decolorization of alcohol distillery wastewater (ADW), 38 fungus strains were studied. Capacity for ligninolytic enzyme production was examined at 35 and 43C on agar media containing 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and MnCl2. At 43°C, four Pycnoporus coccineus strains showed a higher potential for ADW decolorization both on agar media and in liquid media. Immobilized mycelia on polyurethane foam removed about threefold more total phenol than did free mycelia under conditions of shaking at 43°C. Moreover, immobilized mycelia removed nearly 50% more color than did free mycelia.

Screening thermotolerant white-rot fungi for decolorization of wastewaters

To select a thermotolerant fungal strain for decolorization of wastewaters, ligninolytic enzyme production (lignin peroxidase, manganese peroxidase [MnP], and laccase), decolorization, and removal of total phenol and chemical oxygen demand (COD) were detected. Thirty-eight fungal strains were studied for enzyme production at 35 and 43°C on modified Kirk agar medium including 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and MnCl2. Thirteen strains grew on manganese-containing agar and provided green color on ABTS-containing agar plates under culture at 43°C. Decolorization of wastewater from alcohol distillery (WAD) by these strains was compared under static culture at 43°C, and Pycnoporus coccineus FPF 97091303 showed the highest potential. Thereafter, immobilized mycelia were compared with free mycelia for WAD decolorization under culture conditions of 43°C and 100 rpm. The immobilized mycelia on polyurethane foam enhanced the ligninolytic enzyme production as well as total phenol and color removal. At about the same COD removal, MnP and laccase produced by immobilized mycelia were 2 and 19 times higher than by free mycelia; the simultaneous total phenol and color removal were 3.1 and 1.5 times higher than the latter. Moreover, decolorization of synthesis dye wastewater was carried out at 43°C and 100 rpm. More than 80% of 300 mg/L of reactive blue-5 was decolorized by the immobilized mycelia within 1 to 2 d for four cycles.

Determination of nutrient transformation pathways in rivers using a mathematical programming method

Abstract A new methodology for determining nutrient transformation pathways in rivers is described in this paper: (1) we measured the variation of nutrient concentrations continuously at upstream and downstream stations of a river section, together with the flow rate and the suspended sediment concentration; (2) we constructed a model that contains all pathways of the nutrient transformation; and (3) we determined the model parameter values so as to fit the observed data, by using computer simulations and mathematical programming methods. The best algorithm for the parameter determination is the modified Powell method. However, when the CPU time is critical, the BFGS variable metric method is recommended. The river model has many parameters, but when the observed data have had “sufficient fluctuatation”, still nine parameters can be determined in one trial. Even if the model has errors in its basic equations, the determined transformation loads are comparable to real transformation loads when data have had “sufficient fluctuation”. Even if sediment amount data are not available, the correct parameter can be determined by adding the initial sediment amount into parameters for determination. This method was applied to several rivers, and it determined the total mass transfer in each river successfully.

Evaluation of primary production loads and their control in enclosed seas

Abstract The primary production in eutrophic water bodies contributes greatly to water pollution as an organic pollutant. In this study, in order to evaluate quantitatively the organic pollution load originated from origin in the primary production in an enclosed water body (the internal organic pollution load), many methods for its evaluation that have been proposed up to the present, are investigated comparatively. Though strict evaluation of the internal organic pollution load is difficult, its approximate evaluation is possible. For the control of this internal organic production, the reduction of inflowing nutrient loads such as nitrogen and phosphorus is necessary. From the analysis of the relationships between nutrient loads to enclosed coastal seas in Japan and their nutrient levels, the eutrophic potential in each sea area is calculated with a simple procedure. Though nutrients are essential for biological production, the excess of them creates many water quality problems. Therefore, for the control of nutrient impacts to the enclosed coastal seas in Japan, the following strategies are proposed. 1. 1) an effective measure for nutrient load reduction in their originating stage, as a consequence of our structural analysis of nutrient budget in Japan. 2. 2) waste water treatment for nutrient load reduction. 3. 3) appropriate distribution of nutrient load impact based on the eutrophic potential of each coastal sea and each adjacent sea of Japan. The sewer and sewage treatment system is an effective system for reduction and distribution of the nutrient load.