Students and researchers associated with Harcourt Butler Technical University (HBTU) have explored the conversion of food waste, sewage sludge, seaweed-processing waste and wheat straw into methane and biogas, highlighting potential routes for combining waste management with renewable gas production.
The research involved two former MTech students, Prateek Mishra and Harshit Gupta, whose studies were conducted over about 10 months with support from HBTU and Malaviya National Institute of Technology (MNIT) Jaipur.
Mishra investigated the co-digestion of leftover food from HBTU hostels with sewage sludge, while Gupta studied biogas production from seaweed-processing waste and wheat straw using anaerobic digestion and thermal pretreatment.
Food waste and sewage sludge used for methane production
Mishra collected leftover and discarded food from 10 HBTU hostels over a one-week period. He combined the food waste with sewage sludge collected from the sewage treatment plant at MNIT Jaipur.
The two feedstocks were used in an 80:20 proportion and processed in a reactor to assess their potential for methane production.
According to the research findings reported by HBTU, the combination produced a substantial increase in methane yield compared with the reference conditions used in the study, with the reported improvement reaching up to 240%.
The research also examined the carbon-to-nitrogen (C) balance of the feedstock mixture. The reported C value was around 6–7, compared with a commonly cited range of approximately 20–25 for anaerobic digestion feedstocks.
A lower C ratio can affect the balance of nutrients available to microorganisms during anaerobic digestion, making feedstock selection and co-digestion strategies important when developing a stable biogas process.
Ten months of laboratory research
According to Dr Lalit Kumar Singh, Head of the Department of Biochemical Engineering at HBTU, both students carried out their research continuously for around 10 months.
The experimental work was conducted in laboratories at MNIT Jaipur, while the food waste used in Mishra’s study was sourced from HBTU’s hostels.
Singh said the findings were considered significant at the university laboratory and that the research had been submitted to the Chemical Engineering Journal for publication.
The publication status of the reported research could not be independently confirmed from the publicly accessible sources reviewed for this article.
Seaweed waste and wheat straw tested for biogas
Gupta’s research focused on another combination of unconventional feedstocks: waste generated during seaweed processing and wheat straw.
His study examined the two materials individually as well as in different combinations for biogas production through anaerobic digestion.
The research also investigated thermal pretreatment as a way of improving the biodegradability of the feedstocks. According to Gupta’s publicly available academic profile, his dissertation specifically examined biogas production from seaweed-processing waste through co-digestion with wheat straw and evaluated thermal pretreatment under different conditions.
Anaerobic digestion converts biodegradable organic matter into biogas in the absence of oxygen. The resulting gas typically contains methane and carbon dioxide, with methane providing its energy value.
The research explored elevated-temperature treatment, including tests at 100°C, before digestion. The findings indicated that suitable combinations of seaweed-processing waste and wheat straw, together with thermal pretreatment, could improve the conversion of these materials into biogas and methane.
Turning difficult waste streams into renewable gas
The two studies point towards a broader approach to anaerobic digestion in which multiple waste streams can be combined to improve resource recovery.
Food waste is rich in readily biodegradable organic matter, while agricultural residues such as wheat straw contain more structurally complex lignocellulosic material. Sewage sludge, meanwhile, is a residual material generated during wastewater treatment.
Research into co-digestion of food waste with wastewater-derived materials has previously demonstrated the potential for improving methane production compared with digestion of individual feedstocks under certain conditions.
For decentralised biogas systems, the availability of locally generated organic waste could potentially reduce the need to transport feedstocks over long distances. However, actual commercial performance would depend on factors including feedstock composition, moisture content, contamination, pretreatment requirements, reactor conditions and methane recovery efficiency.
HBTU research explores multiple waste-to-energy pathways
Prof. Lalit Kumar Singh said the research demonstrated the potential of using several locally available waste materials, including food waste, sewage-treatment sludge, crop residues and seaweed-processing waste, for methane production.
He also suggested that such feedstocks could potentially be considered for biogas plants in rural areas, where agricultural residues and other organic wastes are available.
The work adds to a growing body of research examining anaerobic digestion as a route for recovering energy from organic waste. Sewage sludge, for example, has also been studied through other biological and thermochemical pathways for methane recovery.
For India, the significance of such research lies not only in renewable gas production but also in the potential integration of waste treatment and energy recovery. Converting food waste, agricultural residues and other organic materials into biogas can create a pathway in which waste streams become feedstocks for energy production rather than remaining solely as disposal challenges.
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The HBTU research illustrates the importance of feedstock combinations in developing biogas systems. Rather than relying on a single waste stream, co-digestion can allow operators to combine materials with different physical and chemical characteristics, potentially improving digestion performance when the mixture and operating conditions are properly controlled.
However, laboratory results should not be interpreted as evidence of immediate commercial-scale gas production. The reported methane-yield improvements will need to be evaluated through reproducible experiments, peer-reviewed publication and, ultimately, larger-scale trials before their practical potential can be established.
The research nevertheless highlights an important area for India’s circular bioeconomy: linking food waste, wastewater residues and agricultural biomass with decentralised renewable-gas production.
