Abstract
This paper reviews the positive attributes and challenges of bamboo usage in carbon absorption, water, and wastewater purification. Bamboo can serve as a habitat for a variety of creatures and supports a diversified ecology. Bamboo roots can cast a fibrous net into the ground to prevent soil erosion and degradation. As the water passes through this woven mesh, the bamboo roots act as a filter, drawing toxins and other contaminants out of the water. Bamboo can treat wastewater effectively in free-water surface, horizontal flow, and vertical flow constructed wetlands. Bamboo charcoal has exceptional filtering properties for cleaner drinking water and better air quality. Additionally, bamboo can be used to form cellulose-based membranes. Bamboo is a renewable resource for creating paper, furniture, and building materials. Bamboo has various benefits. Thus, bamboo forests offer opportunities for rural communities to thrive economically.
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Merits of Bamboo Utilization in Earth Preservation, Water and Wastewater Treatment: A Mini Review
Kuok King Kuok,a,* Muhammad Khusairy Bin Bakri,b,d Chiu Po Chan,c Md. Rezaur Rahman,d,* Murtala Namakka,d Khairul Anwar Mohamad Said,d Chin Mei Yun,a and Mohammed Muzibur Rahman e
This paper reviews the positive attributes and challenges of bamboo usage in carbon absorption, water, and wastewater purification. Bamboo can serve as a habitat for a variety of creatures and supports a diversified ecology. Bamboo roots can cast a fibrous net into the ground to prevent soil erosion and degradation. As the water passes through this woven mesh, the bamboo roots act as a filter, drawing toxins and other contaminants out of the water. Bamboo can treat wastewater effectively in free-water surface, horizontal flow, and vertical flow constructed wetlands. Bamboo charcoal has exceptional filtering properties for cleaner drinking water and better air quality. Additionally, bamboo can be used to form cellulose-based membranes. Bamboo is a renewable resource for creating paper, furniture, and building materials. Bamboo has various benefits. Thus, bamboo forests offer opportunities for rural communities to thrive economically.
DOI: 10.15376/biores.19.2.Kuok
Keywords: Activated bamboo carbon; Absorption; Erosion prevention; Water treatment; Wastewater treatment
Contact information: a: Faculty of Engineering, Computing, and Science, Swinburne University of Technology, Sarawak Campus, Jalan Simpang Tiga, 93400, Kuching, Sarawak, Malaysia; b: Composites Materials and Engineering Center, Washington State University, 2001 East Grimes Way, 99164 Pullman, Washington State, USA; c: Faculty of Computer Science and Information Technology, Universiti Malaysia Sarawak, Jalan Datuk Mohammad Musa, 94300, Kota Samarahan, Sarawak, Malaysia; d: Faculty of Engineering, Universiti Malaysia Sarawak, Jalan Datuk Mohammad Musa, 94300, Kota Samarahan, Sarawak, Malaysia; e: Center of Excellence for Advanced Materials Research (CEAMR) and Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, P.O.Box 80203, Saudi Arabia; * Corresponding authors: mrezaur@unimas.my; kkuok@swinburne.edu.my
GRAPHICAL ABSTRACT
INTRODUCTION
Bamboo belongs to the Poaceae grass family and Bambusoideae subfamily, comprising 1,662 species within 121 genera (Canavan et al. 2016). Some common bamboo species include Bambusa vulgaris, B. tulsa, B. ventricosa, Dendro-calamus giganteus, and Phyllostachys nigra. Bamboo is renowned as the tallest grass species due to its distinctive rhizome-dependent system. Bamboo’s significant carbon absorption ability makes it a crucial element in the endeavor to mitigate climate change and reduce the greenhouse effect, thereby contributing to the preservation of the world and the restoration of the atmosphere (Bakri et al. 2021). Certain bamboo species have a remarkable growth rate, surpassing 91 cm (36 in) within 24 h. This is equivalent to an impressive growth rate of nearly 4 cm (1.6 in) every hour, which means around 1 mm every 90 seconds or 1 inch every 40 min. These extraordinary characteristics position bamboo as the most rapidly growing plant on earth. It is a renewable resource because it can be harvested with little environmental harm and regenerates quickly.
The advantages of bamboo and growing bamboo are listed in many journals, books, and websites (Atanda 2015; Emamverdian et al. 2020; Zeng et al. 2020). Bamboo is well known for its capacity to absorb carbon, purify the air, and indirectly create essential habitats for various plant and animal species. It can support a diverse ecosystem and help protect biodiversity (Nath et al. 2015; Emamverdian et al. 2020). Current technology makes it more advantageous to clean polluted water using bamboo (Wang et al. 2020; Kuok et al. 2022a; Lamaming et al. 2022). Bamboo’s thick web of roots and rhizomes makes it successful in its growth and longevity (Kuok and Chiu 2018; Huang et al. 2022). Bamboo can also prevent erosion, purify water, and gain a tenacious footing in the underground matrix, which is part of the natural ecosystem in the forest (Goswami et al. 2022). The bamboo roots work as a filter, pulling toxins and other pollutants out of the water as they flow through this tightly woven mesh (Bambu Batu 2022). This is a straightforward, organic method of handling contaminated runoff or domestic grey water. Bamboo charcoal offers outstanding purifying qualities for cleaner drinking water and better air (Lamaming et al. 2022; Kuok et al. 2023).
The article explores the diverse components of bamboo, including culms, shoots, leaves, roots, and rhizomes, as well as its by-products. It delves into the significance of bamboo across various domains, such as its role in carbon absorption, erosion prevention, and its use in wastewater treatment through bamboo macrophytes and constructed wetlands. Additionally, it examines bamboo charcoal’s efficacy in water purification and discusses the potential of bamboo-based membranes. The article concludes by summarizing the multifaceted applications of bamboo and its promising prospects in various fields.
BAMBOO COMPONENTS
Bamboo, which is widely utilized in Asian construction, remains a niche material in Europe and the United States. China and India have their standards, i.e. Indian Standard (IS) and Chinese Standard (GB/T), which utilize the use of bamboo construction and building materials. In Europe and the United States bamboo recently has gained popularity for flooring, kitchen tops, and chopping boards. However, its structural use in these markets is limited, often involving treatment with heat and chemicals, due to a lack of standard codes provided by the agencies in both Europe and the United States. Still, bamboo possesses several attributes that contribute to its immense value and versatility, with strength and renewability as pivotal qualities. Each segment of bamboo serves distinct purposes, encompassing bamboo culms, bamboo shoots, bamboo leaves, bamboo roots, and various by-products.
Bamboo Culms
Bamboo stems or culms are long, round, hollow, and woody poles with a strength-to-weight ratio greater than steel. It is the most useful part of bamboo, with a hardness superior to pine and comparable to oak. Bamboo is an adaptable and sustainable supply of wood that may be used for various tasks, including building a dome (Fig. 1), making furniture, and making paper (Kaur et al. 2022). Bamboo plants take about 6 or 7 years to reach maturity compared to 20 to 30 years for trees. The massive poles of Guadua and Moso bamboo are ideal for construction and processing into engineered lumber for building shelters, boats, and scaffolding (Fig. 2.)
Fig. 1. Bamboo Dome for G20 Bali Summit (Abdel 2022)
Fig. 2. Bamboo scaffolding (Neumann 2020)
Larger bamboo poles can be transformed into more advanced applications such as floor panels, fiber panels, and other engineered timber, as presented in Fig. 3, that meet the requirements set by municipal building codes and similar regulations. The bamboo culm was split into small thickness culm, while the waste was cut into small strands (Fang et al. 2018). Some are flattened using a press machine. At the same time, the size and thickness depend on the bamboo species and design. The bamboo is glued or atomized using conventional resin, which is used in timber industries, i.e., polyurethane, epoxy, etc., and pressed using a hot press. Bamboo is a sustainable substitute for wood in various applications, alleviating the intense strain on forests. To accomplish this, larger bamboo poles were divided into strips, which were subsequently assembled into layers by lamination.
Fig. 3. Bamboo flooring (González-Lezcano et al. 2015)
Finer strands of bamboo are superb materials for crafting fishing poles and a variety of light crafts such as fencing (Fig. 4), curtain rods, flutes, and others. Bamboo poles are also well-suited for serving as garden stakes, whether for supporting a row of tomato plants or establishing a plantation of banana trees. To preserve the bamboo from biological attack and create a fire barrier, various laminating resins, fire retardants, chemical treatments, impregnation, and coatings are used to preserve the bamboo (Kaur et al. 2016; Rahman et al. 2021; Matin et al. 2022).
Upon harvesting the poles, the bamboo plant not only endures but flourishes. The life source of bamboo lies within its underground root system. As the culms are harvested, the roots will grow stronger and persistently generate robust shoots and new culms.
Fig. 4. Bamboo fencing (ONETHATCH 2023)
Bamboo Shoots
Emerging early in the growing season, young bamboo shoots, shown in Fig. 5, are soft and suitable for consumption. A healthy and thriving bamboo grove exhibits an impressive capacity for producing fresh shoots. Bamboo is rich in nutrients, boasting high concentrations of protein, vitamins, and minerals. Throughout Asia, people have incorporated the soft, young bamboo growth into their diets for millennia. Before consumption, bamboo shoots require boiling or proper fermentation to eliminate natural toxins.
Fig. 5. Bamboo shoots (Dane 2019)
Bamboo Leaves
Bamboo leaves serve as a primary dietary source for pandas and various mammals, including the mountain gorilla, the golden monkey, and the bamboo lemur of Madagascar. These animals particularly favor the soft and nutritious young bamboo shoots but also consume the leaves, which are abundant in silica. Beyond being a flavorful beverage with nutty notes, bamboo leaf tea is recognized for its capacity to fortify the body’s connective tissues and provide relief from arthritis.
Bamboo Roots and Rhizomes
Bamboo’s vigorous roots and rhizomes are the vital core of the plant, rendering it renewable and resilient against eradication efforts. The extensive rhizome network is an effective erosion control method, particularly on slopes and along waterways. Furthermore, bamboo roots play a crucial role in capturing and storing significant amounts of carbon from the atmosphere, thereby mitigating the impact of climate change.
Figure 6 presents the roots of a bamboo groove. The lower segments of bamboo, where the roots commence, proved valuable for unconventional crafts. Skilled traditional woodcarvers have devised exquisite designs incorporating the smoothness of bamboo with the rugged and bushy texture of the roots.
Fig. 6. Bamboo roots (Ryan 2023)
Bamboo By-products
Some bamboo by-products include bamboo clothing, bamboo paper, and bioethanol from bamboo. These bamboo by-products rely on the cellulose-rich pulp of the plant. Moso bamboo used to be the main source of pulp for bamboo clothing, especially in China (Dlamini et al. 2022). Figure 7 presents clothes made from bamboo. All bamboo species can produce bamboo paper and bioethanol. The thinner tops and side branches of the bamboo are ideal for making toothpicks, bristles for brooms, or other light crafts. Larger bamboo culms sheaths can be utilized to create rustic paper products or various handicrafts. All of these bamboo by-products offer essential alternatives to fossil fuels, deforestation, and pesticide-intensive agriculture.
Fig. 7. Bamboo clothing (Mahapatra 2017)
BAMBOO IMPORTANCE AND MULTIFACETED APPLICATIONS
Carbon Absorption
Bamboo exhibits a four times faster growth rate than most plants and surpasses trees in carbon absorption. This rapid growth rate occurs when individual culms are at their maximum during the growing season and under optimal growing conditions. A well-developed bamboo grove can provide 30 to 35 percent more oxygen than an equivalent area of forest (Espinoza 2023). In photosynthesis, bamboo absorbs carbon dioxide (CO2) from the environment and generates oxygen (O2). The plant then sequesters the carbon in its roots and above-ground biomass. Bamboo’s significant role in combating global warming is noteworthy.
Fig. 8. Photosynthesis process that sequesters CO2 and produces O2
Bamboo’s carbon absorption occurs alongside photosynthesis, where bamboo absorbs sunlight, water, and CO2 to produce crucial nutrients, specifically sugar. The schematic diagram of the photosynthesis process is presented in Fig. 8. Meanwhile, bamboo simultaneously releases O2 which is needed for humans. As such, existing carbon in the atmosphere will be absorbed, stored, or sequestered in the bamboo roots as carbon sinks through photosynthesis (Lou et al. 2010). Carbon sinks are vital in maintaining the balance of the earth’s biosphere and stabilizing the atmosphere. The bamboo roots persist and retain the CO2 even after the bamboo poles (culms) are harvested (Lou et al. 2010).
More carbon is released into the atmosphere when vast forests are logged or burned. Hence, bamboo is one of the best alternatives to replace cut trees to maintain the equilibrium of O2 and CO2 in the atmosphere. Bamboo likely has a higher capacity to convert CO2 into O2 than other vegetation types (Espinoza 2023). According to Japanese research, bamboo can absorb 12 metric tons of CO2 per hectare annually, whereas Chinese estimates suggest a lower value of around five metric tons per hectare (Borowski et al. 2022). Researchers in Uganda have proclaimed that each square meter of bamboo can absorb 267 kg of CO2 annually (Borowski et al. 2022). The numbers exhibit significant variation. However, all researchers proclaimed the superiority of bamboo in absorbing CO2 and releasing O2 through photosynthesis.
The viability of bamboo as a carbon sequestration agent relies heavily on its transformation into durable products. This is analogous to the necessity of ensuring the longevity of grass within a meadow to maintain carbon levels. While bamboo’s rapid growth and carbon absorption capacity are notable, its effectiveness as a carbon sink is contingent upon its utilization in long-lasting items. Harvested bamboo left to decay would release stored carbon, rendering it ineffective for carbon sequestration. Thus, processing bamboo into enduring commodities like furniture, flooring, and textiles is imperative to maximize its carbon sequestration potential. Stakeholders must emphasize not only bamboo’s growth and uptake capabilities but also the importance of its utilization in ways that facilitate prolonged carbon storage, necessitating careful management throughout its lifecycle to prevent premature carbon release into the atmosphere.
Erosion Prevention
Bamboo can grow close to waterways and in areas where water only passes intermittently. Bamboo has an extensive and vigorous rhizome root network (Huang et al. 2022). Bamboo roots usually grow towards moist soils, but not soggy and saturated areas. Apart from anchoring the plant securely to the ground, the tough web-like mesh roots minimize soil erosion and degradation by forming a fibrous net (Lou et al. 2010). Bamboo is a pragmatic and advantageous crop to cultivate on inclines and alongside watercourses, where erosion is prevalent. As such, bamboo emerges as a pragmatic and advantageous crop, particularly on slopes and along waterways, addressing the prevalent erosion issue. Additionally, bamboo’s ability to retain soil makes it a superior pioneer crop (Zhou et al. 2005). In areas where soil erosion poses a threat, the survival prospects of seedlings become more challenging. By binding the topsoil, bamboo facilitates the establishment of other species, fostering a more resilient and diverse habitat (Tardio et al. 2018).
Bamboo Macrophytes for Wastewater Treatment
The extensive bamboo roots and rhizomes network offers a persistent and secure foundation for wastewater purification. As the wastewater flows through the dense woven mesh, the bamboo roots function as a filtration system, extracting harmful substances and contaminants such as nitrogen and phosphorus, effectively purifying the water at riverbanks, lake shores, and areas that experience periodic fluctuation. It is a simple and natural method to purify contaminated runoff or domestic greywater.
Bamboo achieves maximum efficiency in purifying wastewater when the water table is one to two feet below the soil level (Xu et al. 2020). In this manner, the top layer of soil is not excessively saturated, while the root tips can access the water table for filtering. To optimize bamboo’s water filtering capabilities without causing harm to the plant, one can manage and regulate the runoff flow within the bamboo grove (Tadio et al. 2018). To achieve optimal outcomes, it is advisable to channel the water through the bamboo patch and stop the flow once the roots are soaked (Fang et al. 2019).
The root network can filter water as it percolates through the mud, sifting and cleaning it. Because of its phytoremediation capabilities, bamboo may leach certain heavy metals and other pollutants from the water (Kuok and Chiu 2013; Bian et al. 2020). Bamboo can metabolize and filter water if it is not overly contaminated with harmful elements. Bamboo filtering will enhance the water quality for cattle and irrigate other food crops, but it will not be enough to treat toxic runoff into the potable water supply (Were et al. 2017). Hence, wastewater treated with bamboo is best suited for ferti-irrigation, which combines the watering and fertilizing processes by incorporating nutrients directly into the irrigation water, especially for irrigating the bamboo groves via irrigation canals (Chauhan and Kumar 2020). Ferti-irrigation allows for efficient nutrient delivery to the root zones of plants, thus enhancing nutrient absorption and minimizing waste. This is an ideal and affordable wastewater treatment method for developing countries that cannot afford to build proper wastewater treatment facilities.
Constructed Wetland
According to Tilley et al. (2014), constructed wetlands can be categorized into a) Free-water surface constructed wetlands (Fig. 9), b) Horizontal flow constructed wetlands (Fig. 11), and c) Vertical flow constructed wetlands (Fig. 12). Bamboo can be the main wetland plant or macrophytes to replace the cattail wetland plants in Figs. 9, 11 and 12 for treating wastewater.
Fig. 9. Free-water surface constructed wetland (Tilley et al. 2014)