Waste water purification - by directly passing filtrate from combined fabric and alluvial layer filter to biological filter

摘要

In the Parent Patent, waste water purificn. and lowering of biological oxygen demand for waste water purificn. are achieved by treating the waste water with flocculating auxiliaries, pref. precipitants combined with polyacrylate and/or polyacrylamide, and combining pre-clarifying with the sepn. of most of dispersed colloids. The solids-contg. treated waste water is passed under gravity through a support fabric in a mount, whereby (A) a combination filter is formed of (a) fabric and (b) a prim. filter layer of sepd. solids, and, (B), more waste water is purified from most of solid particles on passing through combination filter. The filtrate obtd. is then purified biologically. The filtrate leaving the filter wall is passed directly over a large-surface biological filter unit, in which biological treatment takes place. The filtrate is enriched in O2, e.g. from 1.5-2- to 8-9 mg/l. O2-enrichment and fine O2-distribution in filtrate are made use of for biological treatment of filtrate. Energy consumption and operational costs are reduced.