津野 洋

A combined biological activated carbon (BAG) and biological zeolite (BZ) reactor is under development to remove organics and nitrogen from wastewater which contains both inhibitory organics to nitrification and high concentration of ammonium nitrogen. In this study, the combined BAC and BZ reactor was applied to treatment of scrubber-washed wastewater from sludge drying process. Successful treatment performance was accomplished by decreases in concentrations of the inhibitory organics (in BAC tank) and ammonium nitrogen (in BZ tank) occurred by both adsorption to the mediums and biological reaction. Appropriate nitrogen loading rate for fine and stable treatment was shown to be less than 7 mgNOx(.)-N .(gGAC . d)(-1) for denitrification in BAC tank and less than 4 mgNH(4)(+)-N-(gZeolite . d)(-1) for nitrification in BZ tank. DOC/NOx(-)-N loading ratio to BAC tank is required to be more than 2.0 mgDOC .(mgNOx(-)-N)(-1) for successful denitrification. Copyright (C) 1996 IAWQ.

In this study, anaerobic degradation of PCP was discussed in an expanded-bed GAC anaerobic reactor which was applied to treatment of wastewater containing high concentration of PCP-Na as well as acetate. Total-COD concentration in effluent was kept less than 100 mg/L except for the start-up duration and PCP-Na concentration was kept less than 0.50 mg/L under the experimental conditions (HRT of 5 days, influent PCP-Na concentration of 100 and 400 mg/L, and influent Total-GOD concentration of 480 and 1600 mg/L). It was indicated by methane production rate and material balance of PCP-Na that about 60% of PCP-Na loaded into the reactor was transformed to methane and CO2 for 375 days. GC/MS analysis of extracts of the GAG medium and effluent indicated that reductive dechlorination of PCP occurred and dechlorinated phenols were adsorbed on the GAC in the reactor. Microorganisms collected from the reactor degraded PCP-Na and 2-GP anaerobically and addition of acetate in culture accelerated anaerobic degradation of PCP-Na in batch experiments. Copyright (C) 1996 IAWQ.

A mathematical model was developed to predict the effect of vertical water circulation caused by air-lift on water quality restoration in a lake. In this model, several ecosystem paths such as Algal growth, predation by zooplankton, degradation of organics and so on were combined with completely-mixing series tank model, in which a water body was divided vertically to two districts, epilimnion and hypolimnion. This model was applied to Lake Yogo, where two sets of the vertical water circulation unit were set, and verified by comparing the simulated results with observed data. The vertical circulation effects on lake restoration were discussed with this model from the viewpoints of concentrations of dissolved oxygen in hypolimnion, phytoplankton, total nitrogen and total phosphorus.

Scrubber-washed wastewater of Sludge drying process in sludge melting system contains both ammonium nitrogen and dissolved organic carbon (DOC) in high concentrations, and is also found to contain compounds which show inhibition to nitrification. In batch experiments, the inhibitory compounds are found to be biodegradable and also absorbable to activated carbon. Nitrification activity can be recovered immediately after the inhibition compounds are removed.<br>Therefore in this study, biological treatment process using a expanded-bed activated carbon reactor is applied to accomplish nitrification as well as removal of organic compounds from the wastewater. Under the condition where DO is more than 1mg&middot;l^-1, TKN loading rate can be raised till 5mgN&middot;(gGAC)^-1&middot;d^-1 to attain more than 90% nitrification of influent nitrogen. DOC concentration in the bio-reactor should be maintained less than 40mgC&middot;l^-1 for avoiding inhibition and assuring nitrification.

Scrubber-washed wastewater of Sludge drying process in sludge melting system contains both ammonium nitrogen and dissolved organic carbon (DOC) in high concentrations, and is also found to contain compounds which show inhibition to nitrification. In batch experiments, the inhibitory compounds are found to be biodegradable and also absorbable to activated carbon. Nitrification activity can be recovered immediately after the inhibition compounds are removed.<br>Therefore in this study, biological treatment process using a expanded-bed activated carbon reactor is applied to accomplish nitrification as well as removal of organic compounds from the wastewater. Under the condition where DO is more than 1mg&middot;l^-1, TKN loading rate can be raised till 5mgN&middot;(gGAC)^-1&middot;d^-1 to attain more than 90% nitrification of influent nitrogen. DOC concentration in the bio-reactor should be maintained less than 40mgC&middot;l^-1 for avoiding inhibition and assuring nitrification.

Mathematical models are developed to evaluate treatment performance in a pre-precipitation and biofilm process which is operated for phosphorus removal and nitrification as well as BOD removal. The biofilm process is a fluidized medium reactor with polyurethane foam. Treatment performance is also evaluated by fractionation method, in which pollutants are separated by particle size with filters (pore size; 105, 1.0 and 0.1 micro-meter). A distribution matrix model is developed to show the change in distribution pattern and concentration of each particle size through precipitation and sedimentation. A mathematical model developed for biofilm reactor, which can simulate the competition between autotrophic and heterotrophic bacteria with respect to attached surface of the medium, is demonstrated to predict the treatment performance (BOD removal and nitrification) by comparing the simulated results with experimental results. With these models, the pre-precipitation and biofilm process is evaluated with respect to hydraulic retention time and recovery of organic sludge by comparing with primary sedimentation and biofilm process. As a result, it is shown to shorten the hydraulic retention time and increase the organic recovery effectively.

Mathematical models are developed to evaluate treatment performance in a pre-precipitation and biofilm process which is operated for phosphorus removal and nitrification as well as BOD removal. The biofilm process is a fluidized medium reactor with polyurethane foam. Treatment performance is also evaluated by fractionation method, in which pollutants are separated by particle size with filters (pore size; 105, 1.0 and 0.1 micro-meter). A distribution matrix model is developed to show the change in distribution pattern and concentration of each particle size through precipitation and sedimentation. A mathematical model developed for biofilm reactor, which can simulate the competition between autotrophic and heterotrophic bacteria with respect to attached surface of the medium, is demonstrated to predict the treatment performance (BOD removal and nitrification) by comparing the simulated results with experimental results. With these models, the pre-precipitation and biofilm process is evaluated with respect to hydraulic retention time and recovery of organic sludge by comparing with primary sedimentation and biofilm process. As a result, it is shown to shorten the hydraulic retention time and increase the organic recovery effectively.

本研究では, イオン交換剤であるゼオライトを生物付着担体として用い, イオン交換・吸着による廃水中のアンモニア性窒素濃度の硝化阻害発現濃度以下への低減と, 担体付着硝化菌による硝化およびゼオライトの再生をも行わしめることができる反応器 (生物ゼオライト反応器) の開発を目的とした. アンモニア性窒素の吸着と硝化を同時に作用させ得ること, 単位担体当りのアンモニア性窒素負荷率の値を, 0.15mgN/(gゼオライト・h) まであげることができることなどを示した.

本研究では良好な処理成績で運転されている単一槽高負荷脱窒素システムについて処理特性をシミュレートしうる数理モデルを作成した. モデルは反応槽を無酸素ゾーンおよび好気性ゾーン (2区画) に分け, 各々の区画につき有機物除去および硝化・脱窒ならびにこれらに関与する微生物増殖を組み込んだ詳細なものである. この数理モデルの検証を行うとともに, 操作因子について検討を行い, その結果HRTが4.5日で中区画でのDO濃度が1mg/l程度で運転されることが, 処理性および安定性から適切であることを示した.

Mathematical models are developed to evaluate treatment performance in a pre-precipitation and biofilm process which is operated for phosphorus removal and nitrification as well as BOD removal. The biofilm process is a fluidized medium reactor with polyurethane foam. Treatment performance is also evaluated by fractionation method, in which pollutants are separated by particle size with filters (pore size; 105, 1.0 and 0.1 micro-meter). A distribution matrix model is developed to show the change in distribution pattern and concentration of each particle size through precipitation and sedimentation. A mathematical model developed for biofilm reactor, which can simulate the competition between autotrophic and heterotrophic bacteria with respect to attached surface of the medium, is demonstrated to predict the treatment performance (BOD removal and nitrification) by comparing the simulated results with experimental results. With these models, the pre-precipitation and biofilm process is evaluated with respect to hydraulic retention time and recovery of organic sludge by comparing with primary sedimentation and biofilm process. As a result, it is shown to shorten the hydraulic retention time and increase the organic recovery effectively.

本研究では, イオン交換剤であるゼオライトを生物付着担体として用い, イオン交換・吸着による廃水中のアンモニア性窒素濃度の硝化阻害発現濃度以下への低減と, 担体付着硝化菌による硝化およびゼオライトの再生をも行わしめることができる反応器 (生物ゼオライト反応器) の開発を目的とした. アンモニア性窒素の吸着と硝化を同時に作用させ得ること, 単位担体当りのアンモニア性窒素負荷率の値を, 0.15mgN/(gゼオライト・h) まであげることができることなどを示した.

Ammonium nitrogen is a principal material of concern in treated water discharge. Applicability of completely mixed series reactor with polyurethane foam cubes as attached medium to municipal sewage treatment for BOD removal and nitrification was experimentally examined. Nitrifier grew preferably on the polyurethane foam cubes, and its nitrifying activity reached 0.33 (mg N/hr.cube) for the cubes of 8 cm3. BOD removal was completed in 4 hours, and then nitrification began to occur and was completed in 10 hours under the condition of temperature as low as 15 degrees centigrade. The heterotrophic bacteria and nitrifier grew separately in the different cells of the reactor. Nitrification activity was inhibited by some organics included in the influent. The effect of inhibition was severer with increasing DOC.

Ammonium nitrogen is a principal material of concern in treated water discharge. Applicability of completely mixed series reactor with polyurethane foam cubes as attached medium to municipal sewage treatment for BOD removal and nitrification was experimentally examined. Nitrifier grew preferably on the polyurethane foam cubes, and its nitrifying activity reached 0.33 (mg N/hr.cube) for the cubes of 8 cm3. BOD removal was completed in 4 hours, and then nitrification began to occur and was completed in 10 hours under the condition of temperature as low as 15 degrees centigrade. The heterotrophic bacteria and nitrifier grew separately in the different cells of the reactor. Nitrification activity was inhibited by some organics included in the influent. The effect of inhibition was severer with increasing DOC.

粒状活性炭流動床型嫌気性反応器は,生物学的分解可能な有機物のみならず高濃度の生物分解阻害有機物や難分解性有機物を含む廃水を処理するために開発途上にある。この反応器による石炭ガス化実廃水の処理機構のより良い知見を得,その際の設計操作用因子の検討に資するために,活性炭吸着および付着微生物による分解の両機構を組み込んだ簡単な数理モデルを提示した。この簡単なモデルにより,廃水の希釈度,GAC取り替え速度,流入水COD負荷および滞留時間のような操作用因子の種々の条件下で行われた実験での放流水中溶解性COD濃度,GAC媒体単位量当りのCOD吸着量および一日当りのメタン生成量の時間的変化を良くシミュレートし得ることが示された。そして,各操作条件における各状態変数間の定性的および定量的関係や卓越する機構についての有用な知見が示された。

本研究では,石炭ガス化実廃水の粒状活性炭流動床型嫌気性反応器による処理について既報で提示した数理モデルを用いて,良好な処理成績を得るための設計因子や操作法,さらにはプロセスの安定性について検討を試みた。すなわち,比GAC取り替え速度,GAC媒体量,水理学的滞留時間,COD負荷および廃水の希釈度といった操作因子と処理効果を示す関係式を提示し,良好な処理を得るための各操作因子の範囲の検討を行った。関与細菌群の増殖の限界および最適条件について比GAC取り替え速度との関連で検討し,そのとるべき範囲について提示した。また,廃水強度の変化に対する応答について,x_A-x_H関係図やx_A-x_H相平面での軌跡図により検討を行い,プロセスの安定性についての検討を行った。以上により,粒状活性炭流動床型嫌気性反応器により石炭ガス化実廃水を処理する際の設計・操作法についての有用な知見を提示した。

粒状活性炭流動床型嫌気性反応器は,生物学的分解可能な有機物のみならず高濃度の生物分解阻害有機物や難分解性有機物を含む廃水を処理するために開発途上にある。この反応器による石炭ガス化実廃水の処理機構のより良い知見を得,その際の設計操作用因子の検討に資するために,活性炭吸着および付着微生物による分解の両機構を組み込んだ簡単な数理モデルを提示した。この簡単なモデルにより,廃水の希釈度,GAC取り替え速度,流入水COD負荷および滞留時間のような操作用因子の種々の条件下で行われた実験での放流水中溶解性COD濃度,GAC媒体単位量当りのCOD吸着量および一日当りのメタン生成量の時間的変化を良くシミュレートし得ることが示された。そして,各操作条件における各状態変数間の定性的および定量的関係や卓越する機構についての有用な知見が示された。