الفهرس 
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Abstract
The present work investigated the potential use of spent tea (Camellia sinensis L.) leaves waste (TW) or sugarcane (Saccharum officinarum L.) bagasse (SB) in treatment of wastewater and its possible reuse in certain agricultural aspects.
The present work, involved first an in vitro experiment aimed at investigating the efficiency of TW and SB in adsorption of heavy metals from aqueous solutions at different conditions. Also, the feasibility of using TW- and SB-reclaimed wastewater in seed germination and growth of parsley (Petroselinum crispum Mill) were investigated via its use in soil irrigation.
To achieve the mode of action of TW and SB in clarification of wastewater from heavy metals, both of them were subjected to chemical and physical analysis using infrared (IR) spectroscopic analysis and scanning electron microscopic (SEM) analysis.
In the following, a brief on the main experimental results is given:
1. In vitro experiment which involved the use of TW and SB in removal of Pb+2, Cu+2 and Ni+2 from their aqueous solutions proved their efficiency in this respect, with different ratios.
2. Kinetic studies revealed that the efficiency of TW and SB in heavy metal removal is closely related to contact time, pH, adsorbent dosage and concentration of heavy metals solution.
• There was a gradual increase in % of removal of Pb+2, Cu+2 and Ni+2 in the initial stages; equilibrium was attained after 60 minutes.
• There was a gradual increase in % of removal of Pb+2, Cu+2 and Ni+2 with increasing the used dosage of TW or SB as a result of availability of more binding sites, surface area, increase in ratio between TW or SB particles and metal ions.
• The gradual increase in concentration of Pb+2, Cu+2 and Ni+2 solutions was coupled with appreciable increase in % of removal by TW or SB. However, there was a variance in optimum concentration used of Pb+2, Cu+2 and Ni+2 after which an obvious decrease in removal percentage was obtained.
• In conclusion, the kinetic studies revealed the efficiency of both TW and SB in removal of Pb+2, Cu+2 and Ni+2 from aqueous solutions with a magnitude of efficiency obtained with TW compared with SB. This variance between TW and SB may indicate the presence of difference between them in the affinity of adsorbent to heavy metals, shape, size and mass of its particles and their content of cellulose, hemicellulose, lignin and proteins, which represent the basic concepts of biosorption.
3. To determine the relevant adsorption parameters, the obtained adsorption data were mathematically analyzed using both Langmuir and Freundlich adsorption models.
• The negative values for the Langmuir isotherm constants for Pb+2 using TW and for Ni+2 using TW or SB indicate the inadequacy of the isotherm model to explain the adsorption process.
• Freundlich constant (n), was smaller than one in case of Pb+2 and Ni+2 when using TW which means that, sorption intensity is favorable. Larger values of n (>1) obtained upon using SB for removal of Pb, Cu and Ni mean that, adsorption bond is strong, sorption intensity is good (or favorable) over the entire range of concentrations studied.
• Experimental data were best fitted to the Langmuir equation for Pb+2 and Cu+2 with correlation coefficient R2 = 0.9668 and 0.9885 when using SB.
• The data were best fitted to the Freundlich equation for Pb+2, Cu+2 and Ni+2 with correlation coefficient R2 =0.9183, 0.9946 and 0.955 when using TW and for Ni+2, R2 =0.9171 with SB.
4. Investigating the effect of heavy metals predominate in wastewater on germination of parsley seeds indicated high sensitivity, where there was a delay in onset of radicle protrusion to 14 days and a sharp decrease in percentage of germination (20%). On the other hand, in response to irrigation with tap water serving as control, radicle protrusion takes place after days and the percentage of seed germination reached 80%.
• Number of lateral roots of parsley was not sensitive to heavy metals where appreciable increase was obtained, compared with control.
5. In response to soil irrigation with wastewater, manifest growth inhibition was observed at two different stages of growth. This was recorded in terms of high significant decrease in length of shoots and roots, number of leaves per plant, fresh and dry weights of shoots and roots compared with soil irrigation with TW- or SB-treated wastewater or tap water.
• On the other hand, leaf content of chlorophyll a and chlorophyll b subjected to significant increase in response to soil irrigation with wastewater, compared with irrigation with treated wastewater or tap-water. This increase could be due to the existence of a relatively high content of iron, chromium and copper in wastewater. However, it is most probably that this increase is a result of lower rate of destruction rather than a higher rate of synthesis.
6. Chemical analysis of wastewater revealed the presence of a relatively high level of Cu, Cr and Ni which exceeded the threshold of that of water of irrigation as recommended by FAO.
7. The presence of heavy metals in irrigation water altered the oxidation state of parsley plants as could be traced from the changes induced in the activity level of catalase, superoxide dismutase and peroxidase.
• The significant increase, in general, induced in their activity level, compared with irrigation with treated wastewater, at early stages of growth, denotes the presence of a relatively mild level of free radicals and peroxides which induced their activation may be as acclimation mechanism. However, at second stage of growth, where a probable more accumulation of free radicals as a result of continuous irrigation with wastewater is expected, these enzymes subjected to significant suppression.
8. As a result of soil irrigation with TW- or SB-treated wastewater, a high significant increase in major growth attributes of parsley was obtained compared to those irrigated with wastewater. This enhanced growth may be due to the marked efficiency of TW or SB in removal of heavy metals of wastewater reached to about 50% in certain elements.
9. Chemical analysis of TW and SB revealed their mode of action in heavy metal removals where both of them contained a relatively high content of cellulose, hemicellulose, lignin, fibers and phenolic compounds which efficiently act as biosorbent of heavy metals.
10. The results of infrared spectroscopic analysis (IR) of TW indicated the presence of ionisable functional groups; their ionization leaves vacant sites which can be replaced by metal ions. Thus, the spectral analysis before and after metal adsorption indicated that the bonded -OH groups, -SO3 stretching, C-O stretching, secondary amine groups and -CN stretching were the main functional groups of tea waste involved in metal binding.
11. Infrared spectroscopic analysis of SB revealed a change in position of peaks of adsorption which correspond to the aromatic skeleton vibration, C–H stretching, ring breathing in the C–O stretching in lignin. Also, the band at 1249.8 cm-1 in free sugarcane bagasse is assign to C-O stretching in cellulose, hemicellulose and lignin or C-O-C stretching in cellulose and hemicelluloses.
12. It was clearly evident from scanning electron microscopic studies (SEM) of TW before and after the process of adsorption, that the pores of surface of adsorbent were covered after heavy metals adsorption.
13. SEM results of SB before and after adsorption refer to the presence of rigid and compact morphology in raw free particles of SB which may be related to presence of high percentage of fibers. On the other hand, there was an obvious change in conformation of SB particles after ions adsorption.
14. The results obtained in the present work refer to the efficiency of spent tea leaves waste and sugarcane bagasse in clarification of wastewater of heavy metals. On the other hand, it is possible to reuse treated wastewater in irrigation practices where a flourishing of growth of plants was observed in response to irrigation with TW- or SB-treated wastewater; and restoration of balance in oxidation state of parsley plants via regulating the activity level of antioxidative enzymes (catalase, superoxide dismutase and peroxidase).
15. Growth parameters of parsley plants which were irrigated with TW- or SB-treated wastewater were comparable or higher than that of plants irrigated with tap-water.