Not letting solid waste go waste

Banking on renewable energy:A. Gangagni Rao, senior principal scientist, explaining the project to his students at CSIR-Indian Institute of Chemical Technology in Hyderabad.— Photo: Nagara Gopal  

Hazardous open dump yards or expensive landfills? While local governments continue to scratch their head about garbage disposal with power plants too not taking off, the CSIR-Indian Institute of Chemical Technology (IICT) has come out with a novel high-rate Anaerobic Gas-lift Reactor (AGR).

The reactor helps convert solid waste into biogas and bio-manure with better efficiency when compared to earlier versions of the digesters.

The new age AGR, inspired by its modern versions in Europe, developed for Indian conditions by Gangagni Rao and his team ensures high rate of biogas production through appropriate mixing, biomass high density, buffering capacity, slurry concentration, microbial culture inhibition mechanisms etc.

“Earlier version of small conventional digesters using cattle manure to generate gas and bio-fertiliser became inoperable after a while because of accumulation of scum, choking and poor biogas quality. They could not be scaled up too,” explains Dr. Rao, senior principal scientist, bioengineering and environmental sciences division, IICT.

He points out that since food waste or fruits and vegetable waste are available in large quantities and highly bio-degradable, they can be utilised for generating renewable energy, biogas, instead of taking them to landfills thereby saving land and conserving energy.

After obtaining the patent, the AGR technology was transferred to a local firm, Ahuja Engineering Services Pvt. Ltd, to execute the projects on turnkey basis.

The IICT provides technical guidance and supervision besides getting royalty.

Initially a biogas plant was tested using poultry litter at Pedda Shivanoor, Chegunta mandal, Medak district, where for one tonne of poultry a day, 200 kg of bio-manure was produced and 89 kWh power was generated for operation of farm pumps, Dr. Rao says.

Though it is shut now, Akshaya Patra Foundation, which runs the mid-day meals scheme, is successfully running AGR plants with investment of less than Rs. 50 lakh each at Bellary and Ahmedabad utilising up to 1.5 tonnes of food waste a day and replacing LPG cylinders with biogas for kitchens. Another plant is coming up at Hubli.

More enterprising is the proposed Rs. 2.5 crore biogas plant at KL University in Vijayawada (AP) utilising up to seven tonnes of organic waste to generate power up to 300 kWh a day, besides 10 tonnes of bio-fertiliser. It was also among the nine out of 140 chosen for the PACESetter Fund under Indo-US Science and Technology Forum (IUSTF).

The forum is funding Rs. 2 crore while KL University’s grant is Rs. 50 lakh, says Dr. Rao, adding that the cost of any plant depends on the quantity and quality of waste treated and the location. An alumnus of IIT Delhi (M.Tech) and AU (B.Tech), he has patent for a ‘biofilter’ too for purification of waste and gases emanating from industry that could adversely affect health of people living nearby.

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Printable version | May 15, 2021 6:36:17 AM | https://www.thehindu.com/news/cities/Hyderabad/Not-letting-solid-waste-go-waste/article14470143.ece

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