Kalaichelvan Gurumurthy

Bio: Kalaichelvan Gurumurthy is an academic researcher from VIT University. The author has contributed to research in topics: Fermentation & Probiotic. The author has an hindex of 3, co-authored 7 publications receiving 32 citations.

Enhanced bioleaching of copper from circuit boards of computer waste by Acidithiobacillus ferrooxidans

Abstract: Computer circuit boards are a major electronic waste containing higher concentrations of copper, gold and silver. These metals may be recovered by bioleaching, an eco-friendly process to recover metals from natural ores. However, the application of the bioleaching to electronic waste is still in the infancy stage. Here, the bioleaching capability of Acidithiobacillus ferrooxidans to extract copper from printed circuit boards was investigated at laboratory scale using shake flasks. The effect of initial pH, amount and size of printed circuit boards, and volume of inoculum on copper dissolution rates were evaluated. Results show that the highest dissolution rate of 32.44% was achieved after 7 days of leaching at initial pH 2.0, 10 g/L of waste printed circuit board, 40% v/v of inoculum for 1 mm size of circuit board. The smallest size of 1 mm induces the higher dissolution rates, which is explained by higher surface area and thus better bacterial adhesion. Also, the copper dissolution rates increase with the inoculum volume. Overall, bioleaching of copper from waste printed circuit boards using Acidithiobacillus ferrooxidans is achievable.

Characterization of end-of-life mobile phone printed circuit boards for its elemental composition and beneficiation analysis.

Abstract: Globally, waste electrical and electronic equipment is one of the fastest-growing waste sectors. Mobile phones constitute the major portion of the telecommunication e-waste category. Over the years...

A study on the fermentation pattern of common millets in Koozh preparation - a traditional South Indian food

Abstract: Koozh is a popular South Indian traditional food made from finger millet (Eleucine corocana Gaertn.). The traditional preparation method was applied to other common millets, viz. Pearl millet [Pennisitum typhoides (Burm.f.) Stapf & C.E. Hubbard], Sorghum (Sorghum bicolor (L.) Moench and Maize (Zea mays L.). The fermentation process was monitored for microbial succession. The biochemical changes and sensory properties were evaluated and compared with traditional finger millet fermentation process. Microbial profile and biochemical changes in selected millets were identical to traditional fermentation process. Starch hydrolysers were the primary players in the initial hours (0 -10 hrs) of fermentation in all grains, while lactic acid bacteria (LAB) dominated the later hours (0 – 15 hrs). Starch hydrolysis was the major biochemical transformation occurred during the initial fermentation period, and in later conversion of sugar into acids took place which made the medium acidic. Koozh prepared from pearl millet and sorghum had sharp flavor and received acceptability from consumers, while Maize Koozh did not appeal to the consumers. This study is an attempt to add variety to traditional process and to improve commercial value and marketability.

Microbiological leaching of metals and its recovery from waste electrical and electronic equipment: a review

Abstract: Electronic waste or waste electrical and electronic equipment (WEEEs) is an emerging and fast-growing waste stream with complex characteristics. As per United Nations 'Global E-waste Monitor report, 2015' (Balde et al., 2014), the global quantity of total e-waste generated in 2014 was around 41.8 million metric tonnes (MT). The presence of metals like copper, aluminium, iron and various precious metals like gold, silver, palladium, platinum, etc., in high concentrations, made e-waste an 'urban mine'. Bioleaching is one of the successful bio-hydrometallurgical method, which can be employed for metal recovery from different WEEEs. Recovery of precious metals like copper, gold and silver is possible at high concentrations from WEEEs using acidophilic mesophiles and thermophiles and some fungal species. The current paper mainly aims to reflect on e-waste generation, mechanisms of bioleaching and various microorganisms employed for the extraction of metals from the electronic waste.

Neural network prediction of bioleaching of metals from waste computer printed circuit boards using Levenberg‐Marquardt algorithm

Abstract: The applicability of artificial neural network (ANN) to predict the bioleaching of metals using from computer printed circuit boards (CPCB) and the influence of process parameters were studied. The influence of process parameters initial pH (1.6‐2.4), pulp density (2%‐13%), and the initial volume of Inoculum (5%‐25%) were investigated on the rate of bioleaching of metals from CPCB. Network inputs were fed as initial pH, pulp density, and inoculum volume and with the extraction of Cu, Ag, and Au as output. The ANN was developed using the Levenberg‐Marquardt algorithm and trained for modeling and prediction. The most fitting architectures for Cu, Ag, and Au were [4‐5‐5‐2‐1], [4‐7‐5‐2‐1], [4‐7‐1‐1‐1] trained with Levenberg‐Marquardt algorithm, respectively. The R values were observed to be 0.996, 0.997, and 0.993 for Cu, Ag, and Au extraction predictions, respectively. The genetic algorithm model defined by ANN was used to achieve maximum extraction rates for Cu, Au, and Ag. The predicted data showed that there is a great capability of using ANN for the prediction of Cu, Ag, and Au extraction from CPCB through bioleaching process. Hence, the ANN model can be used to control the operational conditions for improved metals extraction through bioleaching.

Bioleaching: urban mining option to curb the menace of E-waste challenge.

Abstract: Resource Recovery from Waste Electronics has emerged as one of the most imperative processes due to its pressing challenges all over the world. The Printed Circuit Board (PCB) is one of the typical E-waste components that comprise large varieties of metals and nonmetals. Urban Mining of these metals has received major attention all over the world. The existing treatment procedures used extensively for the resource extraction are hydrometallurgy and pyro-metallurgy and crude recycling practices in the informal sector. However, these methods are prone to cause secondary pollutants with certain drawbacks. Also, the existing informal recycling procedures resulted in insignificant occupational health hazards and severe environmental threats. The application of biotechnology is extensively exploited for metal extraction and emerged as one of the sustainable and eco-friendly tools. However, a limited field-scale study is prevailing in the realm of resource recovery from E-waste using bioleaching method. Hence, the application of bioleaching requires more attention and technical know-how in developing countries to curtail crude practices. The application of bioleaching in E-waste, including its available methods, kinetics mechanism associated opportunities, and barriers, have been discussed in this paper. A glance of E-waste management in India and the menace of 95% crude E-waste recycling are also elaborated. The incentives toward profit, socio-economic, and environmentally sustainable approaches have been delineated based on critical analysis of the available literature.

Electronic waste generation, regulation and metal recovery: a review

Abstract: Waste will become the major resource in the future circular economy. In particular, E-waste is a major sector growing at an annual rate of about 2 million tonnes (Mt) with rising users of electrical and electronic items worldwide. This is a consequence of versatility and affordability of technological innovation, thus resulting in massive sales and e-waste increases. Most end-users lack knowledge on proper recycling or reuse, often disposing of e-waste as domestic waste. Such improper disposals are threatening life and ecosystems because e-waste is rich in toxic metals and other pollutants. Here we review e-waste generation, policies and recycling methods. In 2019, the world e-waste production reached 53.6 Mt, including 24.9 Mt in Asia, 13.1 Mt in USA, 12 Mt in Europe. In Asia, China (10.1 Mt), India (3.23 Mt), Japan (2.57 Mt) and Indonesia (1.62 Mt) are the largest producers contributing to about 70% of the total world e-waste generated. Only 17.4% (9.3 Mt) of the world e-waste was recycled by formal means, and the remaining 82.6% (44.3 Mt) was left untreated or processed informally. As a consequence, most countries have framed policies to provide regulatory guidelines to producers, end-users and recyclers. Yet the efficiency of these local policies are limited by the transfer of products across borders in a globalized world. Among formal recycling techniques, biohydrometallurgy appears most promising compared to pyrometallurgy and hydrometallurgy, because biohydrometallurgy overcomes limitations such as poor yield, high capital cost, toxic chemicals, release of toxic gases and secondary waste generation. Challenges include consumer’s contempt on e-waste disposal, the deficit of recycling firms and technology barriers.

Probiotic microorganisms from non-dairy traditional fermented foods

Abstract: Background Food fermentation has been practiced since prehistoric times and developed over the years with modification in substrates, processes and technologies. It is carried out by microbial cultures with techniques such as back slopping and enrichment, enhancing the organoleptic property, nutrient availability and storage life of food and in many cases contributing beneficial microbes to the diet of the consumer. Scope and approach The microorganisms involved in fermentation greatly vary according to the food product. One of the major groups of microbes used in traditional and industrial fermentation of cereals includes the lactic acid bacteria, many of which are known to have probiotic characteristics followed by yeast and mould. While dairy fermented foods have received attention as a source of probiotic microbes, those in non-dairy foods especially millets and cereal mixtures have not been documented. Traditional fermented foods of animal origin as well as other plant foods such as pulse, fruits and vegetables are also discussed. The review examines the presumptive probiotic bacteria found in non-dairy fermented foods around the globe. Key findings and conclusions This review is an attempt to collate the scientific progress with respect to probiotics in millet fermented foods, particularly of Africa and Asia. India has the largest documented number of fermented foods followed by Korea especially made with cereals. These fermented foods containing presumptive probiotic microorganisms may serve as probiotic supplements that are affordable as opposed to expensive probiotic formulations.