Return of filter washings and sludge treatment at the Western Filtration Plant of Ekaterinburg

Summary

In order to abandon discharging polluted filter washings into the water source a system of filter washings treatment in ultrafiltration membranes for reusing was developed alongside with a unit for the treatment of sludge generated at the filtration facilities. The method of ultrafiltration is at the heart of the filter washings treatment technology. Filter washings from the main process line are filtered through special membranes that provide for the separation into clean water (permeate) and concentrate (sludge). The sludge from horizontal clarifiers of the main process line and the sludge from the ultrafiltration unit are removed to the sludge treatment facilities. Precipitated sludge with a moisture content of 98.5% is removed by the scraper system into the sump whereof it is transported further to the belt thickener and then into the chamber filter press. Dewatered sludge with a moisture content of 75% is transported by trucks to the solid waste landfills. The implementation of these innovations provided for the significant reduction of water amount used for own needs; thus, the total water losses do not exceed 1.5%; water abstraction from the water source was also reduced as well as the water supply deficit. The results of the first several months of the ultrafiltration facilities operation showed that the quality of the treated drinking water met the requirements of the sanitary regulation and standards.

Key words

ultrafiltration , filter washings reuse , sludge treatment , water supply deficit

Study of the quality of supernatant separated in the process of sludge thickening at the water treatment plant in Rostov-on-Don

Summary

The results of studying the qualitative and quantitative composition of supernatant separated from the sludge after sedimentation tanks washing at the water treatment plant in Rostov-on-Don. The chemical water analysis carried out in accordance with Standard Methods showed that the given effluent type does not meet the requirements set to the discharge into the municipal sewer and poses a threat to the environment. In connection with this the technology of wash water reuse was chosen as the most efficient under the given conditions. It provides for the effluent returning into the mainstream of the water to be treated or using it for the water plant needs. At that the effluent organoleptic properties shall be considered: at 5 hours sedimentation of sludge with 5–40 g/dm3 concentration it can be classified as low-turbid, medium or high colored (depending on the season of sludge generation in the sedimentation tanks). Increasing the time of supernatant retention above the sludge (up to 120 hours) insignificantly improves the clarification and decoloration efficiency that is indicative of the presence of highly dispersive and dissolved substances highly resistive to sedimentation in supernatant. Improving significantly the supernatant quality is possible by sludge pre-conditioning with lime or cationic polyacrylamides.

Key words

sedimentation tank , filter washings reuse , slime water , sludge thickening , supernatant

Reuse of stained wash water for washing fabric after dyeing

Summary

The processes of aqueous work up of the fabric used at the textile enterprise «Svitanak» OJSC were studied during the fabric preparation, dyeing and subsequent washing. The quality of wash water at various stages of washing the fabric after dyeing was studied by such indicators as the color intensity by dilution rate, COD, permanganate index, foaming capacity and pH. Experimental data are presented that prove the possibility of using ozone for the purification of the wash water mixture from the last six fabric washings after dyeing to the requirements to the quality of water supplied to the dye-finishing processes. An approximate economic calculation has been performed that proves a high economic effect of establishing the reuse of wash water regenerated with ozone for washing fabric after dyeing.

Key words

ozonization , chromaticity , permanganate oxidizability , filter washings reuse , countercurrent , textile industry , fabric dyeing , apparatus of batch operation , color intensity by dilution rate