Friday, October 10, 2008

Biological Aeration

Nualgi - Biological Aeration

Aeration is one of the most critical and expensive processes in Wastewater Treatment. Sewage Treatment Plants and Effluent Treatment Plants that use aerobic process have to provide the oxygen required by the aerobic bacteria to enable them to breakdown the organic matter in sewage.

Aeration is conventionally done using mechanical electric powered aerators. The power consumption by the aerators is very high and accounts for upto 50% of the operating cost of the STP / ETP. In addition it leads to emission of CO2 at the power generation plants.

Diatom Algae are a specie of beneficial algae (unlike Green Algae and Blue Green Algae) that can grow rapidly and these are microscopic aquatic plants that release oxygen during photosynthesis.

These however require iron, silica and other minerals to grow rapidly. Nualgi is a plant nutrient that provides all the nutrients required by diatoms and this results in a rapid bloom of diatoms within minutes of dissolving Nualgi in the water body.

1 kg of Nualgi results in release of about 100 kgs of oxygen over 5 days, this increases the DO level of the water to about 6 mg / litre. Regular use of Nualgi will maintain the DO level.

The aerobic bacteria breakdown the organic matter into base constituents and this becomes food for the diatoms. Thus diatoms and aerobic bacteria have a symbiotic relationship – Diatoms provide the oxygen required by bacteria and the bacteria provide the food required by the diatoms.

The cost of 1 kg of Nualgi is just Rs. 275/- and this treats about 4 million litres of water, thus cost of aeration is just Rs. 0.07 per kilo litre.

Use of electric powered aerators also results in emission of Carbon dioxide by the power plants. Whereas use of biological aeration results in absorption of Carbon dioxide by the diatoms.

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