The University of Manchester Control of Algae in Fuel Storage Ponds A thesis submitted to The University of Manchester for the degree of Doctor of Engineering in the Faculty of Science and Engineering 2019 Julija Konovalovaite School of Earth and Environmental Sciences 1 Table of Contents Table of Contents ......................................................................................................... 2 List of figures ............................................................................................................ 7 List of tables ............................................................................................................ 12 List of images .......................................................................................................... 13 Abbreviations ......................................................................................................... 15 Abstract ...................................................................................................................... 17 Declaration ................................................................................................................. 19 Copyright statement .................................................................................................. 20 Acknowledgements .................................................................................................... 21 1 Introduction ........................................................................................................ 23 1.1 Project context and relevance to the industry .......................................... 23 1.2 Magnox reactor fuel cycle .......................................................................... 25 1.2.1 Spent Magnox fuel storage .................................................................... 25 1.3 The First Generation Magnox Fuel Storage pond ...................................... 26 1.3.1 History of the pond ................................................................................ 26 1.3.2 Structure and processes ......................................................................... 27 1.3.3 Conditions in the pond ........................................................................... 28 1.3.4 Pond simulant medium .......................................................................... 31 1.4 Studies of microbial diversity in First Generation Magnox Storage Pond . 33 1.5 Cyanobacterium Pseudanabaena catenata ............................................... 34 1.5.1 Cyanobacteria ........................................................................................ 34 1.5.2 Pseudanabaena catenata ...................................................................... 37 1.6 Unwanted algal growth treatment methods ............................................. 39 1.6.1 Nutrient removal .................................................................................... 39 1.6.2 Sonication ............................................................................................... 40 2 1.6.3 Photocatalysts ........................................................................................ 42 1.6.4 Oxidation ................................................................................................ 42 1.6.5 Halogenation .......................................................................................... 44 1.6.6 Coagulation ............................................................................................ 45 1.6.7 Filtration ................................................................................................. 46 1.6.8 Electrochemical methods ....................................................................... 47 1.6.9 Barley Straw ........................................................................................... 48 1.6.10 Biofilm removal .................................................................................. 49 1.6.11 Flushing .............................................................................................. 50 1.6.12 Biocides .............................................................................................. 50 1.6.13 Selection of appropriate methods for bloom control........................ 52 1.7 Rig development ........................................................................................ 55 1.8 Research objectives.................................................................................... 57 2 Algal growth in batch cultures ............................................................................ 58 2.1 Abstract ...................................................................................................... 58 2.2 Literature review ........................................................................................ 58 2.2.1 Cyanobacterial adaptations to micro and macro nutrient availability .. 58 2.2.2 Adaptations to highly alkaline conditions .............................................. 62 2.2.3 Pseudanabaena catenata ...................................................................... 63 2.3 Aims of batch culture experiments ............................................................ 67 2.4 Materials and methods .............................................................................. 68 2.4.1 Algal culture ........................................................................................... 68 2.4.2 Effect of reduced inorganic nutrient concentrations: initial experiments 69 2.4.3 Reduced inorganic nutrients- variation in sodium acetate supplements 69 3 2.4.4 Buffered pH experiments ....................................................................... 70 2.4.5 Progressive reduction in inorganic nutrient concentrations ................. 71 2.5 Results and discussion................................................................................ 73 2.5.1 Impact of nutrient availability ................................................................ 73 2.5.2 Pond water simulation experiment: addition of a carbon source ......... 77 2.5.3 Impact of organic carbon availability at reduced inorganic nutrient concentrations .................................................................................................... 83 2.5.4 Buffered pH experiment ........................................................................ 86 2.5.5 Growth of P. catenata at progressively reduced inorganic nutrient concentrations .................................................................................................... 88 2.6 Conclusions .............................................................................................. 101 3 Continuous culture flushing experiments ........................................................ 102 3.1 Abstract .................................................................................................... 102 3.2 Literature review ...................................................................................... 102 3.3 Aims of continuous culture experiments ................................................. 105 3.4 Materials and methods ............................................................................ 106 3.4.1 Continuous culture experiments ......................................................... 106 3.4.2 Cell counting ......................................................................................... 107 3.4.3 Continuous culture: reduced inorganic nutrients ................................ 108 3.4.4 Total inorganic carbon / Total organic carbon ..................................... 108 3.5 Results and discussion.............................................................................. 110 3.5.1 Continuous culture experiment flushed with BG11 medium .............. 110 3.5.2 Repeated continuous culture experiment ........................................... 116 3.5.3 Low nutrient flushing experiment ....................................................... 120 3.5.4 Repeated low nutrient experiment ..................................................... 127 3.5.5 Growth rate analysis in continuous cultures ....................................... 130 4 3.6 Conclusions .............................................................................................. 133 4 Biocide addition experiments ........................................................................... 134 4.1 Abstract .................................................................................................... 134 4.2 Literature review ...................................................................................... 134 4.3 Aims .......................................................................................................... 136 4.4 Materials and methods ............................................................................ 137 4.4.1 Mexel® 432 experiment ....................................................................... 137 4.4.2 Spectrus ® NX1422 biocide trial ........................................................... 140 4.4.3 Repeated experiment .......................................................................... 143 4.5 Conclusions .............................................................................................. 150 5 Prokaryote species succession.......................................................................... 151 5.1 Abstract .................................................................................................... 151 5.2 Literature review .....................................................................................