A hybrid system to treat waste water, produce bio-diesel

Current sewage treatment facilities in the country can only treat about 26 billion litres per day.   | Photo Credit: VG

Researchers at the Indian Institute of Technology, Hyderabad (IITH) are developing algal-bacterial hybrid systems that can reduce the cost of waste water treatment, in addition to providing practical routes to producing recyclable water and bio-diesel. These systems serve the dual purposes of waste water treatment and bio-diesel production.

The research team comprising Debraj Bhattacharyya, Associate Professor, Department of Civil Engineering, and research students Anjana Babu, Keerthi Katam, Marttin Gundupalli, Aishwarya Pandey, Raj Kumar Oruganti, and Vinod Vadithya have worked in this project. The results of this work have been published in the past couple of years in reputed peer-review journals such as Journal of Industrial and Engineering Chemistry, Water Environment Research, and Environmental Science and Pollution Research.

“Decentralised waste water treatment is essential in cities of a country like India where the total waste water generated from Class I cites and Class II towns have exceeded 75 billion litres per day,” said Dr. Debraj Bhattacharyya.

Current sewage treatment facilities in the country can only treat about 26 billion litres per day. The unavailability of an extensive centralised system of waste water treatment in class I cities and class II towns results in the discharge of untreated waste water into water bodies and land, resulting in severe pollution and contamination issues.

Dr. Bhattacharyya added. “One step in current sewage treatment systems is aerobic biological treatment (for example, Activated Sludge Process) in which, microorganisms, dominated by heterotrophic bacteria, use oxygen to break down organic matter.”

While aerobic treatment converts organic matter into carbon dioxide and biomass, they have problems such as high energy use (primarily to satisfy oxygen demand of such processes) and production of too much sludge which is often difficult to dispose of.

Micro algae have the ability to eliminate the problems faced in conventional aerobic biological treatment processes.

“An additional benefit of using algal-bacterial systems for waste water treatment is that the algae that are grown in sewage treatment plants can, in turn, be used to produce bio-diesel and other value-added by-products. If all sewage is treated in microalgae-based systems, the total theoretical algae-derived bio-diesel production would cut our dependence on petroleum-derived diesel noticeably. However, harvesting of microalgae presents a greater challenge than operating the systems for waste water treatment,” adds Dr. Bhattacharyya of the immense promise of the technology.

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Printable version | Nov 29, 2021 5:19:58 AM |

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