Sustainability Opportunities of Okra Waste
Sep. 22, 2023
This blog post serves the function of providing a collection of resources supporting okra-related sustainable design.
The full visual report is delivered to okra Inc.
About Okra
Here are some useful links providing some basic stats from okra, the fruit, to okra production.
Okra, as Food
The nutrient breakdown of okra can be seen here (USDA).
The grading guideline by the US of okra can be seen here (USDA).
Okra, World Production
This report shows the world's product amounts of okra (Knoema, 2021). (Notice there is conflicting information between this report and other reports.)
This report shows the okra production trend in Philippines (Faostat, 2023).
Okra Production Sustainability
This article introduces the health, environment, animal and labour considerations around okra.
Based on the article, the water footprint and carbon footprint are both low for okra production. The labour fairness varies, meaning the production of okra “may involve worker exploitation, laborer issues, human rights concerns“ (Marie, 2023).
Okra Planting Guidelines (Philippine)
In the guide, they suggest “sort and discard malformed and diseased fruits“ (2017).
Okra & okra Waste
After the pods were harvested, the stems were left on the fields to decompose or get burnt (Duman, et al., 2017; Thueall, et al., 2022). Many research institutes and groups are looking for opportunities to utilize those stems, considered a waste of okra production, as new alternatives to synthetic fibres. Many other institutes are also exploring opportunities to use okra leaves or pods in different ways for lower cost or more circular economic benefits. Below is a collection of studies about how different parts of the okra plant can be used.
Okra into BioSorbents
Biosorptions Benefits
Adsorption is commonly used for treating heavy metals and microplastics in water. Biosorbents have been gaining interest from different groups of people because of their advantages over other methods. Compared to traditional chemical treatments, biosorbents are:
Cost-efficient (cheaper) (Singha and Guleria, 2015; Khaskheli et al., 2016)
Non-toxic (Singha and Guleria, 2015; Bhuju, 2022)
Improved selectivity & high metal binding efficiency (Ahmed, 2021; Khaskheli et al., 2016)
Can be used on large or small-scale applications (Singha and Guleria, 2015; Ahmed, 2021)
Compared to traditional carbon sorptions, biosorbents are:
Better targeted combination (Singha and Guleria, 2015)
Lower cost (Singha and Guleria, 2015; Khaskheli et al., 2016)
Simpler regeneration (Singha and Guleria, 2015)
Heavy Metal (Cu2+, Zn2+, Cd2+, Pb2+)
Singha and Guleria extracted cellulosic biomass from okra stems, treated with alkali solution, and used as an adsorbent for the removal of Cu2+, Zn2+, Cd2+ and Pb2+. Effects of time, metal ion concentration, temperature and regeneration were studied and compared (Singha and Guleria, 2015).
Heavy Metal (Fe(III), Cd(II), Pb(II), Zn(II), Ni(II))
Olabanji and Oluyemi used raw sugarcane waste and raw okra waste (dry okra pods) as source materials to create adsorbents for metal ion adsorption. The result shows raw okra waste is more efficient as an adsorbent than raw sugarcane waste (Olabanji and Oluyemi, 2014).
Heavy Metal (As(III), As(V))
Khaskheli et al. used okra leaves to produce adsorbent to handle As(III) and As(V) in water. The sorption efficiency was studied under different conditions. Based on the study, “89.82% of As(III) and 97.11% of As(V) were removed with 1M HCl“(Khaskheli et al., 2021).
Heavy Metal (Cr(III), Cr(VI))
Khaskheli et al. also did a study using okra leaves made biosorbent to remove Cr(III) and CR(VI) from water. Based on the study, “up to 92.15% of chromium metal was removed from the real water samples” (Khaskheli et al., 2016).
Microplastic
Srinivasan and colleagues conducted a study using different supermarket-bought vegetables to extract polysaccharides to study the efficiency of removing microplastic from water (Bhuju, 2022). The result shows that “polysaccharides from okra paired with those from fenugreek could best remove microplastics from ocean water, while polysaccharides from okra paired with tamarind worked best in freshwater samples“ (Tarleton News, 2022).
Okra into fabric & material
Another popular application of okra & okra waste is fabric and industrial materials.
Alkali Treatment
Treated with 10% NaOH at different temperatures, this study investigated how the time of the treatment affects the fabric diameter, weight loss, and thermal qualities (Duman et al., 2017).
Enzyme Treatment
Okra fabric outperformed jute fabric in elongation, tear strength, stiffness and abrasion resistance (Tahman et al., 2023). Treated with enzyme, especially, okra fabric “had stronger color retention properties“ than the Alkali treatment result (Tahman et al., 2023).
Paper, Bioplastics and Absorbent for Dyes
Southeast Missouri State University explored three directions of okra stem applications: “(1) the preparation of paper and textiles, (2) the synthesis of bioplastics, and (3) as an absorbent for the remediation of dyes from water“ (Theall et al., 2022)
Summary
Okra and its agricultural waste provide multiple different sustainability opportunities. They can be turned into biosorbents to treat heavy metals or microplastics in water. The biosorbent has several advantages over traditional methods, including low cost and non-toxic. Okra and okra waste can also be turned into fabric and industrial materials, which potentially could help with circular economics.
In the next blog post, I’ll explore more okra-based materials.