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New Membrane Bioreactor Passes the Test

by 5m Editor
16 January 2009, at 9:41am

FRANCE - A membrane bioreactor performed well in greatly reducing odours and soluble phosphorus levels in wastewater at a small piggery, according to research at the University of Rennes.

Effective aerobic/anoxic treatment of piggery manure wastewater was achieved in a real farm scale using a small piggery (72 pigs) with reuse of the treated water. The experimental procedure was followed for nine months.

Fresh manure (FM) is formed by daily flush on piggeries and biologically treated after centrifuge pre-treatment. For upgrade liquid/solid separation and pathogen retention in biological treatment, a membrane system was used with the aim of effluent reuse in flush.

Despite an evolution of FM through time, centrifuge pre-treatment and bioreactor performances stayed at high level. An elimination of 86 per cent of the suspended solids occurred through pre-treatment, and nitrogen and COD biological degradation remains at 90 per cent over time.

Moreover, interestingly about half of the soluble part of phosphorus (20 per cent of the total phosphorus content) was biologically removed via the recirculation between the anoxic and the aerobic tank which acted as an intermittent aerobic/anoxic sequence.

A part of COD was proved to be non-biodegradable and was accumulated via the reuse of the treated water for flushing purpose. This accumulation justifies washing of the biomass between two runs in purpose to enhance the treated water quality and also to meet the membrane tolerance.

The membrane was proved reliable as far as the maintenance procedure was respected. Maintenance cleaning had to be operated as soon as the TransMembrane Pressure (TMP) achieved 50mbar and curative washing was necessary if the TMP increased over 90mbar or between 2 runs. The temperature was proved to influence both the bioactivity and the membrane fouling kinetic.

It was concluded that the process was sustainable for long-term management of swine wastewater at a semi-industrial scale.

Reference

Prado N., Ochoa J. and Amrane A. 2009. Zero nuisance piggeries: Long-term performance of MBR (membrane bioreactor) for dilute swine wastewater treatment using submerged membrane bioreactor in semi-industrial scale. Water Research, 2009 Jan 3. [Epub ahead of print]