Is it Possible to Achieve MBR Effluent With No Color?

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Is it Possible to Achieve MBR Effluent With No Color?

Membrane bioreactor (MBR) is a wastewater treatment process which combines membranes with the biological process.

The combination of membrane filtration and a suspended growth bioreactor efficiently removes organic and suspended solids.

UF membrane side stream configuration, Representative image,
Source: Wikimedia Commons, Author:  Aquabio Ltd.

The MBR, unlike the conventional activated sludge (CAS) system, doesn’t use a secondary clarifier or a settling tank which would allow the solids to settle and separate them from the liquid. Instead, membranes are used for this purpose. This results in much better water quality.

MBRs produce high quality effluent – the water, after being treated in the MBR is of extremely high quality since all the biomatter, solids and microorganisms are filtered. The effluent is directly reusable or recyclable and can be release in the environment.

MBRs can treat up to 48 million liters of wastewater per day.

Color from natural organic matter:

Natural organic matter (NOM) colors the water. Though the effluent water might meet the standards, it is aesthetically unappealing so industries are trying to remove the water color.

NOM is a range of materials (from catchments in surface and ground water to organic materials from domestic, industrial or agricultural sources) and differs depending on the season.   

Color in effluent wastewater from industries:

If color originates from textile, paper and pulp, dye, tannery or pharmaceutical industries, the color is more difficult to remove.

Color originates from phenolic compounds (tannins, lignins) and organic colourants.

The following methods, including some inexpensive materials, can be used to remove dye from water:

  1. Bagasse pith – an affordable adsorbent. Bagasse is a byproduct in sugarcane mills. It adsorbs dyes from water.
  2. Peat – an adsorbent for polar organic compounds from dye. It is affordable and doesn’t need to be activated in any way.
  3. Wood chips – adsorbs dyes and color-causing polar organics but it is hard and requires longer contact time.