Abstract: An anaerobic fluidized bed (AFB) bioreactor followed by an aerobic bioprocess enables effectively simultaneous removal of suspended solids, organic matter, phosphorus and nitrogen compounds. In the AFB bioreactor, suspended solids, colloidal matter and phosphorus were coagulated with the combined use of small amount of polymerized aluminium chloride and weakly anionic polymers to generate large sized coagulated sludge which could rapidly separate from the liquid. Especially, in the summer season with high water temperature, the pelletized sludge with high effective density can be produced. The microscopic observation showed the pelletization of sewage pollutants was caused by chemical coagulation as well as bacterial growth. Above 18•K of temperature, recycling of nitrified effluent from the aerobic bioprocess to the AFBbioreactor achieved complete denitrificationandnitrificationwitha total retention time of 4h(2h in AFB bioreactor and 2h in the aerobic bioprocess) and a recirculation rate 3 times the feed rate, resulting in above 80% of total nitrogen removal efficiency. Keywords; anaerobic fluidized bed bioreactor, pelletization of sewage, nitrification, denitrification, phosphorus removal 1.は じめに 下水中には固形性(懸 濁性)と 溶解性の有機汚濁物質が含まれている。現在の下水処理システムでの最初 沈殿池における固液分離は不十分であり、微細な懸濁性成分やコロイ ド成分は後段の生物処理プロセスへの 汚濁負荷となっている。したがって前処理によって、これらの懸濁性成分の除去効率を増加させることがで きれば、活性汚泥法などの生物処理プロセスにおいて曝気時間の短縮や曝気動力の節減が可能となる、この ような観点に基づいて、最近凝集剤を添加 した り1)、 材を用いて2)、下水中の懸濁性およびコロイ ド成分 の除去率を増加させることができるプロセスが報告されている。 一方今日下 、有機汚濁成分だけでなく窒素 ・リンなどの栄養塩類の除去が可能な高度 処理プロセスの確立が望まれている。現在A2O法 、UCT法、Phoredox法 などが開発されているがいずれの処理 プロセスにおいても、脱窒 ・脱 リン反応に必要な有機炭素源が不足するために、下 ・廃水中の窒素 ・リンを バランスよく除去することの困難さや処理の安定性が低いなどの問題点が指摘されている。そこで最近、下 ・廃水中に含まれる懸濁物質中の易加水分解成分を脱窒 ・脱 リンの炭素源およびエネルギー源として利用し ようとする研究が行われている。Schonberger3)は 既存の最初沈殿池を流入下水と返送汚泥とを接触させるた めの嫌気性汚泥接触槽に変更 して、懸濁性BODを 利用したリン除去が可能な冠ASC(Extended Anaerobic Shdge Conact)プ ロセスを開発 している、またRabinowitzら4)は 下水処理プラントに新たに醗酵槽を付設 し、 初沈汚泥の酸醗酵を行い、生成する低級脂肪酸を生物学的脱 リンプロセスへ供給 し、リン除去効率の大幅な *北 海道大学工学部衛生工学科 (Dept. of Sanitary and Environmental Engineering, Hokkaido University) **月 島機械KK (Tsukishima Kikai Co., Ltd.)

Abstract: Effect of hydrolysis on mutagenic activity of chlorinated water was investigated. Chromosomal aberration test using Chinese hamster lung (CHL) cell was carried out to evaluate mutagenic activity. It was found that activity-induced chromosomal aberrations of chlorinated humic acids solution decreased with hydrolysis reaction. The observed hydrolysis rate constant at neutral condition (pH7.1), 20•Ž was determined to be 1.76 day-1, and half—life was estimated to be 9.5 hours. While chloroform was produced with hydrolysis reaCtion, activity-induced chromosomal aberrations decreased. Activity-induced chromosomal aberrations of chlorinated water could be attributed to chlorinated and/or oxidized by-products excluding chloroform. Effects of hydrolysis reactions of 1, 3-dichloro-2-propanono and 1, 1, 1—trichloropropanone. whinh were mutagens identified in chlorinated waters, were examined. It was found that the decreases of mutagenic activities of these mutagens proceeded by cleavage of chlorine by hydroxide ion, suggesting that the same mechanism existed in hydrolysis reactions of chlorinated drinking waters and chlorinated effluents from sewage treatment plants. KEYWORDS; chlorination, chloroform, mutagenicity, chromosomal aberration test, hydrolysis

Abstract: It has been recognized that nonpoint source is an impotant element to improve water quality conditins. To discuss the comprehensive management policy of water pollution control including nonpoint source, it is needed to quantify nonpoint source and understand its runoff mechanisms. In this study, we shall construct a model including restoring and runoff processes of point and nonpoint sources, and apply it to analyze differences of pollutants load behaviers between combined and separated sewer systems for wet weather and dry weather.

Abstract: A thermophilic UASB reactor was operated for a period of more than six month by feeding a synthetic wastewater composed of sucrose. Well-settleable granulated sludge with a diameter of 2-3 mm developed successfully after 100 days operation from a start-up. Characterization of thermophilic granules was made with respect to morphological structure and methanogenic activity. The granule showed a double-layered structure. The exterior layer was composed of a sponge-like material, while crystalline precipitates existed in abundance inside the granule (referred to as the core). A major component of the precipitates formed in the core was confirmed to be calcium carbonate, in the form of not only aragonite but also calcite. The presence of calcium-bound phosphorus in the core was three times as large as that in the exterior layer. Methanogenic activities from acetate and hydrogen increased with increasing vial-test temperature from 55•Žto 65•Ž: 1.43 to 2.36 and 0.85 to 1.11kgCH4-COD • kgVSS-1•Ed-1, respectively, for acetate and hydrogen. On the other hand, methanogenic activity from propionate remained unchanged in that temperature range (0.1-0.12kgCH4-COD• kgVSS-1• d-1). The methanogenic activity from propionate was considerably lower than that from acetate or hydrogen, indicating that the propionate degradation is a ratelimiting step in the thermophilic condition. The acetate utilization rate of the granules was significantly inhibited by the presence of hydrogen. This indicates that a large extent of acetate conversion to methane was performed by a syntrophic association between acetate-oxidizers and hydrogenotrophic methanogens. KEY WORDS; Thermophilic anaerobic digestion, granular sludge, calcium precipitation, propionate degradation, acetate oxidation. 1.は じめ に UASB(上 昇流 嫌気 性ス ラ ッジブ ランケ ッ ト)法 は、付着坦体 を用いず、嫌気性細 菌の自 己造粒化(グ ラニ ュ レー シ ョン)機 能 を利 用する ことに より、反応器内 に高濃度 の微 生 物量を保持 する ことを可能 とした高速 メタ ン発酵処 理技術 であ る。近年本 法 は、主に食 品加 工工場 等か ら排出 される、比 較 的分解 しやす い中高濃度 有機性 廃水処 理方法 と して広 く普及 を 重ねて きた。 現在の ところ適応 され る廃水 の種類 はある程度限 られているが、 そ の非常 に優れ た処理性能のゆ えに高 い評価 を受け、技術 的 に成 熟 した段 階に達 している といえる1)。今後、UAS B法 の 普及を さらに広 めてい くためには、本 法の根本的 な成立条件 で ある嫌気性 細菌 の自己造 粒化現象 を よ り明 確 に把 握 しつつ、適応廃水種 の拡大 をはか ることが必 要である。 一方 ある種 の工場 では 、有機 原料 の蒸留、 湯煮 など、 熱を加 えて加 工す る工程 を含 んでお り、 それらの 工程 か ら排出 される廃水 は、一般 に80-90°C と高温 で、かつBODで 数千か ら数 十万ppmと 、非常 に高濃度 である ことが 知 られている。通常 この ような高温廃水 の汚濁負荷 量は、全汚濁負荷 量に対 して40%-90%と 非常 に大 きい2-3)。 *コ マ ツ 研 究本 部 (Research Division, KOMATSU) **長 岡技術 科学大学 建設系 (Department of Civil Engineering, Nagaoka University of Technology)

Abstract: The chemical forms and the run-off characteristics of particulate heavy metals were researched. Before the chemical analysis, the suspended matters contained in water were separated by continuous centrifuge, then the various types of heavy metals were fractionated into 5 groups from them by various solvents. Together with the data of examining the chemical components in water and mud, the followings were found out: (1) The ratio of natural mineral heavy metals becomes high in flood time, (2) Cu originate from human activities because of the close relation with organic matters, (3) Much of Mn and Zn have a similar behavior, and they originate from industries and households . Though the amount of heavy metals in suspended solid in studied area is not so much, run-off control of suspended solids by consolidating drainage system is available for improving water circumstances .