Reduction of organic compounds content of the wastewater milk industry using composite permselective materials

The wastewater results from different foods industry are generally characterized by a high organic load, far above limits discharge referred to legislation. In particular the wastewater results from different technological phases of milk industry processing, contain high quantities of organic compounds, especially proteins (caseine, β-lactoglobuline, α-lactalbumine, serumalbumine, immunoglobuline), lipide (mono, di and triacilglicerides, free fat acids, phospholipids) and disaccharides class (especially lactose). In the treatment processes, the membrane techniques – microfiltration, ultrafiltration, reverse osmosis – are frequently used for their advantages: are continuous processes, the energetic consumption is very low, not implies temperature and phase changes, not uses chemicals adjuvant, occur in modular equipment. The paper present the experimental results obtained in the ultrafiltration process of a wastewater from milk industry processing- washing the reactors from production of yoghurt. The aim of the experiments was to studied the correlation between the membrane characteristics and the reduction of the organic compounds from the wastewater. 2 composite ultrafiltration membranes were used, polysulphone-polyaniline types, different by monomer used on policondensation chemical reaction in porous structure of the base polymer.
The experimental setup that has been used was the KMS Laboratory Cell CF-1 (Koch-Membrane - Germany) ensuring a tangential flow mode in separated process. The following indicators were analyzed from the water samples (the feed wastewater, the permeate and the concentrate): TOC, BOD, COD, total nitrogen, protein contents, conductivity. In the same time were studied the hydrodynamic, electroconductive and structural characteristics of the membranes. Relevant in these experiments were:
- reduction the proteine contents in permeate to 42%
- higher reduction of the DOC contents in permeate to 92%
The BOD/COD ratio in the permeate samples was above 0,3, which indicate the remanent biodegradable characteristics. In this case its possible to introduce the water on the biological treatment setup improving their performances.