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Water pollution in India is posing a significant threat to human health. Large volume of unprocessed wastewater is being discharged by industries into fresh water sources, resulting in frequent outbreaks of waterborne diseases and environmental degradation. While the overall investment potential of the Indian water sector is estimated to be about $130 billion by 2030, the total water and wastewater treatment market alone would be worth about $420 million, with an annual growth rate of 18%. The Wastewater treatment industry in India is definitely looking to grow rapidly in the coming years.

TECHNICALLY, WASTEWATER treatment process comprises chemical, biological and physical treatment. Various chemicals are used at the initial stage to oxidize the soluble organic compounds. Chemical reactions are much faster than the biological process as the latter requires huge retention time that allows live biomass (Bacteria, Bio-phage, Protozoa, Rotifers, or Fungi) to produce thousands of extracellular enzymes suitable to degrade the remaining organic matters coming out or un-oxidized compounds from a chemical reaction.

There are several biological processes as well, which are being used for wastewater treatment. The process implemented depends on the nature of pollutants and on the stringent discharge norms laid down by Pollution Control Boards. Clear understanding is essential for selecting suitable biological processes and we need to understand the nature of effluent to be treated and the end use of the treated effluent.

The biological process is selected based on the nature of raw materials being used in the manufacturing process of the products like, organic solvents, fats, alcohol, humic acid, tannins, dyes and intermediates , All manufacturing ingredients (API) among others. Such manufacturing products require more retention time in order to complete degradation process. Therefore, it is advisable to adopt the combination of biological processes like, moving bed bioreactor (MBBR) with Activated Sludge Process (ASP) or Moving Bed Bio Reactor (MBBR) with Sequential batch reactor (SBR). These combinations are also economically viable. However, ASP though is proven biological process may become expensive in Capital expenditure (CAPEX) & operating expenses (OPEX).


The biological process becomes an imperative and integral part of the wastewater treatment for municipal as well as industrial purposes. Each of the pollutants in the form of Biochemical oxygen demand (BOD) or chemical oxygen demand (COD) requires selective enzymes that are being secreted outside the cell of biomass. The process gets completed by a series of such selective enzymes over a designed period of retention time. This leads to significant reduction in BOD or COD by biological process in comparison to the chemical treatment. Moreover, selection and the combination of biological processes have a greater advantage over conventional treatment processes.

In terms of both operational as well as capital costs for thermal oxidation, the biological process is far superior to other processes like chemical treatment. More is the chemical utilization, more is the sludge production. This makes the total treatment expensive and questionable too. It is, therefore, essential to select and make the biological process much stronger with an aim to eliminate chemical treatment.

Types of biological processes

Membrane Bio-Reactor – The advanced biological process called ‘Membrane Bio-Reactor’ (MBR) is being implemented on a huge scale these days. Although it avoids ultra-filtration (UF) for the downstream membrane process, there are several disadvantages of this sophisticated technology and therefore it becomes limited.

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