A biological treatment process using a biomass carrier of blast-furnace slag was studied to treat waste water from leather industry, which contains refractry organic compounds. Waste water from leather industry contains NH₄-N of 150mg·l^-1 and refractry organic compounds, which makes longer HRT of an aeration tank and easily generates NO₂-N to induce COD.
The two step biological treatment process, which consists of an activated sludge process using blast-furnace slag as a biomass carrier and a fixed bed reactor using saddle-type ceramics made from blast-furnace slag, was examined to treat waste water from leather industry efficiently.
Nitrifying bacteria of Nitrobacter oxidizing NO₂-N to NO₃-N could be cultivated on the surface of the ceramics, which protected the accumlation of NO₂-N in the effluent and restrained COD originated from NO₂-N. And this process could promote the biological oxidation of the organic compounds simultaneously. Thus this process could improve the effluent quality and the treatment efficiency of waste water from leather industry.

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A new superior adsorbent was selected for a convenient and quantitative mutagenicity assay of tap water. Adsorption abilities of various adsorbents such as CSP800, XAD4, XAD4/8, blue rayon, and blue cotton were investigated for recovering mutagens from tap water. CSP800 and XAD4 are highly porous polystyrene resins, but CSP800 has larger surface area and smaller particle size than XAD4. XAD4/8 is a mixture of a XAD4 and XAD8 of porous polyacrylate. Blue rayon and blue cotton are cellulose bonded copper phthalocyanine trisulfonate.
It was confirmed clearly that a new adsorbent CSP800 could recover much more mutagens in a short time than the others. Then convenient refining and conditioning method of the CSP800 was defined as follows ; Five cartridges packed 2ml of CSP800 (Sep-Pak Plus Long) were connected in series, and washed by 400ml of ethyl acetate, 200ml of ethanol, and 100ml of pure water by turns at 10ml·min^-1. After this refining and conditioning method, any mutagens did not elute from the adsorbent, and a little remained ethanol did not disturb the adsorption of mutagens from tap water.

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Sample preparation method using a cartridge (Sep-Pak Plus Long) in which 2ml of a superior adsorbent CSP800 was packed was optimized for convenient and quantitative Ames mutagenicity assay of tap water.
Mutagenicity activities were decreased considerably by free chlorine reduction by sodium sulfite. Recovery of mutagens from tap water augmented much in lower pH. There was no influence of adsorbing flowrate in the range from 8 to 80ml·min^-1 on the recovery of mutagens. Therefore, it is optimal that tap water adjusted at pH2 without free chlorine reduction is fed to the cartridge at a flowrate of c.a. 50ml·min^-1. By this method, the mutagens less than 8,000 net revertants.·l^-1 could be recovered completely from 2l of water sample, and those more than that could be recovered from 1l. The adsorbed mutagens could be desorbed by 2ml-dimethyl sulfoxide (DMSO) at 0.15 ml·min^-1 in upper flow.
This newly developed method requires only 1 or 2l of water sample and less than an hour to concentrate mutagens with over 90% recovery. Furthermore, the desorbing DMSO solution can be used directly to Ames assay without solvent exchange, because concentration factor of mutagens by this method attains 500 or 1,000 times.

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