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Title of Thesis
Environmental Impacts of Reuse of Sewage and Industrial Effluents on Irrigated Farmland

Farzana Bashir
Institute/University/Department Details
Government College University, Lahore, Pakistan
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
Domestic sewage wastewater, combine wastewater,  oxidizable

Growing population and rapid industrialization has increased the volume of wastewater manifold eventually deteriorating the fresh water resources and surrounding environment due to inappropriate management. In developing countries including Pakistan, industrial wastes and municipal effluents are being used for the irrigation of crops in or near urban centers or discharged into canals, rivers, along roadsides or in the vicinity of industrial establishments. Present study was conducted to evaluate the quality of city sewage effluents being used in agriculture in the vicinity of Lahore for growing vegetables and fodder, and also to document the impacts of wastewater irrigation on agricultural soils and crops.

The quality of city sewage effluents was explored under two categories (i) domestic sewage wastewater and (ii) Combine wastewater. Large variations were found in almost all water quality indices with most of the lower values being observed during monsoon season. The irrigation quality of combine wastewater was worst with respect to various parameters including pH, COD, BOD, sulphides and the concentration of heavy metals was also above the FAO limits. There was accumulation of heavy metals in soils receiving wastewater for irrigation. The total metal contents in soil follow the order Mn> Co > Zn > Cr > Ni > Cu > Cd. The sequential extraction procedure developed by Tessier was adopted to demarcate five metal fractions; exchangeable, acid soluble, reducible, oxidizable and residual. Fractionation procedure showed that all the metals except Cd were dominant (>50 %) in the residual fraction. It was observed that the concentration of all studied toxic metals in edible part of the vegetables was above the critical level. The meaningful positive correlation was observed between concentration of metal in vegetable and F1 and F2 fractions, while negative correlation was observed between residual and total metal concentration which indicate the non availability of these fractions. It was observed that the practice of using wastewater in irrigation for growing vegetables and other crops is non-sustainable.

In order to study the bioavailability and uptake of Cd, Cr and Ni in silty clay, silt loam and sandy loam soils, with two levels of organic matter by spinach, cabbage and radish field experiments were undertaken. Previous studies showed that the characteristic of soil, such as texture, and organic matter contents affect the mobility of the metal added. The transfer of metals to plants was reported to be higher in sandy soil and differs among plant species. The non essential elements Cd, Cr and Ni can translocate into the edible parts of spinach, cabbage and radish. Of the three plants under study, uptake of metal was highest in spinach followed by radish and least in cabbage.

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1460 KB
 S. No. Chapter Title of the Chapters Page Size (KB)
1 1 Introduction 1
43 KB
2 2 Review of Literature 9  

110 KB

  2.1 Quality of Sewage 9
  2.2 Impacts of Sewage Iirrigation on Soil and Crops 12
  2.3 Fractionation of Heavy Metals in Soil and Correlation with Plant Uptake 15
  2.4 Role of Organic Matter on Metal Bioavailability 21
  2.5 Effects of Soil Texture to the Distribution of Metals 24
  2.6 Redistribution of Metals in Soil System 25
3 3 Material and Methods 32  

183 KB

  3.1 Study 1: Quality of City Sewage 32
  3.2 Study 2 : Impacts on Soils and Vegetables Irrigated with Untreated Combined Sewage 34
  3.3 Study 3: Metal uptake by Spinach, Cabbage and Radish: Role of Soil Texture and Organic Matter. 37
  3.4 Analytical Procedures 40
  3.5 Statistical Analysis 49
4 4 Results and Discussions 56
1483 KB
  4.1 Study 1: Quality of City Sewage 50
  4.2 Study 2: Impacts on Soils and Vegetables Irrigated 76
  4.3 Study 3: Metal Uptake by Spinach, Radish and Cabbage: Role of Soil Texture and Organic Matter 110
    References 129
130 KB
    Appendices 161
205 KB