In a wastewater treatment process using attached microorganisms, microbial carriers such as plastic resins, porous ceramics, sands etc. have conventionally been employed. Since the performance of the biological wastewater treatment has been regarded as a function of the concentration of microorganisms in a reactor, microbial carriers have been focused on to increase the specific surface area. The fluidized bed process using small particles is one example of the application.
Nonwoven fabrics made of plastic resin are considered highly effective microbial carriers because of the attachment of microorganisms on each thread as well as microbial growth in three dimensional intertwisted spaces. However, there have been few reports on the application of nonwoven fabrics as aerobic microbial carriers.
Experimental studies have been conducted to clarify the features of attachment of microorganisms to nonwoven fabrics by the initial phase filtration test, the intial phase bioattachment test in a reactor and the continuons biofilm growth test.
The highest concentration of attached microbes has been found to be attainable in a specific range of the opening length rather than over a specific surface area. The composition difference of the attached microbes compared with the suspended microbes had a great effect on the kinetic constants.

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A simulation model for changes of phosphorus and organic carbon concentration in a cycle period on biological phosphorus removal is developed in this study. We propose a model based on a simple combination of two species of biomass, based on its phosphorus content. Changes of phosphorus and organic carbon concentrations under anaerobic/aerobic condition are simulated and estimated for the effects of organic carbon loading, the ratio of phosphorus accumulating biomass to total biomass, biomass concentration and the maximum specific growth rate.
Phosphorus release/uptake in the biomass during a cycle period could basically be attained by controlling of orgaic carbon concentration and the ratio of phosphorus accumulating biomass to total biomass.
The prediction of profiles of phosphorus and organic carbon concentrations in the reactor gives fair agreement with the experiment results.

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Volatile organic chlorinated compounds (VOCC) in ground waters (spring and deep well waters) at Kitatama area, Tokyo were studied during 1987-1988. One of the studied spring waters was sampled weekly and the concentration of VOCC was determined. Tetrachloroethylene (PCE) concentration in the spring water decreased gradually (2.20-10.3μg·l^-1), however, that of trichloroethylene (TCE) and trichloroethane (MC) was nearly constant. VOCC concentrations did not show the seasonal changes. VOCC concentrations in very neighboring spring waters showed different values, however no great differenes in other chemical components was observed.
Two deep well waters (150m and 250m depth) were sampled monthly. High concentration of TCE, amountly to 38μg·l^-1 was observed on January 29, 1987 in one well (depth 150m), however it decreased gradually since then. VOCC concentrations did not show seasonal changes and some kind of VOCC were not detected in deep well waters.
After the heavy rain, changes of VOCC concentrations were studied. VOCC concentrations were observed to be nearly constant in spite of the change of the discharge.

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