Membrane bioreactor as polishing step in the treatment of galvanic wastewater

B. Mayr*, T. Garstenauer, EnviCare Engineering GmbH, Austria

In galvanic industry wastewater is formed as a byproduct in surface treatment processes of metallic compounds. The common primary treatment steps are flocculation and precipitation. Depending on the applied unit operations the filtrate of the subsequent chamber filter press usually contains significant amounts of COD, heavy metals (e.g. zinc, iron, chrome) and also filterable solids. In order to reach direct discharge quality a final treatment step is necessary.

In membrane bioreactors (MBR) biological wastewater treatment is combined with membrane technology. Organic compounds will be degraded under aerobic conditions and the activated sludge is confined in the biological system by micro- or ultrafiltration membranes.

Of course, heavy metals cannot be degraded by microorganism, instead the metals are removed from the wastewater through various mechanism such as incorporation of precipitated metals in sludge flocs, adsorption, binding and complexation of metal ions in extracellular polymeric substances (EPS) and diffusion of metal ions into the activated sludge flocs. These heavy metals can also have inhibiting or toxic effects on the biomass in a biological wastewater treatment system.

This article deals mainly with design, construction and operation of an MBR-plant as polishing step in the cleaning of galvanic wastewater.

The project started with a MBR pilot plant, which was installed and operated during a period of three months, in order to evaluate the fundamental suitability of this treatment process. The pilot test showed that the MBR-process is suitable to reach direct discharge quality for the filtrate from the chamber filter press. Based on the results from the pilot phase, a large-scale plant was designed, constructed and operated.

After one month of operation in the pilot phase the COD concentration in the outflow was...

Session: M5 - Process and Waste Water Treatment
Day: 23 October 2019
Time: 13:00 - 14:15 h

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