Tetrachloroethylene (PCE), a prevalent groundwater contaminant, can be completely dechlorinated to ethylene (ETY) and ethane (ETA) under anaerobic conditions in the presence of a suitable electron donor. ETY and ETA are harmless and environmentally acceptable products.
This study was conducted to examine the feasibility of using an anaerobic filter for the treatment of PCE in bioremediation process. A laboratory-scale continuously-fed upflow anaerobic filter was operated at hydraulic retention times (HRTs) of 4.0-1.0 days in a 25°C constant room. Influent PCE concentration was 2.8mg·l^-1 and ethanol (100mg COD·l^-1) was dosed as an electron donor. Anaerobic PCE-dechlorinating enrichment culture was used as inoculum. Immediately after the start-up, the system showed an excellent capability in dechlorinating PCE to trichloroethylene (TCE), dichloroethylene, vinyl chloride, ETY and ETA. PCE and TCE were never detected (less than 0.005mg·l^-1) in the effluent and the conversion efficiency of PCE to ETY and ETA was above 97% at HRTs of 2.0-1.0 days. Moreover, effluent COD concentration was low (20-25mg·l^-1). Results of this study suggest that the anaerobic filter system is a feasible bioremediation process for the treatment of chlorinated ethylenes.

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The purpose of this study is to examine the water treatment system combining adsorbent and membrane separation. The powdered natural zeolite (-100+200mesh) was used as the adsorbent with the membrane systems of ultrafiltration and microfiltration. The experiments were performed by such operation factors as the particle diameter of zeolite, the concentration of ammonia nitrogen, the amount of zeolite and the difference of membrane.
As the results, the ultrafiltration membrane system with natural zeolite (10,000mg·l^-1) gave as higher removal of ammonia nitrogen as 90% from the solution (ammonia nitrogen 10mg·l^-1).

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Seasonal characteristics of the spactial distributions of water temperature and salinity in Tokyo Bay were revealed by applying statistical methods to the monitoring data obtained at 41 observation points every month from April 1985 to March 1990. At the center of the bay, the surface water kept higher temperature than that at the bottom during May to October, and it took a little bit lower one than that at the bottom in Winter. The salinitiy at the surface took its minimum and maximum in Summer and Winter, respectively, and that at the bottom took them in the reverse seasons. Those at both layers were almost equal in February because of surface cooling, and the original salinity of ocean water 34.4 was reduced to 33.
On the other hand, the water temperature at the head of the bay was higher than that at the mouth of the bay during May to October, and this relation was reversed in the other months. Low salinity was prominent near the mouth of the rivers of Ara and Tama, and it expanded along the west coast to the mouth of the bay. The salty ocean water entered from the mouth of the bay through the bottom layer, and it reached to off the mouth of the river of Tama, where relatively high salinity was observed at the surface especially in Spring and Summer.

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Effect of CO₂ partial pressure on the anaerobic digestion of starch and production of methane were investigated by using anaerobic chemostat type reactor at 35°C. The CO₂ partial pressure in the atmosphere of the reactors was controlled in a series of bioreactor from 0.1 to 0.8atm. Since the partial pressure of CO₂ in an uncontrolled condition was about 0.4atm, N₂ was added to the reactors controlled at CO₂ partial pressure of between 0.1 and 0.4atm. At CO₂ partial pressure of 0.5atm, the methane production was approximately 20% more than that in an uncontrolled condition of CO₂. Based on the carbon mass balance, it was concluded that methane production was related to the removal of dissolved organic carbon and consumption of CO₂. The number of acetate consuming methanogenic bacteria, enumerated by the most probable number method, decreased significantly when CO₂ partial pressure exceeded 0.7atm. Homoacetogenic bacteria were increased with increasing CO₂ partial pressure increased from 0.1 to 0.6atm, however, decreased slightly at CO₂ partial pressure above 0.6atm. The number of acidogenic, H₂ consuming methanogenic bacteria, propionate and butyrate degraders were not much influenced by the partial pressure of CO₂. The potential methanogenic activity and potential substrate utilizing activity of acetate, increased at CO₂ partial pressure between 0.5atm and 0.6atm, however, decreased significantly when CO₂ partial pressure exceeded 0.7atm.

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In laboratory experiments using powder converter slag (particle size, 53-75 μm), produced in steel production process, the removal of phosphorous in sea water was examined. The elution of a small amount of phosphorous in the slag was also examined, because the slag contains the small amount of phosphorous.
About 30% of phosphorous originally contained in the slag was possibly eluted in sea water. The net phosphorous removal by the slag was expressed by the Freundlich absorption isotherm at pH7,8 under both aerobic and anaerobic conditions. Although the isotherm was valid for lower phosphorous concentration at pH9, higher removal efficiency was achieved at higher phosphorous concentration due to the precipitation of calcium phosphate. Most of the phosphorous adsorbed on the slag (77%) was held without elution, suggesting chemical adsorption.
Examination of slag surface by a X-ray microanalyzer indicated that (1) the slag could De divided into 3 regions (A, B and C) with relatively the same percentages, (2) phosphorous in the slag was originally contained in the C region, which consisted mainly of CaO and SiO₂, and (3) phosphorous removal was also achieved in the C region.
To confirm phosphorous removal in sea water, converter slags of 1cm cube were submerged on the bottom sediments in a bay for nearly 2 years. Phosphorous removal was achieved in the C region, not only on the surface but also at 5mm deep into the slag. P₂O₅ content in the C region increased from 3.0% to 6.0% (surface) and to 5.2% (5mm deep) after 692 days.

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The effects of ten hazardous chemicals on biosorption behavior, COD removal rate (COD_R) and oxygen uptake rate (OUR) of activated sludge microorganisms were studied.
The IC₅₀ values, 50% inhibition of the OUR, determined to be 2.3mg·l^-1, 4.5mg·l^-1, 7.3mg·l^-1, 9.8mg·l^-1, >2,500mg·l^-1, >12,500mg·l^-1, 950mg·l^-1, 2,800mg·l^-1, 9,500mg·l^-1 and 460mg·l^-1, respectively, for HgCl₂, CUCl₂, (CH₃COO)₂Hg, (CH₃COO)₂Cu, phenol, paraquat (PQ), gramoxone 100^® (24% PQ), tri-n-butyltin chloride (TBTC), tri-n-butyltin oxide (TBTO) and SnCl₂.
As the IC₅₀ value of Hg (II) and Cu (II) low, COD_R low while biosorption behavior high. Conversely, when the IC₅₀ value of phenol, PQ, gramoxone 100^®, TBTC, TBTO and SnCl₂ high, COD_R high and biosorption behavior low.
It has been shown that these findings are related to the IC₅₀ values or COD_R and biosorption behavior on activated sludge microorganisms of the ten hazardous chemicals tested.

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