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Transactions on Engineering and Computing Sciences - Vol. 12, No. 3

Publication Date: June 25, 2024

DOI:10.14738/tecs.123.16957.

Douglas, R. K., Lawrence, C. A., & Ebiundu, K. (2024). Pristine Plantain Peels Biochar and Effect of Weathering on Polycyclic Aromatic

Hydrocarbon Biodegradation in Crude Oil-Contaminated Soils. Transactions on Engineering and Computing Sciences, 12(3). 64-72.

Services for Science and Education – United Kingdom

Pristine Plantain Peels Biochar and Effect of Weathering on

Polycyclic Aromatic Hydrocarbon Biodegradation in Crude Oil- Contaminated Soils

Douglas, R. K.

Department of Chemical Engineering Niger Delta University,

Wilberforce Island, Nigeria

Lawrence, C. A.

Department of Chemical Engineering Niger Delta University,

Wilberforce Island, Nigeria

Ebiundu, K.

Department of Chemical Engineering Niger Delta University,

Wilberforce Island, Nigeria

ABSTRACT

The current research compared the potential of an agricultural waste-plantain

peels derived biochar and weathering for the remediation of polycyclic aromatic

hydrocarbons (PAHs) contaminated soil at laboratory scale. PAHs concentrations

ranged from 0.245 to 348.04 mg/kg for the control sample (concentrations

obtained without amendment after 4 day incubation period). Benzo(a)pyrene had

the least concentration, while Chrysene has the highest concentration. Under

weathering conditions, the sum concentration of PAHs was observed to be 694.213,

687.892, and 670.866 mg/kg after 30, 60, and 90 days experiment, respectively.

More PAHs concentration degradation was observed with the PPB amendment

option. That is, with PPB amendment option, the sum concentration of PAHs

obtained were 649.743, 634.532, and 550.369 mg/kg after 30, 60, and 90 day

experiment, respectively. Furthermore, first-order kinetics was used to determine

the kinetics of PAHs degradation, which was applied on both the weathering and the

PPB amendment options. With weathering, PAHs degradation rate constant (K)

increased with decreasing PAHs concentrations; which shows that PAHs

degradation in contaminated soil is slow under the influence of weathering. With

PPB amendment option, the K value decreased between K30 and K60 with decreasing

PAHs concentrations, which implies faster degradation of PAHs. However, reverse

was the case between K60 and K90. This shows slow degradation of PAHs. Results

suggest that the PPB option is promising for the restoration and/or reclamation of

soil polluted with PAHs.

Keywords: Soil, Hydrocarbons, Weathering, Biochar, Biodegradation, Kinetics

INTRODUCTION

Environmental contamination is currently a critical challenge globally, and a serious threat to

human and environment health [1]. According to [2], crude oil exploration and exploitation

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Douglas, R. K., Lawrence, C. A., & Ebiundu, K. (2024). Pristine Plantain Peels Biochar and Effect of Weathering on Polycyclic Aromatic Hydrocarbon

Biodegradation in Crude Oil-Contaminated Soils. Transactions on Engineering and Computing Sciences, 12(3). 64-72.

URL: http://dx.doi.org/10.14738/tecs.123.16957

activities, accidental spills, sabotage etc, are critical issues accountable for environmental

pollution and degradation from petroleum hydrocarbons (PHCs) and its derivatives. Crude oil

is a complex mixture-comprising aliphatic and aromatic hydrocarbon compounds, and traces

of heterocyclic compounds-comprising sulphur, nitrogen, oxygen; which are acknowledged

environmental contaminants [3; 4]. PHC compounds are generally toxic, and impacts negatively

on soil’s physicochemical properties [5]. PHC induced pollution is a grave environmental

problem due its immobilization and consequent buildup nature in the environment [6]; and is

severely impacting the ecosystems wellbeing and humans [5; 7]. It was reported that the micro- organisms population in the soil was greatly depends on the level of PHC concentration [8].

Crude oil also contains potentially toxic elements (PTEs) including silver, Ag; titanium, Ti;

arsenic, As; nickel, Ni; cobalt, Co; lead, Pb; manganese, Mn; copper, Cu; iron, Fe; zinc, Zn;

cadmium, Cd; magnesium, Mg; chromium, Cr; amongst others [9]. Soil contamination by PTEs

has attracted substantial ecological concern due to their toxicity and bioaccumulation. Nigeria

has been ranked largest natural gas reserve and the second largest oil reserve in Africa. In the

Niger Delta region of Nigeria (Ogoni land in Rivers State), [10] reported that crude oil pollution

has deeply affected soil, air, and water quality criteria and thus posing a serious threat to both

human health and the environment. This is same in the other crude oil producing states,

especially, Bayelsa, Delta, Akwa Ibom, and Ondo states in the region. The devastating

environmental pollution and degradation and associated impacts in the Niger Delta, Nigeria are

primarily due oil theft; oil bunkering; artisanal (illegal) refining of crude oil in Nigeria; technical

or operational error; un-serviced oil infrastructure; and hazardous waste management. Thus,

there is need for contaminated land management in the region; which is the responsibility of

the Environment Unit at the Department of Petroleum Resources (DPR), and the National Oil

Spill Detection and Response Agency (NOSDRA). DPR is responsible for managing legacy sites

and NOSDRA is responsible for the detection and management of emerging oil spills [11; 12;

13]. However, Nigeria lacks the necessary funds and the expertise to handle these critical issues

of environmental pollution and degradation caused by the activities of the oil and gas industries

in the Niger Delta region. Therefore, there is need to develop simple, cost-effective, low-carbon,

and sustainable means and/ or methods (e.g., bioremediation by agricultural waste) to address

the issues of PHCs-contaminated soils and/or land sites in the laboratory first, and later take

the laboratory to the field to address this alarming and devastating problem of land pollution

and degradation in the region.

Remediation of PHCs-contaminated land sites has become a global concern due to the negative

effects of PHCs on the environment (soil, water, and air) and human health. Considerable efforts

have been dedicated to developing simple adoptable methods for the remediation of PHCs- contaminated soils and/or land sites. Currently used PHCs-contaminated soil remediation

methods include excavation, burning (i.e., physical, chemical approaches); chemical (detergent,

surfactant, degreaser), phytoremediation (the use of plants), and biological (bioremediation)

[5; 14]. However, there are shortcomings associated with existing remediation techniques. For

instance, thermal desorption is costly and prone to secondary pollution [15].

Contaminated soil remediation by phytoremediation is the application of plants to remove

and/or mitigate contaminants in the environment [16]. This technique has been proven

effective for the remediation of environmental contaminants including petroleum products,

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Transactions on Engineering and Computing Sciences (TECS) Vol 12, Issue 3, June - 2024

Services for Science and Education – United Kingdom

and heavy metals. However, plant for phytoremediation should tolerate both the climatic and

soil conditions of the prevailing polluted environment [5]. According to [17], for a plant to be

fit for the phytoremediation of contaminated soils, such plant should have the potential to

accumulate the extracted contaminant; should be tolerant enough not only to survive in the

contaminated environment, but also adsorb contaminants into their shoots; be able to grow

rapidly with the capacity to accumulate possible toxins; and be easily harvested and simply

disposed.

Bioremediation by the use of agricultural wastes have been reported cost-effective and a simple

approach for contaminated soil remediation [18; 19]. Consequently, the current research aims

to assess the potential of pristine plantain peels-based biochar (PPB); which might constitutes

environment pollution if not properly dispose of for PAHs biodegradation in crude oil- contaminated soil. Furthermore, the specific objective was to compare the biochar induced

degradation with the effect of weathering.

MATERIALS AND METHODS

Soil Sample Collection

1kg pristine soil sample was collected from the Niger Delta University, Department of

Agricultural and Environmental Engineering Research Farm, Amassoma, Bayelsa State, Nigeria.

The sampling site has no history of hydrocarbon pollution. A subsurface soil sample was

collected from top 0-20cm layer using a hand trowel and taken with polythene bags to the

laboratory. Pristine soil was sieved using 4 mm sieve, and analyzed for hydrocarbon

contamination.

Plantain Peel Collection and Biochar Preparation

A bounce of plantain (fresh) was bought from Swali Ultra-Modern Market (SAM), Bayelsa State,

Nigeria. The plantains were peeled to obtain the peels. The peels were sliced to smaller pieces

and sun dried at ambient condition for 2-3 days. The dried plantain peels were packaged and

taken to the Reaction Kinetics laboratory, Department of Chemical Engineering, Niger Delta

University, Wilberforce Island, Amassoma, Bayelsa State, Nigeria for the production of plantain

peel derived biochar (PPB). The PPB was produced at low-temperature (T = 300oC) at the Niger

Delta University Chemical Engineering Laboratory using a furnace.

Experimental Design

Two (n = 2) soil microcosms (labelled A and C) were set up using 2k soil, and spiked with 250ml

crude oil. The two soil samples were allowed to equilibrate at laboratory conditions for 4 days.

Sample A was amended with 500g PPB, while Sample C was kept as a control (i.e., no

amendment was added to it). All the microcosms were mixed manually to obtain homogenous

samples and kept in the laboratory at laboratory conditions. The soil moisture was adjusted

twice a week by adding deionized water to mimic ambient conditions. Sample B (i.e., the control

sample) was taken for petroleum hydrocarbon analysis by gas chromatography coupled with

mass spectrometry (GC-MS) after the 4 day incubation period. Samples A and B were further

subjected to hydrocarbon analysis by GC-MS at thirty day time intervals (i.e., 30 days, 60 days

and for 90 days) to determine the effect of the amendment option (PPB) on the concentration

of polycyclic aromatic hydrocarbons (PAHs). Furthermore, the influence of weathering and /or