Therefore, the aims of the study are to evaluate the role and effect of biochar combined with composting as an amendment on VOCs, GHGs emissions, enhancement of compost quality/maturity
Trang 1BỘ GIÁO DỤC VÀ ĐÀO TẠO
TRƯỜNG ĐẠI HỌC CÔNG NGHỆ ĐỒNG NAI
BÀI BÁO ĐĂNG TRONG TẠP CHÍ QUỐC TẾ
THUỘC DANH MỤC ISI
CHEMOSPHERE
ISSN: 0045-6535 (Print); 1879-1298 (Online)
Impact Factor: 7.086 (2020)
Published online: 3 April 2022
Research Article:
Evaluate the role of biochar during the organic waste composting process: A critical review
Hong Giang Hoang, Faculty of Health Sciences and Finance - Accounting, Dong Nai Technology University, Bien Hoa, Dong Nai 76100, Vietnam
Đồng Nai - Năm 2022
Trang 2Chemosphere 299 (2022) 134488
Available online 3 April 2022
0045-6535/© 2022 Elsevier Ltd All rights reserved
Evaluate the role of biochar during the organic waste composting process: A
critical review
Minh Ky Nguyena,b, Chitsan Lina,b,**, Hong Giang Hoangc, Peter Sandersond, Bao Trong Dange,
Xuan Thanh Buif,g, Ngoc Son Hai Nguyenh, Dai-Viet N Voi,j, Huu Tuan Trank,l,*
aPh.D Program in Maritime Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan
bDepartment of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, 81157, Taiwan
cFaculty of Health Sciences and Finance - Accounting, Dong Nai Technology University, Bien Hoa, Dong Nai, 76100, Viet Nam
dGlobal Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia
eHUTECH University, 475A, Dien Bien Phu, Ward 25, Binh Thanh District, Ho Chi Minh City, Viet Nam
fKey Laboratory of Advanced Waste Treatment Technology, Vietnam National University Ho Chi Minh (VNU-HCM), Linh Trung Ward, Thu Duc District, Ho Chi Minh
City, 700000, Viet Nam
gFaculty of Environment and Natural Resources, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, 700000, Viet Nam
hFaculty of Environment, Thai Nguyen University of Agriculture and Forestry (TUAF), Thai Nguyen, 23000, Viet Nam
iCenter of Excellence for Green Energy and Environmental Nanomaterials (CE@GrEEN), Nguyen Tat Thanh University, Ho Chi Minh City, 700000, Viet Nam
jSchool of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300, Nibong Tebal, Penang, Malaysia
kLaboratory of Ecology and Environmental Management, Science and Technology Advanced Institute, Van Lang University, Ho Chi Minh City, Viet Nam
lFaculty of Technology, Van Lang University, Ho Chi Minh City, Viet Nam
H I G H L I G H T S G R A P H I C A L A B S T R A C T
•Using biochar as an additive improved
the performance and quality of
composting
•Biochar affects the dynamic and
struc-ture of the microbial community during
composting
•Biochar reduced the availability of
heavy metals and odorous gases
emissions
•Biochar improved the compost maturity
by promoting enzymatic activity and
germination index
A R T I C L E I N F O
Handling Editor: Derek Muir
Keywords:
Additives
Microorganism
Nitrogen losses
A B S T R A C T Composting is very robust and efficient for the biodegradation of organic waste; however secondary pollutants, namely greenhouse gases (GHGs) and odorous emissions, are environmental concerns during this process Bio-char addition to compost has attracted the interest of scientists with a lot of publication in recent years because it has addressed this matter and enhanced the quality of compost mixture This review aims to evaluate the role of biochar during organic waste composting and identify the gaps of knowledge in this field Moreover, the research
* Corresponding author Laboratory of Ecology and Environmental Management, Science and Technology Advanced Institute, Van Lang University, Ho Chi Minh City, Viet Nam
** Corresponding author Ph.D Program in Maritime Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan
E-mail addresses: ctlin@nkust.edu.tw (C Lin), tranhuutuan@vlu.edu.vn (H.T Tran)
Contents lists available at ScienceDirect
Chemosphere
journal homepage: www.elsevier.com/locate/chemosphere
https://doi.org/10.1016/j.chemosphere.2022.134488
Received 16 January 2022; Received in revised form 18 March 2022; Accepted 30 March 2022
Trang 3Chemosphere 299 (2022) 134488
2
Humification
Enzyme activity
Greenhouse gases emission
direction to fill knowledge gaps was proposed and highlighted Results demonstrated the commonly referenced conditions during composting mixed biochar should be reached such as pH (6.5–7.5), moisture (50–60%), initial C/N ratio (20–25:1), biochar doses (1–20% w/w), improved oxygen content availability, enhanced the perfor-mance and humification, accelerating organic matter decomposition through faster microbial growth Biochar significantly decreased GHGs and odorous emissions by adding a 5–10% dosage range due to its larger surface area and porosity On the other hand, with high exchange capacity and interaction with organic matters, biochar enhanced the composting performance humification (e.g., formation humic and fulvic acid) Biochar could extend the thermophilic phase of composting, reduce the pH value, NH3 emission, and prevent nitrogen losses through positive effects to nitrifying bacteria The surfaces of the biochar particles are partly attributed to the presence of functional groups such as Si–O–Si, OH, COOH, C––O, C–O, N for high cation exchange capacity and adsorption Adding biochars could decrease NH3 emissions in the highest range up to 98%, the removal efficiency
of CH4 emissions has been reported with a wide range greater than 80% Biochar could absorb volatile organic compounds (VOCs) more than 50% in the experiment based on distribution mechanisms and surface adsorption and efficient reduction in metal bioaccessibilities for Pb, Ni, Cu, Zn, As, Cr and Cd By applicating biochar
improved the compost maturity by promoting enzymatic activity and germination index (>80%) However,
physico-chemical properties of biochar such as particle size, pore size, pore volume should be clarified and its influence on the composting process evaluated in further studies
1 Introduction
Composting is an effective technique to convert organic wastes into
the final product called “mature compost” through various metabolisms
(Awasthi et al., 2018; Chowdhury et al., 2014; S´anchez-Monedero et al.,
2019) During the composting process, volatile organic compounds
(VOCs), greenhouse gases (GHGs: N2O, CO2, CH4), and other odor
emission (H2S, NH3) could lead to serious secondary pollution, which
may pose adverse environmental and health effects (Chung et al., 2021;
Guo et al., 2020; S´anchez-Monedero et al., 2019) The previous studies
illustrated that default N2O and CH4 emissions factors were 0.6 g kg− 1
and 10 g kg− 1 waste during the composting process, respectively (Pipatti
et al., 2006) In certain conditions, for instance poor aeration, will lead
to anaerobic conditions that favors H2S and NH3 related odorous
emis-sions (Lin et al., 2021; Tran et al., 2021a) The rapid increase in VOCs
and GHGs, leading to the emission of chemical precursors to ozone (O3),
has led to the enhancement of ground-level ozone and raised concerns
about the impact of its pollution (Wang et al., 2017; Xu, 2020), which
may be related to changing ambient environment characteristics (Phan
et al., 2020; Pusede et al., 2015; Wu et al., 2017a) The effects of severe
secondary and primary pollution caused by VOCs and GHGs from
composting process impact natural ecosystems and health issues, which
is a concern and needs to be solved Therefore, it is necessary to manage
those gaseous emissions, which has become one of the most significant
concerns for sustainable development goals
Adding biochar as an additive into the compost mixture is a helpful
way to decrease GHGs and VOCs emissions during the composting
(Chowdhury et al., 2014; Dias et al., 2010; He et al., 2017; Wang et al.,
2018) The porous structure of biochar could enhance aeration rate and
reduce bulk density of the compost pile, also provide main shelters for
microorganisms, thus reducing the anaerobic zone generated, and as a
result, minimize GHGs and odors emissions (Jindo et al., 2012a; Steiner
et al., 2011) Owing to physical properties (e.g., high nano-porosity and
large SSA), biochar can enhance aeration capacity and water retention
The Brunauer-Emmett-Teller (BET) method revealed the specific surface
area (SSA) of nonactivated and rice straw–derived biochars varied from
0.2 to 35.4 m2 g− 1 which have been demonstrated by its helpful
appli-cations (Hwang et al., 2018; Lap et al., 2021; Nguyen et al., 2018; Tran
et al., 2022) Additionally, the BET SSA of nonactivated biochars lightly
changed consistent with the increase related to pyrolysis temperature
Biochar formed from various feedstocks has a SSA of more than 520 m2
g− 1, and the SSA of biochar derived from diverse feedstocks is as follows:
shell, straw, wood, manure, and sludge (Yuan et al., 2016) The benefits
of the application of compost combined with the presence of biochar
have reduced the bulk density inside the composting piles The exist a
strong correlation between bulk density and the microbial community
(bacterial and fungi), indicated depending on the initial organic wastes,
and change in bulk density affecting microbial colonization/structure and its biomass (Bapat et al., 2022; Jindo et al., 2012a) Biochar mi-crospores may be responsible for adsorbing moisture, and biochar par-ticles may also contribute some secondary porosity structure, which is essential for improving aerobic conditions during composting (Steiner
et al., 2011) The bulk density is influenced significantly by the com-posting time and experimental process Reducing bulk density obtained
by using biochar in the composts and reaching potential benefits for their application Furthermore, biochar agent has been investigated as a promising and efficient technology to increase the organic matter degradation and adsorbs GHGs (Wang et al., 2018) The previous illus-trated that poultry manure mixed with wood biochar showed that the organic matter was approximately degraded by 73–75%, and also GHG emissions were reduced around 42.8% (Chowdhury et al., 2014; Dias
et al., 2010) Similarly, coffee husk and sawdust biochar were reported
to decrease GHG emissions by around 46% and 55%, respectively (Chen
et al., 2010; Jiang et al., 2016)
Biochar amendment for composting has also recently been regarded
as a cost-effective and environmentally friendly solution to improve composting humification and performance, increasing microbial activ-ities and decreasing the available of heavy metal contents and organic contaminants (Agegnehu et al., 2017; Guo et al., 2020; Wu et al., 2018;
Xiao et al., 2017) Biochar has favorable physicochemical properties, such as large SSA, high porosity, carbon-residue derived from the thermal conversion related to organic waste and cation exchange ca-pacity, which allows it to interact with essential nutrient cycles and promotes microbial development during the composting (Awasthi et al.,
2017; Gudimella et al., 2022; Qayyum et al., 2017) The results showed that compost mixed with 8–12% biochar became more humified after composting (35 days), and the compost maturity not only revealed that this could be a much more feasible approach to increased important nutrients such as NO3−, PO43−, Na+, K+, DOC and DON, but also bioavailability of heavy metal (i.e., Zn, Cu, Ni, and Pb) was reduced when compared to control Regarding the effect of biochar on the dy-namic of a microbial community, the increased temperature of com-posting piles is related to changes in the richness and diversity of compost mixture (Jindo et al., 2012a; Le et al., 2021; Steiner et al., 2011;
Thakur et al., 2022; Yen et al., 2020) Biochar impacts the microbial community structure and changes in the phospholipid fatty acid analysis (PLFAs) patterns are related to major composting profiles (i.e., tem-perature, C/N ratio, bulk density) as the critical drivers During this stage, the raw materials were mineralized by the biochemical and bio-logical processes in which enzyme (i.e., dehydrogenase) reflected the microbial dynamic of the composting process Also, biochar is an effective tool for producing high-quality compost-based on reducing nutrient losses during the composting process and increasing compost maturity (Awasthi et al., 2016; Jiang et al., 2016) On the other hand,
M.K Nguyen et al
Trang 4Chemosphere 299 (2022) 134488
composting sewage sludge and animal waste with biochar has been
shown to reduce mobility and bioavailability of toxically heavy metals
(Antonangelo et al., 2021) Biochar⸻as an amendment to reduce
the bioavailability of heavy metals and enhance the composting
effec-tiveness during composting by adding 1, 3, 5 and 7% biochar into a
mixture (Liu et al., 2017b) During co-composted biochar investigated
that these heavy metals are usually formed strongly complex with the
organic substances in composting materials The biochar pyrolysed at
temperature conditions between 450 and 500 ◦C demonstrated excellent
ability in immobilization of heavy metals (particularly Zn, Cu) during
biochar blended composting (Li et al., 2015) Biochar was observed to
reduce the bioavailability and toxicity of Cd and Zn to E fetida
earth-worms in the vermicomposting experiments as well as enhancing the
number of juveniles, cocoons in the compost mixture
In recent years, numerous studies have investigated the biochar
ef-fect on the composting process (Guo et al., 2020; Sanchez-Monedero
et al., 2018) Sanchez-Monedero et al (2018) indicated that as an
ad-ditive, biochar enhanced the composting performance and humification
process, resulting in enhanced quality and maturity of the compost
mixture Similarly in Guo et al (2020) reported that biochar is a
valu-able technique to enhance microbial activities, reducing GHGs and
odors emissions, and the availability of heavy metals However, the
interaction between microbial community and biochar during the
composting process has not been addressed yet Also, a comprehensive
review of the role of biochar on compost quality is still ambiguous
Therefore, the aims of the study are to evaluate the role and effect of
biochar combined with composting as an amendment on VOCs, GHGs
emissions, enhancement of compost quality/maturity and their
rela-tionship with the microorganism activities during the organic waste
composting process The key benefits that can be reached by the biochar
mixed composting will also be investigated, especially related to the
organic matter degradation, microbial community, humification,
reduction of nitrogen losses, VOCs, and GHGs emissions Finally, the
future perspectives will be pointed out in this review
2 Effect of biochar on the physio-chemical properties during
composting process
As an additive agent, biochar helps to improve the performance of
composting process (Fig 1) Also, biochar addition could enhance the efficiency and decrease available nutrients due to their characteristic such as larger porosity, functional groups, water holding capacity (WHC), cation exchange capacity (CEC) (Guo et al., 2020; Schmidt et al.,
2014) The critical effects of added biochar on composting physico-chemical profiles and their performance are shown in Table 1
2.1 Moisture
Biochar was added into the compost mixture as a bulking agent, that could decrease the initial moisture content by absorbing excess moisture
of the mixture (Zhang et al., 2016) Also, biochar properties reduced bulk density and enhanced the aeration of compost, leading to a decrease the initial moisture content (Chowdhury et al., 2014; Wang
et al., 2013a) On the other hand, biochar addition has been illustrated
to increase the water retention capacity of the mixture as an absorbent, implying it prolonged the optimal moisture content (50–60%) for composting, and enhanced the performance and humification of the composting process (L´opez-Cano et al., 2016; Prost et al., 2013) The positive effect of biochar addition on the humification related to organic matters during the composting process and has been illustrated in pre-vious research (Dias et al., 2010; Jindo et al., 2012b; Zhang et al., 2014a) For instance, the combined addition of compost (35%) mixed biochar (20%) contributed efficiently to moisture content during the composting (Zhang et al., 2014a) Also, Awasthi et al (2017) showed that 8–12% biochar was blended into biosolids co-composting to improve humification within 35 days of the experiment
2.2 Oxygen content
Oxygen content plays a crucial role during the composting process, their presence in the biochar contributes to the adsorption process, which is also the key factor for aerobic microbial to degrade the organic substrate of the mixture (Tran et al., 2021b) Biochar addition into the mixture was observed enhancing the effectiveness of oxygen supply during the composting process due to higher porosity and their large SSA (Mujtaba et al., 2021; Tran et al., 2022) For instance, the presence
of biochar has increased the range from 21% to 37% in oxygen (O2) uptake rates on the first day of the sludge composting process (Zhang
Fig 1 Effects of biochar addition on physicochemical properties during composting
M.K Nguyen et al
Trang 5Chemosphere 299 (2022) 134488
4
et al., 2014a) Similarly, Steiner et al (2011) indicated that a
com-posting pile with biochar doses (20% v/v) improved oxygen content
availability, accelerating organic matter decomposition through faster
microbial growth Biochar with large surface area provided a home for
microorganisms, that significantly enhanced the microbial structure
(richness and diversity) of mixture (Laird et al., 2010) Furthermore,
biochar’s porous properties can help enhance the physical structures of
compost by increasing pile porosity, which prevents anaerobic
fermen-tation by promoting oxygen supply (Xiao et al., 2017)
2.3 pH
pH is a crucial factor that indicates the microbial activities and
population community during the composting process (Tran et al.,
2020) Increased pH at a later stage (i.e., in composting development)
was thought to impair biochar’s potential for phenolic component
retention, thus causing biochar materials to degrade even more (Bernal
et al., 2009; Tran et al., 2021a) The previous studies illustrated that critical condition for composting is affected by optimal pH during the compost mixture (6.5–7.5) (Godlewska et al., 2017; Hoang et al., 2022;
Tran et al., 2021a; Yunus et al., 2020; Zainudin et al., 2020) Also, the mobility of ions (e.g., heavy metals) is usually determined by pH The solubility of their toxic metals is reduced in compost with a higher pH, lowering its toxicity when used as fertilizer Because some soluble alkaline components in biochar leak away, biochar can elevate compost
pH shortly after being added (Li et al., 2015; Tran et al., 2021b) The pH profile during biochar mixed composting varies depending on biochar characteristics, composting methods/techniques, their compositions (e g., C/N ratio, nutrients, etc.) and composting materials such as food waste, animal waste, biosolids, yard waste, etc (Godlewska et al., 2017) Furthermore, He et al (2017) indicated that negative charge surfaces on biochar could absorb the generated ammonia/ammonium, resulting in a
pH reduction
Table 1
Main effects of added biochar on compost physico-chemical properties and their performance
Composting Biochar Amended rate Scale Periods Effects on composting performance and their
Poultry manure Wood 50% (w/w) Conical piles: 1.5 m high
The turned-pile system 210 days A high polymerization degree of humic compounds leads to reduce TN losses (Dias et al., 2010) Cow dung + hydrilla
+ sawdust Wood 2.5, 5, 10% (w/w) A rotary drum composter: 550 L 20 days Increased TN around 45% (Jain et al., 2018) Pig manure + sawdust Bamboo 0.03% (w/w) A tractor-pull windrow
turner 74 days A shorter time for thermophilic phase and a higher temperature during thermophilic
phase
( Wang et al., 2014 )
Poultry litter +
sugarcane straw Poultry litter 10% (w/w) 220 L compost bin 60 days Decreasing N2O and CH4 emissions Increased TN by 40% (et al., 2017aAgyarko-Mintah ) Chicken litter +
sawdust Hardwood shaving 5, 10% (w/w) Spherical plastic bins (153 L) 133 days The increase in CEC was 6.5 times (Khan et al., 2016) Sewage sludge +
wheat straw Wheat straw 2, 4, 8, 12% (w/w) 130-L PVC composter reactors 56 days Decreasing and degrading volatile fatty acids (VFAs) and odor emission index (2018Awasthi et al., ) Poultry litter +
sugarcane straw Green waste 10% (w/w) 220 L plastic compost bins 60 days Decreased TN losses by 51% Improved N retention (et al., 2017bAgyarko-Mintah ) Municipal solid waste Wood chips 1.5, 3, 5% (w/
w) Real conditions Full-scale 72 days A positive impact on the compost quality and reduction of nitrogen losses
Indicated higher moisture level and lower density
( Malinowski et al.,
2019 ) Dewatered sewage
sludge + wheat
straw
Wheat straw biomas 2, 4, 6, 8, 12, 18% (w/w) 130-L reactor in-vessel 56 days Increased water-soluble nutrients (i.e., NO3–, DOC, DON, PO43–, K+ and Na+)
Reduced bioavailability of heavy metals
( Awasthi et al.,
2017 ) Poultry manure +
barley straw Holm oak 3% (w/w) Pilot-scale Trapezoidal piles (1.5 m
high) Turned pile (windrow) system
19 weeks Biochar accelerated organic matter (OM) degradation Reduce the composting time by around 20%
( S´anchez-García
et al., 2015 )
Poultry manure +
wheat straw Woodchips 5, 10% (w/w) Reactors: 165 L 42 days Addition of biochar caused increasing temperature and shortened the thermophilic phase
Biochar increased CO2 emission
( Czekała et al., 2016 )
Corn wastes Corn wastes 1, 2% (w/w) Plastic pots (35 cm height
and 25 cm diameter) 150 days Improves the physicochemical properties of soil Exhibited high CEC and soil organic carbon (SOC) (Liu et al., 2021a) Hen manure + wheat
straw Bamboo 5, 10, 20% (w/ w) Small laboratory reactor Cylindrical (inner
diameter: 0.25 m, total height: 0.40 m)
28 days Reduced CO2, CH4, N2O and NH3 emissions ( Liu et al., 2017a )
Swine manure +
maize straw N/A 5, 10% (w/w) Medium-scale PVC reactors (100 L) 52 day Decomposition of dissolved organic carbon (DOC) Biochar promoted the composting humification
and increased the P-bioavailability
( Cui et al., 2022 )
Lab-scale N/A Biochar and compost divergently impacted functional groups of soil (Hale et al., 2021) Farm yard manure +
vermicompost Rice husk due N/A Plot size (3.6 m × 2.6 m) N/A Improving soil hydro-physical properties, crop yield (Sharma et al., 2021) Distilled grain waste Coconut
shells 5, 10, 15, 20% (w/w) A computer-controlled 28 L reactor 65 days Adding 10% biochar reduced nitrogen loss up to 25.69% and accelerated OM degradation, thereby
shortening the composting cycle
( Wang et al., 2021 )
Food waste digestate
+ sawdust + mature Tobacco stalk 2.5, 5, 10% (w/w) 20 L composters 42 days 10% biochar distribute to reduce 58% of NH3 emission and 50% of nitrogen loss (Manu et al., 2021) Fresh chicken manure Rice husk 3, 5, 10% (w/
w) 100-L plastic, cylindrical vessels
Pilot-scale
50 days Significant reduction in gaseous emissions (GHGs, NH3 and CO2), microbial pathogens (Chung et al., 2021) Remarks: CEC: Cation exchange capacity, TN: Total nitrogen, OM: Organic matter, DOC: Dissolved organic carbon, DON: Dissolved organic nitrogen, PVC: Polyvinyl chloride, N/A: Not available
M.K Nguyen et al
Trang 6Chemosphere 299 (2022) 134488
2.4 Temperature
Temperature is known as a key vital indicator of the composting
process and reflects the activities of microorganisms and also the organic
matter degradation in the compost piles (Huang et al., 2019) The added
biochar to the compost has been observed to activate the process,
evi-denced by a temperature increase and extending the thermophilic phase
(Chen et al., 2010; Steiner et al., 2010) The presence of biochar in the
composting process leads to temperature rising quickly, and so does the
duration of the thermophilic phase The temperature during composting
process increased faster in case of biochar addition than compared to the
control without biochar (Wei et al., 2014) Biochar added at the start of
the composting process, leads to increased water holding capacity
(WHC), thus ensuring the desired moisture level in the range from 50%
to 60% w/w (Prost et al., 2013) The biochar addition resulted in
obtaining higher temperature, ascribed fewer heat losses, and increased
microbial activity (Li et al., 2015) The higher temperature from the
composting may accelerate the abiotic oxidation process of the biochar
surface, resulting in more hydrophilic functional groups (e.g., carbonyl
groups, hydroxyl) that are available for microbial breakdown (Cheng
et al., 2006) The inclusion of biochar enhances aeration and hence the
number of microorganisms, speeding up the transformations and
increasing the heat produced (Godlewska et al., 2017)
2.5 C/N ratio
Biochar is used popularly to amend the elemental composition
dur-ing the compostdur-ing, and the C/N ratio is one of the most primary factors
that have influenced this process (Lin et al., 2021; Nguyen et al., 2020)
Because of the refractory carbon produced from the biochar addition,
most studies indicated that adding biochar enhanced the C/N ratio
(Chowdhury et al., 2014; Jindo et al., 2012a; Zhang et al., 2014b) A
suitable initial C/N ratio should be reached around 25:1 for aerobic
organic wastes composting (Wu et al., 2017c) The carbon to nitrogen
ratios (C/N) of various feedstock-derived biochars and composts varies,
which has a direct effect on the rate of organic matter decomposition
(Godlewska et al., 2017) The rates of labile carbon mineralization
remained high due to these biochar features, and the biochar in the
compost provided more excellent durability when utilized as the soil
amendments, which has crucial implications for C sequestration (Dianey
et al., 2021; Doan et al., 2022; Godlewska et al., 2017; Kamaruzaman
et al., 2022; Steiner et al., 2010) A high mineralization intensity leads to
decompose/oxidize to easily available forms and conservation of N
levels that are favorable during the N-rich composting process, e.g.,
manures and organic wastes Adding raw materials that contain a high
C/N ratio (e.g., biochar) could improve immobilizing N compounds, and
the nitrogen retained might be plant available for their growth Owing to
the presence of not only acidic functional groups but also in the
condi-tion of low pH, biochar has been reported as an absorber of
water-soluble NH4+or NH3, thus reducing N losses during composting
process (Kastner et al., 2009; Steiner et al., 2010) Biochar may impact
the C/N ratio, which is an essential factor in compost microbiology
(Wang et al., 2015) Biochar produces a favorable micro-environment
for nitrifying bacteria, which convert ammonia (NH4+) to nitrate
(NO3−), resulting in higher nitrogen content in biochar-treated compost
(Zhang et al., 2014a)
In short, biochar was added to the compost mixture as a bulking
agent that might reduce the initial moisture content of the mixture by
absorbing excess moisture The presence of oxygen in biochar
contrib-utes to the adsorption process, which is a significant component for
aerobic microorganisms to decompose the organic substrate of the
mixture during the composting process The optimal conditions of
ox-ygen content (15–20%) and moisture content range of 50–60% could
boost enzyme production and accelerate microbial activity When
bio-char is mixed into the composting piles, it increases the water-holding
capacity (WHC), ensuring the optimum moisture content The pH
profile of biochar mixed compost varies based on biochar properties, composting techniques, and their compositions (e.g., C/N ratio, nutri-ents, etc.), and the ideal pH during the composting mixture should be reached 6.5–7.5 For aerobic organic waste composting, a suitable initial C/N ratio should be about 20–25:1, which is essential for C sequestration
3 Effect of biochar on the dynamic of microbial community during the composting process
3.1 Effect of biochar on the dynamic of microbial community
The biochar itself possesses a highly porous structure that contains valuable substances such as inorganic nutrients, labile aliphatic com-pounds, and minerals (Quilliam et al., 2013; Xiao et al., 2017) Conse-quently, the biochar amended compost essentially contributes to an increase in natural ventilation, temperature, moisture content, a favor-able niche, and nutrition for native microorganisms (Atkinson et al.,
2010) In this regard, added biochar could positively improve the per-formance by changing the microbial community in the compost pile (Agegnehu et al., 2017) However, how much biochar dosage to ensure maximum activity and diversity of the microbial community is still being evaluated
Table 2 presents some studies on the microbial community changes driven by different raw materials and biochar dosage Most studies suggested that biochar is hugely compatible with various feedstock (Bello et al., 2020; Du et al., 2019b; Li et al., 2021) The biochar dosages are commonly used from 1% to 20% (w/w) Besides, adding a high dosage of biochar (10%) could reduce NH3, hydrogen sulfide (H2S), and
total VOCs, while N-cycling microorganisms such as genus Pusillimonas
Moreover, the enzyme’s activity of the bacterial community was strengthened by the biochar addition (10% and 20%) into sewage sludge and sawdust mixtures (Li et al., 2022) It indicated that the high dose of biochar might accelerate the metabolic activity of the adapted strain However, the observed richness (Chao1) and diversity (Shannon-Wi-ener) varied with biochar dosage Some studies have suggested that increasing biochar dosage to 20% recorded lower alpha diversity indices than control compost (Zainudin et al., 2020) Possibly, a high dose of biochar might reduce the biodiversity index It is well known that increasing the decomposition rate can help facilitate treatment times, but high microbial diversity could promote the complete breakdown of a broad type of persistent pollutants (Bird et al., 2011; Novak et al., 2016) Thus, this creates a trade-off to balance the crucial benefits between metabolic rate and microbial community diversity driven by biochar
dosage Excessive biochar (>10%) might cause severe heat dissipation
and water loss, adversely affecting on the composting process (Liu et al., 2017a) In addition, the relative abundance of heavy metals resistant bacteria (HMRB) in composting process was decreased with elevated biochar dosages (0–10%) Heavy metals and biochar content signifi-cantly reduced Firmicutes (52.88–14.32%), Actinobacteria
(35.20–4.99%), while increased phylum of Bacteroidetes (0.05–15.07%) and Proteobacteria (0.01–20.28%) (Zainudin et al., 2020) A moderate
addition of biochar (6%) was considered to have the most abundant HMRB among all treatments (poultry manure, wheat straw, and added chicken manure biochar (0–10%) (Li et al., 2021) Furthermore, the added 7.5% biochar enhances the removal of recalcitrant keratinized waste during pig manure composting (Duan et al., 2020) Taken together, these results point to the use of an appropriate amount of biochar that can help balance the diversity and metabolic activity of the community
3.2 Effect of biochar on the structure of microbial community
Biochar creates a distinct microbial population as a result of its
intervention in the composting process Proteobacteria, Bacteroidetes, M.K Nguyen et al
Trang 7Table 2
Different raw materials and biochar dosages drive microbial communities to change over time
ratios Biochar (%) Max Temp
( ◦ C)
Max
pH Max Shannon Max Chao1 Phylum Major Genus (Early-Middle periods) Major Genus (Middle -Later periods) Refs
1 Poultry manure + rice straw 2:1 20 58.9 9.9 5.2 887 Firmicutes, Proteobacteria,
Bacteroidetes Sinibacillus, Ammonibacillus,
Pseudofulvimonas, Pusillimonas, Petrimonas
Pusillimonas, Pseudomonas, Pseudofulvimona, Petrimonas, Sinibacillu
( Zainudin
et al., 2020 )
Poultry manure + rice straw
+ biochar 2:1 20 71.5 11 4.9 653 Firmicutes, Proteobacteria, Bacteroidetes Ammonibacillus, Sinibacillus, Halomonas,
Pusillimonas, Pseudofulvimonas
Halomonas, Pusillimonas, Pseudofulvimona, Nitriliruptor,
Truepera
2 Chicken manure + peanut
straw (3–5 cm) 2.5:1 0 60.2 8.94 4.1 312 Firmicutes, Bacteroidetes, Proteobacteria,
Halanaerobiaeota, Actinobacteria
Gallicola, Proteiniphilum, Bacillus, Ammoniibacillus Pseudomonas, Pusillimonas,
Ignatzschineria, Thiopseudomonas, Flavobacterium
( Li et al.,
2022 )
Chicken manure + peanut
straw + biochar 2.5:1 10 64.6 8.71 3.9 318 Firmicutes, Bacteroidetes, Proteobacteria,
Halanaerobiaeota, Actinobacteria
Gallicola, Proteiniphilum, Bacillus,
Ammoniibacillus
Pseudomonas, Pusillimonas, Ignatzschineria, Thiopseudomonas, Flavobacterium
3 Sewage sludge + corn cob (7
mm) 5:3 (v/v) 0 54 8.08 4.6 – Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria Bacillus, Ochrobactrum, Proteiniphilum Alicycliphilus, Ochrobactrum, Proteiniphilum (2021cLiu et al., ) Sewage sludge + corn cob +
biochar 5:3 (v/v) 8.2 55 8.07 4.0 – Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria Sphingobacterium, Glutamicibacter,
Ochrobactrum, Rhodanobacter, Enterobacter
Bacillus, Ochrobactrum, Rhodanobacter
Sewage sludge + corn cob +
biochar 5:3 (v/v) 15.2 55 8.13 3.9 – Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria Glutamicibacter, Microbacterium,
Ochrobactrum, Enterobacter, Rhodanobacter
Bacillus, Ochrobactrum, Rhodanobacter
4 Cow manure + sugarcane
straw (1 cm) 5:1 (v/v) 0 60 – – – Firmicutes, Actinobacteria, Proteobacteria, Chloroflexi,
Bacteroidetes
Corynebacterium, Romboutsia, Pseudoxanthomonas, Thermomonospora, Clostridium
Thermopolyspora, Thermomonospora, Ureibacillus (2021Yan et al., )
Cow manure + sugarcane
straw (1 cm) + biochar 5:1 (v/v) 5 68.5 – – – Firmicutes, Actinobacteriota, Proteobacteria, Chloroflexi,
Bacteroidetes
Corynebacterium, Romboutsia, Pseudoxanthomonas, Thermomonospora, Clostridium
Thermopolyspora, Thermomonospora, Ureibacillus
5 Sewage sludge + straw (1 cm) 4:1 0 59.9 8.4 4.7 582 Firmicutes, Proteobacteria,
Chloroflexi, Actinobacteria, Bacteroidetes
Pseudomonas, Chloroflexi, Pedobacter, Planomicrobium, Microtrichales
Vulgatibacter, Anaerolineaceae, Thermobifida (2021Xue et al., )
Sewage sludge + straw (1 cm)
+ biochar 4:1 3.85 61.6 8.2 4.6 556 Proteobacteria, Chloroflexi, Firmicutes, Actinobacteria,
Bacteroidetes
Pseudomonas, Pedobacter, Planomicrobium Psychrobacillus, Paenisporosarcina, Ureibacillus
(continued on next page)
Trang 8Table 2 (continued)
ratios Biochar (%) Max Temp
( ◦ C)
Max
pH Max Shannon Max Chao1 Phylum Major Genus (Early-Middle periods) Major Genus (Middle -Later periods) Refs
Sewage sludge + straw (1 cm)
Bacteroidetes,
Pseudomonas, Chloroflexi, Pedobacter, Planomicrobium, Microtrichales
Vulgatibacter, Thermobifida, Ureibacillus, Chelativorans
Sewage sludge + straw (1 cm)
+ aerobic microorganism
agent + biochar
Firmicutes, Actinobacteria, Bacteroidetes
Pseudomonas, Microtrichales, Planomicrobium, Chloroflexi
Thermopolyspora, Anaerolineae, Chloroflexi, Limnochordaceae, Ureibacillus
Sewage sludge + straw (1 cm)
+ facultative anaerobic agent 4:1 0 61.1 8 4.9 583 Proteobacteria, Chloroflexi, Firmicutes,
Actinobacteria, Bacteroidetes
Pseudomonas, Microtrichales, Chloroflexi, Pedobacter, Planomicrobium
Bacillus, Chelativorans, Thermobifida, Pseudoxanthomonas
Sewage sludge + straw (1 cm)
+ facultative anaerobic agent
+ biochar (3–5 mm)
Firmicutes, Actinobacteria, Bacteroidetes
Microtrichales, Chloroflexi, Pedobacter, Planomicrobium Pseudoxanthomonas, Anaerolineaceae, Thermobifida,
Anaerolineae, Chloroflexi
Bacteroidetes, Chloroflexi, Proteobacteria
Bacilli, Clostridia, Tenericutes, Actinobacteria
Firmicutes, Bacteroidetes, Proteobacteria, Chloroflexi (2020Yang et al., ) Pig manure + wheat straw +
bean dregs (15%) 2:1 0 68 8.1 4.8 840 Actinobacteria, Firmicutes, Bacteroidetes, Chloroflexi,
Proteobacteria
Bacilli, Clostridia, Genus of Tenericutes and Actinobacteria
Firmicutes, Bacteroidetes, Proteobacteria, Chloroflexi Pig manure + wheat straw +
biochar (10%) 2:1 10 68 8.3 5.5 900 Actinobacteria, Firmicutes, Bacteroidetes, Chloroflexi,
Proteobacteria
Bacilli, Clostridia, Tenericutes, Actinobacteria Firmicutes, Bacteroidetes, Proteobacteria Chloroflexi Pig manure + wheat straw +
bean dregs (15%) + biochar
(10%)
Bacteroidetes, Chloroflexi, Proteobacteria
Bacilli, Clostridia, Tenericutes, Actinobacteria Firmicutes, Bacteroidetes, Proteobacteria, Chloroflexi
7 Tomato stalk + chicken
manure + biochar 6:5 1 56 7.2 2.58 – Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria Flavobacterium, Actinobacterium,
Chitinophaga sp., Pseudomonas sp
Acinetobacter, Chitinophaga sp., Flavobacterium, Actinobacterium
( Wei et al.,
2014 )
Tomato stalk + chicken
manure + peat bog 6:5 1 50 7.3 2.03 – Proteobacteria, Firmicutes, Actinobacteria Pusillimonas sp., Microbacterium sp.,
Geobiacillus sp., Pseudomonas sp., Rhizobiales sp
Rhizobiales sp., Acinetobacter sp., Chitinophaga sp
Pusillimonas sp., Tomato stalk + chicken
Acinetobacter sp., Actinobacterium
Pseudomonas sp., Chitinophaga sp., Rhizobiales sp., Pusillimonas sp.,
Actinobacteria, Proteobacteria, Chloroflexi,
Bacteroidetes
Corynebacterium, Bacillus, Atopostipes, Marinilabiaceae, Turicibacter
Thermopolyspora, Thermobifida, Anaerolineaceae (2020Bello et al., )
Cattle manure + maize straw
Proteobacteria, Chloroflexi, Bacteroidetes
Corynebacterium, Bacillus, Atopostipes, Marinilabiaceae, Turicibacter
Actinomadura, Longispora, Streptomyces
Trang 9Chemosphere 299 (2022) 134488
8
Firmicutes, and Actinobacteria were the most predominant phyla in
bio-char amended compost due to their excellent compatibility with biobio-char
and feedstock (Duan et al., 2019a; Li et al., 2022; Yang et al., 2020)
Biochar is likely to promote the proliferation of certain individual
bac-terial phyla rather than entire communities due to biochar affecting
physicochemical properties during composting (Dang et al., 2021)
Proteobacteria was related to the nitrogen and carbon cycle, while
Acti-nobacteria played an essential part in degrading lignin and refractory
cellulose Actinobacteria can utilize biochar as a source of C and
miner-alize it to CO2; these biochars may have guided the metabolism of
Actinobacteria and enriched it through a process known as Copiotrophs
(Bello et al., 2020)
The relative abundance of this bacterium can be altered by C/N
value, biochar dosage, composting phase, and temperature (Czepiel
et al., 1996) Biochar simultaneously increases the temperature and
prolongs the thermophilic phase compared to non-biochar compost
piles, thereby promoting the metabolism of adapted strains as well as
changing the bacterial community over time (Zainudin et al., 2020) The
Actinobacteria and Firmicutes play an important role in decomposing
complex organic materials during the thermophilic phase and are
thermos-tolerant (Bello et al., 2020) With increased temperature, the
relative abundance of genus belonging to Bacteroidetes and
Proteobac-teria decreased and later increased as the compost temperature declined
(Bello et al., 2020) Genera of Proteobacteria and Bacteroidetes are known
to be resistant to antibiotics, and this fact may explain why increased
peak temperature by biochar amendment compost would be beneficial
to enhance the elimination of antibiotic resistance genes (ARG) (Fu
et al., 2021; Li et al., 2017; Siedt et al., 2021)
3.3 Effect of biochar on the microbial community – nitrogen during the
composting
Absorption of biochar increases the activity of nitrifying bacteria,
reduces methanogens, and increases heavy metal fixation The surfaces
of the biochar particles are partly attributed to the presence of functional
groups such as Si–O–Si, OH, COOH, C––O, C–O, N for high cation
ex-change capacity and adsorption (Agegnehu et al., 2017) As a result,
biochar aids in absorbing both NH3 and greenhouse gas released from
the compost pile, increasing oxygen diffusion to reduce the anaerobic
zone (Xiao et al., 2017) After the NH3 is adsorbed by biochar, this is
reported to benefit the growth of nitrifying bacteria, which convert the
ammonium to nitrate and thus retain nitrogen in the compost products
(Godlewska et al., 2017; Li et al., 2022) Consequently, it tends to
in-crease N–NO3− concentration while decreasing the volatilization of NH3
(Chen et al., 2017a) The concentration of NO3− was increased twice
compared to conventional compost (L´opez-Cano et al., 2016) In
addi-tion, biochar also affects the genus denitrification populaaddi-tion, such as
N2O− producing bacteria, by improving oxygen diffusion into the
compost pile, so less N2O is produced (Wang et al., 2013b) The
pre-dominant aerobic zone is responsible for a decrease in the population of
anaerobic species such as denitrifying bacteria and methanogens By
contrast, biochar likely increased the activity of methane-oxidizing
bacteria that convert CH4 to CO2 (Liu et al., 2017a) In addition, when
the compost pile has few anaerobic zones, it results in a limited number
of Methanogens and Methanotrophs present to directly reduce CH4
emission (He et al., 2019a; Mao et al., 2018)
In summary, a proper biochars dosage could reduce organic and
inorganic pollutants by altering the profile and activity of the microbial
community A higher rate of biochar addition will increase pollutant
uptake and carbon sequestration but be more expensive and might hurt
biodiversity Biochar not only helps to create a distinct microbial
pop-ulation in the compost pile, but its high adsorption capacity is beneficial
for heavy metal fixation, improved nitrification, and reduced GHGs
emissions To put such results into practice, it is necessary to carry out
large-scale experiments
4 Effect of biochar on VOCs and GHGs emission during composting process
During composting, VOCs (e.g., hydrocarbons, alcohols, aldehydes, esters, etc.), GHGs (N2O, CO2, CH4), and odorous gases (H2S, NH3) are emitted into the ambient air, which may pose an environmental risk and health concerns Biochar amendment is considered as an efficient solu-tion to adsorb VOCs, GHGs, odorous gases through various previous studies (Awasthi et al., 2016; Chowdhury et al., 2014; Dias et al., 2010;
He et al., 2017; Janczak et al., 2017; Jiang et al., 2016; Wang et al.,
2018) Table 3 and Fig 2 illustrate the effects of biochar on the VOCs and GHGs emissions during composting
4.1 Volatile organic compounds (VOCs)
The biochar addition significantly reduced the emissions of oxygen- and nitrogen-containing VOCs during the composting process (S´anchez-Monedero et al., 2019; Tran et al., 2018) During the ther-mophilic phase belongs to composting process, VOC were classified based on its abundance into three main groups, including nitrogenous, oxygenated and other compounds By using 90% poultry manure plus 10% straw (within 3% biochar addition), improving aerated conditions reduced up to 50% these concentrations during the thermophilic phase
in composting process The greatest efficiency was illustrated in the OVOCs compounds, with most ketones, phenols and volatile fatty acids (VFAs) concentrations reduced significantly in a pile mixing biochar The addition of biochar promoted the aeration rate in the composting matrix due to its higher porosity, leading to increasing gas exchange and preventing the anaerobic zones formation, which could be a source of VOCs (Sanchez-Monedero et al., 2018) Pore structure and surface acid functional groups in biochar could trap toxic emissions, thus preventing toxic volatilization and reducing their pollution Biochar’s strong sorp-tion capacity may represent a mechanism for VOCs eliminasorp-tion in the composting piles, that is aided by their large SSA (S´anchez-Monedero
et al., 2019) For example, wooden biochars showed high removal ef-ficiencies for acetone, toluene and cyclohexane in the value from 50 to
100 mg VOC g− 1 (Zhang et al., 2017) Janczak et al (2017) investigated that 10% biochar can decrease VOCs emissions during biosolid com-posting Biochar could absorb TVOCs (about 17.55%) in the experiment based on distribution mechanisms and surface adsorption (Li et al.,
2021) Furthermore, the most efficient VOCs reduction was investigated
in OVOCs compounds (e.g., phenols, ketones, and organic acids) and dramatically reduced the amounts of volatile nitrogen compounds,
which are produced by microbial modification of N-compounds These
results indicate the importance of biochar application not only impacts the composting progress but also their sorption capacity as key drivers for VOCs reduction
In addition, the environmental conditions are characterized such as temperature, moisture, etc during composting that may affect the sorption of VOCs on biochar surface (Hwang et al., 2018;
S´anchez-Monedero et al., 2019; Tran et al., 2018; Zhang et al., 2017) The impact of biochar could modify these conditions inside the com-posting matrix, and affecting on vital parameters including aeration, temperature, moisture, microbial activity that is related to the for-mation/degradation of VOCs compounds during composting ( Mauli-ni-Duran et al., 2014) More clearly, composting biochar increases pH, aeration, enhances water holding capacity, and thus improving oxygen content and redox conditions (Wu et al., 2017b) Interestingly, the composting piles mixed biochar enhanced favorable environmental conditions for microbial growth, leading to the reduction of VOCs This work may explain that biochar is a promising alternative sorbent and favorable effective in reducing gaseous VOCs
During composting several major greenhouse gas compounds such as
M.K Nguyen et al
Trang 10Chemosphere 299 (2022) 134488
nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) can be
emitted due to organic matter degradation (Chowdhury et al., 2014)
Adding biochar to composts increases carbon stabilization, which raises
the potential benefits of employing co-composting, such as minimizing
nutrient losses through leaching and lowering GHG emissions Biochar
addition to the co-composting is beneficial approach in the reduction of
CH4 emissions, that is due to the better aeration, reduced bulk density,
gas diffusion, and creating suitable conditions for methanotrophs can
consume CH4 (Vandecasteele et al., 2016) Illustration of the GHG
emissions rates measured during the composting process by amending
biochar resulted in a clear reduction in CH4 The average emission rates
for the whole process of the control and the biochar mixed compost were
8.1 and 1.5 g CH4 m2 d− 1, respectively Biochar addition in the feedstock
mixture of green and organic wastes enhance the composting process
and shows the different effects before and after adding biochar 10% into
the composting piles The removal efficiency of CH4 emissions has been
reported with a wide range from 10.8% up to greater than 80%
(Agyarko-Mintah et al., 2017b; Chen et al., 2017a; Vandecasteele et al.,
2016) Also, Steiner et al (2010) found improved aeration when biochar addition at doses of 5% and 20% reduced emissions by 58% and 71%, respectively
He et al (2019b) showed that granular bamboo biochar has a high potential for reducing CO2 emissions The positive effect of additives during co-composting may have significant potential to reduce CO2
emissions In another study, biochar addition led to a reduction of CO2
emissions up to 44% compared to the control (Barthod et al., 2016) This can be explained by the adsorption of organic matters on the biochar surface, and biochar has been used as a co-composting agent to reduce carbon emissions The major mechanism can trap of CO2 during com-posting related to biochars addition, leading to decreased CO2 emis-sions, with biochar as the alkaline agent In addition, it is seen that the organic matter decomposition during the composting process (bio oxidative phase) were partially limited by the biochar adsorption for
CO2 reduction The average CO2 emission rates for the whole com-posting process of the control and the biochar mixed experiments were
401 and 195 g m2 d− 1, respectively (Vandecasteele et al., 2016)
Table 3
Effects of biochar on VOCs and GHGs emissions during composting
Green waste +
bagasse +
chicken manure
Waste willow wood (Salix spp.) Pyrolysis: 550 ◦ C
Compost windrows Field-scale
Lowered N2O emissions Improved soil quality Yield increase
Biochars are more stable in soil, it is resulting in lower CO2 loss (2016Agegnehu et al., ) Green waste +
bagasse +
chicken manure
Waste willow wood (Salix spp.) Pyrolysis: 550 ◦ C
9% w/w Field-scale Period: 98 days Amendment windrows
Reduced N2O emissions Increased Na, K, Mg, P, NO3–, NH4+ and soil carbon
Biochar may be less suited for reducing N2O flux in some agricultural soils, at least on shorter temporal scales
Biochar could act as an electron shuttle, which enhances the last step from N2O to N2
( Agegnehu et al.,
2016 )
Farm manure Garden peat
Pyrolyzer: 450 ◦ C Rate: 2% w/w Laboratory scale
Periods: 3 months Moisture: 60%
Reduced CO2 emission, especially with a higher proportion of biochar
in the compost Increased SOC, yield, N and K contents in plant
Effect of biochar mixed composts illustrated stabilization of native and labile organic carbon present in farm manure (FM), resulting in carbon stabilization in the soil
( Qayyum et al., 2017 )
Pig manure Rice straw
Pyrolysis: 450 ◦ C Reactors: 120 L cylindrical plastic
Period: 84 days Passive aeration composting
Significantly reduced N2O emissions The low degradability of biochar could be led to the core reason for these findings (Vu et al., 2015)
Poultry manure +
wheat straw Wood woodchips Pyrolysis: 350 ◦ C 5% and 10% Laboratory scale
Reactors: 165 L Period: 42 days
5% and 10% of biochar can reduce NH3 emission by 30% and 44%, respectively
Biochar addition to poultry manure contributes
to nitrogen retention in the solid Biochar’s beneficial effect on nitrogen loss is due mainly to its adsorption properties and the presence of surface acid groups
( Janczak et al., 2017 )
Chicken mortality Woodchips
Gasification:
520 ◦ C
1, 5, 10, and 15%
Period: 11 weeks Pilot-scale Composting test:
32-gallon bins Aerated rate: 1.5 L min–1
Biochar amendment at 10 and 15%
could reduce the cumulative NH3 emissions up to 40% and 57%
The potential to decrease NH3 release is due to the adsorption of NH3/NH4+ by biochar pores Acid functional groups on biochar surfaces can trap NH4+ and prevent their volatilization
( Wang et al., 2018 )
Sewage sludge +
zeolite + lime Wheat straw Bench-scale PVC: 130 L
Period: 56 days 12% biochar
12% biochar + zeolite could significantly reduce the CH4 58.03–65.17% and N2O 92.85–95.34%
Biochar enhanced the gaseous NH3 adsorption and as a potential additive
Rapid mineralization of total organic matter (TOM)
( Awasthi et al., 2016 )
Chicken manure
+ straw Holm oak Pyrolysis: 650 ◦ C 3% biochar addition
Trapezoidal piles:
1.5 m × 2 × 3 Pilot scale Period: 20 weeks
Biochar efficiently reduced the levels of VOC during the thermophilic phase The most efficient VOC reduction was observed in OVOCs compounds (e.g., ketones, phenols and organic acids)
Biochar dramatically reduced the amounts of volatile nitrogen compounds, which are
produced by microbial modification of N-
compounds Biochar’s strong sorption capacity may serve as
a mechanism for VOCs removal, which is aided
by the original biochar’s surface area
( S´anchez-Monedero
et al., 2019 )
Swine manure Non-activated
biochar Pyrolysis:
495–505 ◦ C
Pilot-scale Non-activated Biochar can be a promising and comparably-priced option for
reducing NH3 emissions from swine manure
The biochar’s NH3 mitigation is likely related
to creating a semi-porous crust layer over the surface of the manure
( Maurer et al., 2017 )
Fresh chicken
manure +
peanut straw
Biochar made from charcoal at
400 ◦ C Surface area:
35.48 m2 g–1
10% biochar Reactors: 60 L
Aeration rate: 2 L min–1 Period: 40 days
NH3, H2S, and TVOCs emission decreased by 20.04%, 16.18%, and 17.55% in the experiment
Biochar could absorb TVOCs based on distribution mechanisms and surface adsorption
( Li et al., 2021 )
Remarks: PVC: Polyvinyl chloride, VOCs: Volatile organic compounds, TVOCs: Total volatile organic compounds, OVOCs: Oxygenated volatile organic compounds, SOC: and soil organic carbon
M.K Nguyen et al