JPH049119B2 - - Google Patents
Info
- Publication number
- JPH049119B2 JPH049119B2 JP6435984A JP6435984A JPH049119B2 JP H049119 B2 JPH049119 B2 JP H049119B2 JP 6435984 A JP6435984 A JP 6435984A JP 6435984 A JP6435984 A JP 6435984A JP H049119 B2 JPH049119 B2 JP H049119B2
- Authority
- JP
- Japan
- Prior art keywords
- sludge
- denitrification
- tank
- phosphorus
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000010802 sludge Substances 0.000 claims description 94
- 238000000034 method Methods 0.000 claims description 68
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 52
- 229910052698 phosphorus Inorganic materials 0.000 claims description 45
- 239000011574 phosphorus Substances 0.000 claims description 45
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 44
- 230000008569 process Effects 0.000 claims description 42
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 29
- 239000007788 liquid Substances 0.000 claims description 28
- 229910052757 nitrogen Inorganic materials 0.000 claims description 26
- 238000000926 separation method Methods 0.000 claims description 19
- 239000002245 particle Substances 0.000 claims description 16
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 11
- 229910052717 sulfur Inorganic materials 0.000 claims description 11
- 239000011593 sulfur Substances 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 9
- 244000005700 microbiome Species 0.000 claims description 8
- 230000009471 action Effects 0.000 claims description 7
- 239000004579 marble Substances 0.000 claims description 7
- 239000002351 wastewater Substances 0.000 claims description 6
- 229910002651 NO3 Inorganic materials 0.000 claims description 4
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 4
- JVMRPSJZNHXORP-UHFFFAOYSA-N ON=O.ON=O.ON=O.N Chemical compound ON=O.ON=O.ON=O.N JVMRPSJZNHXORP-UHFFFAOYSA-N 0.000 claims description 3
- 238000009825 accumulation Methods 0.000 claims description 3
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims description 2
- 125000001477 organic nitrogen group Chemical group 0.000 claims description 2
- 241001509286 Thiobacillus denitrificans Species 0.000 description 12
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 10
- 239000007789 gas Substances 0.000 description 8
- 238000011282 treatment Methods 0.000 description 8
- 230000008719 thickening Effects 0.000 description 7
- 241000894006 Bacteria Species 0.000 description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- 229910000019 calcium carbonate Inorganic materials 0.000 description 5
- 238000004062 sedimentation Methods 0.000 description 5
- 239000010865 sewage Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000003337 fertilizer Substances 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000010907 mechanical stirring Methods 0.000 description 2
- WHBHBVVOGNECLV-OBQKJFGGSA-N 11-deoxycortisol Chemical compound O=C1CC[C@]2(C)[C@H]3CC[C@](C)([C@@](CC4)(O)C(=O)CO)[C@@H]4[C@@H]3CCC2=C1 WHBHBVVOGNECLV-OBQKJFGGSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229920006328 Styrofoam Polymers 0.000 description 1
- MMDJDBSEMBIJBB-UHFFFAOYSA-N [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] Chemical compound [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] MMDJDBSEMBIJBB-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000004176 ammonification Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000011021 bench scale process Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000004042 decolorization Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000012851 eutrophication Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- -1 is adopted Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000001546 nitrifying effect Effects 0.000 description 1
- 235000015097 nutrients Nutrition 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 150000003017 phosphorus Chemical class 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 239000008261 styrofoam Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Landscapes
- Biological Treatment Of Waste Water (AREA)
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
Description
（技術分野）
本発明は下水や工場廃水などの被処理水から窒
素と燐を同時に除去する脱窒・脱燐活性汚泥法に
関する。
（従来技術）
水域富栄養化防止のために、下・廃水から窒素
や燐などの栄養塩の除去が緊急を要する課題とな
つている。下・廃水からの窒素や燐の除去法とし
ては、処理コストの安い生物学的除去法が有望視
され、各種処理法が開発されている。
生物学的窒素除去と生物学的燐除去とは、その
除去機作の違いから、従来、別個にとり扱われて
きた。しかし、Bardenphoプロセス、A2−Ｏプ
ロセスなどの窒素・燐の生物学的同時除去プロセ
スが開発されるに及び、現在では、窒素・燐を同
一プロセス内で除去する方法が主流となつてきて
いる。これまでに開発された窒素・燐の生物学的
同時除去プロセスでは、脱窒のために、好気硝化
槽から嫌気脱窒槽に汚泥混合液を多量返送（流入
廃水量の２〜４倍）する必要があり、そのポンプ
動力を考えた場合、必ずしも経済的なプロセスと
は言い難い。しかも、燐除去率が低い。汚泥混合
液の多量返送循環を行わない窒素除去法として
は、活性汚泥の内生脱窒能を利用する
Wuhrmamn法が古くから知られている。このプ
ロセスでは、汚泥の内生脱窒速度が低いことか
ら、一般的な窒素除去プロセスに比して、窒素除
去率が低いこと、硝化槽容量の２〜３倍の大容量
の脱窒槽が要求されるなどの欠点がある。
（発明の目的）
本発明は、窒素および燐を同時に、しかも、い
ずれも高除去効率で除去しうる脱窒・脱燐活性汚
泥法を提供することにある。本発明の他の目的
は、処理速度が大でかつランニングコストの低い
脱窒・脱燐活性汚泥法を提供することにある。本
発明のさらに他の目的は、副産物といて系外に放
出される高濃度燐酸溶液を肥料その他の資源とし
て活用できる脱窒・脱燐活性汚泥法を提供するこ
とにある。
（発明の構成）
本発明は、自然界に古くから生存する公知の硫
黄酸化細菌Thiobacillus denitrificansのもつ脱
窒能力を利用するものである。本菌は、酸素の存
在しない嫌気条件下で、NO3−Ｏを最終Ｈ−
acceptorとして利用して還元ＳをSO4 2-に酸化
し、その際得られるエネルギーを利用して無機炭
素を炭素源として生育する。次式に、一例として
単体Ｓを用いた場合のT.denitrificansの脱窒反応
を示す。
1.114S＋NO3 -＋0.699H2O＋0.337CO2
＋0.0842HCO3 -＋0.0842H+
→0.0842C5H7NO2
＋0.5N2＋1.114SO4 2-＋1.228H+
このT.denitrificansの脱窒能を利用すべく、
Wuhrmamnプロセスの脱窒槽内に粒状単体Ｓを
補填し、T.denitrificansの作用する環境条件をと
とのえ、T.denitrificansを活性汚泥中に安定して
組み込めば、T.denitrificansの働きの分だけ脱窒
量が増え、Wuhrmamnプロセスの欠点である低
い窒素除去率が大幅に改善されるはずである。
T.denitrificansは、通常の活性汚泥微生物に比し
て、生育速度が遅いので、活性汚泥中に本菌を安
定して組み込むためには、T.denitrificansが系外
に流亡（Washout）しないように、汚泥の平均
滞留時間（SRT）を充分長くとる必要がある。
Ａ−Ｏ法やA2−Ｏ法などの脱燐法は、活性汚泥
に嫌気stressを与え、活性汚泥内の燐含量を２〜
５％に高めて余剰汚泥の形で流入燐を除去する方
法であるため、活性汚泥のSRTを短くとる必要
がある。それゆえ、硫黄補填好気−嫌気活性汚泥
法にこのＡ−Ｏ法やA2−Ｏ法の処理原理を組み
込むことは、T.denitrificansの流亡を招き、不合
理である。そこで、本発明では、脱燐法として
は、汚泥のSRT値に左右されないPhostripの原
理をとり入れ、これに汚泥濃縮脱燐工程が付加さ
れる。
本発明による硫黄補填好気−嫌気活性汚泥法に
よる廃水中の窒素・燐の同時除去法は、(1)被処理
水を最初沈澱池で固液分離する第１固液分離工程
と、(2)該固液分離処理水中の燐分を活性汚泥微生
物の燐蓄積作用により汚泥に取り込ませかつ該水
中の有機態窒素を汚泥微生物の生物学的硝化作用
により硝酸態・亜硝酸態窒素に変換する硝化工程
と、(3)該硝化工程からの水・汚泥混合液を処理し
て水中の硝酸態亜硝酸態窒素を汚泥微生物の生物
学的脱窒作用により脱窒する脱窒工程と、(4)該脱
窒工程における水・汚泥混合液を固液分離し、分
離液を処理水として系外へ放流する第２固液分離
工程と、(5)該第２固液分離工程における分離汚泥
を嫌気状態で濃縮し汚泥中に取り込まれた燐分を
放出させ、放出された燐分を高濃度で含有する脱
離液を系外へ放出する汚泥濃縮工程と、(6)該濃縮
汚泥を上記硝化工程へ返送する濃縮汚泥返送工程
と、を包含し、上記硝化工程における汚泥中には
大理石の粒子が含有され、そして上記脱窒工程に
おける汚泥中には硫黄の粒子が含有されてなり、
そのことにより上記目的が達成される。大理石
（炭酸カルシウム）と硫黄との粒子はそれぞれ粒
子径が５mm〜100mmの範囲にある。また、硝化工
程における好気槽および脱窒工程における密閉嫌
気脱窒槽の各槽内の汚泥混合液の中には、大理石
（炭酸カルシウム）と硫黄の各粒子（粒径５mm〜
100mm）がそれぞれ各槽の汚泥混合液容積に対し
て0.1〜２％に含ませてある。これら粒子の表面
上には硝化菌、燐蓄積菌、脱窒菌などの有用微生
物が付着する。それゆえ、硝化工程では、大理石
（炭酸カルシウム）による中和緩衝作用を含めて
硝化反応と燐蓄積反応が促進される。脱窒工程の
密閉嫌気脱窒槽では硫黄の脱窒促進作用を含めて
脱窒反応が促進される。炭酸カルシウムは硝化工
程にそして硫黄は脱窒工程にそれぞれ別個に配さ
れる。さらに、固液分離工程および濃縮工程では
活性汚泥の沈澱濃縮作用が促進される。これら炭
酸カルシウムと硫黄は、一度槽内に加えられると
半永久的にその槽内で循環保持され、その槽から
外に流出することはない。それゆえ、極めて経済
的に利用されうる。
本発明において引き抜かれる汚泥量は、第１固
液分離工程へ供給される単位時間当りの被処理水
量をＱとすると、第２固液分離工程からの引抜き
量が0.1Q〜0.4Q、そして濃縮工程からの引抜き
量が0.05Q〜0.2Qである。
本発明方法によれば、一連の処理により、窒素
および燐のいずれをも同時に除去できるのみなら
ず、好気槽の硝化工程と密閉嫌気脱窒槽の脱窒工
程における被処理水を含む混合液中の汚泥濃度
を、好気槽への濃縮汚泥の返送によつて充分高め
ることができ、脱窒効率および脱燐効率を著しく
向上させることができる。そのうえ、燐の取り込
まれた活性汚泥を、密閉嫌気脱窒槽の脱窒工程か
ら、沈澱槽の第２固液分離工程に供給して分離す
るから、汚泥濃縮工程に供給される活性汚泥中に
は硝酸性窒素分や亜硝酸性窒素分が残存しない。
しかも、この汚泥濃縮工程では、燐をはき出させ
るための嫌気状態を容易迅速にかつ良好に現出で
きるため、燐を能率良く除去できるとともにその
除去効率を著しく向上させることができる。ま
た、系外に放出される高濃度燐酸溶液は肥料にそ
の他の資源として極めて有用である。
（実施例）
以下、本発明方法を実施例により説明する。
図に示すように、下水や工場廃水などの被処理
水を第１固液分離工程の最初沈澱池１に供給し、
固液の分離処理を行つて浮遊物を除去する。ゴミ
プラントなどの小規模処理場においてはこの最初
沈澱池１は除外されうる。この固液分離処理水
（最初沈澱池溢流水）を硝化工程の好気硝化槽２
に供給する。好気硝化槽２には、脱燐濃縮槽５に
おいて燐を放出した汚泥が0.05〜0.2Qsの流量で
返送される。最初沈澱池溢流水中のBOD成分は、
この好気槽２中で活性汚泥により吸着分解除去さ
れる。流入水中の窒素成分は、好気槽２中でアン
モニア化および／もしくは硝化を受け、ほぼ
NO3−Ｎに変換される。流入水中の燐成分はPO4
に分解された後、活性汚泥に摂取される。次い
で、この硝化工程の被処理水と活性汚泥との混合
液を活性汚泥中に燐分を取り込んだ状態で脱窒工
程の密閉嫌気脱窒槽３へ供給する。嫌気脱窒槽３
は、完全密閉型のタンク等を用いて空気との接触
を断つ必要がある。嫌気脱窒槽３の混合撹拌に
は、嫌気ガス循環混合法や機械撹拌などが適当で
ある。嫌気脱窒槽３の底部には、10〜100mm程度
の粒径の硫黄粒子が敷きつめられている。前段好
気硝化槽２から流入するNO3−Ｎは、活性汚泥
のもつ内生脱窒能と、T.denitrificansのもつ脱窒
能によつて、N2ガスに脱窒除去される。脱窒槽
３での脱窒特性は、脱窒槽３での燐挙動、そして
後段の最終沈澱池４および脱燐濃縮槽５での汚泥
の挙動や燐挙動に影響するので、大切である。つ
まり完全にNO3−Ｎが検出されなくなる条件下
で脱窒槽３を運転すると、槽３内は完全嫌気状態
となり、前段の好気硝化槽２で汚泥に摂取された
燐が液相に放出されてしまい、燐除去効率が低下
する。他方、不完全な脱窒では、残存NO3−Ｎ
により、最終沈澱池４での汚泥の浮上や脱燐濃縮
槽５での不完全な嫌気度に起因する燐放出能の低
下を招く。
それゆえ、嫌気脱窒槽３での残存NO3−Ｎは
好ましくは２〜５mg／の範囲には入るよう脱窒
槽３を設計する必要がある。ベンチ・スケールの
実験の結果、最適な好気槽容量と嫌気槽容量の比
は２：３〜４であつた。
以上のように、脱窒槽３を適切に運転する限り
においては、好気槽２で汚泥に取り込まれた燐は
脱窒槽３で再放出されない。次いで、脱窒槽３か
らの処理済み水と汚泥との混合液を第２固液分離
工程の最終沈澱槽４に供給し、固液分離処理を行
う。分離液は、そのままあるいは殺菌脱色等の後
処理を施した後、系外へ放流される。分離された
汚泥は、例えば、0.1〜0.4Qsの流量で汚泥濃縮工
程の脱燐濃縮槽５に供給される。ここでは、汚泥
を完全な嫌気状態で一定時間（例えば、４〜20時
間）維持する。これを濃縮処理して前記の窒素除
去過程で汚泥中に取り込まれた燐分を放出させ
る。この燐は、主として、PO4の形で上澄み液中
に放出移行する。脱燐濃縮槽５での混合撹拌は、
嫌気ガスによるガス撹拌や機械式撹拌などにより
なされる。燐放出後の濃縮汚泥は、0.05〜0.2Qs
の流量で、好気硝化槽２に返送循環される。汚泥
からの燐放出を高めるために濃縮槽５に酸を加え
ることが効果的である。
脱燐濃縮槽５から0.05〜0.2Qsで流出する脱燐
濃縮液には、30〜50mg／のPO4 3-が含まれるの
で、この脱燐濃縮液は、肥料その他の資源として
有用である。
この脱燐濃縮槽５は、例えば、図に示すよう
に、その内部にロート状のカバー部材６が設けら
れている。そして、このカバー部材６の上方部に
形成される密閉空間Ｓに沈澱槽４から汚泥を供給
するように構成されている。密閉空間Ｓと濃縮槽
５の下方部に設けたノズル７との間にはガス循環
路８が設けられている。空間Ｓにおいて汚泥から
発生する酸素ガスを含まないガスがこの循環路８
を通つてノズル７へ供給される。供給ガスはノズ
ル７から濃縮槽５内へ流入し汚泥を緩速撹拌して
嫌気状態での濃縮処理を良好に行わせる。ノズル
７からのガスによる汚泥の緩速撹拌は、通常の例
えば平円板タービン付き撹拌機による緩速撹拌
（10〜50rpm）によつても嫌気状態での濃縮処理
を良好に行わせることができる。この濃縮槽５を
用いると、汚泥を安定して一定時間（４〜20時
間）完全嫌気状態下に維持できるため、好気工程
のもとで汚泥が摂取した燐を効率的に脱離液中に
放出させることが可能である。
濃縮槽５からの脱離液は、極めて清澄である。
その理由は、カバー部材６のすそ周辺にできる汚
泥ブリツジにより繊細な汚泥フロツク粒子が捕獲
されるためである。この脱離液は高濃度で燐酸
（30〜50ppm程度）を含有する。これは、それゆ
え、肥料や各種添加剤として有効に資源化でき
る。
濃縮槽５から引き抜かれた濃縮汚泥をさらに濃
縮機で濃縮処理し、その含水量をより低減させて
から、濃縮汚泥を好機槽２に返送すると、より一
層効率の向上をはかることができる。
実験例
上記実施例にもとづき、第１表に示す運転条件
のもとで流入下水を連続的に活性汚泥処理した。
嫌機槽および脱燐槽はいづれも発泡スチロールを
水面に浮かべ、空気との接触を遮断された。脱燐
槽には1NHClが５ml／日の量で添加された。そ
の定常状態における処理成績を第２表に示す。第
２表から明らかなように、窒素と燐の除去率はい
づれも80％以上である。
(Technical Field) The present invention relates to a denitrification/dephosphorization activated sludge method for simultaneously removing nitrogen and phosphorus from treated water such as sewage and industrial wastewater. (Prior art) In order to prevent eutrophication of water bodies, the removal of nutrients such as nitrogen and phosphorus from sewage and wastewater has become an urgent issue. As a method for removing nitrogen and phosphorus from sewage and wastewater, biological removal methods with low processing costs are seen as promising, and various treatment methods are being developed. Biological nitrogen removal and biological phosphorus removal have traditionally been treated separately because of their different removal mechanisms. However, with the development of biological simultaneous removal processes for nitrogen and phosphorus such as the Bardenpho process and the A 2 -O process, methods that remove nitrogen and phosphorus in the same process have now become mainstream. . In the biological simultaneous removal process of nitrogen and phosphorus developed so far, a large amount of sludge mixture (2 to 4 times the amount of inflowing wastewater) is returned from the aerobic nitrification tank to the anaerobic denitrification tank for denitrification. However, considering the pump power required, it is not necessarily an economical process. Moreover, the phosphorus removal rate is low. As a nitrogen removal method that does not require return circulation of a large amount of sludge mixture, the endogenous denitrification ability of activated sludge is utilized.
The Wuhrmamn method has been known for a long time. In this process, the endogenous denitrification rate of sludge is low, so the nitrogen removal rate is lower than that of general nitrogen removal processes, and a denitrification tank with a large capacity 2 to 3 times the nitrification tank capacity is required. There are disadvantages such as being (Objective of the Invention) An object of the present invention is to provide a denitrification/dephosphorization activated sludge method that can simultaneously remove nitrogen and phosphorus with high removal efficiency. Another object of the present invention is to provide a denitrification/dephosphorization activated sludge method that has a high processing speed and low running costs. Still another object of the present invention is to provide a denitrification/dephosphorization activated sludge method in which a high concentration phosphoric acid solution discharged outside the system as a by-product can be utilized as fertilizer or other resources. (Structure of the Invention) The present invention utilizes the denitrification ability of Thiobacillus denitrificans, a known sulfur-oxidizing bacterium that has existed in nature for a long time. This bacterium converts NO 3 -O into final H- under anaerobic conditions in the absence of oxygen.
It is used as an acceptor to oxidize reduced S to SO 4 2- , and the energy obtained at this time is used to grow using inorganic carbon as a carbon source. The following equation shows the denitrification reaction of T. denitrificans when using a simple substance S as an example. 1.114S＋NO 3 - ＋0.699H 2 O＋0.337CO 2 ＋0.0842HCO 3 - ＋0.0842H + →0.0842C 5 H 7 NO 2 ＋0.5N 2 ＋1.114SO 4 2- ＋1.228H + Denitrification of this T.denitrificans In order to utilize the ability,
If granular elemental S is supplemented in the denitrification tank of the Wuhrmamn process, the environmental conditions for T. denitrificans are adjusted, and T. denitrificans is stably incorporated into activated sludge, the denitrification amount will be equal to the amount of T. denitrificans. This should greatly improve the low nitrogen removal rate, which is a drawback of the Wuhrmamn process.
T. denitrificans has a slower growth rate than normal activated sludge microorganisms, so in order to stably incorporate this bacteria into activated sludge, it is necessary to prevent T. denitrificans from washing out of the system. , it is necessary to ensure that the average residence time (SRT) of sludge is sufficiently long.
Dephosphorization methods such as the A-O method and the A 2 -O method apply anaerobic stress to activated sludge, reducing the phosphorus content in the activated sludge to
Since this method removes inflow phosphorus in the form of excess sludge by increasing the amount to 5%, it is necessary to keep the SRT of activated sludge short. Therefore, it is unreasonable to incorporate the treatment principle of the A-O method or the A2 -O method into the sulfur-supplemented aerobic-anaerobic activated sludge method, as this will lead to the disappearance of T. denitrificans. Therefore, in the present invention, as a dephosphorization method, the principle of Phostrip, which is not affected by the SRT value of sludge, is adopted, and a sludge concentration dephosphorization step is added to this. The simultaneous removal of nitrogen and phosphorus from wastewater by the sulfur-supplemented aerobic-anaerobic activated sludge method according to the present invention includes (1) a first solid-liquid separation step in which the water to be treated is separated into solid-liquid in an initial settling tank; ) The phosphorus content in the solid-liquid separation treated water is incorporated into sludge through the phosphorus accumulation action of activated sludge microorganisms, and the organic nitrogen in the water is converted into nitrate/nitrite nitrogen through the biological nitrification action of sludge microorganisms. a nitrification step; (3) a denitrification step in which the water/sludge mixture from the nitrification step is treated to remove nitrate and nitrite nitrogen from the water through the biological denitrification action of sludge microorganisms; ) a second solid-liquid separation step of separating the water/sludge mixture in the denitrification step into solid-liquid and discharging the separated liquid to the outside of the system as treated water; and (5) separating the separated sludge in the second solid-liquid separation step. (6) a sludge concentration step in which the phosphorus content that has been concentrated in anaerobic conditions and taken into the sludge is released, and a desorbed solution containing a high concentration of released phosphorus content is released to the outside of the system; and (6) the concentrated sludge is a concentrated sludge return step for returning to the nitrification step, the sludge in the nitrification step contains marble particles, and the sludge in the denitrification step contains sulfur particles,
This achieves the above objective. The marble (calcium carbonate) and sulfur particles each have a particle size in the range of 5 mm to 100 mm. In addition, marble (calcium carbonate) and sulfur particles (particle size 5 mm to
100mm) is contained in an amount of 0.1 to 2% of the volume of the sludge mixture in each tank. Useful microorganisms such as nitrifying bacteria, phosphorus accumulating bacteria, and denitrifying bacteria adhere to the surfaces of these particles. Therefore, in the nitrification process, the nitrification reaction and phosphorus accumulation reaction are promoted, including the neutralization buffering effect of marble (calcium carbonate). In the closed anaerobic denitrification tank used in the denitrification process, the denitrification reaction is promoted, including the denitrification promoting effect of sulfur. Calcium carbonate is placed separately in the nitrification process and sulfur is placed in the denitrification process. Furthermore, in the solid-liquid separation step and the concentration step, the sedimentation and concentration action of activated sludge is promoted. Once these calcium carbonate and sulfur are added to the tank, they are kept circulating in the tank semi-permanently and do not flow out of the tank. Therefore, it can be used very economically. In the present invention, the amount of sludge extracted is 0.1Q to 0.4Q, and the amount of sludge extracted from the second solid-liquid separation step is 0.1Q to 0.4Q, and the amount of water to be treated per unit time supplied to the first solid-liquid separation step is Q The amount of extraction from the process is 0.05Q to 0.2Q. According to the method of the present invention, not only can both nitrogen and phosphorus be removed simultaneously through a series of treatments, but also in the mixed liquid containing the water to be treated in the nitrification process of the aerobic tank and the denitrification process of the closed anaerobic denitrification tank. The sludge concentration can be sufficiently increased by returning the concentrated sludge to the aerobic tank, and the denitrification efficiency and dephosphorization efficiency can be significantly improved. Furthermore, since the activated sludge containing phosphorus is supplied from the denitrification process of the closed anaerobic denitrification tank to the second solid-liquid separation process of the sedimentation tank for separation, the activated sludge supplied to the sludge concentration process contains No nitrate nitrogen or nitrite nitrogen remains.
Moreover, in this sludge concentration step, an anaerobic state for expelling phosphorus can be easily and quickly created, so that phosphorus can be efficiently removed and the removal efficiency can be significantly improved. In addition, the highly concentrated phosphoric acid solution released outside the system is extremely useful as a fertilizer and other resources. (Example) The method of the present invention will be explained below with reference to Examples. As shown in the figure, water to be treated such as sewage or factory wastewater is supplied to the first settling tank 1 of the first solid-liquid separation step,
Solid-liquid separation treatment is performed to remove suspended matter. In small-scale treatment plants such as garbage plants, this initial settling tank 1 may be excluded. This solid-liquid separation treated water (first settling tank overflow water) is transferred to the aerobic nitrification tank 2 in the nitrification process.
supply to. The sludge from which phosphorus has been released in the dephosphorization concentration tank 5 is returned to the aerobic nitrification tank 2 at a flow rate of 0.05 to 0.2 Qs. The BOD components in the initial sedimentation pond overflow water are:
In this aerobic tank 2, activated sludge adsorbs and decomposes and removes it. Nitrogen components in the inflow water undergo ammonification and/or nitrification in the aerobic tank 2, and are almost completely reduced.
Converted to NO 3 -N. The phosphorus content in the influent water is PO 4
After being decomposed, it is ingested into activated sludge. Next, the mixed liquid of the water to be treated in the nitrification process and activated sludge is supplied to the closed anaerobic denitrification tank 3 in the denitrification process with phosphorus incorporated into the activated sludge. Anaerobic denitrification tank 3
It is necessary to cut off contact with air using a completely sealed tank, etc. For mixing and stirring in the anaerobic denitrification tank 3, an anaerobic gas circulation mixing method, mechanical stirring, etc. are suitable. The bottom of the anaerobic denitrification tank 3 is covered with sulfur particles having a particle size of about 10 to 100 mm. NO 3 -N flowing from the front aerobic nitrification tank 2 is denitrified and removed into N 2 gas by the endogenous denitrification ability of activated sludge and the denitrification ability of T. denitrificans. The denitrification characteristics in the denitrification tank 3 are important because they affect the behavior of phosphorus in the denitrification tank 3, as well as the behavior of sludge and the behavior of phosphorus in the final settling tank 4 and the dephosphorization thickening tank 5 in the subsequent stages. In other words, if the denitrification tank 3 is operated under conditions where NO 3 -N is completely undetectable, the inside of the tank 3 will become completely anaerobic, and the phosphorus taken into the sludge in the aerobic nitrification tank 2 will be released into the liquid phase. This will reduce the phosphorus removal efficiency. On the other hand, in incomplete denitrification, residual NO 3 −N
As a result, sludge floats up in the final settling tank 4 and the phosphorus release ability decreases due to incomplete anaerobic degree in the dephosphorization concentration tank 5. Therefore, it is necessary to design the denitrification tank 3 so that the residual NO 3 -N in the anaerobic denitrification tank 3 is preferably in the range of 2 to 5 mg/. As a result of bench scale experiments, the optimal ratio of aerobic tank volume to anaerobic tank volume was 2:3-4. As described above, as long as the denitrification tank 3 is operated appropriately, the phosphorus taken into the sludge in the aerobic tank 2 will not be re-released in the denitrification tank 3. Next, the mixed liquid of treated water and sludge from the denitrification tank 3 is supplied to the final settling tank 4 of the second solid-liquid separation step, and solid-liquid separation processing is performed. The separated liquid is discharged out of the system as it is or after being subjected to post-treatment such as sterilization and decolorization. The separated sludge is supplied to the dephosphorization/concentration tank 5 of the sludge concentration process at a flow rate of, for example, 0.1 to 0.4 Qs. Here, the sludge is maintained in a completely anaerobic state for a certain period of time (for example, 4 to 20 hours). The sludge is concentrated to release the phosphorus that was incorporated into the sludge during the nitrogen removal process. This phosphorus is primarily released into the supernatant in the form of PO 4 . The mixing and stirring in the dephosphorization concentration tank 5 is as follows:
This is done by gas stirring using anaerobic gas or mechanical stirring. Thickened sludge after phosphorus release is 0.05~0.2Qs
It is returned and circulated to the aerobic nitrification tank 2 at a flow rate of . It is effective to add acid to the thickening tank 5 to increase the release of phosphorus from the sludge. The dephosphorization concentrate that flows out from the dephosphorization concentration tank 5 at 0.05 to 0.2 Qs contains 30 to 50 mg of PO 4 3- , so this dephosphorization concentrate is useful as fertilizer and other resources. For example, as shown in the figure, this dephosphorization/concentration tank 5 is provided with a funnel-shaped cover member 6 therein. The sludge is supplied from the settling tank 4 to the closed space S formed in the upper part of the cover member 6. A gas circulation path 8 is provided between the closed space S and a nozzle 7 provided in the lower part of the concentration tank 5. Gas that does not contain oxygen gas generated from the sludge in the space S flows through this circulation path 8.
is supplied to the nozzle 7 through. The supply gas flows into the thickening tank 5 from the nozzle 7 and slowly stirs the sludge to perform the thickening process in an anaerobic state. Slow stirring of the sludge by the gas from the nozzle 7, for example, by slow stirring (10 to 50 rpm) using a stirrer equipped with a flat disc turbine, can also perform the concentration treatment in an anaerobic state well. . By using this thickening tank 5, the sludge can be stably maintained in a completely anaerobic state for a certain period of time (4 to 20 hours), so the phosphorus taken up by the sludge during the aerobic process can be efficiently transferred to the desorption solution. It is possible to release the The desorbed liquid from the concentration tank 5 is extremely clear.
The reason for this is that delicate sludge floc particles are captured by the sludge bridges formed around the base of the cover member 6. This desorbed solution contains phosphoric acid at a high concentration (approximately 30 to 50 ppm). This can therefore be effectively utilized as a resource as fertilizer or various additives. If the thickened sludge drawn from the thickening tank 5 is further concentrated with a thickener to further reduce its water content and then returned to the opportunity tank 2, efficiency can be further improved. Experimental Example Based on the above example, inflowing sewage was continuously treated with activated sludge under the operating conditions shown in Table 1.
Both the anaerobic tank and the dephosphorization tank had Styrofoam floating on the water surface to prevent contact with air. 1NHCl was added to the dephosphorization tank at a rate of 5 ml/day. Table 2 shows the processing results in the steady state. As is clear from Table 2, the removal rates of nitrogen and phosphorus are both over 80%.
【表】【table】
【表】【table】
【表】
（発明の効果）
本発明は、次のような効果を奏しうる。
嫌気脱窒槽の底部に粒状硫黄を敷きつめてい
るため嫌気脱窒槽中でのT.denitrificansの働く
環境条件が充分に設定されている。
従来の窒素除去プロセスにみられるような、
好気硝化槽から嫌気脱窒槽への汚泥混合液の多
量返送循環が不要なため、低コストでの窒素除
去が可能である。
生育速度の遅いT.denitrificansを安定して活
性汚泥中に組み込むため、汚泥のSRT値を大
きくとつている。それゆえ、余剰汚泥の生成が
ほとんどなく、汚泥処理コストが大幅に軽減さ
れうる。
脱燐濃縮槽で汚泥に嫌気シヨツクを与えてい
るため、汚泥のSVI値を長期間にわたり低く維
持できるという利点がある。
窒素除去機作と燐除去機作とを独立させてい
る本プロセスでは、他のA2−Ｏプロセス、
BardenphoプロセスおよびPhoredoxプロセス
のような窒素・燐同時除去プロセスに比較し
て、窒素および燐を安定して除去することが可
能である。
脱燐濃縮槽内部に設けたロート状のカサの効
果で汚泥が良好に濃縮され、澄明な脱燐液が得
られる。[Table] (Effects of the Invention) The present invention can have the following effects. Since the bottom of the anaerobic denitrification tank is covered with granular sulfur, the environmental conditions for T. denitrificans to work in the anaerobic denitrification tank are set sufficiently. As seen in traditional nitrogen removal processes,
Since there is no need to return a large amount of the sludge mixture from the aerobic nitrification tank to the anaerobic denitrification tank, nitrogen can be removed at low cost. In order to stably incorporate T. denitrificans, which has a slow growth rate, into activated sludge, the SRT value of the sludge is set high. Therefore, almost no surplus sludge is generated, and sludge treatment costs can be significantly reduced. Since the sludge is given an anaerobic shock in the dephosphorization thickening tank, it has the advantage of being able to maintain the SVI value of the sludge at a low level for a long period of time. This process, in which the nitrogen removal mechanism and phosphorus removal mechanism are independent, is similar to other A 2 -O processes,
Compared to simultaneous nitrogen and phosphorus removal processes such as the Bardenpho process and the Phoredox process, it is possible to remove nitrogen and phosphorus stably. The funnel-shaped cap installed inside the dephosphorization concentration tank allows the sludge to be well concentrated, resulting in a clear dephosphorization solution.
図は本発明の窒素・燐同時除去法の一実施例を
示すフローシートである。
１……最初沈澱池、２……好気硝化槽、３……
密閉嫌気脱窒槽、４……最終沈澱槽、５……汚泥
脱燐濃縮槽。
The figure is a flow sheet showing an example of the nitrogen and phosphorus simultaneous removal method of the present invention. 1...First sedimentation pond, 2...Aerobic nitrification tank, 3...
Closed anaerobic denitrification tank, 4...Final sedimentation tank, 5...Sludge dephosphorization concentration tank.
Claims (1)
１固液分離工程と、 (2) 該固液分離処理水中の燐分を活性汚泥微生物
の燐蓄積作用により汚泥に取り込ませかつ該水
中の有機態窒素を汚泥微生物の生物学的硝化作
用により硝酸態・亜硝酸態窒素に変換する硝化
工程と、 (3) 該硝化工程からの水・汚泥混合液を処理して
水中の硝酸態亜硝酸態窒素を汚泥微生物の生物
学的脱窒作用により脱窒する脱窒工程と、 (4) 該脱窒工程における水・汚泥混合液を固液分
離し、分離液を処理水として系外へ放流する第
２固液分離工程と、 (5) 該第２固液分離工程における分離汚泥を嫌気
状態で濃縮し汚泥中に取り込まれた燐分を放出
させ、放出された燐分を高濃度で含有する脱離
液を系外へ放出する汚泥濃縮工程と、 (6) 該濃縮汚泥を上記硝化工程へ返送する濃縮汚
泥返送工程と、 を包含し、 上記硝化工程における汚泥中には大理石の粒子
が含有され、そして上記脱窒工程における汚泥中
には硫黄の粒子が含有されてなる硫黄補填好気−
嫌気活性汚泥法による廃水中の窒素・燐の同時除
去法。 ２ 前記大理石と硫黄との粒子がそれぞれ粒子径
５mm〜100mmの範囲にある特許請求の範囲第１項
に記載の除去法。 ３ 前記大理石の粒子が硝化工程においてそして
前記硫黄の粒子が脱窒工程において、それぞれ、
その水・汚泥混合液容量の約0.1〜約２％含有さ
れる特許請求の範囲第２項に記載の除去法。[Claims] 1. (1) A first solid-liquid separation step in which the water to be treated is first separated into solid-liquid in a settling tank; (2) The phosphorus content in the solid-liquid separation treated water is reduced by the phosphorus accumulation action of activated sludge microorganisms. (3) a nitrification process in which organic nitrogen in the water is incorporated into sludge and converted into nitrate/nitrite nitrogen by the biological nitrification action of sludge microorganisms; (3) a water/sludge mixture from the nitrification process; (4) a denitrification process in which nitrate and nitrite nitrogen in the water is denitrified by the biological denitrification action of sludge microorganisms; (4) solid-liquid separation of the water/sludge mixture in the denitrification process; a second solid-liquid separation step in which the liquid is discharged outside the system as treated water; (5) the separated sludge in the second solid-liquid separation step is concentrated in an anaerobic state, and the phosphorus incorporated in the sludge is released; (6) a thickened sludge return process to return the thickened sludge to the nitrification process; The sludge in the denitrification process contains marble particles, and the sludge in the denitrification process contains sulfur particles.
Simultaneous removal of nitrogen and phosphorus from wastewater using anaerobic activated sludge method. 2. The removal method according to claim 1, wherein the marble and sulfur particles each have a particle size in the range of 5 mm to 100 mm. 3. The marble particles in the nitrification process and the sulfur particles in the denitrification process, respectively.
The removal method according to claim 2, wherein the water/sludge mixture contains about 0.1 to about 2% by volume.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59064359A JPS60206494A (en) | 1984-03-30 | 1984-03-30 | Simultaneous removal of nitrogen and phosphorus in waste water by sulfur replenishing aerobic-anaerobic activated sludge method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59064359A JPS60206494A (en) | 1984-03-30 | 1984-03-30 | Simultaneous removal of nitrogen and phosphorus in waste water by sulfur replenishing aerobic-anaerobic activated sludge method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60206494A JPS60206494A (en) | 1985-10-18 |
| JPH049119B2 true JPH049119B2 (en) | 1992-02-19 |
Family
ID=13255979
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59064359A Granted JPS60206494A (en) | 1984-03-30 | 1984-03-30 | Simultaneous removal of nitrogen and phosphorus in waste water by sulfur replenishing aerobic-anaerobic activated sludge method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60206494A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000018694A1 (en) * | 1998-09-25 | 2000-04-06 | Nitchitsu Co, Ltd. | Denitrifying composition for removing nitrate nitrogen and process for producing the same |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2720736B1 (en) * | 1994-06-02 | 1998-05-07 | Degremont | Process for the treatment of liquid effluents by activated sludge. |
| KR100336483B1 (en) * | 1999-02-27 | 2002-05-15 | 조양호 | Method for removing nitrogen from waste water through sulfur-utilizing denitrification |
| KR20010055891A (en) * | 1999-12-13 | 2001-07-04 | 김형벽ㅂ | Post-Denitrification Device of Conventional Activated Sludge Process Using Sulfur |
| KR100362742B1 (en) * | 2000-01-27 | 2002-11-30 | 정호봉 | Livestock wastes and high density nitrogen water wastes nitrogen remove method |
| KR20020029738A (en) * | 2000-10-13 | 2002-04-19 | 김효근 | Biological denitrification process using sulfur for the wastewater containing low BOD |
| KR20020038322A (en) * | 2000-11-17 | 2002-05-23 | 김효근 | Simultaneous removal process of N, P for the wastewater |
| KR100431394B1 (en) * | 2002-03-21 | 2004-05-14 | 한국과학기술연구원 | In-situ and Ex-situ Remediation of Groundwater and Remediation of Meander filtrate Water Using Autotrophic Sulfur Oxidizing Bacteria |
| JP5951416B2 (en) * | 2012-09-04 | 2016-07-13 | 株式会社東芝 | Method and apparatus for recovering phosphorus from waste water containing phosphorus |
| JP5951533B2 (en) * | 2013-03-13 | 2016-07-13 | 株式会社東芝 | Method and apparatus for recovering phosphorus from waste water containing phosphorus |
| US10494282B2 (en) * | 2017-04-18 | 2019-12-03 | DOOSAN Heavy Industries Construction Co., LTD | Bioreactor for treating sewage and sewage treatment system comprising the same |
-
1984
- 1984-03-30 JP JP59064359A patent/JPS60206494A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000018694A1 (en) * | 1998-09-25 | 2000-04-06 | Nitchitsu Co, Ltd. | Denitrifying composition for removing nitrate nitrogen and process for producing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60206494A (en) | 1985-10-18 |
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