Environmental releases of chemical compounds from Pharmaceuticals and Personal Care Products (PPCPs) are receiving growing attention in the scientific community. Most research suggests that the main pathway for these substances to reach the environment is via Wastewater Treatment Plants (WWTPs) due to the effluents from households, industry and hospitals, which can contain substantial amounts of these compounds. Many of these contaminants are poorly treated in conventional WWTPs and are often discharged into the environment with the effluent and sludge, posing ecotoxicological risks to the wildlife and humans. Therefore, it is necessary to limit their release into the environment by controlling their discharge from WWTPs. This can be achieved by adopting advanced wastewater treatment techniques, currently not used as there are no legislative limits on PPCP compounds. However, as the scientific evidence is growing on their adverse impacts, it is only a matter of time before their advanced treatment becomes compulsory. To help guide future developments and inform policy in this area, this work considered a range of advanced treatment techniques with the aim of identifying the most sustainable options. Adopting a life cycle approach and considering all three dimensions of sustainability (economic, environmental and social), nine technologies were assessed on sustainability: four for WWTP effluent and five for sludge treatment. The advanced wastewater treatment methods considered are: (i) granular activated carbon, (ii) nanofiltration, (iii) solar photo-Fenton, and (iv) ozonation. The sludge treatment techniques comprise: (i) anaerobic digestion of sludge for agricultural application; (ii) sludge composting, also for agricultural application; (iii) incineration; (iv) pyrolysis; and (v) wet air oxidation. They were assessed on sustainability using over 28 indicators, some of which were also used to evaluate the implication of different treatment techniques for the energy-water-food (EWF) nexus. Multi-Criteria Decision Analysis (MCDA) was applied to aggregate the sustainability indicators into an overall sustainability index for each alternative and identify the most sustainable option(s). The results suggest that, among the four techniques considered for advanced effluent treatment, nanofiltration and granular activated carbon have the lowest life cycle environmental impacts. Although not preferable at all operating ranges, they have the lowest burdens and are, overall, most sustainable. The latter also has the lowest impact on the EWF nexus at mean operating parameter, and is the preferred option as the treated effluent can be used for potable water due lower concerns over the presence of PPCPs. However, the results also suggest that, from the ecotoxicological point of view, there is little benefit in using any of the advanced wastewater treatment techniques assessed. This is due to the life cycle ecotoxicological impacts from the treatment itself being similar or even higher than for the effluent released into the environment untreated. For sludge treatments, anaerobic digestion and pyrolysis are environmentally and economically preferable techniques. The former is the best with respect to the EWF nexus due to the recovery of energy and agricultural fertilizers. In relation to social aspects, wet air oxidation is amongst the most desirable for high resource recovery, together with the two former techniques. The heavy metals content in the sludge applied on agricultural soils is a major concern for freshwater ecotoxicity potential, posing risks orders of magnitude higher than PPCP compounds.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:728241 |
| Date | January 2017 |
| Creators | Tarpani, Raphael |
| Contributors | Azapagic, Adisa |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/sustainability-assessment-of-wastewater-and-sludge-treatment-techniques-for-removal-of-compounds-from-pharmaceuticals-and-personal-care-products-ppcps(91f7fe09-e0f0-4560-924f-15d5725e0794).html |
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