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Home , Phytoremediation

DOI: http://dx.doi.org/10.4314/gjes.v12i1.2

GLOBAL JOURNAL OF ENVIRONMENTAL SCIENCES VOL. 12, 2013: 13-19 13 COPYRIGHT© BACHUDO SCIENCE CO. LTD PRINTED IN NIGERIA ISSN 1596-6194 www.globaljournalseries.com , Email: [email protected] OF SLUDGE IN CONTAMINATED WITH HEAVY METALS

CORNELIUS O. AWALLA

ABSTRACT

The main source of heavy metals in most soils is sewage sludge. Naturally, the heavy metals in soils are transported to vegetations and cultivated crops. These need to be either reduced or eliminated in the to remediate the effects to man, animals, , soils, and . Hence, Jatropha curcas seedlings were planted on six different media to determine the concentration of heavy metals. Thereafter, it was discovered that Jatropha curcas plants through their , stems and leaves , morphology and mechanisms can reduce the concentration of heavy metals like , , , , and etc effectively from any medium containing 100% sewage sludge. Thus, it was discovered that Jatropha curcas is suitable as a phytoremediator of heavy metals in soils.

KEYWORDS: Heavy metal, phytoremediation, sewage sludge, metabolism, morphology.

INTRODUCTION and non-essential elements like As, Cd, and Hg (Batiha, et al, 2008) Worldwide, heavy metals cause Jatropha is a great plant for restoring which is a serious environmental crises. Heavy in the soil, and has the ability to turn metals exist in soils as free metal ions, soluble poorly-over used soil into great purposeful metal complexes, exchangeable metal ions, agricultural productivity and yields (Awalla, 2013). organically bound metals, precipitated or However, organic and inorganic pollutants greatly insoluble compounds like oxides, carbonates and impact human health and ecological biodiversity hydroxides. They cause soil pollution by the systems. Harmful inorganic pollutants in the soil repeated increase daily or weekly application of like heavy metals can be eliminated through sewage sludge, municipal wastes, animals phytoremediation mechanisms and techniques. slurries, activities of , smelting and The sources of sewage sludge are the agricultural industries, and also impurities in solid waste products from wastes treatment, fertilizers, , germicides and mining residues and agricultural wastes. Heavy decomposition and burning of fossil fuels. metals like cadmium, and zinc in the The environmental pollutants are soil and plant tissues increase after sewage different types of like sludge had been applied to them. This (TCE), , trinitroluene (TNT), oil, gasoline, phenomenon contributes great pollution of the benzene, polycyclic aromatic hydrocarbons waterways (Jones and Johnson, 1989). (PAHs), and fuel additives (Hong et al 2001). The most common heavy metals in soils These are inorganic pollutants which include and plants are Lead PB, Cadmium (Cd), plant phosphate, Cr, Fe, Mn, Mg, Ni, Zn, and Cu, Chromium (Cr), (Hg), Zinc( Zn) and

Cornelius O. Awalla , Department of Geology and Mining, Faculty of Applied Natural Sciences, Enugu State University of Science and Technology Enugu, Enugu State, Nigeria.

14 CORNELIUS O. AWALLA Copper (Cu) (Kabata-Pendias and Pendias, compounds are resistant to plant metabolism. It 2001). All of them cause health problems (Yadav can also occur where uptake and translocation of et al, 2009) especially mercury which is highly these compounds in the soils by plants tissues toxic if breathed or ingested. Mercury is residual are in recoverable state of existence. These in the environment, showing biological plants are hyperacumulators of metals. However, accumulation in all aquatic organisms, especially when the plants are matured, harvested and in fish and shellfish. Chronic exposure to airborne disposed, they are processed by and mercury can have serious effects on the central composted for recycling in case of organic nervous system (CNS). pollutants. Thus, phytoremediation is the use of Bioavailable contaminants like PAHs and green vegetables for the in-situ or ex-situ NACs after incineration of plants can be treatment of contaminated soils, sediments and decontaminated effectively by careful disposal in polluted water and to detoxify inorganic and a . The non- availability organic metals (Salt, et al, 1995; Damian, 2007; of other pollutants can be bioavailable by adding Afkar et al, 2010). Phytoremediation is a green chemical additives like bio-surfactant, and EDTA technology which has been used to facilitate the to the soil (Maier et al, 2001). removal of heavy metals from soils and plants. It Phytodegradation/ phytotransformation is very important to clean up soils. occurs when contaminants are taken up from soil and/ or water by the plant roots, then metabolized JATROPHA CURCAS PLANTS AS A CHOICE. into less toxic and non-toxic compounds within • It has promising characteristics like the plant tissues through the actions of robust nature, rapid gestation period, substances produced by the plants (Shimp et al, excessive recovery and survives all 1993). phytodegradation extends to seasons. Jatropha curcas plant is cell cultures of non-crops species including suitable as a phytoremediator that hybrid poplar trees. The metabolic processes in removes hydrocarbons from phytodegradation are analogous to human contaminated soil (Agamuthu, et al, metabolism of chemical. Hydrophobic 2010), and also removes Cadmium,(Cd) organic chemicals are not very efficient for and Lead, (Pb) (Chehregani and phytoremediation, because these contaminants Malayeri, 2007). cannot be easily translocated within the plants as • The research was carried out at the they are either bound strongly to the surface of Nigerian Institute for Oil Palm Research the roots or are not absorbed by roots and thus (NIFOR) Benin , Delta State of Nigeria. not actively transported through plant • The humid rainforest climate with membranes (Batiha et al, 2008) perennial streams and rivers and lowland Phytovolatilization occurs when volatile shales encourage luxurious grasses chemicals/contaminants like trichloroethylene trees like cashew, mango, palm, raffia, (TCE), polychlorinated biphenyls (PCBs) and banana, bamboos etc total petroleum hydrocarbons are released into • Contaminants attenuation mechanisms the atmosphere through plant transpiration. by phytoremediation are very complex, Some inorganic pollutants that are very difficult to and thus should be limited to the direct control at the subsurface environment react metabolism of contaminants by plants, rapidly in the atmosphere with hydroxyl radicals. but other indirect attenuation * The transfer of contaminants from mechanisms like the metabolism of soil/groundwater to atmosphere may not contaminants by plant-associated be as desirable as in-situ degradation, microbes and plants-induced changes in but better than long time exposure of the contaminated environment, contaminants in soil to reduce ground of contaminants into the plant system is water contamination. highly dominated by up-taking of the * Rhizodegradation occurs when the liquids by the roots of the plants. (Shimp contaminants are transformed by et al, 1993; Macek et al, 1998) microbes in the , i.e. microbe- Phytoextraction takes effect where heavy rich zone within the vascular - system metals, radionuclide and some organic of the plant. The plant roots manipulate PHYTOREMEDIATION OF SEWAGE SLUDGE IN SOILS CONTAMINATED WITH HEAVY METALS 15

the soil redox characteristics, organic MECHANISMS OF CONTAMINANTS matter and moisture content. Here deep- METABOLISM rooted plants remove petroleum The chemical composition of hydrocarbons from soil. Microbial activity contaminants, contaminated medium and causes removal of polycyclic aromatic physiological properties of the plant roots control hydrocarbons (PAHs) which is the interactions of the contaminants with the soil, associated with chemical oxidation, water and plants. These reactive characteristics and microbial determine whether a contaminant can be transformation. Microbial activity is higher subjected to either phytoextraction, in the rhizosphere due to readily phytodegradation, phytovolatilization or availability of biodegradable substrates rhizodegradation. Generally, phytoremediation that exude front the plant (fig.1) starts with contaminants transport to all parts of the plant, and this depends on the part, like the roots, stem or leaves where the contaminants accumulation is more prominent. Most organic matters undergo transformation in plant cells before being sequestered in vacuoles or bound to insoluble cellular structures like (fig.1).

Xenobiotic and organic contaminants

RHIZOSPHERE (Algae, Bacteria, Fungi) and plant carbon compounds (exudates, mucilage, dead cells)

Activation, Detoxification, Mineralization Fig.1. Schematic diagram showing Rhizodegradation of toxic contaminants by rhizospheric microorganisms

16 CORNELIUS O. AWALLA

*Advantages of Jatropha curcas plant and used to settle disputes brought before traditional leaders, e.g. if an accused person Jatroph curcas tree is drought resistant drinks the concoctions and did not vomit, he/ she and relatively easy to propagate. It cannot be is presumed guilty. It is perfect in bees keeping. damaged by any adverse environmental Jatropha plant is used to manufacture conditions. It is very environmental friendly and biogas and fertilizers. It is used as green manure capable of stabilizing sand dunes. It is highly and fire wood. Farmers must be careful of adaptable to wind, all soil-types, desertification phytotoxicity expressed as reduced germination. and deforestation. It repels insects and naturally Organic fertilizers can substitute inorganic animals cannot browse it. It is all weather friendly fertilizers, especially for small farmers that cannot and lives more than 50years producing fruits all afford inorganic fertilizers. Therefore, Jatropha the time. cake used as organic fertilizers must be allowed In addition Jatropha tree produce oil from total decomposition before application in its seeds which is used to lubricate farm farmlands. It produces insecticides, herbicides, equipment and machinery, and also to soften fungicides and veterinary chemicals. hides when ropes and whips are produced in Jatropha stem/root extracts control Zimbabwe. Jatropha oil used in lanterns for light Helicoverpa armigera, Aphis gossypii, because the oil burns with smoke-free flame. The phthorimaea operculela, sitophilus zeamays and jatropha is used as live fence to protect crops empoasca spp. Jatropha leaf extracts control gardens/farmlands (and irrigated areas) from selerotium and schistoseme vector snails, and damage by livestock. Jatropha seeds produce also tick- related diseases and kills bilharzias good detergents and soaps manufacture in the snails. Jatropha seed husks are used as ratio of 5 parts oil: 8 parts water: 2 parts caustic combustible fuel, and the seed cake in biogas soda. production and folder i.e. non-toxic varieties The plant is used for land reclamation (Agamuthu et al 2010, Batiha et al 2008, and soil conservation works, because it has Chehregani and malayeri, 2007). favourable root systems that easily bind soil particles and aggregates together to reduce soil EXPERIMENTS erosion. Therefore, it can be planted on marginal The experiment was performed on 6 th land, paddocks (i.e. a small field where horses May, 2011 at the Nigerian Institute For Oil-palm are kept), hilly slopes, valleys and gullies. The Research (NIFOR), Benin, Delta State of Nigeria. roots grow close to soil surface which anchor The seeds of matured Jatropha curcas plants soils like miniature dykes or earthen. It slows run- were collected and planted in polythene bags off and allows more water to infiltrate and (16. 0x 16cm) in the ratio of soils: organic percolate deep into the root-zones to aid and matters: river sand. After one month, the seedling boost large agricultural harvests. were transplanted to plastic pots of 32cm height, Jatropha oil cures cardiac problems 106cm upper diameter and 69cm low diameter ,rheumatism (i.e. pain in joints) and back pains, which were filled with soil and sewage sludge. or aches. Its nut sap is used to treat bleeding. Using Completely Randonized Lesign (CRD), Concoction of Jatropha leaves is used as each pot was labeled according to its antiseptic after birth. Its roots cure snake bites composition, e.g. T 0 (100% soil), T 1 (80% soil and and its seeds are used to reduce constipation. 20% sewage sludge), T 2 (60% soil and 40% The plant treats skin diseases and also remedies sewage sludge), T 3 (40% soil and 60% sewage sores on domestic livestock. Its latex with sludge), T 4 (20% soil and 80% sewage sludge), alkaloids, namely Jatrophine, Jatrophen, and T 5 (100% sewage sludge). The height and Jatrophore and curtain are anti-carcinogenic. basal diameter of each jatropha plant is Jatropha latex remedies the effects of burns, measured with venier caliper and diameter tape. eczema, inflammation, paralysis and yellow Inductively Coupled Plasma- Mass fever. Satrometer (ICP-MS) was used to analyze the Jatropha plants around homesteads sample solutions of heavy metals concentration prevent entry of snakes and repels evil spirits, (Sahoo, Das and Mukherjee, 2009), while PHYTOREMEDIATION OF SEWAGE SLUDGE IN SOILS CONTAMINATED WITH HEAVY METALS 17 hydrochloric acid (HCl) and nitric acid (HNO 3) was 6.5 due to the presence of heavy metals in were used as extractants. Local carbon was the soil which made the soil to be slightly acidic determined with a loss on ignition analyzer and and after harvesting P H tended to alkalinity 8.0 5g of air dried soil at 500 0C. ICP-MS can scan all due to absorption of soil nutrients by plant roots, elements in a sample simultaneously. This allows but according to Sally, 2000 the control treatment for more rapid sample processing and acceptable has p H 7.5 which is the test for p H level of the results output. However, atomic absorption soil. The P H of soils stored in air-tight plastic bags spectroscopy (AAS) can only measure a single is generally affected as result of microbial activity element at a time. eg. the occurrence of moulds (Faniran and Areola, 1978). OBSERVATIONS After three to six months (i.e. 12 to 24 RESULTS weeks), it was observed that the Jotropha curcas Jatropha curcas plant can reduce heavy plant in T 3 medium (40% soil and 60% sewage metals like Zn, Pb, Cr and Cu in T 5 (100% sludge) had the tallest height (8.59cm) while T 2 sewage sludge), e.g. Zn, content of the sewage (60% soil and 40% sewage sludge) had the sludge was 29.55mg/kg in roots, 6.21mg/kg in shortest height (6.75cm); T 4 (20% soil and 80% stem and 3.15mg/kg in leaves (Tabs 1-3). This is sewage sludge) had largest basal diameter same for Pb, Cr, Cd and Cu. (3.95cm) compared to the plant in 100% soil After the 3 – 6 months of planting medium (T 0), but 100% soil medium allows (Tab.3), Jatropha curcas plant has the highest highest number of leaves, followed by T 1 and T 2. accumulation of Zn (29. 55mg/kg) in the roots of Every week the number of leaves increased, T5, (100% sewage sludge) than in the stem and except plants in T4 and T 5 with less leaves. The leaves (Tab .1), but the highest accumulation of highest total carbon was found in T 5 (0.25g/kg) Pb (4.65mg/kg) was in the leaves of T 4 (20% soil H followed by T 4. In all T 1-T5, soil P before planting and 80% sewage sludge).

Table 1: Heavy metal concentration in leaves of Jatropha curcas plant after 3 – 6 months (mg/kg).

Medium Zinc Lead Chromium Copper Cadmium T0 0.45 0.06 0.01 0.06 bdl T1 1.37 1.35 0.02 0.09 bdl T2 5.09 3.38 0.03 0.09 bdl T3 1.98 4.15 0.03 0.05 bdl T4 4.35 4.65 0.04 0.09 bdl T5 3.15 2.55 0.02 0.08 bdl (bdl means below detection limit)

Table 2: Heavy metal concentration in stem of Jatropha curcas plant after 3 – 6 months (mg/kg).

Medium Zinc Pb Cr Cu Cd T0 1.13 bdl 0.18 0.13 bdl T1 4.94 bdl 0.33 0.35 bdl T2 8.00 bdl 0.17 0.23 bdl T3 9.18 bdl 0.20 0.10 bdl T4 5.02 bdl 0.15 0.15 bdl T5 6.21 bdl 0.18 0.11 bdl (bdl means below detection limit)

18 CORNELIUS O. AWALLA

Table 3: Heavy metal concentration in roots of Jatropha curcas Plant after 3 – 6 months (mg/kg)

Medium Zinc Pb Cr Cu Cd T0 1.05 bdl 0.22 0.21 0.00 T1 6.52 bdl 0.18 0.17 3.18 T2 15.87 bdl 0.15 0.15 8.39 T3 13.62 bdl 0.25 0.23 2.11 T4 12.45 bdl 0.47 0.47 5.20 T5 29.55 bdl 0.35 0.35 8.29 (bdl means below detection limit)

ANALYSES areas and developed cities, the effects of sewage For the accumulation of heavy metals sludge in soils and groundwater will be drastically like zinc, lead, chromium, copper and cadmium in reduced and subsequently remediated. the leaves, stem and roots of Jatropha curcas plants, within three to six months of planting, zinc CONCLUSION is accumulated in the leaves of medium T 2 (60% soil and 40% sewage sludge) with 5.09mg/kg, Therefore, T 2 (60% soil and 40% sewage and lead, 4.65mg/kg in T 4 (20% soil and 80% sludge) medium with highest number of leaves is sewage sludge). ideal for the phytoremediation of most heavy In the stem, zinc is accumulated metals like zinc, lead, chromium, copper and 9.18mg/kg in medium T 3 (40% soil and 60% cadmium. However, the accumulations of these sewage sludge) and 8.00mg/kg in medium T 2 heavy metals occur mainly in the leaves, stems (60% soil and 40% sewage sludge). However, and roots of Jatropha curcas plant. Jatropha zinc is accumulated 29. 55mg/kg in the roots of curcas plant has been accepted worldwide as an medium T 5 (100% sewage sludge), and in environmental friendly plant and most valuable T215.87mg/kg ( 60% soil and 40% sewage phytoremediator controller of groundwater and sludge). . The highest Zn accumulation, RECOMMENDATIONS 29.55mg.kg was in roots of T 5 with 100% sewage sludge, than leaves and stem. Pb accumulation, Jatropha curcas plant as an 4.65mg/kg was higher in leaves than stem and environmental-frendly plant survives in all roots of T4 with 20% soil and 80% sewage weather conditions, that is both rainy and dry sludge. However, Jatropha plant is not a good seasons. It is therefore recommended as an accumulator of lead (Pb), because only small effective means and method of phytoremediation amount is absorbed due to less adaptability and of heavy metals and other contaminants in soil small strength of absorption strength of lead (Pb) and groundwater. into the plant tissues. More Chromium (Cr), The effective characteristics of the Copper (Cu), and Cadmium (Cd) were Jatropha curcas plant depend mainly on the accumulated in roots than in stems and in leaves accumulative capacity of its leaves, stems and (Tabs 1,2,3). roots. Thus, due to its effective accumulative Either soil or sewage sludge that capacity and metabolism of the contains high amount of zinc (Zn) retards plant contaminants,jatropha curcas plant has been growth. Jatropha curcas plant growth very slowly recommended worldwide as all-weather where sewage sludge is 100% (T 5) due to high environmental friendly and an effective zinc content. Generally, plant growth can be phytoremediator. retarded due to low soil nutrients (especially Therefore, with the availability of N.P.K) and low water holding capacities, high Jatropha curcas plant around residential toxic substances, high salinity and excess acidity houses, industries, schools, offices, hospitals, and alkalinity in soils. markets and other public buildings in both rural PHYTOREMEDIATION OF SEWAGE SLUDGE IN SOILS CONTAMINATED WITH HEAVY METALS 19

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