Decontamination of aqueous liquors

摘要

Aqueous liquor is decontaminated by passing it through a body of finely-divided soil which has been aggregated into a water-stable granular form by admixture with a water-soluble linear polymer or copolymer containing hydrophilic groups. The preferred proportion by weight is from 0.05 to 1 per cent in the range 0.005 to 5 per cent. The molecular weight of the additive is preferably in the range 30,000 to 100,000 as determined by the Debye light-scattering method. The polymer or copolymer may contain numerous recurring units indicated by the structural formula: where X is selected from -OM, ONH4, -ONRH3, -ONR2H2, -ONR3H, -OH, -NH2, -OCH2NR2, -OCH2CH2NR2, -OCH2CH2NHR, -OCH2CH2 NH2, -NHR or -NR2, M being an alkali metal, R being an alkyl group having one to four carbon atoms and m being zero or one. Examples of these are polyacrylamide, the ammonium salt of polyacrylic acid and hydrolysed polyacrylonitrile. Alternatively the polymer may contain numerous recurring units having the formula: in which X and Y are selected from -OM, -O 1/2 L, -ONH4, -ONR1H3, -ONR12H2, -ONR13H, -OH, -NH2, -OCH2-N-R2, -OCH2-CH2-NR2, -OCH2CH2NHR, -OCH2CH2NH2, -OR, -NH-C2H4-NR2, -NHR or -NR2, not more than one of X and Y being -OR, or in which X and Y together are -O-; M being an alkali metal and L an alkaline earth metal and R being an alkyl group having one to four carbon atoms and R1 being an alkyl group having one to four carbon atoms or a -CH2CH2OH group; Z, Z1, Z11 and Z111 being selected from -OCOCH3, -OCOH, -OH, -Cl, -CH3, -COOH, -C6H5, -H, -OR, or -COOR, at least two of Z, Z1, Z11 and Z111 being hydrogen atoms, and not more than one thereof being -OCOCH3, -OH, -C6H5, -OCOH, -OR, -COOR or -COOH, a chlorine and a methyl group when simultaneously present being attached to the same carbon atom; and Q and Q1 being both hydrogen atoms or one being a hydrogen atom and the other a chlorine atom or a methyl group. Examples of these are the sodium, ammonium and calcium salts of a copolymer of vinyl acetate and maleic acid. The Specification contains many other examples of both kinds. The soil may be excavated, mixed with the polymer or copolymer and then aggregated by mechanical working. After suitable granules have been formed the treated soil may be moved by bulldozers or the like into open tanks having water-impervious walls. Backflushing means may be provided. Alternatively the solution or suspension to be treated may be passed into a large open area the surface of which has been aggregated to a substantial depth by means of the additive, the treated liquid being allowed to dissipate through the sub-soil; or the treated area may be gently sloped so that the liquid collects at a lower point and may be conducted away by a channel. Where the liquid contains substantial quantities of solid matter the area may be regenerated by scraping the surface and if necessary retreating the new surface with additive. Liquids such as milk wastes, distillery wastes, fermentation wastes and paper manufacturing wastes may be fed to aggregated soils on slightly sloping areas or in shallow receptacles in quantities such that the soil interstices are not entirely filled with liquid, under which conditions an optimum rate of aerobic bacterial decomposition may be achieved. Sewage is also referred to.