Production of microalgal concentrates by flocculation and their assessment as aquaculture feeds (original) (raw)

Marine Microalgae: Culture and their Industrial Applications

2018

Microalgae such as Chaetoceros gracilis, C. calcitrans, Chlorella salina, C. marina, Chromulina pleoides, Dunaliella tertiolecta, Isochrysis galbana, Nannochloropsis oculata, Pavlova lutheri, Skeletonema costatum, Tetraselmis chuii, Thalassiosira sp., are microscopic unicellular phytoplankton having size less than 10 μ, and have widely used in the aquaculture industry. The selection of these live feed organisms are based on many factors such as nutritional requirements of the cultured larvae, size of the mouth gape of larvae, development of the digestive tract of the cultured larvae, nutritional value and availability of the live feed and suitability for mass scale production. Though much efforts are been taken world-wide to supplement live feed totally or partially with artificial feeds, various studies pointed out that supply of suitable live feed organisms fortified with vitamins and fats are essential for the successful completion of the larval stages.

ENVIRONMENTAL ASSESSMENT OF THE PROCESS OF FLOCCULATION MICROALGAE CULTURED IN WASTEWATER

In this paper we investigated the global warming potential (PWG), and efficiency of flocculation of iron sulfate coagulants (FeCl3), sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2) and aluminum sulfate (Al2(SO4)3). For analysis of the PWG coagulants software SimaPro 7.3 was used. The results indicated that FeCl3 and Al2(SO4)3 were highly effective for the recovery of microalgal biomass and it showed less PWG respectively 0.25 kgCO2eq/UA and 1.48 kgCO2eq/UA when compared to NaOH coagulants and Ca(OH)2. The results show that it is important to consider both aspects of flocculation efficiency and environmental impacts to identify the best coagulants in industrial scale. However, more studies are needed in order to assess the energy efficiency of the process, coupled with other technologies recovery of microalgal biomass, such as filtration, centrifugation and thermal dehydration, since these are already being used in NPDEAS. Studies with natural coagulant is also needed, since these are produced in a more sustainable way than synthetic organic polymers and have the potential to generate a biomass free of undesirable contaminants.