Numerous industries are emerging in Ethiopia and urban developments are accelerated giving rise to multiple waste generations. As used lubrication oil is one of the hazardous wastes 

generated at different development sectors, it should not be utilized and/or disposed in ways which are  unsafe to the environment hence calling for its proper management. This study primarily focuses on the recycling of used oil by applying acid-clay treatment process. Used engine oil properties gave expected undesired characteristics caused by oil deterioration. The characterization was indicative to the sources of contaminations from conditions during the oils application period. For instance, the lower flash point (132°C) indicated light fuel contamination effect; increased density (0.93 g/ml) and viscosity (kinematic Viscosity @ 40 °C was 126.41 cSt) showed possible oxidation and polymerization products dissolved and suspended in the used oil; and ash content (2.3%) indicated contamination from incombustible solid particles of dirt, dust, grit and metallic fragments. Similarly, deviations of other parameters also referred different contamination sources.  Recycling experiments utilized 15, 

20 and 25% acid and adsorbent (Bentonite clay) ratios with different combinations. Nine combinations with their respective triplicates were conducted. The experiments showed that the acid-clay treatment process was effective in recovering valuable oil from used oil samples with comparable qualities. From the twenty seven runs performed, yields within the range of 55% to 74.7 % was obtained. The run with acid percentage of 20% and adsorbent percentage of 15% was chosen as the optimum combination using statistical analysis that considered selected quality parameters of recovered oil i.e. density, kinematic viscosity @ 40 °C and ash content. The optimum combination gave a 69% yield; density of  0.886 g/ml; kinematic viscosity @ 40 °C of 94 cSt; and 0.34% ash content. Eight to ten percent of valuable light fuel was also recuperated from the vacuum distillation step of the process. The preliminary cost analysis showed, an estimated sum amount of 22.86 birr is expected to recover a liter of usable oil which is 61.64 birr less, relative to the amount required to import the original fresh oil that costs 84.5 birr/liter.

 

LIST OF TABLES  -- -- -- -- -- -- -- -- -- V 

LIST OF FIGURES  -- -- -- -- -- -- -- -- V 

ABSTRACT  -- -- -- -- -- -- -- -- -- -- --  VI 

11  Statement of the Problem  -- -- -- -- -- -- -- --   2 

12  Objectives  -- -- -- -- -- -- -- -- --   3 

121  General Objective -- -- -- -- -- -- --  3 

122  Specific Objective  -- -- -- -- -- -- --  3 

13  Significance of the Study -- -- -- -- -- -- -- --   3 

21  Lubricating Oil  -- -- -- -- -- -- -- -- -- --   4 

22  Used Lubricating Oil  -- -- -- -- -- -- --  5 

221  Lubricating oil Properties-- -- -- -- -- -- --   5 

222  Degradation of Lubricating oil  -- -- -- -- -- -- --   10 

223  Contaminants in Used Lubricating Oil -- -- -- -- -- --  13 

224  Physical and Chemical Tests of Used Lubricating Oil  -- -- -- -- --  15 

225  Impacts of Used Lubricating Oil  -- -- -- -- -- --  17 

23  Used Oil Recycling and Reuse  -- -- -- -- -- -- -- --   19 

231  Importance of Used Oil Recycling and Reuse  -- -- -- -- -- --   22 

232  General Regeneration Scheme  -- -- -- -- -- -- --   23 

2 33  Acid-Clay Process  -- -- -- -- -- -- -- -- --  25 

31  Materials  -- -- -- -- -- -- -- -- --   32

32  Methods  -- -- -- -- -- -- -- -- --  33 

321  Characterization of Used Generator Engine Oil  -- -- -- -- --  33 

322  Treatment of the Used Oil Sample  -- -- -- -- -- --   37 

323  Characterization of Treated Oil Sample  -- -- -- -- -- --   40 

33  Experimental Design  -- -- -- -- -- -- -- -- --  41 

331  Experimental Factors -- -- -- -- -- -- -- --   41 

332  Response Factors-- -- -- -- -- -- --  42 

41  Characterization of Used Lubricating Oil Sample  -- -- -- -- -- --   44 

42  Experimental Results of Acid-Clay Treatment  -- -- -- --  45 

43  Effects of Experimental Factors on Results  -- -- -- -- -- --   46 

431  Effects of Acid Quantity  -- -- -- -- -- -- --  46 

432  Effects of Adsorbent Ratio  -- -- -- -- -- --   48 

433  Statistical Analysis  -- -- -- -- -- -- -- -- --   50 

44  Properties of Regenerated Base Oil -- -- -- -- -- --   52 

45  Light Fuel Characterization  -- -- -- -- -- -- --  54 

46  Cost Analysis Consideration  -- -- -- -- -- --  55 

51  Conclusions  -- -- -- -- -- -- -- -- -- --  56 

52  Recommendations  -- -- -- -- -- -- -- --  58 

APPENDIX A: Viscosity Index Evaluation Data  -- -- -- -- -- --   62 

APPENDIX B: Experimental Design and Analysis Data  -- -- -- -- --  63 

APPENDIX C: Material Balance & Energy requirement  -- -- -- -- --   69 

LIST OF TABLES 

Table 2-1: Typical contaminants found in used oils  -- -- -- -- --  13 

Table 2-2: Comparison of fresh base engine oil and used oil  -- -- -- --  16 

Table 2-3: Environmental impact assessment of local uses of changed engine oil  -- -- --  17 

Table 2-4: Typical levels of contaminants in used oils   -- -- -- -- -- --   19 

Table 2-5: Comparison of environmental aspect of treatment technologies -- -- -- --  21 

Table 2-6: Comparison of economic aspect of treatment technologies  -- -- --  21 

Table 2-7: Advantages and disadvantages of used oil recycling and reusing methods  -- --   22 

Table 3-1 Typical characteristics of RUBIA TIR 7400 oil-- -- -- -- -- --   32 

Table 3-2: List of major equipment and chemicals -- -- -- -- -- --  33 

Table 3-3: Experimental factors and corresponding levels  -- -- -- -- --   42 

Table 4-1: Used oil sample characterization results  -- -- -- -- --   44 

Table 4-2: Experimental results of acid-clay treatment  -- -- -- -- -- --   45 

Table 4-3: Experimental results at different acid ratios  -- -- -- -- -- --   47 

Table 4-4: Experimental results at different adsorbent ratios  -- -- -- --   49 

Table 4-5: Analysis of variance results summary  -- -- -- -- --  51 

Table 4-6: Optimization solution summary  -- -- -- -- --   52 

Table 4-7: Comparative properties of used oil, recovered oil and fresh oil -- --   53 

Table 4-8: Chemical and energy costs estimation for recycling one liter of usable oil  -- --   55 

Table C-1: Material balance results of the selected optimum experimental run -- -- --  69 

Table C-2: Material balance based on one liter product yield  -- -- -- --  71 

LIST OF FIGURES 

Figure 2-1: Waste oil treatment hierarchy  -- -- -- -- -- --   20 

Figure 2-2: Typical acid-clay treatment process flow diagram  -- -- --   26 

Figure 3-1: Acid treatment setup -- -- -- -- -- -- -- --  38 

Figure 3-2: Product separation set-up  -- -- -- -- -- -- -- --  38 

Figure 3-3: Atmospheric distillation experimental set-up  -- -- -- -- -- --  39 

Figure 3-4: Vacuum distillation experimental set-up -- -- -- -- -- --   39 

Figure 3-5: Clay adsorption set-up -- -- -- -- -- -- -- --   40 

Figure 4-1: Effects of acid concentration  -- -- -- -- -- -- --   48 

Figure 4-2: Effects of adsorbent ratio  -- -- -- -- -- -- -- --  50 

Figure B-1: Normal plot of residuals  -- -- -- -- -- --   67 

Figure B-2: Plot of residuals vs predicted values -- -- -- -- -- -- --  68