Nitrogen-Fertilizer : Human Hair
in this article, Amir focuses on human hair potential for fertilizer production and illustrates economic feasibility as an opportunity for entrepreneurs in the middle east upon ammonia price volatility and fertilizer shortages
Hair is essentially composed of complex arrangement of keratins forming an external cuticular layer and an inner cortex. Particularly, keratins interlace into proto-fibrils that are arranged into macro-filaments further reinforcing fibrils as this compact protein complex is essential to promote mechanical resilience in resistance to environmental factors or chemical treatments.
Keratins are poly-petides in which amino acids are primary components as human hair is composed mainly of alpha-keratin thus amino acids such as cystine, serine, glutamic acid, threonine, glycine, and arginine are abundant. Therefore, human hair waste is an optimum source for amino acids not to mention that human hair is considered useless and found in municipal waste and landfills.
Normally, plants reduce applied conventional ammonium and nitrates fertilizers into amino acids. On the other hand, applying amino acids or related derivatives directly saves energy as plants readily absorb essential nitrogen-rich content. For this reason, amino acids fertilizer is obtained by hydrolyzing human hair waste in alkaline or acidic environment in which hydrolysis is enhanced by heat treatment.
Although conventional ammonium and nitrates fertilizers provide nutrients for plant growth, yet not persistent to enrich soil in the long term including species diversity of necessary soil microorganisms. Another critical aspect is that conventional fertilizers are not regarded sustainable in reference to petrochemical value chain, besides the economic perspective upon conventional fertilizer shortages. In contrast, an organic fertilizer containing amino acids derived from waste human hair increases plant growth and soil fertility in the long-term while considered sustainable regarding waste hair utilization.
Production is based on contacting waste human hair with an alkaline aqueous solution to hydrolyze alpha-keratin followed by neutralizing with concentrated acid, relatively simple process in which control of reaction parameters including alkaline concentration, temperature and reaction time are considered upon immersing waste human hair in an alkaline medium inside the hydrolyzer -an agitator stirred tank provided with heating coils- and heated to an optimum temperature within (90 ºC - 150 ºC) for 15 minutes to an hour. The alkaline solution is obtained by mixing caustic potash in water to maintain an optimum (0.3 - 0.9) molarity. In addition, combination of caustic soda, caustic potash, and slaked lime is applicable no ore than recommended mixing ratio. Furthermore, concentrated phosphoric acid is used to neutralize hydrolyzed amino acids to preferably (pH = 8) as industrial-grade phosphoric acid is available in the range of (7.0 - 13.0) molarity. Notice mthat hydrolyzed amino acid fertilizer is actually nitrogen-enriched potassium phosphate fertilizer.
Recently, new production method based on contacting waste human hair with diluted hydrochloric acid was used in laboratory scale to hydrolyze alpha-keratin in which diluted acid compensate with longer reaction time and moderate heating as waste human hair is immersed in acidic medium and heated initially to 97 ºC till hydrolysis takes place then temperature is kept within 60 ºC for 6 hours. The acidic solution is obtained by diluting hydrochloric acid in water to maintain an optimum (5.6 - 6.0) molarity as industrial-grade hydrochloric acid is available in the range of (9.0 - 12.0) molarity. Practically, 3 liters of diluted acid are required per kilogram of human hair for almost full hydrolysis.
As might be expected, waste human hair pre-treatment using soap or shampoo followed by rinsing with water removes impurities, moisture, and natural oil thus imporves fertilizer product quality.
Upon expanding Chemiprobe coverage to include agrochemicals besides conventional fertilizers, there is no market players in the middle-east as human hair to fertilizer is new concept which has been addressed recently upon ammonia price volatility and fertilizer shortages.
According to Chemiprobe, producing hydrolyzed amino acid fertilizer in the middle-east through treatment with caustic potash and phosphoric acid requires approx. 0.22 USD per liter in which 0.13 USD are raw materials and 0.09 USD are operational expenses.
Business appraoch is illustrated below through simple (SWOT) analysis :
Strength : abundant cheap resource
Weakness : affected by market trends for caustic potash, phosphoric acid, or hydrochloric acid
Opportunity : conventional fertilizer shortages, no regional competitors
Threats : changing regulatory environment for agrochemicals, emerging competitors
1. method for fertilizer preparation by hydrolysis of waste human hair.
Kim, J. Et al. (2011). KR101043568B1. South Korea
2. Nagarjuna P, Verma S, Sharma A. amino acids production through human waste hair, pollution research 2020;39(3): 714-717