The treatment and disposal of waste waters from dairies and milk products factories.

  • Great Britain. Water Pollution Research Board.
Date:
1941
Catalogue details

Licence: Public Domain Mark

Credit: The treatment and disposal of waste waters from dairies and milk products factories. Source: Wellcome Collection.

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    TABLE LXXX. Results of Exposure of Cubes of Cement Mortar in Primary Sedimentation Tank for Crude Liquid Specimens partially immersed | Specimens completely immersed Nature of = SE ee a en ee ee Sey After exposure | After exposure | After exposure | After exposure for 7 months for 15 months | for 7 months — for 15 months (A) (B) (C) | (D) Portland Cement Mortar | 1. Untreated Ageregate -ex-| Slightly worse | Slight softening | Slight softening posed below; than 1A but noerosion | of faces of cube level of liquid; | and some ero- sound above sion near edges level of liquid 2. Treated with | Similar to 1A | Similar to1B | Similar to 1© Similar to [Dp sodium. silicate but less erosion 8. Treated with | Similar to 1A similar to 1B | Similar to 1C Similar to 2D magnesium | | silicofluoride | 4. Coated with tar-| Paint slightly | Paint gone at Littlechangein| Most of paint base paint blistered but| edges; mortar condition of | intact but mor- still intact soft where ex-| specimen tar soft where posed | paint had been | removed 5. Coated with bitu- | Paint gone in| Similarto4B Paint blistered | Paint almost in- men-base paint | some __ places | but intact tact above level of liquid, but mortar sound Aluminous Cement | Mortar | 6. Untreated _ | Sound Sound Sound | Sound 7. treated with | Sound Sound Sound | Sound magnesium) | | silicofluoride plant. The amount of attack on the specimens was small in every case, but some softening and erosion occurred in cubes of untreated Portland cement mortar. Under these condi- tions of exposure the rate of attack of Portland cement mortar was reduced by treatment with sodium silicate or with magnesium silicofluoride. Tar-base and bitumen-base paints, though partly removed after exposure for 15 months, gave complete protection against softening of the mortar during this period. Aluminous cement mortar was unaffected under the conditions of the test. Summarizing the results of the experiments, the greatest rate of attack occurred in speciinens exposed to liquid in the storage and balancing tank where the acidity, con- centration of organic matter, and temperature were highest. Under the most severe conditions, treatment of Portland cement mortar with sodium silicate or with magnesium silicofluoride had a slightly adverse effect on the resistance of the mortar, but gave some protection under less severe conditions of exposure. Tar-base paint and bitumen-base paint afforded protection to the mortar for a short time, but were removed by softening and powdering under the more severe conditions of exposure within the period of the tests, and attack of the mortar then occurred in some cases. Bitumen-base paint was more effective than tar-base paint. The only completely, satisfactory material tested was untreated aluminous cement mortar, which was unaffected under any of the conditions of exposure. [Lables LXXXI and LXXXII follow]