Organic and hydraulic shock loadings on a biological aerated filter

The performance of a biological aerated filter (BAF) during short-term (60 min) organic and hydraulic shock loads was investigated. The BAF used for t he present experiment was not capable of absorbing high peak organic shock loads when the organic loads were increased from a normal load of 1.2-1.4 k g soluble chemical oxygen demand (sCOD) m(-3) d(-1) to shock loads between 5.1- 7.3 kg sCOD m(-3) d(-1), based on empty bed volumes. Nevertheless, the effect on the biomass was limited as normal performance resumed very quick ly. Increases in the hydraulic velocity from 0.7-1.0 m h(-1) to 1.5-2.9 m h (-1) had little effect on BAF performance in terms of soluble COD removal. Yet, sCOD effluent concentrations of <55 mg l(-1) (<similar to>22 mg l(-1) biochemical oxygen demand) were alway; achieved. The recovery of the reacto r in both cases was fast, resuming normal performance within 60 min after t he application of the shock load.