The development of waste management legislation in the 1990's has placed great importance on the sustainability of waste disposal/treatment options. Landfill of wastes is increasingly seen as a last resort and reduction, re-use and recovery of wastes is encouraged. The wastes investigated in this study (caustic tar and sewage sludges) are often disposed of by non-sustainable methods. In addition production of sewage sludge will have doubled by 2005 and disposal options are increasingly limited. Alternative treatment options are required for both these waste types that offer re-use potential. In this study the carbonisation and activation of these wastes has been demonstrated to be an effective means of treatment that also produces adsorbents that can be safely and usefully applied to treatment of aqueous waste streams. Previous studies have examined the production of clay-carbon adsorbents from spent bleaching earth and limited studies have been conducted on producing adsorbents from sewage sludges. However, the majority of these have limited investigations to production of oils from sludge and no previous studies of caustic tar carbonisation have been conducted. Treatment of caustic tar involved neutralisation with HCl and absorption of the organic content of the waste by Fullers or Acid Activated Earth. The clay-waste mix was subsequently carbonised (375°C for 2 hours) and activated using an optimised ZnClj activation procedure (600°C for 1 hour). Activated carbons were produced from sewage sludges using carbonisation (500°C for 2 hours), CO^ activation (700°C for I hour) and ZnCl^ activation (450°C for 2 hours and 600°C for 1 hour). The adsorbents produced had well developed porosity and large surface areas (up to 225mVg for caustic tar derived carbons and up to 995mVg for sewage sludge based carbons) and were adsorptive of a range of organic pollutants common in effluents. ZnC^ activated, un-digested sewage sludges proved to be the most effective adsorbents. COj activated sewage sludges and caustic tar derived carbons had similar adsorption capacities for the organic pollutants studied. Leaching tests demonstrated that metals present in the adsorbents other than the ZnClj activated carbons were not readily leachable and would not prevent re-use of the carbons in the treatment of aqueous effluents.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:360709 |
| Date | January 1997 |
| Creators | Gee, Ivan L. |
| Contributors | Perry, Roger ; Sollars, Christopher |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/56249 |
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