Runoff water from small treatment plants

This page is a translated version of the page Ablaufwasser aus Kleinkläranlagen and the translation is 100% complete.

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In Europe, the quality of water discharged from small treatment plants is governed in 91/271/EEC directive.

Class CSB mg/l BSB5 mg/l NH4-N mg/l Nanorg. mg/l P mg/l Faecal coliforme Keime je 1000 ml AFS mg/l
C 150*/100*** 40*/25** - - - - 75*
N 90*/75*** 20*/15** 10** - - - 50*
D 90*/75*** 20*/15** 10** 25** - - 50*

* obtained from certified sample, ordinary sample of faecal coliform bacteria

** ** determined from 24 h mixed sample; NH4-N and Nanorg.. with temperature of discharged water T ≥ 12°C

Most modern water treatment plants have improved over BOD5 discharge values of < 25 mg/l.