Bioscience Methods 2017, Vol.8, No.1, 1-17
1
Research Article Open Access
Assessment of Pollution Load Indices of Heavy Metals in Cassava Mill Effluents
Contaminated Soil: a Case Study of Small-scale Processors in a Rural
Community in the Niger Delta, Nigeria
Sylvester Chibueze Izah , Sunday Etim Bassey, Elijah Ige Ohimain
Department of Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria
Corresponding author email
Bioscience Methods, 2017, Vol.8, No.1 doi
Received: 15 Sep., 2017
Accepted: 30 Oct., 2017
Published: 17 Nov., 2017
Copyright © 2017
Izah et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Izah S.C., Bassey S.E., and Ohimain E.I., 2017, Assessment of pollution load indices of heavy metals in cassava mill effluents contaminated soil: a case
study of small-scale processors in a rural community in the Niger Delta, Nigeria, Bioscience Methods, 8(1): 1-17 (doi
Abstract
Cassava mill effluents are discharged into the environment by smallholder cassava processor in rural communities in the
Niger Delta region of Nigeria. Cassava mill effluents are known to induce toxicity in some biodiversity such as livestock (sheep,
goat), vegetation, microorganisms and fisheries. This study evaluated the pollution load indices of heavy metals in cassava mill
effluents contaminated soil in rural community in the Niger Delta region of Nigeria. Secondary data from cassava mill effluents soil
were used for the study. The data were classified based on seasons. The pollution load was calculated following standard protocol.
Nine pollution indices were considered including Contamination factor (CF), Degree of contamination (CD), Pollution load index
(PLI), Pollution index (PI), Sum of pollution index (SPI), Pollution index/ Contamination Index (PI/CI), Metal pollution Index (MPI),
Average Pollution Index (API) and Nemerow integrated pollution index (NIPI). In few instance that some heavy metals was not
detected, 50% of mean detected individual metals were considered for the location that the metals were not detected. Geometric
(BGM) and median mean (BMM) were considered for the background scenarios except for API and PI/CI in which median mean was
used. The pollution load resulting from these heavy metals viz: Fe, Cr, Zn, Cu, Co, Ni, Mn, Pb and Cd revealed that CF and CD had
low to moderate contamination level in both seasons apart from Pb that had considerable pollution in one of the locations for wet
season, PLI were within no pollution to moderate pollution, PI were also within no pollution to low pollution level and NIPI were
within warning line of pollution to low level of pollution for dry season, and warning line of pollution to high pollution in wet season.
MPI, PI/CI and API showed slight pollution. The findings of this study also showed that cassava processing by smallholder in rural
communities in the Niger Delta is slightly contributing to heavy metals pollution is receiving soil which varies according to seasons.
Furthermore, age and heavy metal content in the cassava tuber and quantity of cassava processed in each mill and other
anthropogenic activities could account for difference in pollution among the various locations, while runoff resulting from rainfall
could account for the seasonal influence.
Keywords
Cassava mill effluents; Degree of contamination; Heavy metals; Pollution load
Background
Environmental sustainability is under threat mostly due to anthropogenic activities and to lesser extent natural
effects. Industrial activities releases wide range of waste streams into the environment. For instance, artesian and
automobile repairs workshops which comprises of auto mechanic, auto welding, auto electrician and auto painting
units releases several waste streams such as used oil and fluids, dirty shop rags, used parts, asbestos from brake
pads and waste from solvents used for cleaning different parts of their daily operations (Al-Anbari et al., 2015).
Several other processing sectors such as food processing also release wastes into the environment. For instance,
oil palm processing releases three wastes stream including gaseous emission (air pollutants), palm oil mill
effluents (liquid wastes), oil palm processing chaff, fiber, empty fruit bunch and palm kernel shell (solid wastes)
(Ohimain and Izah, 2013; Ohimain et al., 2013a,b; Izah et al., 2016a). Also the processing of cassava tuber into
garri, fufu and or lafun releases three wastes stream including whey (cassava mill effluents-liquid wastes),
gaseous emission (air pollutants) and solid wastes (peels and seivate) (Ohimain et al., 2013c; Izah, 2016; Izah et
al., 2017a). Typically, the diversity and concentration of pollutants released into the environment have increased
in the last few decades (El-Metwally et al., 2017).
