JP4456461B2 - Method for reducing hexavalent chromium concentration - Google Patents
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- JP4456461B2 JP4456461B2 JP2004306425A JP2004306425A JP4456461B2 JP 4456461 B2 JP4456461 B2 JP 4456461B2 JP 2004306425 A JP2004306425 A JP 2004306425A JP 2004306425 A JP2004306425 A JP 2004306425A JP 4456461 B2 JP4456461 B2 JP 4456461B2
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- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 title claims description 155
- 238000000034 method Methods 0.000 title claims description 67
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 176
- 239000002689 soil Substances 0.000 claims description 125
- 239000010802 sludge Substances 0.000 claims description 108
- 239000002699 waste material Substances 0.000 claims description 103
- 238000000855 fermentation Methods 0.000 claims description 48
- 235000015099 wheat brans Nutrition 0.000 claims description 41
- 235000007164 Oryza sativa Nutrition 0.000 claims description 8
- 235000009566 rice Nutrition 0.000 claims description 8
- 108010068370 Glutens Proteins 0.000 claims description 6
- 240000008042 Zea mays Species 0.000 claims description 6
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 claims description 6
- 235000002017 Zea mays subsp mays Nutrition 0.000 claims description 6
- 235000005822 corn Nutrition 0.000 claims description 6
- 235000021312 gluten Nutrition 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 240000007594 Oryza sativa Species 0.000 claims 1
- 239000011651 chromium Substances 0.000 description 88
- 239000000203 mixture Substances 0.000 description 67
- 239000002361 compost Substances 0.000 description 32
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 30
- 238000002474 experimental method Methods 0.000 description 28
- 229910052804 chromium Inorganic materials 0.000 description 22
- 239000004576 sand Substances 0.000 description 20
- 238000002156 mixing Methods 0.000 description 18
- 238000010276 construction Methods 0.000 description 14
- 244000005700 microbiome Species 0.000 description 14
- 230000003247 decreasing effect Effects 0.000 description 13
- 239000000463 material Substances 0.000 description 13
- 239000002351 wastewater Substances 0.000 description 12
- 241000894006 Bacteria Species 0.000 description 11
- 239000000047 product Substances 0.000 description 11
- 230000007423 decrease Effects 0.000 description 9
- 238000003912 environmental pollution Methods 0.000 description 9
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 8
- 229910001430 chromium ion Inorganic materials 0.000 description 8
- 150000001875 compounds Chemical class 0.000 description 8
- 238000005259 measurement Methods 0.000 description 8
- 241000209094 Oryza Species 0.000 description 7
- 150000001845 chromium compounds Chemical class 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 230000008635 plant growth Effects 0.000 description 7
- 238000012545 processing Methods 0.000 description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000008399 tap water Substances 0.000 description 6
- 235000020679 tap water Nutrition 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- -1 etc.) Substances 0.000 description 5
- 239000000706 filtrate Substances 0.000 description 5
- 239000008235 industrial water Substances 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 238000011160 research Methods 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 241000186660 Lactobacillus Species 0.000 description 4
- 240000004808 Saccharomyces cerevisiae Species 0.000 description 4
- 235000010323 ascorbic acid Nutrition 0.000 description 4
- 229960005070 ascorbic acid Drugs 0.000 description 4
- 239000011668 ascorbic acid Substances 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 239000004568 cement Substances 0.000 description 4
- 239000003638 chemical reducing agent Substances 0.000 description 4
- VQWFNAGFNGABOH-UHFFFAOYSA-K chromium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Cr+3] VQWFNAGFNGABOH-UHFFFAOYSA-K 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 230000004151 fermentation Effects 0.000 description 4
- 239000003456 ion exchange resin Substances 0.000 description 4
- 229920003303 ion-exchange polymer Polymers 0.000 description 4
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 4
- 238000012423 maintenance Methods 0.000 description 4
- 238000001139 pH measurement Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 239000010865 sewage Substances 0.000 description 4
- 231100000331 toxic Toxicity 0.000 description 4
- 230000002588 toxic effect Effects 0.000 description 4
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 3
- 241000196324 Embryophyta Species 0.000 description 3
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 239000000975 dye Substances 0.000 description 3
- 239000001963 growth medium Substances 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 239000010985 leather Substances 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 230000033116 oxidation-reduction process Effects 0.000 description 3
- 239000000049 pigment Substances 0.000 description 3
- 238000007747 plating Methods 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 239000006228 supernatant Substances 0.000 description 3
- 241000195493 Cryptophyta Species 0.000 description 2
- KSPIHGBHKVISFI-UHFFFAOYSA-N Diphenylcarbazide Chemical compound C=1C=CC=CC=1NNC(=O)NNC1=CC=CC=C1 KSPIHGBHKVISFI-UHFFFAOYSA-N 0.000 description 2
- 244000061456 Solanum tuberosum Species 0.000 description 2
- 235000002595 Solanum tuberosum Nutrition 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000005273 aeration Methods 0.000 description 2
- 239000003570 air Substances 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 2
- 208000035475 disorder Diseases 0.000 description 2
- 239000010840 domestic wastewater Substances 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 235000013312 flour Nutrition 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 230000002262 irrigation Effects 0.000 description 2
- 238000003973 irrigation Methods 0.000 description 2
- 239000004310 lactic acid Substances 0.000 description 2
- 235000014655 lactic acid Nutrition 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 235000015097 nutrients Nutrition 0.000 description 2
- 239000011368 organic material Substances 0.000 description 2
- 239000003002 pH adjusting agent Substances 0.000 description 2
- 235000012015 potatoes Nutrition 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000009991 scouring Methods 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 241000195940 Bryophyta Species 0.000 description 1
- 201000004624 Dermatitis Diseases 0.000 description 1
- 208000005577 Gastroenteritis Diseases 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 208000025371 Taste disease Diseases 0.000 description 1
- 206010044565 Tremor Diseases 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000012620 biological material Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
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- 238000006297 dehydration reaction Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
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- 229940093915 gynecological organic acid Drugs 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 150000007529 inorganic bases Chemical class 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 239000011499 joint compound Substances 0.000 description 1
- 231100001231 less toxic Toxicity 0.000 description 1
- 208000019423 liver disease Diseases 0.000 description 1
- 239000010871 livestock manure Substances 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
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- 238000006386 neutralization reaction Methods 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
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- 238000010298 pulverizing process Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 235000019669 taste disorders Nutrition 0.000 description 1
- 241001148471 unidentified anaerobic bacterium Species 0.000 description 1
- 238000004927 wastewater treatment sludge Methods 0.000 description 1
Classifications
-
- Y02W10/12—
Description
本発明は、六価クロムを含有する水、土壌、汚泥または廃材中の六価クロム濃度を低減する方法に関する。より詳細には、本発明は、六価クロムを含有する水、土壌、汚泥または廃材を、還元剤、特定の化合物、特定の微生物などを使用せずに嫌気的条件下に処理して、六価クロム濃度を、安全に、簡単に且つ低コストで低減する方法に関する。 The present invention relates to a method for reducing the concentration of hexavalent chromium in water, soil, sludge or waste material containing hexavalent chromium. More specifically, the present invention treats water, soil, sludge or waste material containing hexavalent chromium under anaerobic conditions without using reducing agents, specific compounds, specific microorganisms, etc. The present invention relates to a method for reducing valent chromium concentration safely, simply and at low cost.
精練工場、クロムメッキ工場、化学工場（顔料、染料、触媒、防錆剤などの製造工場等）、合金製造工場、皮革工場（クロムなめし）、金属製品製造工場、鉱山などから排出される廃水や汚泥にはクロムが多く含まれており、また場合によっては前記工場の跡地（土壌中）にもクロムが多量に含まれていることがある。
また、セメントなどのアルカリ性の地盤固化用資材（土壌固化用資材）を用いて行われることの多いトンネル工事やダム工事で排出される土壌や汚泥は、アルカリ分を多く含み高いｐＨ（通常ｐＨ１０〜１２程度）を有しているが、工事現場の土壌環境などによっては排出されるアルカリ性の土壌または汚泥中に六価クロムがかなりの濃度（例えば許容量以上の濃度）で含まれていることがある。
更に、土木工事や建設工事などに伴って排出されるコンクリートブロック廃材、車両廃材、電気・電子部品廃材などの廃材においても、六価クロムがかなりの濃度で含まれていることがある。
Sewage factories, chrome plating factories, chemical factories (manufacturing factories for pigments, dyes, catalysts, rust inhibitors, etc.), alloy factories, leather factories (chromium tanning), metal product factories, mines, etc. The sludge contains a lot of chromium, and in some cases, the factory site (in the soil) may contain a large amount of chromium.
In addition, soil and sludge discharged in tunnel construction and dam construction, which are often performed using alkaline ground solidification materials (soil solidification materials) such as cement, contain a large amount of alkali and high pH (usually pH 10 to 10). However, depending on the soil environment at the construction site, the alkaline soil or sludge that is discharged may contain hexavalent chromium in a considerable concentration (for example, a concentration higher than the allowable amount). is there.
Furthermore, in some waste materials such as concrete block waste materials, vehicle waste materials, and electrical / electronic component waste materials that are discharged along with civil engineering work and construction work, hexavalent chromium may be contained in a considerable concentration.
クロムには、二価、三価および六価の化合物などがあり、これらの化合物のうち、二価のクロム化合物は不安定で、酸化されて三価のクロム化合物になり易く、三価のクロム化合物は最も安定である。
クロム化合物のうち、六価のクロム化合物（六価クロム）は、胃腸炎、皮膚炎、味覚障害や嗅覚障害、肝障害などの種々の障害を引き起こし、更には発癌性を有するとされている有毒物質であり、一方三価のクロム化合物（三価クロム）は六価クロムに比べて毒性が低い。
Chromium includes divalent, trivalent, and hexavalent compounds. Among these compounds, divalent chromium compounds are unstable and are easily oxidized to trivalent chromium compounds. The compound is the most stable.
Among the chromium compounds, hexavalent chromium compounds (hexavalent chromium) cause various disorders such as gastroenteritis, dermatitis, taste disorders, olfactory disorders, and liver disorders, and are also toxic. On the other hand, trivalent chromium compounds (trivalent chromium) are less toxic than hexavalent chromium.
かかる点から、工場などから排出される廃水や、上水（水道水）などにおいては、クロム、特に六価クロムの含有量が法律によって規制されており、例えば下水（排水）中の六価クロムの含有量は０．５ｐｐｍ以下に、また上水中の六価クロムの含有量は０．０５ｐｐｍ以下に定められている。 From this point, the content of chromium, especially hexavalent chromium, is regulated by law in waste water discharged from factories and the like, and tap water (tap water). For example, hexavalent chromium in sewage (drainage) Is set to 0.5 ppm or less, and the content of hexavalent chromium in tap water is set to 0.05 ppm or less.
水に含まれる六価クロムを低減または除去するための代表的な方法としては、沈殿法またはイオン交換法が挙げられる。そのうち、沈殿法は、六価クロムイオンを含有する水をｐＨ４以下の酸性下に硫酸第一鉄、重亜硫酸ナトリウム、その他の還元剤を用いて還元して三価クロムイオンに変えた後、アルカリを加えてｐＨを８前後にして三価クロムイオンを不溶性の水酸化クロム（III）にし、生成した水酸化クロム（III）を凝集沈殿させて分離する方法である（非特許文献１参照）。また、イオン交換法は、六価クロム濃度の低い水に対して主に適用される方法であり、耐酸化性の強塩基性イオン交換樹脂を用いて水中の六価クロムイオンを分離除去する方法である。 A typical method for reducing or removing hexavalent chromium contained in water includes a precipitation method or an ion exchange method. Among them, the precipitation method is a method in which water containing hexavalent chromium ions is reduced to ferric sulfate, sodium bisulfite, and other reducing agents under acidity of pH 4 or less to convert them into trivalent chromium ions, and then alkaline. Is added to adjust the pH to around 8 to convert the trivalent chromium ions into insoluble chromium hydroxide (III), and the resulting chromium hydroxide (III) is agglomerated and separated (see Non-Patent Document 1). In addition, the ion exchange method is a method mainly applied to water having a low hexavalent chromium concentration, and a method of separating and removing hexavalent chromium ions in water using an oxidation-resistant strong basic ion exchange resin. It is.
上記した沈殿法による場合は、水中に含まれる六価クロムを不溶性の水酸化クロム（III）沈殿にして分離除去することができるが、六価クロムを含有する水を、硫酸第一鉄、重亜硫酸ナトリウムなどの還元剤が作用するｐＨ４程度の酸性領域に予め調整してから還元処理を施し、さらに還元処理によって生成した三価クロムイオンを今度はｐＨを８前後に調整して水酸化クロム（III）にして沈降分離するものであるため、手間および特別の設備を要し、経費がかかり、簡便性、経済性に欠ける。また、イオン交換樹脂を用いる方法も、高価なイオン交換樹脂を用いる必要があり、しかも一度に大量の水を処理することは困難であるため、やはり簡便性、経済性に欠ける。 In the case of the precipitation method described above, hexavalent chromium contained in water can be separated and removed by insoluble chromium (III) hydroxide precipitation. A reduction treatment such as sodium sulfite is preliminarily adjusted to an acidic region of about pH 4 and then a reduction treatment is performed. Further, the trivalent chromium ions generated by the reduction treatment are adjusted to a pH of about 8 this time, and chromium hydroxide ( III) Since it separates and settles, it requires labor and special equipment, is costly, and lacks convenience and economy. Also, the method using an ion exchange resin needs to use an expensive ion exchange resin, and it is difficult to treat a large amount of water at one time, so that it is also lacking in simplicity and economy.
また、土壌や汚泥などに含まれる六価クロムの濃度を化学的に低減する方法が知られており、例えば、六価クロムで汚染された土壌を、十分な量のアスコルビン酸で処理して、三価クロムなどの低原子価にして六価クロム濃度を低減する方法（特許文献１参照）などを挙げることができる。しかしながら、この特許文献１の方法では、比較的高価なアスコルビン酸を多量に使用する必要があるため、処理すべき水、土壌、汚泥の量が多い場合は、処理コストが膨大になり、実用性に乏しい。 In addition, a method of chemically reducing the concentration of hexavalent chromium contained in soil or sludge is known, for example, treating soil contaminated with hexavalent chromium with a sufficient amount of ascorbic acid, A method of reducing the hexavalent chromium concentration by using a low valence such as trivalent chromium (see Patent Document 1) can be given. However, in the method of Patent Document 1, since it is necessary to use a relatively expensive ascorbic acid in a large amount, if the amount of water, soil, and sludge to be treated is large, the treatment cost becomes enormous and practicality is increased. It is scarce.
また、上記した化学的な方法とは別に、微生物を利用する処理方法として、（ａ）六価クロムを含有する固体に、堆肥、汚泥、排水処理スラッジなどの有機材料とバクテリア、栄養分を混合し、これに水を加え、無機酸または塩基でｐＨを６．５〜９．５に調整して還元処理を行う方法（特許文献２参照）；（ｂ）六価クロムを含有する排水に硫酸還元菌を含む嫌気性汚泥を加えてｐＨ６．０〜７．５程度の条件下に嫌気性処理を行う方法（特許文献３参照）；（ｃ）六価クロムなどを含む汚泥を木材チップと混合し、それに主として乳酸桿菌と酵母菌とからなる発酵菌を散布して、２週間程度の一次発酵、２〜３週間程度の二次発酵および１週間程度の仕上げ発酵を行って六価クロムなどの含有量を低減させる方法（特許文献４参照）などが知られている。 In addition to the chemical method described above, as a treatment method using microorganisms, (a) a solid containing hexavalent chromium is mixed with organic materials such as compost, sludge, wastewater treatment sludge, bacteria, and nutrients. , A method of reducing the pH by adding water to this and adjusting the pH to 6.5 to 9.5 with an inorganic acid or base (see Patent Document 2); (b) reducing sulfuric acid to wastewater containing hexavalent chromium A method of performing anaerobic treatment under conditions of pH 6.0 to 7.5 by adding anaerobic sludge containing bacteria (see Patent Document 3); (c) mixing sludge containing hexavalent chromium and the like with wood chips. In addition, fermented bacteria composed mainly of lactobacilli and yeast are sprayed on it, followed by primary fermentation for about 2 weeks, secondary fermentation for about 2 to 3 weeks, and finish fermentation for about 1 week, containing hexavalent chromium, etc. Method for reducing the amount (see Patent Document 4), etc. It is known.
しかしながら、上記（ａ）の方法は、六価クロムを含有する固体に有機材料、バクテリア、栄養分および水を混合し、混合物のｐＨを６．５〜９．５に調整して処理を行う必要があるため、還元処理に要する配合成分の種類が多く、しかも高ｐＨの固体ではｐＨ調整を行わずにそのまま処理することができないため、やはり手間や時間などを要する。
また、上記（ｂ）の方法は、硫酸還元菌という特定の菌を含む嫌気性汚泥の入手が困難であり、しかも被処理物のｐＨを６．０〜７．５程度のほぼ中性域に予め調整してから処理を行う必要があるため、実用性に乏しい。
更に、上記（ｃ）の方法は、乳酸桿菌および酵母菌という特定の発酵菌を使用する必要があり、しかも処理に５〜６週間という比較的長い期間を要することから、コスト面および処理期間などの点から、やはり実用的ではない。
However, in the method (a), it is necessary to perform treatment by mixing organic material, bacteria, nutrients and water with a solid containing hexavalent chromium and adjusting the pH of the mixture to 6.5 to 9.5. For this reason, there are many kinds of blending components required for the reduction treatment, and in addition, it is not possible to perform the treatment as it is without adjusting the pH in the case of a solid having a high pH.
In the method (b), it is difficult to obtain anaerobic sludge containing a specific bacterium called a sulfate-reducing bacterium, and the pH of the object to be treated is approximately in the neutral range of about 6.0 to 7.5. Since it is necessary to carry out the treatment after adjustment in advance, it is not practical.
Furthermore, since the method (c) requires the use of specific fermentative bacteria such as lactobacilli and yeast, and the treatment takes a relatively long period of 5 to 6 weeks, the cost and the treatment period, etc. From the point of view, it is still not practical.
本発明の目的は、水、土壌、汚泥または廃材中に含まれる六価クロムの濃度を、予めｐＨを調整するというような手間や時間のかかる予備処理工程を行わずに、しかも硫酸第一鉄、重亜硫酸ナトリウムなどの還元剤や、アスコルビン酸などのようなコストのかかる化合物を使用せずに、さらには硫酸還元菌、乳酸桿菌、酵母などの特別な微生物を使用せずに、簡単に、安全に、確実に、しかも低コストで短期間に低減することのできる処理方法を提供することである。 The object of the present invention is to carry out the pretreatment step which requires time and effort such as adjusting the pH in advance in the concentration of hexavalent chromium contained in water, soil, sludge or waste material, and also ferrous sulfate. Without using reducing agents such as sodium bisulfite or costly compounds such as ascorbic acid, and without using special microorganisms such as sulfate-reducing bacteria, lactobacilli, and yeast, It is an object of the present invention to provide a processing method that can be safely, reliably, and reduced at a low cost in a short time.
上記の目的を達成すべく、本発明者らは検討を重ねてきた。その結果、六価クロムを含有する水、土壌、汚泥または廃材に、小麦フスマ、末粉、米糠、コーンブラン、グルテンフィードなどの糟糠類を添加混合して嫌気的状態で発酵させると、ｐＨ調整などを行わなくても、また特別の化学薬品、化合物、微生物などを使用しなくても、水、土壌、汚泥または廃材中に含まれる六価クロムが二価クロムや三価クロムなどの低原子価のクロム、特に三価クロムに確実に還元されて、水、土壌、汚泥または廃材に含まれている有害な六価クロムの濃度を短期間に、確実に且つ低コストで低減できることを見出した。 In order to achieve the above object, the present inventors have repeatedly studied. As a result, when water, soil, sludge or waste materials containing hexavalent chromium are added to and mixed with wheat bran, powder, rice bran, corn bran, gluten feed and other moss, the pH is adjusted. Without using chemicals, compounds, microorganisms, etc., hexavalent chromium contained in water, soil, sludge or waste materials is a low atom such as divalent chromium or trivalent chromium. It has been found that the concentration of harmful hexavalent chromium contained in water, soil, sludge or waste materials can be reduced reliably and at low cost in a short period of time by reducing to chromium, especially trivalent chromium. .
そして、本発明者らは、この方法によって六価クロムを含有する水、土壌、汚泥または廃材を処理して水、土壌、汚泥または廃材中の六価クロムの含有量を低減するに当たっては、水、土壌、汚泥または廃材に含まれる六価クロム１ｍｇに対して、糟糠類を１ｇ以上（乾物換算）の割合で添加して嫌気的発酵を行うのが好ましいことを見出した。 Then, the present inventors treated water, soil, sludge or waste material containing hexavalent chromium by this method to reduce the content of hexavalent chromium in water, soil, sludge or waste material. The present inventors have found that it is preferable to perform anaerobic fermentation by adding moss in a ratio of 1 g or more (in terms of dry matter) to 1 mg of hexavalent chromium contained in soil, sludge or waste material.
また、本発明者らは、処理の対象が六価クロムを含有する土壌、汚泥または廃材である場合は、ときとして、土壌、汚泥または廃材中での六価クロムの含有量（質量）を測定してその含有量に応じて六価クロム１ｍｇ当り糟糠類を１ｇ（乾物換算）以上の割合で添加混合する上記の方法を行わずに、土壌、汚泥または廃材１００質量部（乾物換算；以下質量部を表示するときは乾物換算として表す）に対して、糟糠類を２質量部以上の割合で添加混合する方法が簡便性や作業性の点で適しており、その場合にも土壌、汚泥または廃材中に含まれる六価クロムの低減処理が良好に行われることを見出した。 In addition, the present inventors sometimes measure the content (mass) of hexavalent chromium in soil, sludge or waste material when the object of treatment is soil, sludge or waste material containing hexavalent chromium. Then, according to the content, 100 parts by mass of soil, sludge or waste material (in terms of dry matter; hereinafter mass) The method of adding and mixing moss at a ratio of 2 parts by mass or more is suitable in terms of simplicity and workability, and in that case also soil, sludge or It has been found that the reduction of hexavalent chromium contained in the waste material is performed well.
さらに、本発明者らは、処理の対象が六価クロムを含有する水である場合は、六価クロムを含有する水に糟糠類を添加して非曝気下に処理を行うことにより嫌気的発酵が進行して六価クロムの低減が図れること、また処理の対象が土壌、汚泥または廃材である場合は、土壌、汚泥または廃材１００質量部に対して水の存在量を１５〜３００質量部にすると、嫌気的発酵が円滑に進行して、土壌、汚泥または廃材中に含まれる六価クロムの低減処理が良好に行われることなどを見出し、それらの知見に基づいて本発明を完成した。 Furthermore, when the subject of the treatment is water containing hexavalent chromium, anaerobic fermentation is performed by adding moss to the water containing hexavalent chromium and performing the treatment under non-aeration. Progresses to reduce hexavalent chromium, and when the object of treatment is soil, sludge or waste, the amount of water is 15 to 300 parts by weight with respect to 100 parts by weight of soil, sludge or waste. Then, it discovered that anaerobic fermentation progressed smoothly and the reduction | restoration process of the hexavalent chromium contained in soil, sludge, or a waste material was performed favorably, and completed this invention based on those knowledge.
すなわち、本発明は、
（１） 六価クロムを含有する水、土壌、汚泥または廃材に、糟糠類を添加混合して嫌気的発酵を行って、水、土壌、汚泥または廃材中の六価クロム濃度を低減することを特徴とする六価クロム濃度の低減方法である。
That is, the present invention
(1) To reduce the concentration of hexavalent chromium in water, soil, sludge or waste materials by adding anaerobic substances to water, soil, sludge or waste materials containing hexavalent chromium and performing anaerobic fermentation. This is a feature of reducing the hexavalent chromium concentration.
そして、本発明は、
（２） 水、土壌、汚泥または廃材に含まれる六価クロム１ｍｇに対して、糟糠類を１ｇ（乾物換算）以上の割合で添加して嫌気的発酵を行う前記（１）の六価クロム濃度の低減方法；
（３） 六価クロムを含有する土壌、汚泥または廃材１００質量部（乾物換算）に対して、糟糠類を２質量部（乾物換算）以上の割合で添加混合する前記（１）の六価クロム濃度の低減方法；
（４） 六価クロムを含有する土壌、汚泥または廃材１００質量部（乾物換算）に対して、水の含有量が１５〜３００質量部である状態下に嫌気的発酵を行う前記（１）〜（３）のいずれかの六価クロム濃度の低減方法；および、
（５） 糟糠類が、小麦フスマ、末粉、米糠、コーンブランおよびグルテンフィードから選ばれる少なくとも１種である前記（１）〜（４）のいずれかの六価クロム濃度の低減方法；
である。
And this invention,
(2) Concentration of hexavalent chromium as described in (1) above, in which anaerobic fermentation is performed by adding moss at a ratio of 1 g (dry matter equivalent) or more to 1 mg of hexavalent chromium contained in water, soil, sludge or waste material Reduction method of;
(3) Hexavalent chromium according to (1) above, in which moss is added and mixed at a ratio of 2 parts by mass (in terms of dry matter) or more with respect to 100 parts by mass (in terms of dry matter) of soil, sludge or waste material containing hexavalent chromium. A method of reducing the concentration;
(4) Said (1)-which performs anaerobic fermentation in the state whose water content is 15-300 mass parts with respect to 100 mass parts (dry matter conversion) of the soil, sludge, or waste material containing hexavalent chromium. The method for reducing the hexavalent chromium concentration of any one of (3); and
(5) The method for reducing the hexavalent chromium concentration according to any one of (1) to (4), wherein the moss is at least one selected from wheat bran, powder, rice bran, corn bran and gluten feed;
It is.
本発明による場合は、六価クロムを含有する水、土壌、汚泥または廃材を、そのｐＨに拘わらず予めｐＨの調整を行う必要なしに、さらには硫酸第一鉄、重亜硫酸ナトリウムなどの還元剤や、アスコルビン酸などのコストのかかる化合物を使用せずに、高価なイオン交換樹脂を使用せずに、また硫酸還元菌、乳酸桿菌、酵母などの特別な微生物を使用せずに、小麦フスマ、末粉、米糠、コーンブラン、グルテンフィードなどの糟糠類を加えて水の存在下に嫌気的に発酵させるだけで、水、土壌、汚泥または廃材中に含まれる六価クロムを低原子価のクロムに還元して（特に三価クロムに還元して）、六価クロムの濃度を簡単に、安全に、確実に、しかも低コストで短期間に低減することができる。
本発明の方法は、六価クロムを含む種々の水（例えば六価クロムを含有する工場排水、鉱業排水、研究機関排水、生活排水、工業用水、農業用水、上水、下水、河川水、雨水など）、六価クロムを含む種々の土壌、汚泥（例えば工場、鉱山、土木工事現場、建設現場、排水処理場、研究機関などから排出される六価クロムを含有する土壌や汚泥、工場、鉱山、研究機関などの六価クロムを含有する跡地など）、六価クロムを含む廃材（例えば六価クロムを含有する、土木工事や建設工事などに伴って排出されるコンクリート廃材、自動車やその他の車両廃材、電気・電子部品廃材など）に対する六価クロム濃度の低減方法として有効である。
In the case of the present invention, water, soil, sludge or waste material containing hexavalent chromium need not be adjusted in advance regardless of the pH, and further, a reducing agent such as ferrous sulfate or sodium bisulfite. Without using expensive compounds such as ascorbic acid, without expensive ion exchange resins, and without using special microorganisms such as sulfate-reducing bacteria, lactobacilli, and yeast, Just add algae such as powder, rice bran, corn bran and gluten feed and ferment anaerobically in the presence of water to convert hexavalent chromium contained in water, soil, sludge or waste materials into low-valent chromium. The concentration of hexavalent chromium can be reduced easily, safely, reliably, and at a low cost in a short time.
The method of the present invention can be applied to various kinds of water containing hexavalent chromium (for example, industrial wastewater containing hexavalent chromium, mining wastewater, research institution wastewater, domestic wastewater, industrial water, agricultural water, tap water, sewage, river water, rainwater). Etc.), various soils and sludge containing hexavalent chromium (for example, soil and sludge containing hexavalent chromium discharged from factories, mines, civil engineering sites, construction sites, wastewater treatment plants, research institutions, factories, mines) , Ruins containing hexavalent chromium from research institutions, etc., waste materials containing hexavalent chromium (for example, concrete waste materials containing automobiles and other vehicles containing hexavalent chromium, etc., and automobiles and other vehicles) This is an effective method for reducing the hexavalent chromium concentration of waste materials, electrical / electronic component waste materials, etc.).
本発明の方法による場合は、処理を施した後の水、土壌、汚泥中には、植物にとって肥料ともなる糟糠類の発酵生成物が含まれ、しかも安全性、環境汚染、植物の生育などの点で問題となる薬剤や化合物などが残留せず、その上有害な六価クロムの濃度が大幅に低減していて安全性の点でも極めて優れている。 In the case of the method of the present invention, the water, soil, and sludge after the treatment contains fermented products of moss that also serve as fertilizers for plants, and safety, environmental pollution, plant growth, etc. In this respect, there is no residual drug or compound remaining in question, and the concentration of harmful hexavalent chromium is greatly reduced, which is extremely excellent in terms of safety.
本発明の方法で処理した水は、有毒な六価クロムの濃度が大幅に低減していて、安全性に優れるので、工業用水、農業用水などとして再利用することができ、また河川などに放流しても環境汚染を生じない。
また、本発明の方法で処理した土壌または汚泥は、有毒な六価クロムの濃度が大幅に低減していて、安全性、取扱性、植物生育性に優れ、しかも環境汚染を生じないので、植物生育用の培地、覆土用の土壌、環境整備用の土壌、土木工事や建設工事などであいた穴などの埋め戻し用土壌、法面吹付用緑化基盤材などの用途に有効に使用することができる。
さらに、本発明の方法で処理した例えばコンクリート廃材、特にコンクリート破砕物は、有毒な六価クロムの濃度が大幅に低減していて、安全性、取扱性に優れ、環境汚染などを生じないので、覆土用の土壌、環境整備用の土壌、土木工事や建設工事などであいた穴などの埋め戻し用、路面工事用などの用途に有効に使用することができる。
The water treated by the method of the present invention has a greatly reduced concentration of toxic hexavalent chromium and is excellent in safety. Therefore, it can be reused as industrial water, agricultural water, etc., and discharged into rivers and the like. However, no environmental pollution occurs.
In addition, the soil or sludge treated by the method of the present invention has a greatly reduced concentration of toxic hexavalent chromium, and is excellent in safety, handleability and plant growth, and does not cause environmental pollution. It can be used effectively for applications such as growth medium, soil for covering soil, soil for environmental maintenance, soil for backfilling such as holes used in civil engineering and construction work, and greening base materials for slope spraying. .
Furthermore, for example, concrete waste materials treated with the method of the present invention, in particular, concrete crushed material, the concentration of toxic hexavalent chromium is greatly reduced, because it is excellent in safety and handling, and does not cause environmental pollution. It can be used effectively for applications such as soil for covering soil, soil for environmental maintenance, backfilling of holes used for civil engineering work and construction work, and road surface work.
さらに、本発明による場合は、製粉や精米の副産物である小麦フスマ、末粉、米糠、コーンブラン、グルテンフィードなどの糟糠類を有効に活用して、低コストで六価クロム濃度の低減を達成することができる。 Furthermore, in the case of the present invention, reduction of hexavalent chromium concentration is achieved at low cost by effectively using wheat bran, powdered flour, rice flour, rice bran, corn bran, gluten feed and other by-products of milling and milling. can do.
本発明で処理の対象としている「六価クロムを含有する水」は、何らかの形態の六価クロム（例えば六価クロム化合物や六価クロムイオンなど）を含有し、そのまま排出したり、放置したり、使用すると、安全性、環境汚染などの問題を生じ、六価クロム濃度の低減が必要であるかまたは望ましい水であればいずれでもよく、水の種類、性状、組成などは特に制限されない。何ら限定されるものではないが、本発明の処理の対象となる水としては、例えば、クロム化合物や金属クロムを扱う工場［精練工場、クロムメッキ工場、化学工場（顔料、染料、触媒、防錆剤などの製造工場等）、合金製造工場、皮革工場（クロムなめし）、金属製品製造工場など］で排出される排水（廃水）、鉱山などから排出される排水、クロム化合物や金属クロムを扱う研究機関で排出される排水（廃水）、六価クロムの低減が必要または望ましい六価クロム含有生活排水、工業用水、農業用水、上水、下水、河川水、雨水などを挙げることができる。 The “water containing hexavalent chromium” to be treated in the present invention contains some form of hexavalent chromium (for example, hexavalent chromium compounds and hexavalent chromium ions) and is discharged or left as it is. When used, it causes problems such as safety and environmental pollution, and any water may be used as long as it is necessary or desirable to reduce the hexavalent chromium concentration, and the type, properties, composition, etc. of water are not particularly limited. Although not limited in any way, examples of water to be treated in the present invention include, for example, factories that handle chromium compounds and metal chromium [scouring factories, chrome plating factories, chemical factories (pigments, dyes, catalysts, rust prevention). Waste water (waste water) discharged from mines, etc., chromium compounds and metal chromium, etc.), alloy manufacturing plants, leather factories (chrome tanning), metal product manufacturing plants, etc.] Wastewater discharged from the organization (wastewater), domestic wastewater containing hexavalent chromium that requires or desirable reduction of hexavalent chromium, industrial water, agricultural water, tap water, sewage, river water, rainwater, and the like.
また、本発明で処理の対象としている「六価クロムを含有する土壌、汚泥」は、セメント系資材を用いる工事によって排出される六価クロムを含有するアルカリ性の土壌や汚泥、前記以外の土壌または汚泥であって、且つ何らかの形態の六価クロム（例えば六価クロム化合物や六価クロムイオンなど）を含有し、そのまま廃棄したり、放置したり、埋め戻しなどに使用すると、安全性、環境汚染、植物の生育不良などの問題を生じ易く、六価クロム濃度の低減が必要であるかまたは望ましい土壌または汚泥であればいずれでもよく、土壌または汚泥の種類、形態、性状、組成などは特に制限されない。何ら限定されるものではないが、本発明の処理の対象となる土壌または汚泥としては、例えば、クロム化合物や金属クロムを扱う工場［精練工場、クロムメッキ工場、化学工場（顔料、染料、触媒、防錆剤などの製造工場等）、合金製造工場、皮革工場（クロムなめし）、金属製品製造工場など］や研究機関などで排出される汚泥、鉱山などで排出される汚泥、排水処理場で排出される六価クロムを含有する汚泥、前記した工場や研究機関が設けられている六価クロムを含有する土壌（跡地））、ゴミ廃棄場の土壌、ゴミ処理場の土壌などを挙げることができる。 In addition, the “soil and sludge containing hexavalent chromium” which is the object of treatment in the present invention is alkaline soil or sludge containing hexavalent chromium discharged by construction using a cement-based material, soil other than the above or It is sludge and contains some form of hexavalent chromium (for example, hexavalent chromium compounds and hexavalent chromium ions). If it is used as it is for disposal, leaving, or backfilling, it is safe and environmental pollution. Any soil or sludge that is prone to problems such as poor plant growth and that requires or is desirable to reduce the hexavalent chromium concentration may be used, and the type, form, properties, composition, etc. of the soil or sludge are particularly limited. Not. Although not limited in any way, examples of the soil or sludge to be treated according to the present invention include, for example, a factory that handles chromium compounds and metal chromium [scouring factory, chrome plating factory, chemical factory (pigment, dye, catalyst, Manufacturing plant for rust prevention agents, etc.), alloy manufacturing plant, leather factory (chrome tanning), metal product manufacturing plant, etc.] and sludge discharged from research institutions, sludge discharged from mines, etc., discharged from wastewater treatment plants Sludge containing hexavalent chromium, soil containing hexavalent chromium provided by the above-mentioned factories and research institutes (soil), soil at waste disposal sites, soil at waste disposal sites, etc. .
さらに、本発明で処理の対象としている「六価クロムを含有する廃材」は、土木工事、建設工事、その他の工事などに伴って排出される廃材、使用済みの電気製品や電気・電子部品、車両部品などのような廃材であって、何らかの形態の六価クロム（例えば六価クロム化合物や六価クロムイオンなど）を含有し、そのまま廃棄したり、放置したり、埋め戻しなどに使用すると、安全性に欠け、環境汚染などの問題を生じ易く、六価クロム濃度の低減が必要であるかまたは望ましい廃材であればいずれでもよく、その種類は特に制限されない。限定されるものではないが、本発明の処理の対象となる廃材としては、例えば、土木工事や建設工事などに伴って排出される六価クロムを含有するコンクリート廃材、使用済みの電気製品、電気・電子部品、自動車やその他の車両部品で六価クロムを含有するものなどを挙げることができる。廃材の処理に当たって、廃材のサイズが大きい場合は、粉砕してから処理を行うことが好ましく、特に２ｍｍ以下に粉砕し、そこに糟糠類を添加・混合して嫌気的発酵を行うことが、廃材中に含まれる六価クロムの低減が円滑に且つ速やかになされることからより好ましい。 Furthermore, the “waste material containing hexavalent chromium” that is the object of treatment in the present invention includes waste materials discharged during civil engineering work, construction work, and other work, used electrical products and electric / electronic parts, Waste materials such as vehicle parts, which contain some form of hexavalent chromium (for example, hexavalent chromium compounds and hexavalent chromium ions). Any waste material may be used as long as it is lacking in safety and easily causes problems such as environmental pollution, and it is necessary to reduce the concentration of hexavalent chromium or is desirable, and the type is not particularly limited. Although it is not limited, examples of the waste material subject to the treatment of the present invention include concrete waste materials containing hexavalent chromium discharged in connection with civil engineering work and construction work, used electrical products, -Electronic parts, automobiles and other vehicle parts containing hexavalent chromium can be listed. When processing the waste material, if the size of the waste material is large, it is preferable to perform the processing after pulverization, and in particular, it is possible to pulverize to 2 mm or less, and to add and mix the moss to perform anaerobic fermentation. The hexavalent chromium contained therein is more preferably reduced smoothly and promptly.
本発明で処理の対象としている六価クロムを含有する水、土壌、汚泥または廃材のｐＨは特に制限されず、酸性、中性またはアルカリ性のいずれであってもよく、本発明の嫌気的発酵を直接行って六価クロムの含有量を低減させることができる。 The pH of water, soil, sludge or waste material containing hexavalent chromium to be treated in the present invention is not particularly limited and may be acidic, neutral or alkaline, and the anaerobic fermentation of the present invention. This can be done directly to reduce the hexavalent chromium content.
本発明で用いる糟糠類としては、例えば、小麦フスマ、末粉、米糠、コーンブラン、グルテンフィードなどを挙げることができ、これらの１種または２種以上を用いることができる。そのうちでも、本発明では、糟糠類として、小麦フスマ、末粉および米糠の１種または２種以上が、入手の容易性、六価クロムの含有量の低減性能、コスト、作業性などの点から好ましく用いられる。 Examples of the moss used in the present invention include wheat bran, powder, rice bran, corn bran, gluten feed and the like, and one or more of these can be used. Among them, in the present invention, one or more of wheat bran, powder and rice bran are used as potatoes from the viewpoints of availability, hexavalent chromium content reduction performance, cost, workability, and the like. Preferably used.
六価クロムを含有する水、土壌、汚泥または廃材への糟糠類の添加量は、水、土壌、汚泥または廃材中における六価クロムの濃度、水、土壌、汚泥または廃材のｐＨ、水、土壌、汚泥または廃材の種類、性状、処理後の水、土壌、汚泥または廃材の用途、糟糠類の種類などに応じて調整することができる。一般的には、六価クロムを含有する水、土壌、汚泥または廃材に含まれる六価クロム１ｍｇに対して、糟糠類を１ｇ（乾物換算）以上、特に１０ｇ（乾物換算）以上の割合で添加して嫌気的発酵を行うことが、六価クロムの含有量を短期間に効果的に低減できることから好ましい。糟糠類の添加量の上限値は特に制限されないが、コスト、作業性などの点から、水、土壌、汚泥または廃材に含まれる六価クロム１ｍｇ当り１０００ｇ（乾物換算）以下であることが好ましく、５００ｇ（乾物換算）以下であることがより好ましい。 The amount of moss added to water, soil, sludge or waste material containing hexavalent chromium is the concentration of hexavalent chromium in water, soil, sludge or waste material, pH of water, soil, sludge or waste material, water, soil It can be adjusted according to the type and properties of sludge or waste material, the treated water, soil, the use of sludge or waste material, the type of moss, and the like. Generally, potatoes are added at a rate of 1 g (dry matter equivalent) or more, especially 10 g (dry matter equivalent) or more with respect to 1 mg of hexavalent chromium contained in water, soil, sludge or waste materials containing hexavalent chromium. And anaerobic fermentation is preferable because the content of hexavalent chromium can be effectively reduced in a short time. The upper limit of the amount of moss added is not particularly limited, but from the viewpoint of cost, workability, etc., it is preferably 1000 g (in terms of dry matter) or less per 1 mg of hexavalent chromium contained in water, soil, sludge or waste material, More preferably, it is 500 g (in terms of dry matter) or less.
なお、本明細書でいう、「六価クロム１ｍｇ当りの糟糠類の添加量（ｇ）」とは、水、土壌、汚泥または廃材における六価クロムの濃度（ｐｐｍ）を測定し、その測定値から水、土壌、汚泥または廃材の単位質量当りに含まれる六価クロムの質量（ｍｇ）を算出して、その１ｍｇ当りについて加える糟糠類の質量（ｇ）（乾物換算）を意味する。
例えば、六価クロムの濃度が１ｐｐｍの水では、水１ｋｇ（１×１０6ｍｇ）中に六価クロムが１ｍｇ含まれているから、その水１ｋｇに対して（六価クロム１ｍｇ当りとなる）糟糠類を上記した１ｇ（乾物換算）以上［特に１０ｇ（乾物換算）以上］の割合で添加混合して嫌気的発酵を行うのが好ましい。
As used herein, “addition amount of moss per 1 mg of hexavalent chromium (g)” means the concentration (ppm) of hexavalent chromium in water, soil, sludge or waste material, and the measured value. The mass (mg) of hexavalent chromium contained per unit mass of water, soil, sludge or waste material is calculated from the above, and the mass (g) of moss added per 1 mg (in terms of dry matter) is meant.
For example, in the case of water having a hexavalent chromium concentration of 1 ppm, 1 mg of hexavalent chromium is contained in 1 kg (1 × 10 6 mg) of water, and therefore 1 kg of the water (per 1 mg of hexavalent chromium). It is preferable to carry out anaerobic fermentation by adding and mixing moss at a ratio of 1 g (in terms of dry matter) or more [particularly 10 g (in terms of dry matter)].
六価クロム濃度の低減処理に当っては、上記したように水、土壌、汚泥または廃材中の六価クロムの含有量を測定し、その含有量に応じた量の糟糠類を添加混合することが好ましい。しかしながら、処理対象が土壌、汚泥または廃材の場合は、水の場合に比べて、六価クロムの含有量の測定に一般に手間および時間がかかるため、現場で迅速な作業や処理が困難になることがある。そのため、そのような場合は、六価クロムを含有する土壌、泥または廃材１００質量部（乾物換算）に対して、糟糠類を２質量部（乾物換算）以上の割合で添加混合して処理を行ってもよい。その際に、土壌、汚泥または廃材の種類や発生源などから土壌、汚泥または廃材に含まれる六価クロムの大凡の量を予測し、それに適応した量を前記した「２質量部以上」を満たすようにして決めて添加するようにするとよい。 When reducing the hexavalent chromium concentration, measure the content of hexavalent chromium in water, soil, sludge or waste as described above, and add and mix the amount of moss according to the content. Is preferred. However, when soil, sludge, or waste materials are treated, it generally takes time and labor to measure the content of hexavalent chromium compared to water, which makes it difficult to work quickly and process on site. There is. Therefore, in such a case, moss is added and mixed at a ratio of 2 parts by mass (in terms of dry matter) or more with respect to 100 parts by mass (in terms of dry matter) of soil, mud or waste material containing hexavalent chromium. You may go. At that time, the approximate amount of hexavalent chromium contained in the soil, sludge or waste material is predicted from the type and source of the soil, sludge or waste material, and the amount adapted thereto satisfies the above “2 parts by mass” or more. It is good to decide and add in this way.
本発明では、六価クロムを含有する水、土壌、汚泥または廃材に、糟糠類を添加混合して、嫌気的発酵を行うことが必要である。好気的状態で発酵させた場合には、六価クロム濃度は低減しない。
処理対象が六価クロムを含有する水である場合は、六価クロムを含有する水に糟糠類を添加混合してそのまま非曝気下に発酵させると、一般に嫌気的発酵が進行して水中での六価クロムの濃度が低減する。その際に、水中の溶存酸素を低減するための処理（例えば炭酸ガスや窒素ガスなどの不活性ガスの導入、減圧吸引処理など）を嫌気的発酵の前または嫌気的発酵中に行うと、嫌気的発酵がより速やかに進行し、水中の六価クロム濃度をより短期間に低減させることができる。
In the present invention, it is necessary to carry out anaerobic fermentation by adding moss to water, soil, sludge or waste material containing hexavalent chromium. When fermented in an aerobic state, the hexavalent chromium concentration is not reduced.
When the treatment target is water containing hexavalent chromium, adding an algae to water containing hexavalent chromium and fermenting it as it is without aeration, generally anaerobic fermentation proceeds and The concentration of hexavalent chromium is reduced. At that time, if treatment for reducing dissolved oxygen in water (for example, introduction of inert gas such as carbon dioxide or nitrogen gas, vacuum suction treatment, etc.) is performed before anaerobic fermentation or during anaerobic fermentation, anaerobic Fermentation proceeds more rapidly, and the hexavalent chromium concentration in water can be reduced in a shorter time.
また、処理対象が六価クロムを含有する土壌、汚泥または廃材である場合は、土壌、汚泥または廃材中にはかなりの酸素が含まれることが多いので、嫌気的発酵が円滑に行われるように酸素含有量を少なくして処理を行うことが好ましい。土壌、汚泥または廃材中の酸素含有量を少なくする方法は特に制限されず、例えば、糟糠類を添加混合した後に土壌、汚泥または廃材から空気を吸引除去する方法、水を加えて糟糠類や土壌、汚泥または廃材中に含まれている空気を排出して糟糠類や土壌、汚泥または廃材と空気の接触を断つ方法、土壌に水を添加混合した後に重機などで加圧、圧し固め、成形などを行う方法、土壌に水を添加混合した後に容器内に詰め込む方法などを採用することができる。 In addition, if the treatment object is soil, sludge or waste material containing hexavalent chromium, the soil, sludge or waste material often contains a considerable amount of oxygen, so that anaerobic fermentation can be carried out smoothly. It is preferable to perform the treatment with a reduced oxygen content. The method for reducing the oxygen content in the soil, sludge or waste is not particularly limited. For example, the method of sucking and removing air from the soil, sludge or waste after adding and mixing moss, the moss and soil by adding water , Exhaust air contained in sludge or waste material to cut off contact between moss and soil, sludge or waste material and air, add water to soil, mix and press with heavy machinery, compaction, molding, etc. The method of performing, and the method of stuffing in a container after adding and mixing water to soil etc. are employable.
そのうちでも、土壌、汚泥または廃材では、嫌気的状態の形成の容易性、操作の容易性、コストなどの点から、糟糠類を添加混合した土壌、汚泥または廃材に水を含有させる方法が嫌気的条件の形成に好ましく採用される。その際の水の含有量は、嫌気的発酵の促進、発酵が終了した後の排水の処理の容易性やコストなどの点から、土壌、汚泥または廃材１００質量部に対して、１５質量部以上であることが好ましく、１５〜３００質量部であることがより好ましく、１５〜１００質量部程度であることが更に好ましい。水の含有量を前記した範囲に調整するに当たっては、土壌、汚泥または廃材中に水が元々多く含まれていて、その水の含有量が土壌、汚泥または廃材１００質量部に対して１５質量部以上である場合は、新たに水を添加せずにそのまま嫌気的発酵を行ってもよいし、または必要に応じて更に水を加えて含水量を多くして嫌気的発酵を行ってもよい。土壌、汚泥または廃材中の水分含量が少ない場合は、水分含量が土壌、汚泥または廃材１００質量部に対して１５質量部以上、好ましくは１５〜３００質量部の範囲になるように不足分の水を加えてから嫌気的発酵を行うとよい。 Among them, soil, sludge, or waste materials are anaerobic due to the ease of formation of anaerobic conditions, ease of operation, cost, etc., by adding water to soil, sludge, or waste materials mixed with moss. It is preferably employed for forming conditions. In this case, the content of water is 15 parts by mass or more based on 100 parts by mass of soil, sludge, or waste material from the viewpoint of promotion of anaerobic fermentation, ease of treatment of waste water after completion of fermentation, cost, and the like. It is preferably 15 to 300 parts by mass, more preferably about 15 to 100 parts by mass. In adjusting the water content to the above-mentioned range, the soil, sludge or waste material originally contains a large amount of water, and the water content is 15 parts by mass with respect to 100 parts by mass of soil, sludge or waste material. When it is above, anaerobic fermentation may be performed as it is without newly adding water, or anaerobic fermentation may be performed by adding water as necessary to increase the water content. When the water content in the soil, sludge or waste material is low, the water content is 15 parts by mass or more, preferably 15 to 300 parts by mass with respect to 100 parts by mass of the soil, sludge or waste material. It is recommended to perform anaerobic fermentation after adding.
水、土壌、汚泥または廃材に糟糠類を添加混合して嫌気的発酵を行わせることによって、水、土壌、汚泥または廃材中に含まれる六価クロムがそれよりも毒性の低い低原子価のクロム（二価クロムおよび三価クロム、特に三価クロム）に還元されて、水、土壌、汚泥または廃材中での六価クロム濃度が低減して、水、土壌、汚泥または廃材の安全性が向上する。そのことは、本発明の方法を行った場合に、水、土壌、汚泥または廃材の酸化還元電位が低下することからも確認される。 Hexavalent chromium contained in water, soil, sludge or waste material is mixed with water and soil, sludge or waste material to cause anaerobic fermentation. Reduced to (divalent chromium and trivalent chromium, especially trivalent chromium), reducing the hexavalent chromium concentration in water, soil, sludge or waste materials, improving the safety of water, soil, sludge or waste materials To do. This is also confirmed from the fact that the redox potential of water, soil, sludge or waste material decreases when the method of the present invention is performed.
本発明の方法を行うに当たっては、水、土壌、汚泥または廃材中の六価クロムの濃度が０．０５ｐｐｍ以下、特に０．０１ｐｐｍ以下になるように、糟糠類の添加量、処理時間、処理条件などを調整して処理を行うことが好ましい。 In carrying out the method of the present invention, the amount of moss added, treatment time, treatment conditions so that the concentration of hexavalent chromium in water, soil, sludge or waste material is 0.05 ppm or less, particularly 0.01 ppm or less. It is preferable to perform the processing while adjusting the above.
また、本発明の方法による場合は、水、土壌、汚泥または廃材中の六価クロム濃度が低減するだけでなく、嫌気的発酵によって有機酸（酢酸、乳酸など）などが生成するので、処理対象である水、土壌、汚泥または廃材がアルカリ性である場合はその中和処理も同時に行うことができる。但し、前記処理対象物のアルカリ性が強すぎる場合には、公知の手段（例えば炭酸ガスの導入など）によってｐＨを予め低下させてから（例えばｐＨ１１以下にしてから）、本発明の方法を行うことが六価クロム濃度の低減効果の点から好ましい。 Further, in the case of the method of the present invention, not only the concentration of hexavalent chromium in water, soil, sludge or waste materials is reduced, but also organic acids (acetic acid, lactic acid, etc.) are generated by anaerobic fermentation, so When the water, soil, sludge or waste material is alkaline, the neutralization treatment can be performed at the same time. However, when the alkalinity of the object to be treated is too strong, the method of the present invention is carried out after the pH is lowered in advance by a known means (for example, introduction of carbon dioxide gas, etc.) (for example, after the pH is made 11 or less). Is preferable from the viewpoint of the effect of reducing the hexavalent chromium concentration.
六価クロムの還元によって生じた三価クロムは、一般に、酸性状態では安定で、酸化されにくい（六価クロムに戻りにくい）が、アルカリ性状態では比較的酸化され易い（酸化されて六価クロムに戻り易い）という性質を有する。そのため、本発明の方法を行うに当たって、水、土壌、汚泥または廃材中の六価クロム濃度の低減状態と、水、土壌、汚泥または廃材のｐＨを同時にチェックしながら処理を行うことが望ましい。 In general, trivalent chromium produced by reduction of hexavalent chromium is stable in an acidic state and hardly oxidized (not easily returned to hexavalent chromium), but is relatively easily oxidized in an alkaline state (oxidized to hexavalent chromium). It is easy to return. Therefore, in carrying out the method of the present invention, it is desirable to perform treatment while simultaneously checking the reduced state of the hexavalent chromium concentration in water, soil, sludge or waste material and the pH of water, soil, sludge or waste material.
嫌気的発酵による六価クロム濃度の低減処理は、処理対象である水、土壌、汚泥または廃材の種類や状態、処理する場所、処理後の用途などに応じて、嫌気的発酵が自然に停止するまで行ってもよいし、または適当な時点で嫌気的発酵を積極的に停止させて終了してもよい。嫌気的発酵を終了する方法としては、処理対象が水である場合は、例えば、水中に空気や酸素を吹き込んで非嫌気的状態にする方法（但しこの場合に好気的雰囲気が強くなると六価から三価または二価の状態に還元されたクロムが再度六価クロムになってしまうので、好気的雰囲気が強くなり過ぎないように注意する必要がある）などを挙げることができる。また、処理対象が土壌、汚泥または廃材である場合は、土壌、汚泥または廃材を含む混合物の水分含有量を低下させた後に、撹拌、切り返し、空気の吹き込みなどによって該混合物内に空気を取り込んで、混合物の嫌気状態を解消する方法などを挙げることができる。但し、この場合も、土壌、汚泥または廃材内の好気的雰囲気が強くなると、六価から三価または二価の状態に還元されたクロムが酸化されて再度六価クロムになり、折角低減した六価クロム濃度が増加するので、好気的雰囲気が強くなり過ぎないように注意する必要がある。 The reduction of hexavalent chromium concentration by anaerobic fermentation will naturally stop the anaerobic fermentation depending on the type and state of the water, soil, sludge or waste material to be treated, the place to be treated, the use after treatment, etc. Or anaerobic fermentation may be actively stopped and terminated at an appropriate time. As a method for terminating anaerobic fermentation, when the object to be treated is water, for example, a method in which air or oxygen is blown into water to make it non-anaerobic (in this case, if the aerobic atmosphere becomes stronger, hexavalent Since the chromium reduced to the trivalent or divalent state again becomes hexavalent chromium, it is necessary to be careful not to make the aerobic atmosphere too strong. In addition, when the object to be treated is soil, sludge or waste material, after reducing the water content of the mixture containing soil, sludge or waste material, air is taken into the mixture by stirring, turning over, blowing air, etc. And a method for eliminating the anaerobic state of the mixture. However, even in this case, when the aerobic atmosphere in the soil, sludge, or waste material becomes stronger, the chromium reduced from the hexavalent to the trivalent or divalent state is oxidized to hexavalent chromium again, and the angle is reduced. Care must be taken not to make the aerobic atmosphere too strong as the hexavalent chromium concentration increases.
本発明の方法を行うに当たっては、糟糠類と共に、必要に応じて、堆肥、嫌気的条件下で働く無害な微生物や該微生物を含有する生物資材、木材チップやその他の動植物残渣などの１種または２種以上を添加して嫌気的発酵を行ってもよい。
糟糠類と共に堆肥を添加することによって、嫌気的発酵が促進されて、処理期間が短縮される場合がある。
その際の堆肥としては、例えば、バーク堆肥、伐採材堆肥、剪定材堆肥、汚泥堆肥、畜糞堆肥などの１種または２種以上を用いることができる。糟糠類と共に堆肥を添加混合する場合は、六価クロムを含有する水、土壌、汚泥または廃材１００質量部に対して、堆肥を１〜３０質量部、特に５〜１０質量部の割合で添加するとよい。
In carrying out the method of the present invention, together with moss, if necessary, compost, harmless microorganisms working under anaerobic conditions, biological materials containing the microorganisms, wood chips and other animal and plant residues, etc. Two or more kinds may be added to perform anaerobic fermentation.
By adding compost together with moss, anaerobic fermentation is promoted and the treatment period may be shortened.
As compost in that case, 1 type, or 2 or more types, such as bark compost, felling material compost, pruning material compost, sludge compost, and livestock manure compost, can be used, for example. When compost is added and mixed with moss, compost is added at a ratio of 1 to 30 parts by weight, particularly 5 to 10 parts by weight, with respect to 100 parts by weight of water, soil, sludge or waste material containing hexavalent chromium. Good.
また、嫌気的条件下で働く無害な微生物としては、例えば、乳酸菌、酢酸菌などの嫌気性菌などを挙げることができる。微生物同士が互いにその働きを阻害しない場合は、前記した微生物の２種以上を併用してもよい。微生物の使用量は、六価クロムを含有する水、土壌、汚泥または廃材の種類や状態、糟糠類の種類や添加量などに応じて調整することができる。無害な微生物を添加する場合は、一般的には、糟糠類１ｇに対して、該微生物の添加量を１０3〜１０7個、特に１０4〜１０6個にすることが、該微生物による発酵促進効果などの点から好ましい。 Examples of harmless microorganisms that work under anaerobic conditions include anaerobic bacteria such as lactic acid bacteria and acetic acid bacteria. When the microorganisms do not inhibit their functions, two or more of the microorganisms described above may be used in combination. The amount of microorganisms used can be adjusted according to the type and state of water, soil, sludge or waste material containing hexavalent chromium, the type and amount of moss, and the like. In the case of adding harmless microorganisms, generally, the amount of the microorganisms to be added is 10 3 to 10 7 , especially 10 4 to 10 6 per 1 g of moss. This is preferable from the viewpoint of the promoting effect.
六価クロムを含有する水、土壌、汚泥または廃材を嫌気的に発酵させる際の操作や条件などは特に制限されず、水、土壌、汚泥または廃材の種類、状態、形態、嫌気的発酵を行う場所の種類、周辺環境、処理後の用途などに応じて選択することができる。 The operation and conditions for anaerobically fermenting water, soil, sludge or waste material containing hexavalent chromium are not particularly limited, and the type, state, form, and anaerobic fermentation of water, soil, sludge or waste material are performed. It can be selected according to the type of place, surrounding environment, usage after processing, and the like.
また、六価クロムを含有する土壌（土地）をそのまま直接処理して、植物が生育し易くするためには、植物の根が生育する深さまで少なくとも土地を耕し、そこに糟糠類および必要に応じて堆肥などの他の成分を添加混合し、その部分の土地を嫌気的状態にして、土壌中の六価クロム濃度が所定値以下になるまで嫌気的発酵を行わせる方法などにより処理を行うことができる。この場合に、耕して糟糠類を添加混合した土地を嫌気的状態に保つ方法としては、例えば、該土地に継続的または断続的に灌水チューブやその他の手段により灌水し、必要に応じてその表面部分を非通気性の合成樹脂シートやゴムシートなどで覆う方法などを挙げることができる。 In addition, in order to facilitate the growth of plants by directly treating the soil (land) containing hexavalent chromium as it is, the land is cultivated at least to the depth at which the roots of the plants grow, and there are mosses and, if necessary, Add other ingredients such as compost, make the land in an anaerobic state, and treat it by anaerobic fermentation until the hexavalent chromium concentration in the soil falls below the specified value. Can do. In this case, as a method of maintaining the anaerobic state of the land that has been cultivated and added with moss, for example, the land is continuously or intermittently irrigated with a irrigation tube or other means, and the surface thereof is used as necessary. Examples thereof include a method of covering the portion with a non-breathable synthetic resin sheet or rubber sheet.
六価クロムを含有する水、土壌、汚泥または廃材を処理する際の温度は、嫌気的条件下で働く微生物が死滅せずに働き得る温度であればよく、水、土壌、汚泥または廃材の処理を行う場所や施設、目標とする処理期間などに応じて決めるとよい。一般的には、雰囲気温度が０〜５０℃、特に１５〜３５℃の温度であると（糟糠類を添加混合した水、土壌、汚泥または廃材の内温が５〜４５℃、特に１５〜３５℃であると）、処理が円滑に進行する。
また、処理期間は、水、土壌、汚泥または廃材中の六価クロム濃度、処理すべき水、土壌、汚泥または廃材の量、添加混合する糟糠類の量、処理の方法、処理時の温度、処理時の嫌気状態、処理後の目標とする六価クロム含有量などに応じてそれぞれ異なる。例えば、六価クロム濃度が０．１ｐｐｍ前後の水に、水中の六価クロム１ｍｇ当りにつき糟糠類を１０ｇ（乾物換算）の割合で添加して、雰囲気温度２５℃で嫌気的発酵を行った場合には、約３〜１０日で、前記水中の六価クロム濃度を０．０１ｐｐｍ未満に低下させることができる。
Water, soil, sludge or waste material containing hexavalent chromium may be treated at a temperature that allows microorganisms working under anaerobic conditions to work without being killed. Water, soil, sludge or waste material treatment It is good to decide according to the place and facility to perform, and the target processing period. In general, when the ambient temperature is 0 to 50 ° C., particularly 15 to 35 ° C. (the internal temperature of water, soil, sludge or waste material mixed with moss is 5 to 45 ° C., particularly 15 to 35 When the temperature is 0 ° C., the process proceeds smoothly.
In addition, the treatment period includes the hexavalent chromium concentration in water, soil, sludge or waste material, the amount of water to be treated, soil, sludge or waste material, the amount of moss to be added and mixed, the method of treatment, the temperature during treatment, It varies depending on the anaerobic state during processing, the target hexavalent chromium content after processing, and the like. For example, when anaerobic fermentation is carried out at an ambient temperature of 25 ° C. with 10 g of moss per 1 mg of hexavalent chromium in water added to water with a hexavalent chromium concentration of around 0.1 ppm. In about 3 to 10 days, the hexavalent chromium concentration in the water can be reduced to less than 0.01 ppm.
本発明の方法で処理した水、土壌、汚泥または廃材は、六価クロム濃度が低減していて、安全性、取扱性、植物生育性などに優れ、しかも環境汚染性が低下しているので、被処理物の種類などに応じて、例えば、工業用水やその他の用水、上水、植物生育用の培地、覆土用の土壌、環境整備用の土壌、土木工事や建設工事などであいた穴などの埋め戻し用土壌、法面吹付用緑化基盤材、道路舗装用材料などの用途に有効に使用することができる。 The water, soil, sludge or waste material treated by the method of the present invention has a reduced hexavalent chromium concentration, is excellent in safety, handleability, plant growth, etc., and has reduced environmental pollution. Depending on the type of material to be treated, for example, industrial water and other water, tap water, plant growth medium, soil for covering soil, soil for environmental maintenance, holes used for civil engineering and construction, etc. It can be used effectively for applications such as backfilling soil, greening base material for slope spraying, and road pavement materials.
以下に本発明を実施例などにより具体的に説明するが、本発明は以下の例により何ら限定されない。
以下の例において、糟糠類（小麦フスマ）、脱水ケーキ（（ダム工事現場で発生したセメント分を多く含む高アルカリ性の汚泥を沈降処理した後に加圧脱水して得たケーキ）、川砂、コンクリートブロック解砕物またはバーク堆肥の水分含量は、次のようにして測定した。
［小麦フスマ、脱水ケーキ、川砂、コンクリート解砕物又はバーク堆肥の水分含量測定］
小麦フスマ、脱水ケーキ、川砂、コンクリート解砕物またはバーク堆肥の所定量（乾燥前の質量Ｗ0）を採取し、それを温度１０５℃で質量の減少がなくなるまで乾燥し、その時の質量（Ｗ1）を測定し、下記の式（１）から、小麦フスマ、脱水ケーキ、川砂、コンクリート解砕物またはバーク堆肥の水分含量（含水率）（質量％）を求めた。
水分含量（質量％）＝｛（Ｗ0−Ｗ1）／Ｗ0｝×１００ ・・・（１）
Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited to the following examples.
In the following example, moss (wheat bran), dehydrated cake (cake obtained by pressure dehydration after sedimentation of highly alkaline sludge containing a large amount of cement generated at the dam construction site), river sand, concrete block The water content of the crushed material or bark compost was measured as follows.
[Measurement of water content of wheat bran, dehydrated cake, river sand, crushed concrete or bark compost]
A predetermined amount (mass W 0 before drying) of wheat bran, dehydrated cake, river sand, crushed concrete or bark compost is sampled and dried at a temperature of 105 ° C. until there is no decrease in mass, and the mass at that time (W 1 ) And the moisture content (water content) (mass%) of wheat bran, dehydrated cake, river sand, crushed concrete or bark compost was determined from the following formula (1).
Water content (mass%) = {(W 0 −W 1 ) / W 0 } × 100 (1)
《実施例１》
脱水ケーキ（ダム工事現場で発生したセメント分を多く含む高アルカリ性の汚泥を沈降処理した後に加圧脱水して得たケーキ；ｐＨ＝１０．５；水分含量＝１７質量％）の粉砕物５８０質量部に、小麦フスマ（水分含量＝１４質量％）を下記の表１に示す量で添加混合し、さらに水を１０００質量部の量で混合してそれぞれの混合物を調製し、それぞれの混合物の混合直後の六価クロム［以下「Ｃｒ(VI)」ということがある］の濃度、ｐＨおよびＥｈを測定した後、それぞれの混合物を雰囲気温度２５℃で１０日間嫌気的に発酵させて、３日後および１０日後における混合物のＣｒ(VI)の濃度、ｐＨおよびＥｈを測定したところ、下記の表１に示すとおりであった。
なお、この実施例１では、それぞれの混合物における混合直後、３日後、１０日後のＣｒ(VI)の濃度、ｐＨおよび酸化還元電位（以下「Ｅｈ」ということがある）は、次のようにして測定した。
Example 1
580 mass of pulverized dehydrated cake (cake obtained by settling high alkaline sludge containing a large amount of cement generated at the dam construction site and then pressure dewatering; pH = 10.5; moisture content = 17 mass%) In each part, wheat bran (water content = 14% by mass) is added and mixed in the amount shown in Table 1 below, and water is further mixed in an amount of 1000 parts by mass to prepare each mixture. Mixing of each mixture After measuring the concentration, pH and Eh of hexavalent chromium (hereinafter sometimes referred to as “Cr (VI)”) immediately after, each mixture was fermented anaerobically at an ambient temperature of 25 ° C. for 10 days, and after 3 days and When the Cr (VI) concentration, pH and Eh of the mixture after 10 days were measured, they were as shown in Table 1 below.
In Example 1, the concentration, pH and oxidation-reduction potential (hereinafter sometimes referred to as “Eh”) of Cr (VI) immediately after mixing, 3 days, and 10 days in each mixture were as follows. It was measured.
［Ｃｒ(VI)の濃度の測定］
Ｃｒ(VI)の濃度は、ＪＩＳ Ｋ ０１０２の「６５．２．１ ジフェニルカルバジド吸光光度法」に記載されている方法に準じて測定した。
測定に当たっての試料の調製は、次のようにして行った。
・Ｃｒ(VI)の濃度の測定用試料の調製方法：
（ｉ） 上記で調製した混合物（脱水ケーキと小麦フスマと水の混合物、脱水ケーキと水の混合物）の５０ｇを採取し、それを５００ｍｌのフラスコに入れ、振とう機（株式会社池田理化製「ＳＳ２０Ｄ」；１００Ｖ，３Ａ）を使用して、温度２０℃、大気圧下、振とう回数２００回／分、振とう幅５ｃｍの条件下に６時間連続して振とうした。
（ii） 上記（ｉ）の振とう処理を行って得られた試料を３０分間静置した後、３０００回／分の回転速度で２０分間遠心分離し、上澄みを孔径０．４５μｍのメンブランフィルターで濾過して濾液を採取し、この濾液をＣｒ(VI)の含有量の測定用試料として用いた。
[Measurement of Cr (VI) concentration]
The concentration of Cr (VI) was measured according to the method described in “65.2.1 Diphenylcarbazide absorptiometry” of JIS K 0102.
The sample preparation for the measurement was performed as follows.
-Preparation method of Cr (VI) concentration measurement sample :
(I) 50 g of the mixture prepared above (a mixture of dehydrated cake, wheat bran and water, a mixture of dehydrated cake and water) was collected and placed in a 500 ml flask, and shaker (“Ikeda Rika Co., Ltd.” SS20D "; 100V, 3A) was used for 6 hours of continuous shaking under conditions of a temperature of 20 ° C, atmospheric pressure, a shaking frequency of 200 times / minute, and a shaking width of 5 cm.
(Ii) The sample obtained by carrying out the shaking treatment of (i) above was allowed to stand for 30 minutes, then centrifuged at a rotation speed of 3000 times / minute for 20 minutes, and the supernatant was filtered with a membrane filter having a pore size of 0.45 μm. The filtrate was collected by filtration, and the filtrate was used as a sample for measuring the Cr (VI) content.
［ｐＨおよび酸化還元電位（Ｅｈ）の測定］
（ｉ） 使用した脱水ケーキは、ほぼ乾燥した状態にあり（水分含量が少なく）、そのままではｐＨおよびＥｈの測定が困難であったので、脱水ケーキ１００質量部に対して水２００質量部を混合し、その混合物のｐＨおよびＥｈを、ｐＨ測定装置（東亜ディーケーケー株式会社製「ｐＨメーターＨＭ−５０Ｓ」）を使用して測定した。
（ii） 上記で調製した混合物（脱水ケーキと小麦フスマと水の混合物、脱水ケーキと水の混合物）については、上記（ｉ）で使用したのと同じｐＨ測定装置を使用して、そのｐＨおよびＥｈをそのまま直接測定した。
[Measurement of pH and oxidation-reduction potential (Eh)]
(I) The dehydrated cake used was almost dry (low water content), and it was difficult to measure pH and Eh as it was, so 200 parts by mass of water were mixed with 100 parts by mass of the dehydrated cake. The pH and Eh of the mixture were measured using a pH measuring device (“pH meter HM-50S” manufactured by Toa DKK Co., Ltd.).
(Ii) For the mixture prepared above (a mixture of dehydrated cake, wheat bran and water, a mixture of dehydrated cake and water), using the same pH measuring device as used in (i) above, the pH and Eh was measured directly.
上記の表１にみるように、脱水ケーキに水だけを加えた実験番号１では、３日後および１０日後に、Ｃｒ(VI)の濃度の低下が極めて少なかった。また、ｐＨおよびＥｈの低下も殆どなかった。
それに対して、脱水ケーキに小麦フスマと水を混合して嫌気的発酵を行った実験番号２〜４では、３日後にＣｒ(VI)の濃度が大きく低下し、そのうち実験番号２と３では１０日後に０．０１ｐｐｍ未満になり、実験番号４では３日後に０．０１ｐｐｍ未満にまで低下していた。また、実験番号２〜４では、ｐＨおよびＥｈも当初より低下しており、実験番号４では３日後にｐＨが７．５に低下していた。
As shown in Table 1 above, in Experiment No. 1 in which only water was added to the dehydrated cake, the decrease in the Cr (VI) concentration was extremely small after 3 days and 10 days. Further, there was almost no decrease in pH and Eh.
In contrast, in Experiment Nos. 2 to 4, in which wheat bran and water were mixed with dehydrated cake and subjected to anaerobic fermentation, the concentration of Cr (VI) decreased greatly after 3 days. After the day, it became less than 0.01 ppm, and in Experiment No. 4, it decreased to less than 0.01 ppm after 3 days. In Experiment Nos. 2 to 4, pH and Eh were also lowered from the beginning, and in Experiment No. 4 the pH was lowered to 7.5 after 3 days.
《実施例２》
実施例１で使用したのと同じ脱水ケーキの粉砕物５８０質量部に、バーク堆肥（水分含量＝４０質量％；さかえ農事有限会社製）を８０質量部、および小麦フスマ（水分含量＝１４質量％）を下記の表２に示す量で添加混合し、さらに水を下記の表２に示す量で混合してそれぞれの混合物を調製し、それぞれの混合物の混合直後のＣｒ(VI)の濃度、ｐＨおよびＥｈを測定した後、それぞれの混合物を雰囲気温度２５℃で１５日間嫌気的に発酵させて、３日後、１０日後および１５日後における混合物のｐＨ、ＥｈおよびＣｒ(VI)の含有量を測定したところ、下記の表２に示すとおりであった。なお、表２に示すように、実験番号７および８は１０日で処理を終了した。また、実験番号５では１５日後にＣｒ(VI)の濃度とｐＨのみを測定し、実験番号６では１５日後にｐＨのみを測定した。
なお、ｐＨ、ＥｈおよびＣｒ(VI)の含有量の測定は、実施例１と同様に行った。
Example 2
To 580 parts by mass of the same dewatered cake pulverized product used in Example 1, 80 parts by mass of bark compost (water content = 40% by mass; manufactured by Sakae Agricultural Co., Ltd.) and wheat bran (water content = 14% by mass) ) Are added and mixed in the amounts shown in Table 2 below, and water is mixed in the amounts shown in Table 2 below to prepare each mixture. The concentration and pH of Cr (VI) immediately after mixing each mixture And Eh were measured, each mixture was anaerobically fermented at an ambient temperature of 25 ° C. for 15 days, and the pH, Eh and Cr (VI) contents of the mixture were measured after 3, 10 and 15 days. However, it was as shown in Table 2 below. As shown in Table 2, the experiment numbers 7 and 8 were completed in 10 days. In Experiment No. 5, only Cr (VI) concentration and pH were measured after 15 days, and in Experiment No. 6, only pH was measured after 15 days.
The pH, Eh and Cr (VI) contents were measured in the same manner as in Example 1.
上記の表２にみるように、脱水ケーキにバーク堆肥と水だけを加えた実験番号５では、Ｃｒ(VI)の濃度は１０日後にようやく当初の約２７％に低下した。また、実験番号５では、ｐＨは低下せず、むしろ多少上昇した。
それに対して、脱水ケーキに小麦フスマ、バーク堆肥および水を混合して嫌気的発酵を行った実験番号６〜８のうち、実験番号６では１０日後にＣｒ(VI)の濃度が０．０１ｐｐｍ未満にまで低下し、実験番号７および８では３日後にＣｒ(VI)の濃度が０．０１ｐｐｍ未満に低下した。また、実験番号７および８では、１０日後にｐＨが当初に比べて大きく低下した。
As shown in Table 2 above, in Experiment No. 5 in which only bark compost and water were added to the dehydrated cake, the Cr (VI) concentration finally decreased to about 27% of the original after 10 days. In Experiment No. 5, the pH did not decrease but rather increased somewhat.
In contrast, among Experiment Nos. 6 to 8 in which wheat bran, bark compost and water were mixed with dehydrated cake and subjected to anaerobic fermentation, in Experiment No. 6, the concentration of Cr (VI) was less than 0.01 ppm after 10 days. In Experiment Nos. 7 and 8, the Cr (VI) concentration decreased to less than 0.01 ppm after 3 days. In Experiment Nos. 7 and 8, the pH was greatly reduced after 10 days from the beginning.
《実施例３》
実施例１で使用したのと同じ脱水ケーキの粉砕物５８０質量部に、実施例２で使用したのと同じバーク堆肥を８０質量部、および小麦フスマ（水分含量＝１４質量％）を６６質量部の量で添加混合し、さらに水を下記の表３に示す量で混合してそれぞれの混合物を調製し、それぞれの混合物の混合直後のＣｒ(VI)の濃度、ｐＨおよびＥｈを測定した後、それぞれの混合物を雰囲気温度２５℃で３日間発酵させて、３日後における混合物のＣｒ(VI)の濃度、ｐＨおよびＥｈを測定したところ、下記の表３に示すとおりであった。
なお、ｐＨ、ＥｈおよびＣｒ(VI)の含有量の測定は、実施例１と同様に行った。
Example 3
580 parts by weight of the same dewatered cake pulverized product used in Example 1, 80 parts by weight of the same bark compost used in Example 2, and 66 parts by weight of wheat bran (water content = 14% by weight) In addition, water was added in the amounts shown in Table 3 below to prepare each mixture, and the Cr (VI) concentration, pH, and Eh immediately after mixing each mixture were measured. Each mixture was fermented at an ambient temperature of 25 ° C. for 3 days, and the Cr (VI) concentration, pH and Eh of the mixture after 3 days were measured, and the results were as shown in Table 3 below.
The pH, Eh and Cr (VI) contents were measured in the same manner as in Example 1.
上記の表３にみるように、実験番号９では、脱水ケーキにバーク堆肥と小麦フスマだけを添加混合し水を混合しなかったために、嫌気的状態にならず、好気的発酵が行われた結果、Ｃｒ(VI)の濃度は低下していなかった。
それに対して、実験番号１０〜１４では、脱水ケーキにバーク堆肥および小麦フスマと共に、十分な量の水を混合して嫌気的発酵を行った結果、３日後にはＣｒ(VI)の濃度は０．０１ｐｐｍ未満にまで低下していた。また、実験番号１０〜１４では、３日後に混合物のｐＨおよびＥｈも混合直後に比べて大きく低下していた。
As shown in Table 3 above, in Experiment No. 9, only bark compost and wheat bran were added to the dehydrated cake, and water was not mixed. Therefore, anaerobic fermentation was performed without anaerobic conditions. As a result, the concentration of Cr (VI) was not lowered.
On the other hand, in Experiment Nos. 10 to 14, a sufficient amount of water was mixed with dehydrated cake together with bark compost and wheat bran, and as a result of anaerobic fermentation, the concentration of Cr (VI) was 0 after 3 days. It was reduced to less than 0.01 ppm. In addition, in Experiment Nos. 10 to 14, the pH and Eh of the mixture were greatly reduced after 3 days compared to immediately after mixing.
《実施例４》
（１） 水に重クロム酸カリウム（Ｋ2Ｃｒ2Ｏ7）を添加し、またｐＨ調整剤として塩酸および／または水酸化ナトリウムを使用して、下記の表４に示すＣｒ(VI)濃度およびｐＨ（ｐＨ３、７または１２）を有する水をそれぞれ調製した。
（２） 上記（１）で調製したＣｒ(VI)を含有する水１ｋｇに対して、小麦フスマ（水分含量１４質量％）を下記の表４に示す量で添加した後、水温２５℃で３日間嫌気的に発酵させて、当初および３日後における水中のＣｒ(VI)の濃度およびＥｈを測定したところ、下記の表４に示すとおりであった。
なお、この実施例４では、Ｃｒ(VI)の濃度、ｐＨおよびＥｈは、次のようにして測定した。
Example 4
(1) Adding potassium dichromate (K 2 Cr 2 O 7 ) to water and using hydrochloric acid and / or sodium hydroxide as a pH adjuster, the Cr (VI) concentrations shown in Table 4 below and Water having a pH (pH 3, 7 or 12) was prepared respectively.
(2) To 1 kg of water containing Cr (VI) prepared in (1) above, wheat bran (water content: 14% by mass) was added in the amount shown in Table 4 below, and the water temperature was 25 ° C. The concentration of Cr (VI) and Eh in water at the beginning and after 3 days were measured as shown in Table 4 below.
In Example 4, the Cr (VI) concentration, pH and Eh were measured as follows.
［水中のＣｒ(VI)の濃度の測定］
この実施例４で用いた（調製した）、小麦フスマ未添加のＣｒ(VI)を含有する水、または小麦フスマを添加したＣｒ(VI)を含有する水の上澄み液を孔径０．４５μｍのメンブランフィルターで濾過して濾液を採取し、この濾液中のＣｒ(VI)の含有量（濃度）を、ＪＩＳ Ｋ ０１０２の「６５．２．１ ジフェニルカルバジド吸光光度法」に記載されている方法に準じて測定して、水中のＣｒ(VI)の濃度とした。
[Measurement of Cr (VI) concentration in water]
A supernatant containing Cr (VI) containing no wheat bran added or water containing Cr (VI) added with wheat bran was used in this Example 4 to prepare a membrane having a pore size of 0.45 μm. The filtrate was collected by filtration, and the content (concentration) of Cr (VI) in the filtrate was determined according to the method described in “65.2.1 Diphenylcarbazide spectrophotometry” of JIS K 0102. The concentration was measured in accordance with the concentration of Cr (VI) in water.
［ｐＨおよびＥｈの測定」
この実施例４で用いた（調製した）、小麦フスマ未添加の水、および小麦フスマを添加した水についてそのｐＨおよびＥｈを、実施例１で使用したのと同じｐＨ測定装置を使用して測定した。
[Measurement of pH and Eh]
Using the same pH measurement apparatus used in Example 1, the pH and Eh of water used in Example 4 (prepared), to which wheat bran was not added, and water to which wheat bran was added were measured. did.
上記の表４にみるように、Ｃｒ(VI)を含有する水に小麦フスマを添加して嫌気的発酵を行った場合には、ｐＨの如何に拘らずＣｒ(VI)の濃度が低下した。その際に、小麦フスマの添加量が多くなるにつれ、Ｃｒ(VI)の濃度の低下が大きい。 As shown in Table 4 above, when anaerobic fermentation was performed by adding wheat bran to water containing Cr (VI), the concentration of Cr (VI) decreased regardless of the pH. At that time, as the amount of wheat bran added increases, the concentration of Cr (VI) decreases greatly.
《実施例５》
（１）（ｉ） 川砂（水分含量５．８質量％）に、所定量の重クロム酸カリウム（Ｋ2Ｃｒ2Ｏ7）を添加し、更に水を添加して、Ｃｒ(VI)濃度１０ｐｐｍ、水分含有率１５％（混合物の全質量に対する割合）、ｐＨ７．９のＣｒ(VI)を含有する川砂と水の混合物を調製した。
（ii） 上記（ｉ）で調製したＣｒ(VI)を含有する川砂と水の混合物に対して、小麦フスマ（水分含量１４質量％）を下記の表５に示す量［川砂１ｋｇに対する添加量（乾物換算）］で添加した後、雰囲気温度２５℃で１０日間嫌気的に発酵させて、当初および１０日後におけるＣｒ(VI)の濃度およびＥｈを測定したところ、下記の表５に示すとおりであった。
Example 5
(1) (i) A predetermined amount of potassium dichromate (K 2 Cr 2 O 7 ) is added to river sand (water content 5.8% by mass), water is further added, and Cr (VI) concentration is 10 ppm. A mixture of river sand and water containing Cr (VI) having a water content of 15% (ratio to the total mass of the mixture) and a pH of 7.9 was prepared.
(Ii) For the mixture of river sand and water containing Cr (VI) prepared in (i) above, wheat bran (water content 14% by mass) is the amount shown in Table 5 below [addition amount to 1 kg of river sand ( In addition, it was fermented anaerobically at an ambient temperature of 25 ° C. for 10 days, and the concentration of Cr (VI) and Eh at the beginning and after 10 days were measured. As shown in Table 5 below, It was.
（２）（ｉ） 川砂（水分含量５．８質量％）に、所定量の重クロム酸カリウム（Ｋ2Ｃｒ2Ｏ7）を添加し、更に水を添加して、ｐＨ調整剤として０．１Ｎ塩酸を用いて、Ｃｒ(VI)濃度１０ｐｐｍ、水分含有率１４％（混合の全質量に対する割合）、ｐＨ４．５のＣｒ(VI)を含有する川砂と水の混合物を調製した。
（ii） 上記（ｉ）で調製したＣｒ(VI)を含有する川砂と水の混合物に対して、小麦フスマ（水分含量１４質量％）を下記の表５に示す量［川砂１ｋｇに対する添加量（乾物換算）］で添加した後、雰囲気温度２５℃で１０日間嫌気的に発酵させて、当初および１０日後におけるＣｒ(VI)の濃度およびＥｈを測定したところ、下記の表５に示すとおりであった。
(2) (i) A predetermined amount of potassium dichromate (K 2 Cr 2 O 7 ) is added to river sand (moisture content of 5.8% by mass), water is further added, and a pH adjuster of 0. A mixture of river sand and water containing Cr (VI) having a Cr (VI) concentration of 10 ppm, a moisture content of 14% (ratio to the total mass of the mixture), and a pH of 4.5 was prepared using 1N hydrochloric acid.
(Ii) For the mixture of river sand and water containing Cr (VI) prepared in (i) above, wheat bran (water content 14% by mass) is the amount shown in Table 5 below [addition amount to 1 kg of river sand ( In addition, it was fermented anaerobically at an ambient temperature of 25 ° C. for 10 days, and the concentration of Cr (VI) and Eh at the beginning and after 10 days were measured. As shown in Table 5 below, It was.
なお、この実施例５では、Ｃｒ(VI)の濃度、ｐＨおよびＥｈは、次のようにして測定した。
［川砂混合物中のＣｒ(VI)の濃度］
この実施例５で調製した、川砂と水との混合物、または川砂と水と小麦フスマの混合物の５０ｇを採取し、それぞれの混合物に溶媒（純水に塩酸を加えてｐＨ５．８〜６．３に調整したもの）を混合物１０ｇ当り溶媒１００ｍｌの割合で添加・混合し、それを５００ｍｌのフラスコに入れ、振とう機（株式会社池田理化製「ＳＳ２０Ｄ」；１００Ｖ，３Ａ）を使用して、温度２０℃、大気圧下、振とう回数２００回／分、振とう幅５ｃｍの条件下に６時間連続して振とうした。次いで、それを３０分間静置した後、３０００回／分の回転速度で２０分間遠心分離し、上澄みを孔径０．４５μｍのメンブランフィルターで濾過して濾液を採取し、この濾液中のＣｒ(VI)の含有量（濃度）を測定して、川砂混合物中のＣｒ(VI)の濃度とした。
In Example 5, the Cr (VI) concentration, pH and Eh were measured as follows.
[Concentration of Cr (VI) in river sand mixture]
50 g of a mixture of river sand and water or a mixture of river sand, water and wheat bran prepared in Example 5 was collected, and a solvent (pH 5.8 to 6.3 by adding hydrochloric acid to pure water to each mixture). Was added and mixed at a rate of 100 ml of solvent per 10 g of the mixture, put into a 500 ml flask, and using a shaker ("SS20D" manufactured by Ikeda Rika Co., Ltd .; 100V, 3A), the temperature The mixture was shaken continuously for 6 hours under the conditions of 20 ° C., atmospheric pressure, the number of shakings of 200 times / minute, and the shaking width of 5 cm. Next, after allowing it to stand for 30 minutes, it was centrifuged for 20 minutes at a rotation speed of 3000 times / minute, the supernatant was filtered through a membrane filter having a pore size of 0.45 μm, and the filtrate was collected. Cr (VI ) Content (concentration) was measured and used as the concentration of Cr (VI) in the river sand mixture.
［川砂混合物のｐＨおよび酸化還元電位（Ｅｈ）の測定］
この実施例５で用いた（調製した）川砂と水との混合物、または川砂と水と小麦フスマの混合物についてそのｐＨおよびＥｈを、実施例１で使用したのと同じｐＨ測定装置を用いて測定した。
[Measurement of pH and redox potential (Eh) of river sand mixture]
The pH and Eh of the mixture of river sand and water (prepared) used in Example 5 or the mixture of river sand, water and wheat bran were measured using the same pH measuring apparatus used in Example 1. did.
上記の表５にみるように、Ｃｒ(VI)を含有する川砂に水と小麦フスマを添加して嫌気的発酵を行った場合には、１０日後にＣｒ(VI)の濃度が０．０１ｐｐｍ未満と大幅に低下した。 As seen in Table 5 above, when anaerobic fermentation was performed by adding water and wheat bran to Cr (VI) -containing river sand, the Cr (VI) concentration was less than 0.01 ppm after 10 days. And decreased significantly.
《実施例６》
コンクリートブロック粉砕物（市販のコンクリートブロックを金槌で叩いて粉砕したもの；粒径２ｍｍ以下；水分含量＝７質量％）１０００質量部に、小麦フスマ（水分含量＝１４質量％）を下記の表６に示す量で添加混合し、さらに水を２０００質量部の量で混合してそれぞれの混合物を調製し、それぞれの混合物の混合直後の六価クロム［以下「Ｃｒ(VI)」ということがある］の濃度およびＥｈを測定した後、それぞれの混合物を雰囲気温度２５℃で１０日間嫌気的に発酵させて、３日後および１０日後における混合物のＣｒ(VI)の濃度およびＥｈを測定したところ、下記の表６に示すとおりであった。
なお、この実施例６では、それぞれの混合物における混合直後、３日後、１０日後のＣｒ(VI)の濃度および酸化還元電位（以下「Ｅｈ」ということがある）は、被測定混合物として、コンクリートブロック粉砕物と水の混合物、またはコンクリートブロック粉砕物と水と小麦フスマの混合物を用いた以外は、実施例１と同様にして測定した。
Example 6
Concrete block pulverized product (commercially crushed concrete block hit with metal hammer; particle size 2mm or less; moisture content = 7% by mass) 1000 parts by weight wheat bran (moisture content = 14% by mass) Are added and mixed in an amount shown in the following, and water is further mixed in an amount of 2000 parts by mass to prepare each mixture. Hexavalent chromium immediately after mixing each mixture [hereinafter sometimes referred to as “Cr (VI)”] After measuring the concentration and Eh of each mixture, each mixture was anaerobically fermented at an ambient temperature of 25 ° C. for 10 days, and the Cr (VI) concentration and Eh of the mixture after 3 days and 10 days were measured. It was as shown in Table 6.
In Example 6, the concentration of Cr (VI) and the oxidation-reduction potential (hereinafter sometimes referred to as “Eh”) immediately after mixing, 3 days, and 10 days in each mixture were measured as concrete blocks. The measurement was performed in the same manner as in Example 1 except that a mixture of a pulverized product and water, or a mixture of a concrete block pulverized product, water and wheat bran was used.
上記の表６にみるように、コンクリートブロック粉砕物に水だけを加えた実験番号４７では、３日後および１０日後に、Ｃｒ(VI)の濃度は殆ど低下しておらず、Ｅｈの低下もなかった。
それに対して、コンクリートブロック粉砕物に小麦フスマと水を混合して嫌気的発酵を行った実験番号４８〜５１は、３日後にＣｒ(VI)の濃度がかなり低下し、１０日後には大きく低下し、特に実験番号４９〜５１では０．０１ｐｐｍ未満になっていた。
As shown in Table 6 above, in Experiment No. 47 in which only water was added to the crushed concrete block, the concentration of Cr (VI) hardly decreased and the Eh did not decrease after 3 and 10 days. It was.
On the other hand, in Experiment Nos. 48 to 51 in which wheat bran and water were mixed with crushed concrete block and subjected to anaerobic fermentation, the concentration of Cr (VI) decreased considerably after 3 days and decreased greatly after 10 days. Especially in Experiment Nos. 49 to 51, it was less than 0.01 ppm.
《実施例７》
実施例６で使用したのと同じコンクリートブロック粉砕物１０００質量部に、バーク堆肥（水分含量＝４０質量％；さかえ農事有限会社製）を１５０質量部、小麦フスマ（水分含量＝１４質量％）を下記の表７に示す量で添加混合し、さらに水を２０００質量部の量で混合してそれぞれの混合物を調製し、それぞれの混合物の混合直後のＣｒ(VI)の濃度およびＥｈを測定した後、それぞれの混合物を雰囲気温度２５℃で１５日間嫌気的に発酵させて、３日後および１０日後における混合物のＥｈおよびＣｒ(VI)の含有量を測定したところ、下記の表７に示すとおりであった。
なお、ＥｈおよびＣｒ(VI)の含有量の測定は、被測定混合物として、コンクリートブロック粉砕物とバーク堆肥と水の混合物、またはコンクリートブロック粉砕物とバーク堆肥と水と小麦フスマの混合物を用いた以外は、実施例１と同様にして行った。
Example 7
To 1000 parts by mass of the same pulverized concrete block used in Example 6, 150 parts by mass of bark compost (moisture content = 40% by mass; manufactured by Sakae Agricultural Co., Ltd.) and wheat bran (water content = 14% by mass) After adding and mixing in the amounts shown in Table 7 below, and further mixing water in an amount of 2000 parts by mass to prepare each mixture, after measuring the Cr (VI) concentration and Eh immediately after mixing each mixture Each mixture was anaerobically fermented at an ambient temperature of 25 ° C. for 15 days, and the contents of Eh and Cr (VI) of the mixture after 3 days and 10 days were measured. As shown in Table 7 below, It was.
In addition, the measurement of the content of Eh and Cr (VI) used a mixture of crushed concrete block and bark compost and water, or a mixture of crushed concrete block and bark compost, water and wheat bran as the mixture to be measured. Except for this, the same procedure as in Example 1 was performed.
上記の表７にみるように、コンクリートブロック粉砕物にバーク堆肥と水だけを加えた実験番号５２では、Ｃｒ(VI)の濃度は１０日後にようやく当初の５０％に低下した。また、実験番号５２では、Ｅｈの低下は僅かであった。
それに対して、コンクリートブロック粉砕物に小麦フスマ、バーク堆肥および水を混合して嫌気的発酵を行った実験番号５３〜５６のうち、実験番号５６では３日後にＣｒ(VI)の濃度が０．０１ｐｐｍ未満にまで低下し、実験番号５３〜５５では１０日後にＣｒ(VI)の濃度が０．０１ｐｐｍ未満にまで低下した。また、実験番号５３〜５６ではＥｈが当初に比べて大きく低下した。
As shown in Table 7 above, in Experiment No. 52 in which only bark compost and water were added to the crushed concrete block, the concentration of Cr (VI) was finally reduced to 50% after 10 days. In Experiment No. 52, the decrease in Eh was slight.
On the other hand, among experiment numbers 53 to 56 in which wheat bran, bark compost and water were mixed with crushed concrete block and subjected to anaerobic fermentation, in experiment number 56, the concentration of Cr (VI) was 0 after 3 days. In the experiment numbers 53 to 55, the Cr (VI) concentration decreased to less than 0.01 ppm after 10 days. Further, in the experiment numbers 53 to 56, Eh significantly decreased compared to the initial value.
《実施例８》
実施例６で使用したのと同じコンクリートブロック粉砕物１０００質量部に、バーク堆肥（水分含量＝４０質量％；さかえ農事有限会社製）を１５０質量部、小麦フスマ（水分含量＝１４質量％）を１０質量部、水を下記の表８に示す量で添加混合してそれぞれの混合物を調製し、それぞれの混合物の混合直後のＣｒ(VI)の濃度およびＥｈを測定した後、それぞれの混合物を雰囲気温度２５℃で１５日間嫌気的に発酵させて、３日後および１０日後における混合物のＥｈおよびＣｒ(VI)の含有量を測定したところ、下記の表８に示すとおりであった。
なお、ＥｈおよびＣｒ(VI)の含有量の測定は、被測定混合物として、コンクリートブロック粉砕物とバーク堆肥と水の混合物、またはコンクリートブロック粉砕物とバーク堆肥と水と小麦フスマの混合物を用いた以外は、実施例１と同様にして行った。
Example 8
To 1000 parts by mass of the same pulverized concrete block used in Example 6, 150 parts by mass of bark compost (moisture content = 40% by mass; manufactured by Sakae Agricultural Co., Ltd.) and wheat bran (water content = 14% by mass) 10 parts by mass and water are added and mixed in the amounts shown in Table 8 below to prepare each mixture. After measuring the Cr (VI) concentration and Eh immediately after mixing each mixture, The content of Eh and Cr (VI) in the mixture after 3 days and 10 days after anaerobic fermentation at a temperature of 25 ° C. for 15 days was as shown in Table 8 below.
In addition, the measurement of the content of Eh and Cr (VI) used a mixture of crushed concrete block and bark compost and water, or a mixture of crushed concrete block and bark compost, water and wheat bran as the mixture to be measured. Except for this, the same procedure as in Example 1 was performed.
上記の表８にみるように、コンクリートブロック粉砕物にバーク堆肥と小麦フスマを加え、水を加えなかった実験番号５７では１０日後においてもＣｒ(VI)の濃度は低下せず、Ｅｈも殆ど低下しなかった。
それに対して、コンクリートブロック粉砕物に小麦フスマ、バーク堆肥および水を混合して嫌気的発酵を行った実験番号５８〜６１では３日後にＣｒ(VI)の濃度が０．０１ｐｐｍ未満にまで低下し、Ｅｈも当初に比べて大きく低下した。
As shown in Table 8 above, in Experiment No. 57 in which bark compost and wheat bran were added to the crushed concrete block and water was not added, the Cr (VI) concentration did not decrease even after 10 days, and Eh also decreased substantially. I did not.
In contrast, in Experiment Nos. 58-61, in which wheat bran, bark compost and water were mixed with crushed concrete block and subjected to anaerobic fermentation, the Cr (VI) concentration dropped to less than 0.01 ppm after 3 days. , Eh also decreased significantly compared to the beginning.
本発明の方法による場合は、六価クロムを含有する水、土壌、汚泥または廃材中の六価クロム濃度を短期間に大きく低減して、水、土壌、汚泥または廃材の安全性を向上させることができ、また六価クロムによる環境汚染を防止することができる。そして、本発明の方法で処理された水、土壌、汚泥または廃材は、工業用水やその他の用水、植物生育用の培地、覆土用の土壌、環境整備用の土壌、土木工事や建設工事などであいた穴などの埋め戻し用土壌、法面吹付緑化用基盤材、道路舗装用資材などの用途に有効に利用することができる。
In the case of the method of the present invention, the concentration of hexavalent chromium in water, soil, sludge or waste material containing hexavalent chromium is greatly reduced in a short time to improve the safety of water, soil, sludge or waste material. And environmental pollution by hexavalent chromium can be prevented. The water, soil, sludge or waste material treated by the method of the present invention may be industrial water or other water, plant growth medium, soil for covering soil, soil for environmental maintenance, civil engineering work or construction work, etc. It can be effectively used for applications such as soil for backfilling such as pits, base materials for slope spraying greening, and road pavement materials.
Claims (5)
The method for reducing the hexavalent chromium concentration according to any one of claims 1 to 4, wherein the moss is at least one selected from wheat bran, powder, rice bran, corn bran, and gluten feed.
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