Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C11/00—Regeneration of pulp liquors or effluent waste waters
  • D21C11/0064—Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
  • C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
  • C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
  • C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
  • C02F11/143—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
  • C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
  • C02F11/143—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances
  • C02F11/145—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances using calcium compounds

Definitions

• the present invention relates to a process foi"* treating settlings formed during the biological purification of municipal and industrial waste water and may foe used in various fields of industry, in particular in paper and pulp production.
• the main disadvantage of the known process consists an low effectiveness and high duration of a process for dehydrating the settlings by filtering, which is caused by an unfavorable structure of said settlings that firmly retain water and have a high specific filtration resist-ance.
• the known process requires the use of expensive alkaline ⁇ *eagents .-'see Y ⁇ . N. Nelepin, "Sulfate Pulp Production”, “ esnaya Promyshlennost", Moscow, l£-80, p. 531/'.
• the present invention is made in order to solve the above problems included in the prior arts, and an object of this invention is t provide a new process for treating a surplus activated sludge enabling intensification of the process fo* dehydrating the settlings by filtering, avoiding the use of expensive chemical reagents, a complete utilisation of the process products so obtained t clarified alkaline hydrolysate and an ash residue) as well as utilisation of the sulfate-pulp production waste with minimal costs.
• the present process differs from the known one in that it provides for the treatment of the pre-dehydrated surplus activated sludge with white slime obtained at the stage of cau ⁇ ticising green liquor in the process of the sulfate-pulp production, with stirring and in a volume ratio of white slime : surplus activated sludge equal to 1 : 5 - 10.
• White slime used in the present process for treating the surplus activated sludge is a sulfate-pulp production waste being a black suspension with a density of 1.25 - 1.35 Kgj/'cub. dm and having the following chemical composition, % wt. :
• Using white slime in accordance with the present process allows solution of two problems at once: on the one hand, to intensify and lower the price of the process for treating the surplus activated sludge and, on the other hand, to significantly simplify nd lower the price of the process for utilising white slime.
• a process for treating the surplus activated sludge thickened when p-resettling the precipitate, by means of white slime containing alkali residues is accompanied with practically a complete alkaline hydrolysis of the bioorganic part of the sludge (constituting no less than 83 % wt. 2 ⁇ dry residue) with the formation of salts of amino acids, amino alcohols and a number of protein derivatives.
• calcium carbonate constituting the major contents of white slime is uniformly distributed, when stirred thoroughly, among undissolved large fibres and solid particles present in the surplus activated sludge in the amount up to 17 w . on dry basis.
• the present process is carried out. m the following manne .
• the surplus activated sludge is subjected to pre- hickening in a radial or vertical pond. Most preferably, '' thickening is carried out up to the surplus activated sludge concentration of 18 - 40 g/1. Upon thickening, the surplus ' activated sludge is fed to a mixer where it is treated with white slime, while stirring. White slime is used in a volume ratio to the surplus activated sl ⁇ jdge equal to 1 : 5 - 10 which allows achievement of a maximal efficiency of post-filtering. When treating the sludge with white slime taken in the amount less than that mentioned above, a filtering rate reduces significantly. It is not to the purpose of technology to use white slime in the amounts exceeding the claimed ratio.
• stirring is carried out at a temperature of between 75 and 104 C. It is also possible to use lower temperatures, up to room temperature, but in this case a process for treating becomes more prolonged.
• the treatment is carried out to a complete dissolution of a bioorganic part of the surplus activated sludge. Then, a mixture so obtained which contains an alkaline hydrolysate, undissolved fibres and solid particles present in the surplus activated sludge, ae well as calcium carbonate uniformly distributed among the particles of sludge settlings as a result of stirring, are fed to a vacuum filter or a pressure filter and subjected to dehydration.
• a clarified alkaline hydrolysate obtained upon filtration may be used, without a subsequent treatment, in the manufacturing cycle of the sulfate-pulp production at the stage of reagent regeneration.
• a dehydrated precipitate formed on a filter surface is readily removed from the filter surface, thereupon it is subjected to heat drying in drier drums and fed to burn down in an utilisation plant furnace.
• An ash residue comprising calcium oxide is used in the manufacturing cycle of the sulfate-pulp ( production at the stage of a green liquor causticising.
• a concentration of 80 g,-l, 0.75 1 of a white slime suspension is added and thoroughly stirred for 15 minutes at 95 C.
• a mixture so obtained is fed to a vacuum filter and subjected to dehydration of the settlings.
• a filtration rate is determined to be 40 I/sq. m/rnin.
• a clarified alkaline hydrolysate is fed to be used in the manufacturing cycle of the sulfate-pulp production.
• a dehydrated precipitate formed on a filter surface is removed and subjected to heat drying at 850 C, the ⁇ v eupon it is burned down.
• An ash residue obtained is fed to the stage of a green liquor causticising.
• the present process for treating the surplus activated sludge allows intensification of the filtration process, avoiding the use of expensive chemical reagents (at. the expense of using waste of the sulfate-pulp production), a complete utilisation of products obtained when treating the sludge (an ash residue and a clarified alkaline hydrolysate) as well as utilisation of the sulfate-pulp production waste, that is white slime, with simplifica ion of the production procedures and techniques and significant reduction of material costs.
• a filtration rate in accordance with the known process is 4 i/sq. m min. Besides, reduction in a dehydration process time according to the present process results in the decrease of energy consumed to realise thereof.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Hydrology & Water Resources (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)
• Treatment Of Sludge (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=20170155

Family Applications (1)

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Cited By (1)

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• 1995
  • 1995-07-18 RU RU9595112218A patent/RU2079454C1/ru active
• 1996
  • 1996-02-12 AU AU46802/96A patent/AU4680296A/en not_active Abandoned
  • 1996-02-12 JP JP9506587A patent/JPH11510090A/ja active Pending
  • 1996-02-12 CN CN96196796A patent/CN1196033A/zh active Pending
  • 1996-02-12 WO PCT/RU1996/000032 patent/WO1997003928A1/en active IP Right Grant
  • 1996-02-12 CA CA002224683A patent/CA2224683A1/en not_active Abandoned
  • 1996-02-12 EP EP96902522A patent/EP0842125A1/en not_active Withdrawn
  • 1996-02-12 BR BR9609736-1A patent/BR9609736A/pt not_active Application Discontinuation
  • 1996-02-12 KR KR1019970709562A patent/KR19990028251A/ko active IP Right Grant
• 1998
  • 1998-01-16 FI FI980091A patent/FI980091A/fi unknown
  • 1998-01-16 NO NO980210A patent/NO980210L/no unknown

Non-Patent Citations (1)

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