Fertilizer from Hair!!!

Fertilizer from hair is not as crazy as it sounds. In fact, people had used hair as fertilizer long before researchers began their study on this exceptional characteristic of hair. However it produced mixed results as it takes long for hair to decompose and give away nitrogen, the main element that supplies nutrition to the plants. To increase the consistency, studies have been conducted to extract the nitrogen from hair and use it as fertilizer instead of applying the hair directly to the soil.

Reuse of wastes in modern times has inexorably become a major part of waste management and devising possible reuses of hair, a potential human waste, has long been a challenging task. Recently researchers* from the Chemical Engineering Department, BUET have conducted a research work aiming to synthesize fertilizer by extracting the nitrogen of the proteinaceous structure of waste human hair which contains nitrogen up to 16.1% of its own weight. The disulphide cross-links in cystine-rich cuticle layer largely account for the toughness and resilience of hair; hence a pathway has been developed to dissolve hair proteins or so called keratins by reductive cleavage at high pH, the reaction rate being controlled by moving boundary kinetics [1]. Little presence of arsenic (As) and other trace elements in hair determined elsewhere [2, 3] was found to be well below the tolerable limit, reducing the primary concern for health hazards.

Performance of Potassium Hydroxide (KOH) and Tetramethylammonium Hydroxide (TMAH) as solvents was analyzed and compared both individually and with different combinations. Experiments showed KOH is better in case of maximum amount and rate of dissolving hair and extraction of nitrogen in ammonium and nitrate ion forms. Improvements in solubilities by manipulating operating variables and with modifications were also studied. The results of this series of experiments were finally compiled to formulate a model equation for predicting solutesolvent relationship in large scale production. Application of this fertilizer for plantation of amaranthus dubius by soil culture was conducted to prove the activity of this liquid fertilizer.

Besides greener and juicy leaves, the physical growth of plants was also impressive. The researchers found that with the application of this synthesized fertilizer in theoretical amount (in terms of nitrogen content) and double amount, after 30 days plants were 15.4% and 20.5% taller, respectively, than that grown without any fertilizer. For double amount of commercial NPK fertilizer this growth was only 7.7%. This research finding may be considered as a major success and since no similar work has so far been reported, this may lay the platform for further works on impacts of this fertilizer on plant physiology and in turn on human body.

* Md. Masudur Rahman and Zannatul Ferdous of the Department of Chemical Engineering, BUET have demonstrated the above work in their BSc Eng (Chem) final year thesis project: ‘Synthesis of Nitrogen Based Fertilizer from Human Hair’. The research works was supervised by Asst. Prof. Mominur Rahman.

References

[1] C.R. Robbins, Chemical and physical behaviour of human hair (Springer Verlag, New York, 4th ed, 1994, pp. 124)
[2] A. S. Ribeiro et al, Determination of As, Cd, Ni and Pb in human hair by electrothermal atomic absorption spectrometry after sample treatment with tetramethylammonium hydroxide, Microchemical Journal 64 (2000) 105-110
[3] J. L. Rodrigues et al, A fast method for the determination of 16 elements in hair samples by inductively coupled plasma mass spectrometry (ICP-MS) with tetramethylammonium hydroxide solubilization at room temperature, J. Anal. At. Spectrometry 23 (2008), 992-996
 

 

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Rahman, M.M., Fertilizer from Hair!!, ChE Thoughts 1 (1), 20-21, 2010.

 

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