Expanded-bed granular activated carbon (GAC) anaerobic reactor was applied to treat artificial wastewater which contains high concentration of chloroacetaldehyde as well as sodium acetate. Organic loadings were changed from 1.0 to 6.1g-COD_cr·kg^-1-GAC·d^-1 by changing concentrations of organics (from 90 to 900 mg·l^-1 for chloroacetaldehyde, and from 1,000 to 2,000 mg·l^-1 for sodium acetate). Hydraulic retention time was changed from 2.2 to 1.1 days based on expanded-bed volume. The operation of the reactor was successfully started without any dilution of the wastewater and the reactor could respond without any deterioration of treatment efficiency to shock load by the adsorption ability of GAC used as attached medium. COD and chloroacetaldehyde removal efficiencies were kept more than 87% and 97% respectively. Biomass in the reactor was 114μgDNA·g^-1-GAC, which corresponds to 2,000 mgVSS·l^-1 based on the expanded-bed volume.

抄録全体を表示

The concentrations of TCP isomers both for dissolved and particulate forms and those in bottom sediment were investigated (October 1992-August 1994) in upper Kurose River basin (Higashi-Hiroshima City). Also, sources of TCP isomers flowed into the river were examined.
The significant fluctuation in the concentrations of TCP isomers was not observed along the flow of the river. The concentrations of o- and m-TCP in river were high, while those of p-TCP was extremely low.
TCP concentrations in bottom sediment were approximately 1/1000 compared to those of particulate forms in river water. This difference in the TCP concentrations can be attributed to that in organic carbon content, and TCP adsorbed on sediment does not attain equilibrium with that in river water.
No seasonal variation of TCP in the river was observed. The fluctuation in the concentrations of TCP isomers was related to stormwater runoff, indicating that TCP in the river was not discharged from point sources but from non-point sources such as vinyl film of greenhouse, waste PVC pipes and ditch of gas station.

抄録全体を表示

Growth of phytoplankton and its limiting nutrient were investigated to elucidate the mechanism of phytoplankton growth caused by inflow of freshwater.
Limiting nutrient of phytoplankton growth was nitrogen on little volume of freshwater inflow. However, the limiting nutrient was shifted from nitrogen to phosphorus after heavy rain. This may be due to the inflow of freshwater of DIN/DIP ratio higher than Redfield ratio 16 : 1.
Chlorophyll a concentration was very low on little volume of freshwater inflow. On the other hand, after high volume inflow of fresh water, high value of the chlorophyll a concentration was recorded.
The occurrence of marked phytoplankton growth after heavy rain can be explained as follows. First, inflow of freshwater that has high concentration of nitrogen induced the growth of phytoplankton. Second, phytoplankton growth was controlled by phosphorus loaded from fresh water, because the limiting nutrient was shifted from nitrogen to phosphorus after heavy rain.

抄録全体を表示

A solution of molasses wastewater, pre-treated by activated sludge, was ozonated and then completely decolorized by ozone. Total organic carbon (TOC) could be reduced only to about 50% during a period of 60 minutes ozonation. The ozonated solution, after being mixed with activated sludge culture, was incubated for 10 days at 25°C, and biodegradability was then assessed by dissolved organic carbon (DOC) reduction. DOC of the non-ozonated solution could hardly be reduced even after 10 days incubation, indicating biodegradability. It only be slight. For the ozonated solution of pre-treated molasses wastewater, DOC removal more than 70% was achieved and DOC in the solution was less than 10mg·l^-1. Ozonation thus greatly improves the biodegradability of refractory organic compounds. A solution of molasses wastewater was ozonated directly. Ozone decolorized about 90% of the molasses wastewater but TOC was reduced to only about 8%. Biodegradability of ozonated molasses wastewater was improved much more than that non-ozonated.

抄録全体を表示

This paper describes the vertical profile of adhered suspended matter on the filter sand and its composition in the upper column of a slow sand filter. The water source of the studied slow sand filter is a surface water of a stream. An active growth of algal mat of filamentous diatom and the floating algal mat peeled off from the bottom were commonly observed during the study period in summer. The upper sand column was taken when the supernatant water drained off for the filter cleaning after the long filter run.
The majority of suspended matter was adhered on the filter sand in the upper 1cm of the sand column. The amount of adhered matter was quickly decreased with the depth. The order in the decreasing rate of suspended matter with the depth was: Chlorophyll a > Pheophytin a > Consumption of KMnO₄ > Ignition loss > Mud (adhered suspended matter). These results show the biological degradation is active in the surface sand column. And almost all the suspended matters penetrated into the sand are easily trapped and are decomposed within the surface sand layer.

抄録全体を表示

Chemical constituents of ground water collected in Akiu area in Sendai city were analyzed. There are 3 samples containing arsenic above 0.01mg·l^-1. In ground water samples, we can detect arsenic at high concentration of sodium ion comparing with the samples where no arsenic was detected. The area in which arsenic was detected is located near a hot spring. The relation between the concentrations of major inorganic conponents and arsenic will be cause by the prolonged contact of ground water with the sediments of the stratum.

抄録全体を表示