Sewage sludge is an unavoidable consequence of wastewater treatment (WWT). Increasing legislation has propagated sludge production whilst limiting disposal options. WWT effluent contains many trace contaminants, one group of significant concern being endocrine disrupting chemicals (EDCs). Their removal is becoming a priority. Sludge is a potentially valuable material which offers opportunities for reuse and valorisation. This research has undertaken an in depth and rigorous study of the optimization of sludge carbonization and activation to produce inorganic-carbonaceous adsorbents akin to activated carbon. The resulting sludge based adsorbents (SBAs) have been comprehensively evaluated for their adsorption of EDCs using bisphenol A (BPA). This data has enabled a fundamental analysis of SBA-EDC adsorption processes and the proposal of an adsorption mechanism. SBA production using various European sludge types was undertaken, to produce high performance SBAs based on surface area (SA) and EDC adsorption. Key research findings were: • SBAs can be produced from most types of municipal sludge, except lime added sludge. • Carbonized or carbonized/steam activated SBAs presented low SA (270_m2/g) and BPA adsorption capacity (87 mg/g) when compared to chemically activated SBAs. • K2CO3 was the best chemical reagent in producing high SA up to 1979 m2/g and BPA adsorption of 714 mg/g. • FeCl3 is a very attractive chemical reagent in giving high BPA adsorption and SBA yield of 119_mg/g and 59.3_%, respectively. • Bisphenol A adsorption fitted well with Langmuir, Freundlich and Temkin equations with the best fit depending on the production conditions (temperature, time, activating reagent). • BPA adsorption by SBAs generally depend on SA and pore volume, with surface chemistry also influencing adsorption, especially for chemically activated SBAs. • The SBAs produced from K2CO3 activation outperformed all commercial activated carbons (CACs); the best SBA outperformed the best CAC by nearly 2-fold indicating the significant potential of SBAs as effective adsorbents for WWT effluents.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:676800 |
| Date | January 2015 |
| Creators | Pullket, Suangusa |
| Contributors | Fowler, Geoffrey |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/28571 |
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