分離技術シリーズ 29

環境プロセス工学
室

山

勝

彦

分 離 技 術 会著

｢分離技術シリーズ｣ の継続刊行に当たって研究開発とは，新しい原理や現象を発見することばかりではなく，原理・現象は既知であっても新しい方法を案出するとか，あるいは新しい組み合わせを創案することによって，新しい技術，商品，品質，機能，用途，方法等々を創出することである．
本会は主に化学品の製造に関わる分離技術を包括的に扱う専門の学会である
が，研究者・技術者を糾合して正に関連分野の研究・開発の進展を目指し，急激な変化に対応しようと心がけている．
すでに何冊か刊行された本シリーズのなかには，本会会誌 ｢分離技術｣ 誌に掲載された論文によっているものもある．しかし，論文に記載された技術を取捨選択し，それらの組み合わせを考えて執筆されたものであるから，上述の視点から成書としての価値は高いといえるであろう．
さて，最近あらたな構想のもとに，本委員会よりいろいろな分野の権威者に執筆を依頼し，本シリーズに書き下ろしの著作物が加えられることになったのは誠に慶賀に堪えない次第である．分離技術の益々の発展に寄与することは勿論，読者諸兄姉に研鑽のお役に立つものと信じている．
分離技術シリーズ出版委員会
委員長

小

島

博

光

序 文
21 世紀に入った今，地球環境問題は特に温暖化に関して大変深刻な事態を迎えている．これは産業や経済の発展と，生活の利便のために必要となったエ
ネルギー生産に伴う化石燃料消費が増大を続け，温室効果に責任のある大気中の 2 酸化炭素濃度が増大し続けているためである．一方では，大気環境の汚染に関して，日本が高度成長を始めた昭和 30 年代から公害問題が深刻になった．
これに対して公害対策基本法をはじめとした法規制と共に，大気汚染防止技術の開発を進めた結果，工業生産と共に亜硫酸ガスや窒素酸化物などの大気汚染
気体や粒子状物質の排出を排出源でくい止めることに成功している．もう一方の水環境の汚染に関しても，日本は深刻な公害問題を抱えていたが，技術者は水質汚濁防止の技術開発を進めて，深刻な水汚染による住民の犠牲はあったが，現在は水環境の公害の押さえ込みに成功している．このように，工業生産において同時に発生源での汚染防止を進めることが環境保全において重要であることはいうまでもない．
しかし，大気環境問題に関しては，自動車排ガスに起因する NOx やジーゼ
ル車排ガスに起因するジーゼル排煙粒子による大気汚染防止に関して十分な注意が払われる必要がある．さらに，水質汚濁の防止に関しては，河川水や湖沼
水の富栄養化の防止に注意が払われる必要がある．
日本は今工業生産や経済では成熟期を迎えているが，なお廃棄物処理の問題
や，環境保全に関して直多くの問題を抱えている．すなわち 20 世紀型の大量生産・大量消費・大量廃棄の経済構造から脱却し，3R(Reduce，Reuse，
Recycle)とゼロエミッションの考え方にもとづいて，廃棄資源から資源回収を進め，物質生産のために新たに投入する資源を最小化して「循環型社会」を構築すること，さらには，太陽電池や風力発電などの太陽エネルギーの利用，バ
イオマスエネルギーや廃棄物の熱エネルギー利用を進めることによって省エネ
ルギーと代替エネルギー(新エネルギー)の開発を進めて化石燃料の消費を最小化する「低炭素社会」を実現することが将来に向けての重要な課題となっている．近年廃棄物処理において，バイオマスを主とする湿潤廃棄物，厨芥，紙類，畜産廃棄物，などの循環型資源の焼却エネルギー化，堆肥化，バイオガス化などに関して，めざましい技術的発展が認められる．さらに，人間活動による環境への負荷を自然回復能力以内におさえて，人類社会の持続を可能にする「持続可能な発展の社会」に導かなければならない．
そこで，環境プロセス工学では，大気環境と水環境の公害防止に応用される
基本的な技術について整理して解説する．特に，物理化学，生物工学，化学工学に基づいた物質の分離や変換操作における理論解析を重視しており，有害物質の分離や分解のためのプロセス装置の合理的設計を行うことを目標としている．また，バイオマス廃棄物を循環資源として，エネルギー化，資源化するための方法論についても，最新の技術を整理して収録した．
最後に，本書のコンセプトについて補足する．本書は，著者が開講していた
大学化学工学系学科 3 回生向けの専門科目｢大気･水環境工学｣の講義要項に，バイオマス廃棄物処理の単位操作を加えてまとめたものである．本書は，各章に配置した【例題】によって理論に基づいた技術計算が十分理解できるようにし，章末の演習問題を解くことによってさらに問題の理解が深まることを企図したので，教科書として使用できる．また執筆中に気づいた事項を随所にトピックスとして(【コラム】囲み記事)として入れた．本書が，現場の技術者，
あるいは企業研究者の参考になるとすれば，これは著者の望外の喜びである．
平成26年 3 月
室

山

勝

彦

目

次

第１章

大気環境の保全 ····································································· 1

1．1

大気汚染物質 ········································································ 2

1．2

大気汚染の発生源 ·································································· 3

1．3

大気汚染による影響 ······························································· 4

1．3．1

人体に及ぼす影響··························································· 4

1．3．2

生活環境への影響··························································· 6

1．4

大気汚染物質の拡散 ······························································· 61．4．1

有効煙突高さ ································································ 7

1．4．2

大気中の拡散 ································································ 8

1．4．3

サットンの拡散式 ·························································· 9

1．4．4K 値式 ······································································· 11

1．4．5

大気の安定性 ······························································· 11演習問題 ······················································································ 13
第２章

排ガス処理 ·········································································· 14

2．1

排煙脱硫技術 ······································································· 14

2．1．1

湿式吸収法··································································· 15

2．1．2

乾式吸収法··································································· 15

2．2

排煙脱硝技術 ······································································· 15

2．2．1

乾式法········································································· 15

2．2．2

湿式脱硝法··································································· 18

2．3

有害ガスの除去 ···································································· 19

2．3．1

塩化水素および塩素······················································· 202．3．2

フッ化水素··································································· 20

2．4排ガス処理法と処理装置 ························································ 20

2．4．1

乾式法で用いられる排ガス処理装置·································· 20

2．4．22．5

湿式法で用いられる排ガス処理装置·································· 21

悪臭の除去 ·········································································· 35

2．5．1

悪臭と化学構造····························································· 37

2．5．2

悪臭防止技術································································ 37

演習問題 ······················································································ 38
第３章

ばいじんと粉じん ································································· 403．1

粒度分布(粒径分布) ······························································ 40

3．2

煤塵の処理技術 ···································································· 41

3．2．1

集塵装置の性能····························································· 41

3．2．2

重力集塵と慣性集塵······················································· 47

演習問題 ······················································································ 55
第４章

水環境の保全 ······································································· 57

4．1

水質汚濁 ············································································· 59

4．2

水質汚濁項目 ······································································· 60

4．3浄水処理 ············································································· 64

4．3．1
4．4

浄水処理プロセス·························································· 65

廃水処理·········································································· 66

4．4．1

汚水の発生源 ······························································ 66

4．4．2

排水の性質と分類·························································· 66

4．4．3

排水処理計画 ······························································ 67

4．4．4

排水の種類と処理方式···················································· 69

4．4．5

排水処理の分類····························································· 72

演習問題 ······················································································ 72
第５章

物理化学的処理 ···································································· 73

5．1

スクリーン ·········································································· 74

5．2

沈降分離 ············································································· 74

5．2．1

単一粒子沈降速度·························································· 74

5．2．2

沈殿池の効率································································ 76

5．2．3

沈降濃縮······································································ 77

5．3

ろ過 ··················································································· 84

5．3．1

濾過方程式 ································································· 84

5．3．2

連続式回転円筒濾過器(Oliver型)の設計方程式 ···················· 86

5．4

凝集沈殿(flocculation) ·························································· 87

5．5

浮上分離(floatation)······························································· 88

5．6

中和・pH調整(neutralization) ··················································· 89

5．7

酸化・還元(oxidation・reduction) ············································· 895．8イオン交換法(ion exchange) ···················································· 90

5．9

逆浸透法(reverse osmosis, hyperfiltration) ···································· 815．10

電気透析法(electro-dialysis) ··················································· 93

5．11

清澄濾過法(clarifying filter) ··················································· 945．12液相活性炭吸着··································································· 95

5．12．1吸着平衡 ···································································· 95

5．12．2

回分吸着の理論 ··························································· 96

5．12．3吸着塔の設計 ···························································· 100

5．13

泡沫分離，イオンフローテーション法··································· 108

5．14

蒸発法············································································· 1085．15

電解処理法······································································· 109演習問題 ···················································································· 109
第６章

生物学的処理 ····································································· 112

6．1

微生物による水処理操作 ······················································ 112

6．1．1

可溶性有機物の微生物酸化············································ 113

6．1．2

消化および脱窒素························································ 116

6．1．3

生物学的脱リン(生物学的リン除去・リン回収)················· 117

6．1．4

嫌気性消化································································· 117

6．2

微生物固定化法 ·································································· 120

6．2．1

担体結合法································································· 120

6．2．2

包括法······································································· 121

6．2．3

自己固定化法······························································ 122

6．3

好気性酸化プロセスにおける生物相 ······································· 122

6．4

活性汚泥法 ········································································ 124

6．4．1

活性汚泥法の原理························································ 121

6．4．2

活性汚泥槽の設計理論·················································· 123

6．4．3

活性汚泥槽における曝気槽の種類··································· 127

6．4．4

BOD 除去と汚泥の発生················································· 130

6．4．5

BOD 負荷··································································· 130

6．4．6

曝気·········································································· 130

6．4．7

膜分離活性汚泥法························································ 131

6．5

高度生物学的処理法 ···························································· 132

6．5．1

生物学的脱窒素法························································ 132

6．5．2

生物学的脱リン··························································· 133

6．5．3

嫌気-無酸素-好気法(A2O法) ·········································· 134

6．6

散水ろ床法 ········································································ 135

6．7

回転円板法 ········································································ 136

6．8

嫌気性処理法 ····································································· 137

6．8．1

有機物の嫌気分解の過程 ············································· 139

6．8．2

湿潤バイオマス廃棄物のメタン発酵································ 140

6．8．3

嫌気性消化技術··························································· 140

6．8．4

微生物固定化法によるメタン発酵の高速化······················· 142

6．8．5

高濃度廃水のメタン生成率············································ 1436．9

処理水の水質に関する基準 ··················································· 151

演習問題 ···················································································· 153
第７章

廃棄物処理総論 ·································································· 155

7．1

廃棄物の処理体系 ······························································· 1557．2

廃棄物処理の流れ ······························································· 157

7．3

廃棄物からの資源およびエネルギーの回収 ······························ 159

演習問題 ···················································································· 161
第８章

廃棄物の焼却処理 ······························································· 162

8．1

発熱量 ·············································································· 162

8．1．1

廃棄物の元素組成の推定··············································· 1628．1．2

元素組成による発熱量の推定········································· 163

8．1．3燃焼計算···································································· 165

8．1．4

燃焼空気量································································· 1668．2

燃焼ガス量とガス組成 ························································· 1668．3

燃焼ガス温度 ····································································· 168

8．4

燃焼装置 ··········································································· 170

8．4．1

ストーカ式燃焼炉························································ 1718．4．2

流動層式ゴミ焼却炉····················································· 172

8．5

燃焼熱利用 ········································································ 173

8．5．1

熱精算······································································· 173

8．5．2

発電利用···································································· 175

8．5．3

熱利用······································································· 176

8．6

焼却残渣の資源化 ······························································· 177

8．6．1

溶融固化···································································· 177

8．6．2

セメント化································································· 177

8．7

焼却処理における公害対策 ··················································· 178

演習問題 ···················································································· 180
第９章

バイオマス廃棄物のコンポスト化 ·········································· 171

9．1

コンポスト化の微生物反応 ··················································· 182

9．1．1

炭水化物の分解··························································· 182

9．1．2

タンパク質および脂肪の分解········································· 182

9．1．3

生物体の合成(同化作用)··············································· 183

9．1．4

生物体の分解(異化作用) ············································· 183

9．1．5

消化 ········································································ 184

9．1．6

嫌気状態での反応 ······················································ 1849．2

微生物の増殖 ····································································· 1849．2．1

増殖速度···································································· 1849．2．2

最大比増殖速度の温度依存性········································· 184

9．2．3

コンポスト化反応の量論関係········································· 1879．2．4

基質の消費速度··························································· 1879．2．5

水分の蓄積速度··························································· 188

9．2．6

エネルギー収支··························································· 189

9．2．7

断熱発酵槽のエネルギー収支········································· 191

9．2．8

必要空気量 ······························································· 193

9．2．9

滞留時間(発酵時間)····················································· 195

9．2．10

発酵槽容積 ······························································· 196

9．2．11

計算のための基礎物性値 ············································· 197

9．3

コンポストの原料 ······························································· 197

9．4

コンポスト化に影響する操作因子 ·········································· 198

9．4．1

水分量······································································· 198

9．4．2

通気·········································································· 199

9．4．3

C/N 比 ······································································· 200

9．4．4

温度·········································································· 200

9．4．5

pH ············································································ 201

9．5

コンポストの最終成分 ························································· 201

9．6

コンポスト化プロセス ························································· 201

9．7

コンポスト発酵装置 ···························································· 202

9．7．1

スクープ式発酵槽························································ 203

9．7．2

縦型レーキ式発酵槽····················································· 203

9．8

コンポストの品質 ······························································· 204

9．8．1

組成．物理化学性状····················································· 204

9．8．2

腐熟度······································································· 204

9．8．3

コンポストの施肥効果·················································· 205

9．8．4

有害物質と規制··························································· 206

演習問題 ···················································································· 206
第10章

湿潤有機性廃棄物のメタン発酵 ············································· 208

10．1

メタン発酵におけるメタン収率············································ 208

10．1．1

原料の元素組成の利用 ················································ 208

10．1．2CODCr収支の利用······················································· 210

10．1．3

VS分解率の利用 ························································ 211

10．1．4

TOC分解率の利用 ······················································ 213

10．2

メタン発酵特性の温度依存性··············································· 213

10．3

メタン発酵におけるアンモニア阻害および原料の C/N 比の影響····························································································· 214
10．4

メタン発酵に及ぼす pH の影響とプロセスの最適化

10．5

湿潤バイオマス廃棄物のメタン発酵プロセス·························· 217·············· 215

10．6

廃棄物の前処理(破砕と加水)··············································· 22010．7

湿式メタン発酵································································· 221

10．7．1

ガス撹拌式 ······························································· 221

10．7．2

機械撹拌式 ······························································· 222

10．7．3複合撹拌式 ······························································· 222

10．7．4

無動力撹拌式 ··························································· 222

10．7．5

液ポンプによる混合方式 ············································· 224

10．7．6

発酵槽の加温方式 ······················································ 224

10．7．7

発酵槽容積 ······························································· 227

10．8

乾式メタン発酵································································· 228

10．8．1

乾式メタン発酵特性 ·················································· 229

10．8．2

縦型乾式メタン発酵 ·················································· 230

10．8．3

横型乾式メタン発酵槽 ················································ 231

10．8．4

横型乾式メタン発酵の操作特性 ···································· 233

10．8．5

横型乾式メタン発酵槽の容積 ······································· 235

演習問題 ···················································································· 236
付

録 ·························································································· 239

１．重要物理量 ············································································· 239
２．大気汚染指標 ··········································································· 239
３．水質汚濁指標 ··········································································· 240
４．単位一覧 ················································································· 242
５．物理量数値の表現方法 ······························································· 243
索引 ····························································································· 245