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Applications of Biochar for Environmental Safety

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Nguyễn Gia Hào

Academic year: 2023

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He is one of the leading biochar scientists in the Arab region. Challenges of using biochar in arid soils: a case study in the Kingdom of Saudi Arabia.

Introduction

There is no effect of pyrolysis temperature and type of feedstock on hydraulic properties of biofuel and amended sandy soil. 17] reported that the commercialization of biochar in Malaysia is relatively new and still at an early stage.

Production of biochar

Pyrolysis

Referring to Table 2, the ideal biochar production route is via slow pyrolysis, also known as conventional carbonization, as compared to fast or flash pyrolysis aimed at bio-oil production. In addition, slow pyrolysis for biochar production holds promise due to lower capital investment compared to fast pyrolysis ($132 vs. $200 million) [43].

Hydrothermal carbonization

Nevertheless, it has been reported that the torrefaction process is not a promising technique for biochar production, regardless of the higher product yield (70–80 wt%), as the torrefied biomass still contains a significant proportion of volatile components from the raw biomass. , and the physicochemical properties are intermediate between raw biomass and biochar [44, 50]. Furthermore, although the torrefaction process alone cannot be used for biochar production, the combination of torrefaction and pyrolysis pretreatment is feasible for exceptional biochar production (in terms of yield) in addition.

Gasification

For example, oxygen-to-carbon (O/C) ratio of the torrefied biomass that is >0.4 is contrary to the European Biochar Certification (EBC) of biochar [44]. Therefore, this torrefaction process is often applied as a pretreatment process for moisture removal, biomass compaction and to improve the biomass properties.

Biochar’s characterization, standardization, and legislations

Unlike the pyrolysis, the gasification process is carried out in the presence of O2 (including O2, air, steam, CO2 or mixture of the gases) and is primarily used for the syngas production (i.e. CO, CO2, CH4, hydrogen [H2] ) rather than the biochar production. In addition, it should be noted that these certifications only apply to the categorization of biochar and their suitability as a soil conditioner and to exclude hydrochar [65].

Conclusions and future outlook

Energy balances, greenhouse gas emissions and economics of biochar production from empty palm oil clusters. A critical review of a sustainable biochar system with a mini-review of biochar synthesis, characterization and associated standardization.

Forest trees for biochar

Carbon sequestration by planted Eucalyptus

Eucalyptus, (3) BC production systems varying in size and associated quality of BC, (4) promising BC applications, (5) recent and ongoing BC research, and (6) carbon sequestration potential and associated costs of eucalyptus plantations using wood BC as soil conditioner. The resulting estimates of total carbon sequestration ranged from 38 to 95 mt/ha at the time of annual peak accumulation (Table 2), with longer term totals exceeding 100 mt/ha in 6 years, again depending on cultivar, location, plant density, and harvest age (Figure 1).

Biochar production systems

  • Pit, mound and brick kilns
  • Metal kilns
  • Missouri-style kiln
  • Kon-Tiki kiln
  • Rotary kiln
  • Mobile biochar production
  • Continuous production technologies

What differentiates high quality BC from lower quality BC or simple charcoal is the production system ie. the ability to control the process and operating conditions and ultimately the physical and chemical properties of BC. While Missouri-type furnaces can be designed to have reduced emissions compared to other furnaces – stacks can be connected to afterburners to reduce CO and VOC emissions – mass production makes this difficult as there is no continuous process and steady state.

Biochar applications

Representative continuous BC production systems: (1) Polchar production plant, GCS's (2) vertical retort process, and (3) vertical retorts. Comparison of BC production technologies for cost, technical expertise, BC quality and consistency, and ability to control emissions.

Biochar research

Six months after treatment applications, the cultivars receiving only GE and GE + BC doubled in height, approximately twice the increase with no treatment. Eleven months after application, cultivars receiving GE + BC were taller than those receiving only GE and no GE.

Carbon sequestration potential of Eucalyptus plantations

Conclusions

Tar removal from biomass is one of the main challenges for the biomass gasification industry [7, 8]. The influence of H2O and CO2 on homogeneous conversion and heterogeneous reforming of biochar as a function of biomass tar development remains to be understood in detail.

Experiment

  • Material preparation
  • Biochar catalyst preparation
  • Homogeneous/heterogeneous reforming of biomass tar
  • Sampling and analysis of biochar and tar

As shown in Figure 2, a two-stage fluidized bed/fixed bed reactor was used to investigate the homogeneous conversion and heterogeneous reforming of biomass tar over biochar. Schematic diagram of a two-stage fluidized bed/fixed bed reactor for the homogeneous conversion and heterogeneous reforming of biomass tar.

Results and discussion

Homogeneous conversion of biomass tar

O and OH free radicals can be formed by ionization of H2O (H2O → H + OH) in the presence of steam. These free radicals can react with the active free tar fragments generated from the first stage of thermal decomposition demonstrating the importance of the H2O and CO2 reforming agents in the homogeneous conversion of biomass tar.

Heterogeneous reforming of biomass tar over biochar .1 Biomass tar reforming

After reforming the tar in an Ar atmosphere, the BET surface area and pore volume of the biochar samples decreased noticeably. The content of elements (C, O, K and Ca) on the surface of the biochar samples is shown in Figure 10.

Conclusions

Simultaneous steam reforming of tar and steam gasification of charcoal from the pyrolysis of potassium-laden woody biomass. Effects of H2O and CO2 on the homogeneous conversion and heterogeneous reforming of biomass tar over biochar.

Phosphate in water bodies

Studies have shown that 97% of the total phosphorus content (TP) can be removed from aqueous solutions using phosphate biological treatment methods that carry no risk of adding chemical contaminants to the water. Factors affecting the effectiveness of the adsorption of anionic pollutants should be considered, such as the amount of functional site, affinity, dispersion and surface accessibility [7].

Biochar production through pyrolysis and hydrothermal carbonization (HTC)

Biochar production from hydrothermal carbonization

It also plays a significant role as a limiting nutrient that prevents the development of algae and aquatic plants in the aquatic ecosystem [14]. Various researchers have studied production conditions such as raw material, temperature and residence time on hydrochar.

Biochar production from biomass pyrolysis

The reaction is carried out at atmospheric pressure and a residence time greater than 1 hour at a heating rate in the range of 5-7°C/min [25, 26]. Another factor that can contribute to a high biochar yield is the increasing particle size of the sample.

Remediation technologies for phosphate removal in aqueous solutions using biochar

The use of biochar and impregnation of metal oxides on the surface for phosphate adsorption was investigated as a pollutant removal technique. The modified biochar was pyrolyzed at different temperatures and tested for phosphate removal from aqueous solution.

Factors impacting phosphate adsorption 1 Influence of temperature

Influence of pH

On the other hand, there is no clear impact of the change of temperature on phosphate adsorption from wastewater. The characteristics of the biochar and phosphate species distribution can explain the negative impact of the increase in pH on phosphate adsorption.

Characteristics of adsorbed surfaces

The biochar surface charge contributes to the interaction of biochar with its environment (soil, water, organic matter) [47]. Moreover, high pyrolysis temperature reduces the amount of volatile matter in biochar and also its particle size.

Adsorption kinetic, isotherm, and thermodynamics 1 Adsorption kinetics

Adsorption isotherms

Comparative evaluation of hydrochars and pyrochars for phosphate adsorption from wastewater DOI: http://dx.doi.org/10.5772/intechopen.92612. In this chapter, an overview of hydrochar and pyrochar production techniques is discussed in addition to the application of biochar for phosphate adsorption from waste water.

Figure 7 shows that the initial phosphate adsorption rate increases with an increase  in phosphate concentration
Figure 7 shows that the initial phosphate adsorption rate increases with an increase in phosphate concentration

Biochar for C-use efficiency

The resistance of biochar to microbial degradation depends on the chemical composition resulting from the heat treatment and the properties of the initial biomass [8]. This is possible because crop residues serve as a precursor to soil organic C stores, and returning more crop residues to the soil in the form of biochar is associated with an increase in organic C concentration [2].

Biochar increases crop productivity

However, the effect of biochar on soil carbon emissions is very complex and changes in emissions can result from several mechanisms. The increase in soil microbial biomass may be due to the increased C utilization efficiency following the accumulation of soil organic C and microbes on the biochar surface.

Biochar for mitigating greenhouse gas emissions

The mechanism may be complex, but the effect of biochar on soil quality could be significant in affecting yield. Our study demonstrated a positive effect of biochar addition on soil quality and yield of spring wheat, which is maintained over three years.

Biochar for soil fertility

Changes in soil pH can result in changes in nitrifier or denitrifier enzymatic activity and thus soil N2O emissions. However, the effect of biochar on soil temperature and soil pH has not been suggested as mechanisms to explain differences in overall soil CH4 [10].

Biochar improves nitrogen use efficiency

It is not clear about the potential effects of biofuel on soil microbial activity. Biochar application resulted in increased N uptake by plants, which was attributed to the ability of biochar to supply more N.

Biochar for pests and disease suppression

37] reported that the application of biochar proved effective in suppressing foliar pathogens such as Rhizoctonia solani, Fusarium and Phytophthora species. Similarly, the application of biochar was reported to reduce the severity of gray mold disease on both Lycopersicon esculentum and Capsicum annuum [38].

Biochar application: a case study in Ghana

In addition to its disease suppressive potential, biochar also reduces the impact of pesticides on the environment through absorption and adsorption of various pesticides [43] to reduce pesticide bioavailability due to its large surface area and high porosity. The absorptive capacity of the biochar amendment is however age dependent as Martin et al.

Conclusion

The application of biochar and compost, alone or in combination, also increased soil total organic carbon (TOC) in both the Aiyinase and Cape Coast soils (Figure 6). Biochar application to soil and N2O emissions: Potential effects of mixing fast-pyrolysis biochar with anaerobically digested manure.

Applications of biochar and their effect on soil properties

Physical properties

A systematic representation of the potential of biochar in the soil and plant system is presented in Figure 1. Significant improvements in plant productivity have been achieved depending on the amount of biochar added to the soil, but these reports come mainly from studies in the tropics [11, 12].

Chemical properties

Biological activity

Applications of Biochar for Environmental Safety. BET) surface areas of olive pit biochars increased with increasing mass loss (burn-off) regardless of the activation temperature [21]. Weathering of biochar in soil fixes the immobilization of nitrogen on its surface, studies showed that high application rate of biochar (10% or 20%, w/w) significantly reduced NH4 volatilization due to its high cation exchange capacity [25] but in case of NO3− the leaching increased especially if the initial N content of biochar is high [28].

Application of biochar in decontamination/removal of organic pollutants from soil and water

Microbial biomass carbon in the soil increase in basal respiration due to addition of carbon in the soil. The loss of volatile and condensable compounds from biochar and the simultaneous relative increase in the organized phase formed by graphite-like crystallites leads to the increase in solid density (or true density) of the round 1.5-1.7 g cm−3.

Application of biochar for soil carbon sequestration and mitigate GHGs emission

Higher porosity of biochar therefore creates a favorable environment for microbes to make a habitat in soil [40] researchers have suggested that biochar benefits microbial communities by providing suitable habitats for microorganisms that protect them from predation [41 -43].

Biochar prospects and essential research

Use of biochar in the decontamination/removal of organic pollutants from soil and aquatic pollutants from soil and water. Several evidences are available in the literature on the use of biochar for the removal of organic pollutants from contaminated soil and water in Table 3 [54].

Conclusion

Effect of biochar on yield and heavy metal uptake in rice grown on soil amended with sewage sludge. Effect of Biochar Application in Soil Amended with Sewage Sludge on Growth, Yield and Uptake of Primary Nutrients in Rice (Oryza sativa L.).

Biochar production process

Biochar sources

The main reason is the lack of appropriate technology to use and limited informed strategy to promote biochar production in the region. This is a fundamental element in the bioeconomy discourse on biochar, which aims to revolutionize agronomic operations in East Africa while highlighting the spectrum of its applicability and viability [11].

Slow pyrolysis

Furthermore, this mixture can minimize nutrient leaching in the highly weathered tropical soils, in addition to increasing crop productivity in acidic soils [14, 15]. Careful implementation of sustainable biochar production is a powerful incentive to span agricultural productivity, better economic growth and minimizing negative environmental impacts in the area.

Slow pyrolysis versus traditional charcoal making

Environmental usefulness of biochar

  • Biochar from biomass as a fertilizer and a soil conditioner
  • The potential of biochar in carbon sequestration
  • The extent of biochar use in agriculture
  • How does biochar improve soil properties?

The use of biochar from plant biomass as a soil fertilizer or conditioner has received considerable attention in the recent past [12]. The potential of biochar as a viable tool for carbon sequestration has recently been centered on the general discourse of climate change.

Potential of biochar use to boost East African agricultural productivity

How abundant are agricultural residues in East Africa?

Maize is the most popular crop grown in East Africa because it is the staple food. Despite this tremendous dependence on agriculture, agricultural production in East African countries is mainly on a subsistence basis.

Economic savings and biochar adoption potential for agricultural use A plethora of evidence has shown that biochar use has the potential to improve

These factors are systematically used to quantify the possible maize residues that can be generated based on the current maize production rates in the East African countries. Thus, based on the probable biochar yield in East Africa, a total of 2.7 million hectares (about 30% of the total planted area) could be sufficiently fertilized by biochar each season.

Possible barriers to biochar production in East Africa

The basis for the production and use of biochar in East Africa depends on the current practices and the use of crop residues in the region, especially the main food crop, maize. According to Berazneva [41], most of the residues are burned in situ on the farms to clean the soil for the following season and also to sterilize traces of pests and diseases.

Future of biochar production and use

Promotion and adoption of biochar technology in East Africa and across sub-Saharan Africa (SSA) is hampered by several obstacles ranging from policy and legal frameworks, institutional, socio-economic, fiscal, ecological, health and technical issues [1]. Furthermore, the real potential and benefits of sustainable production and use of biochar for crop production can be underlined based on the perceived usefulness.

Conclusion

Today, the use of biochar has expanded to its use in industry, agriculture, forestry and the natural environment. Today, the use of biochar has expanded to its utilization in industry, agriculture, forestry and.

Biochar properties that enhance environmental safety

The temperatures of the pyrolytic processes at the point of biofuel production are also shown. Biochar porosity increases the water holding capacity of soil and increases the ability of soil to form aggregates [13].

Production processes of biochar and biochar efficiency

Soil fertility and biochar soil amendment

Application of biochar and environmental safety standards

The composition of the raw materials determines the structural and chemical properties of the biochar. If the use of the product does not cause long-term defects on the living and non-living entities in the environment [6, 22].

Applications of biochar for soil sustainability

If the product itself or its use does not harm the environment and people directly or indirectly affected by the product or its use. If the use of biochar will not pose an environmental disturbance or health hazard [25].

Soil enhancement tendencies of biochar

  • Absorption tendencies of biochar
  • Soil amelioration of biochar
  • Enhanced nitrogen fertilizer
  • Soil structure improvements of biochar
  • Biochar and mitigation of greenhouse gases
  • Biochar in environmental conservation
  • Biochar in enhancing soil microbial community

Biochars also increase soil pH due to the presence of carbonized compounds such as calcium carbonate [23, 30]. However, there are also anaerobic organisms (that do not require the presence of oxygen to survive) in the soil.

The implications of amending soils with biochar

Discussion

Conclusion

However, there are other economic interests associated with the use of biochar, these include the geographic distribution of the effective use of biochar [38, 39]. In addition, the effect of biochar on the soil microbial community is significant given the increase in the bacterial and fungal community in the soil with a higher increase in the latter.

Distribution pattern of arid and semiarid soils

However, the negative implications of the use of easily decomposed organic amendments on the environment must be taken into account, e.g. emissions from greenhouses possessing global warming [15]. Consequently, biochar can be the appropriate organic amendments to improve the properties of such soils, but on the other hand reduce the emission of greenhouse gases.

Major characteristics of arid soils

In the next section, we will discuss the distribution of arid and semi-arid land and the potential of using biochar to improve soil properties and achieve sustainability in crop production.

Agricultural and food wastes in the Kingdom of Saudi Arabia

Biochar

Ancient production of biochar

Usually, the soil pH of the Kingdom of Saudi Arabia is above 8 with high CaCO3. These conditions hinder the development of the agricultural sector in the Kingdom of Saudi Arabia.

Production technologies of biochar

In terra preta soils, the acidic conditions were the limiting factors that negatively affected crop production, with these soils severely suffering from Al toxicity. To solve this problem, the liming effect of biochar was an effective approach to overcome the Al toxicity in the soil [33].

Physical and chemical characteristics of biochar

Applications of biochar for soil fertility improvement

Limitation of biochar application in the Kingdom of Saudi Arabia soils As mentioned above the high pH of biochar limited its applications in arid soils

Limiting the application of biochar in the soil of the Kingdom of Saudi Arabia As mentioned above, the high pH of biochar limited its applications in arid soils. The role of biochar in improving soil pH, organic carbon (OC) and CEC was also highlighted by [16].

Biochar increases soil pH and soil organic carbon content and affects PTMs phytoavailability

Potentially toxic metal (heavy metal) immobilization to ryegrass shoots and roots as a function of biochar application rates. The results of PTM content in the extracts and SOC (%) as a function of biochar application rates are summarized in Figures 3 and 4 and Table 2.

The effect of biochar feedstock sources on PTMs phytoavailability While investigating the effects of chicken manure (CMB) and greenwaste

The effect of biochar feedstock sources on PTMs phytoavailability While investigating the effects of chicken manure (CMB) and green waste. The effect of biochar feedstock sources on PTMs phytoavailability While investigating the effects of chicken manure (CMB) and green waste. .

The effects of biochar conversion processes on PTMs phytoavailability

On the other hand, the combination of biochar with green waste compost (GWC) was more effective in reducing lead in soil pore water and uptake by ryegrass. Biochars are effective in immobilizing PTMs and this effect varies depending on the nature of the biochar and the pyrolysis conditions.

Figure 6 was adapted from the recent work of [51] and clearly shows that  simply increasing pyrolysis temperature of BCs to enhance PTMs immobilization  is not a pragmatism
Figure 6 was adapted from the recent work of [51] and clearly shows that simply increasing pyrolysis temperature of BCs to enhance PTMs immobilization is not a pragmatism

Mechanisms of PTMs adsorption into biochars

Biochar is the term given to biomass subjected to the process of change in composition through the action of high temperatures. However, the potential use of biochar as a soil amendment to mitigate the stress caused by salt in the plant has received little attention [26].

General considerations about biochar production

The purpose of this chapter was thus to approach the role of biochar in connection with amelioration of adverse salinity effects in soil.

Application of biochar in saline soils and improvement of plant growth

Some studies have reported the differences in results of biochar applications in saline soils according to the method used to obtain them [31]. The benefits of biochar in plant growth in saline soils observed in several studies conducted by Saifullah et al.

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Figure 7 shows that the initial phosphate adsorption rate increases with an increase  in phosphate concentration
Figure 6 was adapted from the recent work of [51] and clearly shows that  simply increasing pyrolysis temperature of BCs to enhance PTMs immobilization  is not a pragmatism

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cover will have a 50% reduction in soil loss compared to a bare field. This effect of residue cover on reducing soil loss occurs for a variety of reasons. As previously discussed,