Improving wastewater (WW) treatment process is a major issue in different parts of the world. For a developed country like the UK where eutrophication is a problem that causes environmental and economical losses, and for a developing country like Jordan that is considered one of the most water scarce countries in the world, it is crucially important to improve the quality of the WW for safe reuse. Applying microalgae for WW treatment and biomass production is an economical and environmentally friendly method. However, this method has some challenges that need to be addressed, such as microalgae species selection, harvesting of the microalgae and the large area footprint. In this research, the overall aim was to bioprospect for microalgae that are adapted to the wastewater treatment plants (WWTPs) and evaluate the obtained microalgae depending on specific criteria for a successful application in high rate algal ponds (HRAPs), then there were attempts to improve the phosphorus removal in microalgae to increase the efficiency of the treatment process and reduce the area footprint. Bioprospecting for indigenous microalgae to the WW took place from January to May 2014. Water samples were collected from wastewater treatment plants (WWTPs) in the UK and Jordan. Eight different microalgae isolates were identified from each country. The results showed the Chlorella, Scenedesmus and Desmodesmus are common genera between the two countries and dominated the obtained isolates from the UK and Jordan. The isolates were identified using 18S rDNA and ITS1 5.8S ITS2 DNA barcoding markers. It was difficult to identify some of the isolates at the species level, as the 18S rDNA is too conserved to differentiate between the closely related species and due to the relatively poor representation of algae in GenBank. Then the obtained microalgae isolates were evaluated by their growth, efficiency in removing nutrients (i.e. nitrogen and phosphorus) and the settleability of the microalgae by gravity. Depending on the results the microalgae species were ranked to come up with some promising candidates to be applied on large scale. From the UK, Avonmouth_12 (Av_12) and Avonmouth_10 (Av_10) and from Jordan, Jordan_18 (Jo_18) and Jordan_29 (Jo_29) were distinguished in their performance in the WW. Since phosphorus is a major cause of eutrophication in the fresh water and it is important to reduce the level of phosphorus in the released WW to the legally permitted limits, this research aimed to study the possibility of improving phosphorus removal by microalgae. Using Chlamydomonas reinhardtii as a model to optimise the protocol to be applied in parallel with Av_12, which is a promising microalga isolate that has been applied on large scale in HRAPs in Beckington WWTP, the strategy was to overexpress a Phosphorus Starvation Response (PSR1) gene. The transformation process was successful in C. reinhardtii but not in Av_12. There was an enhancement of the specific phosphate removal rate in the transformed microalgae isolate CC 1010_B2 and CC 1010_A6 in comparison to the wild type strain CC 1010.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:760883 |
| Date | January 2017 |
| Creators | Sweiss, Mais Ahed |
| Contributors | Scott, Roderick ; Arnot, Thomas |
| Publisher | University of Bath |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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