| 摘要 |
A method for recovery of wastewater residues containing the activated sludge biomass, fibre and rind and recycling the recovered residues back to the main production process comprising the steps of treating the waste water residues with alkali solution having a concentration of 5-80 g/l on the Na2O basis at a temperature of 20-70 DEG C and dewatering, e.g. in a vacuum filter, the reaction mixture obtained, the alkali filtrate decanted containing the activated sludge alkali hydrolysis products being used to dissolve the melt in the course of preparing an alkali pulping liquor used in the main production process, and the dewatered alkali mass being added, in an amount of up to 40 percent by mass, to a fibred mass composition for the manufacture of cardboard and wood-fibre board. The alkali solution may be a white sulphate liquor. From a sump 1, waste activated sludge is forwarded to a mixer 2 to which sewage containing fibre and rind is also fed. The mixture is dewatered in a vacuum filter 3, and the filtrate decanted from the vacuum filter is forwarded for washing the pulp or discharged on the purification structures. The dewatered layer of the residue is placed in an agitator 4 where the alkali solution (on an Na2O basis) is added. Liquid and solid phases are finally obtained from a second vacuum filter 5. <IMAGE> |
