Effect On Cassava Mill Effluent In The Soil

Project and Seminar Material for Microbiology

Effect On Cassava Mill Effluent In The Soil


The microbiological and physiochemical characteristics of soil receiving cassava effluent in Orji, Imo State, Nigeria were carried out, soil samples were collected from site polluted with cassava mill effluent and also from adjacent site not polluted with cassava effluent to serve as control. The overall population of microorganisms in cassava mill effluent was determined. Isolation and characterization of succession of microorganism in cassava mill effluent was studied microbial count, Bacterial counts and fungal counts were also determined using a pour plate method. The microbial count ranges from 2.2 X 105 – 1.30 X 105 for THBC, 2.2 X 106 – 1.12 X 106 for TCC for 10-2 – 10-6, 2.28 X 105 – 1.20 X 107 for THBC and 1.68 X 105 – 1.0 X 109. Fungal count was contaminated on the 96 hour. The bacteria isolated were Klebsiella spp., Escherichia coli , Pseudomonas spp., Staphylococcus aureus, and Streptococcus spp. while the fugal isolates include Penicillium spp., Aspergillus spp., mucor spp., and yeast cells Candida spp. the cassava mill effluent should be treated before discharge into the environment to prevent pollution.

Chapter One

1.0 Introduction / Literature Review

1.1 Introduction

The genus manihot incorporates will over 200 species of which manihot esculent or crantz is the most important, from the nutritional and economic point of view commonly known as cassava, manioc, tapioca and yucca cassava (manihot esculenta crantz) is a root tuber crop that is widely cultivated in the tropical regions of the world (oboh and Akindahunsi, 2003). It is mainly a food crop whose tubers are harvested between 7-13months based on the cultivars planted the tubers are quite rich in carbohydrate (85.9%) with very small amount of protein (1.3%) in addition to cyanogeric glucoside (Nwabueze and Odunsi, 2007). This high carbohydrate content makes cassava a major food items especially for the low income earners in most tropical countries especially Africa and Asia (Desse and Taye 2006)

Cassava is believed to have originated from south America to other Northern America, cassava was introduced in the 16th century around Congo river basins (cock 1985). In sub Sahara Africa, cassava is a major stable food that is consumed in processed forms in many areas. In West Africa and Nigeria in a particular the crop is mostly consumed as garri, a dry granulated meal made from fermented cassava (IITA, 1990). Currently, Nigeria is the highest producer of cassava in the world with growth and processing of more cassava for domestic and international needs.
However if the contribution that cassava can make to the live hood of poor people is to be increased, there is need to consider also its post harvest handing, processing, and marketing. Both cassava roots and leaves can be used as food , but economically the roofs are usually more important, although in some part of African countries, the leaves may be more important or more important than the roofs. Cassava is one of the most important food crops in Africa. It derives its importance from the fact that its starch, thickened tuberous roots are valuable source of cheap calories especially in developing countries, carlories, caloric deficiency and malnutrition are wide spread. Over two thirds of the total production of cassava is consumed in various forms by humans, its usage as a source of ethanol for fuel, energy in animal feed and starch for industry increasing. The crops are amenable to agronomic as well as genetic improvement, has a high yield potential under good contrition’s and performs better than other crops under sub-optional conditions. It is grown widely in several countries in sub-Sahara Africa and Madagascar the importance of cassava in food security and nutritional issues has led IITA (international institute of Tropical Agriculture ) and the united nations children’s education fund (UNICEF) to establish their joint household food security and nutrition programs with the goals of extending the benefits of IITA research to Africa countries through UNICEF’s country programs of social mobilization development (Nweke, 1992). Africa as one of the largest produce worldwide produces over 50 million tones of cassava annually (FAO, 1992). Total world cassava use is expected to increased from 172.7 million tons to 275 million tons in the period of 1993-2020 using the international food policy. Research institutes (IFPRI’s) base line data. As higher prediction of demand and production growth puts the 2020 production at 291million tons (Scott et al; 2000).

Traditional garri production is associated with discharged of large amount of water, hydrocyanic acid and organic matter in the form of peels and sieves from the pulp as waste products. Around cassava mill, the liquid waste is indiscriminately discharged and allowed to accumulate, producing offensive odour and unsightly scenarivs (FAO, 2004; Okafor, 2008; shiadgonare etal; 2009). The high cyanide content from the effluent equally posses significant threat to humans and the environment, which calls for regulations in the discharge of the waste generated (Akani et all; 2006; Adewoye et al; 2005). Kolwan et al, 2006) defined soil as the top layer of the earth’s lithosphere , formed from weathered rock that has been transformed by living organisms soil formation is the result of the combination action of weathering and coloiyation of geological material by microbes ( wiley et al;2008). Soil also has many layers, with the topsoil being the most productive. The biological components of the topsoil consist mainly of soil organisms especially microorganisms which are key players in the cycling of nitrogen, sulphur and phosphorus and the decomposition of organic residues these affects nutrient and carbon cycling on global scale (burning and Jimenez, 2003). The topsoil receive the greatest impact from pollutants. The effluents when incorporated into the soil exert effects on the soil itself. When discharged, it is acted upon by nutrients and soil microorganisms, releasing gases into the soil which other breakdown products are trapped in the soil (pelczar et al; 1993).

1.2 Aims and Objectives

  1. This is determining the effect of cassava mill effluent on some groups of soil bacteria and soil fungus (fungi).
  2. To estimate the overall population of the microorganisms present on the cassava effluent on the soil
  3. To isolate and identify the microorganisms in the cassava mill effluent on the soil.

1.3 Literature Review

The plant manihot esculanta and its products are relatively unknown in the industrial countries and consequently the biology of the plant has received very little attention the situation is different in Africa, Asia , the west indies and south America where the plant is a very familiar and its products form one of the most important sources of dietary carbohydrate for millions of people as reported lay Bradbury and Holloway (1998) consequently, a great deal of information exists in the developing countries about manihot esculenta.

Barely years ago, the international institute of tropical Agriculture, Ibadan, Nigeria and the centro international de agricultural tropical cali, Colombia, south America were established with international funds for the purpose of undertaking intensive biological research on breeding agromy production, utilization and nutritional value of manihot esculenta and its products (Bradbary and Holloway 1998). Current devotion of international effort to scientific research or manihot esculeta is clearly a result of the recognition of the fact that the plant has played most important role in the nutrition of the people of the developing countries where its products are utilized as human food and animal feed, besides being an item of export to the industrial countries.

Most work undertaken was to gain basic chemical, biochemical and physiological knowledge of Manihot esculenta as a contribution to investigation of the biological potentials and limitation of the plant. These studies must necessarily be considered as a prerequisite in the present international scientific effort to increase the production and usefulness of the plant, and the enhance its nutritional, economic and industrial value to the developing countries. The utilization of Manihot esculenta as one of the major stable food crop in the tropics has two major nutritional advantages.

Firstly the root tubers and tuber food products are notoriously deficient in protein, and consumption of these products lends to nitrogen imbalance and to kwashiorkor, protein deficiency syndrome that is typical of the tropics.

– Secondly, the plant synthesized and accumulates cyanogenic materials in its edible leaves and roof tuber the intake of large amounts of roof tubers and products leads and root tuber the intake of large amounts of root tubers and products leads to the release of high concentration of hydrogen cynnide (HCN) from these food material of manihot esculenta play play a considerable role in the etiology of several pathological conditions characteristic of the developing countries. The production of hydro cyanide from manihot esculents and chemical stuffs of plants origin has been known for over a century and chemical studies have established that cyanogenic is evoled from glucasidal derivatives of 8-hydroynetrite these compounds are widly distributed in plants as well as certain animals.

The cyanogens ic glucoside have recently attracted much scientific attention, not only because of their chemical structures, which makes them denvative of amino acids and their conversion into cyanogenic glucoseides instead of proteins the mechanism of their digration production and themetabolism of their degradation products have therefore assumed greater relevance in the understanding of their role in manihot esculenta and other cyanophoric plants utilized by man as sources of food (Essers, 1995).

– Industrial activities release substantial amounts of pollutants into natural environment. Such pollutants include crude oil and its refined product, palm oil mill effluent, cassava mill effluent, waste water from agro-allied industries, refiners, human and animal wastes and mining effluents (walsh et al; 2002, wade et al; 2002, ojumu, 2004, arimoro and osakwe 2006). Soil pollution causes imbalance in soil flora and fauna, which leads to reduced soil fertility. This is mostly because microorganisms which are involed in all nutrient cycling are destroyed cassava composes approximately 57% of tropical root and tuber production (Nwoko et al; 2009). Nigeria is the world largest producer of cassava, Manihot esculenta (crantz) (FAO, 2004). In Nigeria cassava can be converted to diverse traditional delicacies which include; garri, fufu, lafun flour e.t.c some of which are from cassava, garri is the most common in Nigeria. Garri production is done in varying scale in a small medium and large scale. Most garri processing plants in Nigeria produce between 7-10 million tons of garri annually. (FAO, 2004). Much waste from cassava mills are generated which are usually discharged on land or into water bodies indiscriminately and this in turn affects the biota (Olonunfemi et al; 2008) when these waste products are improperly disposed they generate offensive odours and unsightly scenanos (FAO,200, Okafor, 2008). The major component of the effluent from garri processing industries is cyanide and in most cases, the effluent is channel into pits where it continues to accumulates and sink gradually into the surrounding soils there by posing a serious health and environmental hazard (Okafor, 2008).

1.3.1 Description of Cassava

The cassava root is long and tapered, with a firm, homogeneous flesh encased in a detachable rind, about 1 mm thick, rough and brown on the outside. Commercial varieties can be 5 to 10 cm (2.0 to 3.9 in) in diameter at the top, and around 15 to 30 cm (5.9 to 11.8 in) long. A woody vascular bundle runs along the root’s axis. The flesh can be chalk-white or yellowish. Cassava roots are very rich in starch and contain significant amounts of calcium (50 mg/100g), phosphorus (40 mg/100g) and vitamin C (25 mg/100g). However, they are poor in protein and other nutrients. In contrast, cassava leaves are a good source of protein (rich in lysine) but deficient in the amino acid methionine and possibly tryptophan (Ravindran and Velmerugu, 1992).

1.3.2 History

Wild populations of M. esculenta subspecies flabellifolia, shown to be the progenitor of domesticated cassava, are centered in west-central Brazil, where it was likely first domesticated no more than 10,000 years BP. Forms of the modern domesticated species can also be found growing in the wild in the south of Brazil. By 4,600 BC, manioc (cassava) pollen appears in the Gulf of Mexico lowlands, at the San Andrés archaeological site (Pope et al., 2001).

The oldest direct evidence of cassava cultivation comes from a 1,400-year-old Maya site, Joya de Cerén, in El Salvador. With its high food potential, it had become a staple food of the native populations of northern South America, southern Mesoamerica, and the Caribbean by the time of the Spanish conquest. Its cultivation was continued by the colonial Portuguese and Spanish.

Cassava was a staple food for pre-Columbian peoples in the Americas and is often portrayed in indigenous art. The Moche people often depicted yuca in their ceramics (Berrin et al., 1997).

Mass production of Casabe bread became the first Cuban industry established by the Spanish. Ships departing to Europe from Cuban ports such as Havana, Santiago, Bayamo and Baracoa not only carried goods to Spain. The Spanish also needed to replenish their boats with dried meat, water, fruit and large amounts of casabe bread. Cuban weather was not suitable for wheat planting and casabe would not go stale as quickly as regular bread.

Cassava was introduced to Africa by Portuguese traders from Brazil in the 16th century. Maize and cassava are now important staple foods, replacing native African crops. Cassava is sometimes described as the ‘bread of the tropics’ (Adams C., et al., 2009) but should not be confused with the tropical and equatorial bread tree (Encephalartos), the breadfruit (Artocarpus altilis) or the African breadfruit (Treculia africana).

1.3.3 Economic Importance and Production

World production of cassava root was estimated to be 184 million tonnes in 2002, rising to 230 million tonnes in 2008. The majority of production in 2002 was in Africa, where 99.1 million tonnes were grown; 51.5 million tonnes were grown in Asia; and 33.2 million tonnes in Latin America and the Caribbean, specifically Jamaica. Nigeria is the world’s largest producer of cassava. However, based on the statistics from the FAO of the United Nations, Thailand is the largest exporting country of dried cassava, with a total of 77% of world export in 2005. The second-largest exporting country is Vietnam, with 13.6%, followed by Indonesia (5.8%) and Costa Rica (2.1%) (Berrin et al., 1997).
In 2010, the average yield of cassava crops worldwide was 12.5 tonnes per hectare. The most productive cassava farms in the world were in India, with a nationwide average yield of 34.8 tonnes per hectare in 2010.

Cassava, yams (Dioscorea spp.), and sweet potatoes (Ipomoea batatas) are important sources of food in the tropics. The cassava plant gives the third-highest yield of carbohydrates per cultivated area among crop plants, after sugarcane and sugar beets. Cassava plays a particularly important role in agriculture in developing countries, especially in sub-Saharan Africa, because it does well on poor soils and with low rainfall, and because it is a perennial that can be harvested as required. Its wide harvesting window allows it to act as a famine reserve and is invaluable in managing labor schedules. It offers flexibility to resource-poor farmers because it serves as either a subsistence or a cash crop (Stone, G.D., 2002).

No continent depends as much on root and tuber crops in feeding its population as does Africa. In the humid and subhumid areas of tropical Africa, it is either a primary staple food or a secondary costaple. In Ghana, for example, cassava and yams occupy an important position in the agricultural economy and contribute about 46% of the agricultural gross domestic product. Cassava accounts for a daily caloric intake of 30% in Ghana and is grown by nearly every farming family. The importance of cassava to many Africans is epitomised in the Ewe (a language spoken in Ghana, Togo and Benin) name for the plant, agbeli, meaning “there is life”.

In Tamil Nadu, India, there are many cassava processing factories alongside National Highway 68 between Thalaivasal and Attur. Cassava is widely cultivated and eaten as a staple food in Andhra Pradesh and in Kerala. In Assam it is an important source of carbohydrates especially for natives of hilly areas.

In the subtropical region of southern China, cassava is the fifth-largest crop in term of production, after rice, sweet potato, sugar cane and maize. China is also the largest export market for cassava produced in Vietnam and Thailand. Over 60% of cassava production in China is concentrated in a single province, Guangxi, averaging over 7 million tonnes annually.

1.3.4 Nutritional Profile

Cassava root is essentially a carbohydrate source (Olumide O. Tewe, 2004). Its composition shows 60–65 percent moisture, 20–31 percent carbohydrate, 1–2 percent crude protein and a comparatively low content of vitamins and minerals. However, the roots are rich in calcium and vitamin C and contain a nutritionally significant quantity of thiamine, riboflavin and nicotinic acid. Cassava starch contains 70 percent amylopectin and 20 percent amylose. Cooked cassava starch has a digestibility of over 75 percent.

Cassava root provides little protein, but that protein does contain essential amino acids. Methionine, cysteine and cystine are the limiting amino acids in cassava root.

Cassava is attractive as nutrition source in certain ecosystems because cassava is one of the most drought-tolerant crops, can be successfully grown on marginal soils, and gives reasonable yields where many other crops do not grow well. Cassava is well adapted within latitudes 30° north and south of the equator, at elevations between sea level and 2,000 m (6,600 ft) above sea level, in equatorial temperatures, with rainfalls from 50 mm (2.0 in) to 5 m (16 ft) annually, and to poor soils with a pH ranging from acidic to alkaline. These conditions are common in certain parts of Africa and South America.

Cassava is a highly productive crop in terms of food calories produced per unit land area per unit of time, significantly higher than other staple crops. Cassava can produce food calories at rates exceeding 250,000 cal/hectare/day compared with 176,000 for rice, 110,000 for wheat, and 200,000 for maize (corn).

Cassava, like other foods, also has antinutritional and toxic factors. Of particular concern are the cyanogenic glucosides of cassava (linamarin and lotaustralin). On hydrolysis, these release hydrocyanic acid (HCN). The presence of cyanide in cassava is of concern for human and for animal consumption. The concentration of these antinutritional and unsafe glycosides varies considerably between varieties and also with climatic and cultural conditions. Selection of cassava species to be grown, therefore, is quite important. Once harvested, bitter cassava must be treated and prepared properly prior to human or animal consumption, while sweet cassava can be used after simple boiling.

Chapter Four

4.0 Discussion / Conclusion

4.1 Discussion

This research has shown the microbiological and physiochemical characteristics of soil receiving cassava effluent. There was an observed increase and decrease in most of the physiochemical parameters.

The microbial load of the contaminated soil was lower that the control sample. The relatively low count of contaminated soil could be attributed to the effluent making the soil acidic due to the presence of cynide. The presence of cyanide in the soil could lead to inhibition of bacteria growth (Desse and Tray, 2001).

The bacteria isolated from cassava effluent include Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella spp. and Streptococcus spp., while the fungi isolated were Penicillium spp., Aspergillus spp., Mucor spp., and Candida spp. the microorganism isolated from the effluent contaminated soil were in line with works of (Akani, N.P. et al., 2006; Atlas and Bartha, 1998) who isolated similar organisms. The organisms may release toxins in the effluent which can be very harmful. Fungal infection acquired through the environment causes allergies and only a few are transmissible from infected humans (Atlas and Bartha, 1998).

The presence of coliform is an indication of human faecal contamination. This may result from inhabitants who defecates near the bushes where the cassava effluent is being produced. Escherichia coli is not specifically confined to human intestine. It is also present in the faeces of many domestic animals and birds and can be source of contamination (Wilson P.A., et al.,2010; Ebhoaye and Dada, 2004).

Cassava effluent can also be contaminated with normal flora of cassava users and handlers as well as some pathogenic microorganism which are not visible but can be detected by careful isolation procedures.

Cassava effluents are of concern because of much pollutant they contain (Uzochukwu, S.U., et al., 2001). The liquid residu, technically called manipueira contain such as nitrogen, carbon, phosphorus, calcium, magnesium, sulfur, manganese, sodium, which after anaerobic biodigestion can still be used for irrigation, since the digestion process does not substantially decrease the mineral content (Oloninfemi, D.I., et al., 2008). Continous application of effluent to soil result into withering (Nambisan and Saundanesan, 1985). The physiochemical parameters investigated showed variations among samples. Soil contaminated with cassava effluent caused some changes in soil samples collected. The cyanide content in the contaminated soil samples were higher than the control sample.

Cassava tubers contain cyanogenic glycosides namely: Linamarin and Louaustralin which are formed from amino acid. They were stored in the vacuoles of plant cells and are converted into hydrogen cyanide (HCN) when the contents of the vacuoles of plant cell wall, they allow Linamarin and Louaustralin to occur. The hydrogen cyanide dissolves in the effluent and remain in the solution, when it enters the soil part of the cyanogenic glycosides remain unconverted by microorganism because of the few enzymes present in the cassava fibre which are not enough for complete conversion. This is detrimental to soil health and reduces quality of the soil.

A cassava mill should be sited far from residential homes, cassava mills must be owned and managed by individuals who have basic knowledge of environmental protection. Effluents from cassava processing plants must be regarded as harmful waste water and should not be allowed to spread over farm lands without thought of possible negative side effects. Effluent can also be used as herbicide or for weed control.

The colonial morphology of fungi isolates was by microscopic observation of their characteristic features. Somewhere colony grey to white greenish yellow (Penicillium spp.), fluffy white mycelium turing greenish after 4 days (Aspergillus spp.), colony grey white to cream colored and yeast like appearance (Candida spp.) and colony like cottony white to gray cotton (Mucor spp.). as it is represented in table 3.

4.2 Conclusion

The effluent from cassava plant when discharged on soil causes physiochemical and microbiological changes in the soil which calls for serious concern if the soil will be used for agricultural and other purposes. It is clear that most of these is therefore the need for an introduction of regulations to control the disposal of effluent generated from cassava.

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